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Ariyaratnam JP, Mishima RS, McNamee O, Emami M, Thiyagarajah A, Fitzgerald JL, Gallagher C, Sanders P, Elliott AD. Exercise echocardiography to assess left atrial function in patients with symptomatic AF. IJC HEART & VASCULATURE 2024; 50:101324. [PMID: 38204984 PMCID: PMC10776650 DOI: 10.1016/j.ijcha.2023.101324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 11/30/2023] [Accepted: 12/10/2023] [Indexed: 01/12/2024]
Abstract
Background Left atrial (LA) function contributes to the augmentation of cardiac output during exercise. However, LA response to exercise in patients with atrial fibrillation (AF) is unknown. We explored the LA mechanical response to exercise and the association between LA dysfunction and exercise intolerance. Methods We recruited consecutive patients with symptomatic AF and preserved left ventricular ejection fraction (LVEF). Participants underwent exercise echocardiography and cardiopulmonary exercise testing (CPET). Two-dimensional and speckle-tracking echocardiography were performed to assess LA function at rest and during exercise. Participants were grouped according to presenting rhythm (AF vs sinus rhythm). The relationship between LA function and cardiorespiratory fitness in patients maintaining SR was assessed using linear regression. Results Of 177 consecutive symptomatic AF patients awaiting AF ablation, 105 met inclusion criteria; 31 (29.5 %) presented in AF whilst 74 (70.5 %) presented in SR. Patients in SR augmented LA function from rest to exercise, increasing LA emptying fraction (LAEF) and LA reservoir strain. In contrast, patients in AF demonstrated reduced LAEF and reservoir strain at rest, with failure to augment either parameter during exercise. This was associated with reduced VO2Peak compared to those in SR (18.4 ± 5.6 vs 22.5 ± 7.7 ml/kg/min, p = 0.003). In patients maintaining SR, LAEF and reservoir strain at rest and during exercise were associated with VO2Peak, independent of LV function. Conclusion The maintenance of SR in patients with AF is associated with greater LA reservoir function at rest and greater augmentation with exercise compared to patients in AF. In patients in SR, reduced LA function is associated with reduced exercise tolerance, independent of LV function.
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Affiliation(s)
- Jonathan P. Ariyaratnam
- Centre for Heart Rhythm Disorders, University of Adelaide, South Australian Health & Medical Research Institute and Royal Adelaide Hospital, Adelaide, Australia
| | - Ricardo S. Mishima
- Centre for Heart Rhythm Disorders, University of Adelaide, South Australian Health & Medical Research Institute and Royal Adelaide Hospital, Adelaide, Australia
| | - Olivia McNamee
- Centre for Heart Rhythm Disorders, University of Adelaide, South Australian Health & Medical Research Institute and Royal Adelaide Hospital, Adelaide, Australia
| | - Mehrdad Emami
- Centre for Heart Rhythm Disorders, University of Adelaide, South Australian Health & Medical Research Institute and Royal Adelaide Hospital, Adelaide, Australia
| | - Anand Thiyagarajah
- Centre for Heart Rhythm Disorders, University of Adelaide, South Australian Health & Medical Research Institute and Royal Adelaide Hospital, Adelaide, Australia
| | - John L. Fitzgerald
- Centre for Heart Rhythm Disorders, University of Adelaide, South Australian Health & Medical Research Institute and Royal Adelaide Hospital, Adelaide, Australia
| | - Celine Gallagher
- Centre for Heart Rhythm Disorders, University of Adelaide, South Australian Health & Medical Research Institute and Royal Adelaide Hospital, Adelaide, Australia
| | | | - Adrian D. Elliott
- Corresponding authors at: Centre for Heart Rhythm Disorders, Department of Cardiology, Royal Adelaide Hospital, 1 Port Road, Adelaide, SA 5000, Australia.
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Radu AD, Zlibut A, Scarlatescu A, Cojocaru C, Bogdan S, Scafa-Udriște A, Dorobantu M. Cardiac Resynchronization Therapy and Left Atrial Remodeling: A Novel Insight? Biomedicines 2023; 11:1156. [PMID: 37189774 PMCID: PMC10136256 DOI: 10.3390/biomedicines11041156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/04/2023] [Accepted: 04/08/2023] [Indexed: 05/17/2023] Open
Abstract
Cardiac resynchronization therapy (CRT) restores ventricular dyssynchrony, improving left ventricle (LV) systolic function, symptoms, and outcome in patients with heart failure, systolic dysfunction, and prolonged QRS interval. The left atrium (LA) plays tremendous roles in maintaining cardiac function, being often inflicted in various cardiovascular diseases. LA remodeling implies structural-dilation, functional-altered phasic functions, and strain and electrical-atrial fibrillation remodeling. Until now, several important studies have approached the relationship between LA and CRT. LA volumes can predict responsiveness to CRT, being also associated with improved outcome in these patients. LA function and strain parameters have been shown to improve after CRT, especially in those who were positive responders to it. Further studies still need to be conducted to comprehensively characterize the impact of CRT on LA phasic function and strain, and, also, in conjunction with its impact on functional mitral regurgitation and LV diastolic dysfunction. The aim of this review was to provide an overview of current available data regarding the relation between CRT and LA remodeling.
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Affiliation(s)
- Andrei Dan Radu
- Cardiology Department, Emergency Clinical Hospital of Bucharest, 014461 Bucharest, Romania
- Faculty of Medicine, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania
| | - Alexandru Zlibut
- Cardiology Department, Emergency Clinical Hospital of Bucharest, 014461 Bucharest, Romania
- Department of Internal Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania
| | - Alina Scarlatescu
- Cardiology Department, Emergency Clinical Hospital of Bucharest, 014461 Bucharest, Romania
- Faculty of Medicine, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania
| | - Cosmin Cojocaru
- Cardiology Department, Emergency Clinical Hospital of Bucharest, 014461 Bucharest, Romania
- Faculty of Medicine, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania
| | - Stefan Bogdan
- Faculty of Medicine, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania
- Cardiology Department, Elias University Emergency Hospital, 011461 Bucharest, Romania
| | - Alexandru Scafa-Udriște
- Cardiology Department, Emergency Clinical Hospital of Bucharest, 014461 Bucharest, Romania
- Faculty of Medicine, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania
| | - Maria Dorobantu
- Cardiology Department, Emergency Clinical Hospital of Bucharest, 014461 Bucharest, Romania
- Faculty of Medicine, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania
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Left atrial strain evaluation to assess left ventricle diastolic dysfunction and heart failure with preserved ejection fraction: a guide to clinical practice : Left atrial strain and diastolic function. THE INTERNATIONAL JOURNAL OF CARDIOVASCULAR IMAGING 2023; 39:1083-1096. [PMID: 36826616 DOI: 10.1007/s10554-023-02816-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Accepted: 02/11/2023] [Indexed: 02/25/2023]
Abstract
Although frequently unrecognized, left atrium (LA) function plays a key role in global cardiac performance as it modulates left ventricle (LV) filling through three main functions: the LA reservoir, conduit and booster pump. Given the interdependence between the LA and the LV, it is known that LA dimension and/or LA function can be used as a surrogate for LV diastolic function.Recently, LA deformation analysis using 2-dimensional (2D) speckle tracking echocardiography (STE) strain emerged as a promising non-invasive technique that can help to estimate LV filling pressures (LVFP) and diagnose heart failure with preserved ejection fraction (HFpEF), as recently proposed in the recent 2022 European Association of Cardiovascular Imaging (EACVI) consensus which included LA reservoir strain as an additive parameter to estimate LVFP.This article aims to review the latest evidence regarding the role of LA strain in the assessment and management of LV diastolic dysfunction (LVDD) and HFpEF, providing a clinical guide with tips and tricks to use LA strain as a new technique to help to estimate LVFP.
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Fukuhara E, Mine T, Kishima H, Kitagaki R, Ishihara M. Increase in Heart Rate-dependent Left Atrial Pressure is Associated with Symptoms in Patients with Paroxysmal Atrial Fibrillation: Conclusion. J Cardiovasc Electrophysiol 2022; 33:855-863. [PMID: 35170138 DOI: 10.1111/jce.15411] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 01/20/2022] [Accepted: 01/24/2022] [Indexed: 11/27/2022]
Abstract
BACKGROUND It remains unclear why some patients with the same heart rate (HR) during an atrial fibrillation (AF) have subjective symptoms, whereas others do not. We assessed the hypothesis that different responses of arterial and left atrial blood pressures to rapid stimulation may be associated with the symptoms of AF. METHODS A total of 110 patients who underwent catheter ablation for paroxysmal AF were retrospectively studied. Asymptomatic AF was defined as a European Heart Rhythm Association (EHRA) score of Ⅰ for AF-related symptoms. The left atrial pressure (LAP) was measured during sinus rhythm (SR), in 10 pacing per minute (ppm) increments from 100 ppm to the Wenckebach block rate in high right atrial pacing. RESULTS Asymptomatic AF was observed in 19/110 patients (17%). Patients with symptomatic AF showed higher E/e' ratio and gradual LAP increase that was dependent on the pacing rate. Patients with asymptomatic AF had decreased LAP at 100 ppm compared that at SR, and thereafter, LAP gradually increased depending on the pacing rate. The rate of LAP change compared to that at SR was significantly lower in patients with asymptomatic AF than that in patients with symptomatic AF. The rate of LAP change was independently associated with AF symptoms. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Eiji Fukuhara
- Department of Cardiovascular and Renal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Takanao Mine
- Department of Cardiovascular and Renal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Hideyuki Kishima
- Department of Cardiovascular and Renal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Ryo Kitagaki
- Department of Cardiovascular and Renal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Masaharu Ishihara
- Department of Cardiovascular and Renal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
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Jain V, Ghosh R, Gupta M, Saijo Y, Bansal A, Farwati M, Marcus R, Klein A, Xu B. Contemporary narrative review on left atrial strain mechanics in echocardiography: cardiomyopathy, valvular heart disease and beyond. Cardiovasc Diagn Ther 2021; 11:924-938. [PMID: 34295714 DOI: 10.21037/cdt-20-461] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 08/19/2020] [Indexed: 12/14/2022]
Abstract
Left atrial (LA) strain mechanics refer to the measurement of LA myocardial deformation expressed as a percentage, and have been gathering interest over the last decade with expanding research supporting their utility in multiple cardiovascular disorders. Measured through advanced dynamic imaging techniques which include tissue Doppler imaging (TDI) and two-dimensional (2D) speckle tracking echocardiography (STE), LA strain mechanics are affected by left ventricular diastolic dysfunction prior to the onset of functional and structural changes in the left ventricle (LV). There is a need for practising cardiologists to become more familiar with the clinical utility of LA strain mechanics. In this article, we begin by reviewing the physiologic function of the LA, using this as a basis for understanding LA strain mechanics. The focus of this review article is to provide a contemporary update on the utility of LA strain mechanics in a range of cardiovascular disorders, including atrial fibrillation (AF), hypertrophic cardiomyopathy (HCM), valvular pathologies, coronary artery disease (CAD) as well as systemic diseases, such as hypertension (HTN), obesity and diabetes mellitus (DM). This article also highlights the current limitations in more widespread clinical applications of LA strain mechanics, as well as outlining the future perspectives on the clinical applications of LA strain mechanics.
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Affiliation(s)
- Vardhmaan Jain
- Department of Internal Medicine, Cleveland Clinic, Cleveland, OH, USA
| | - Raktim Ghosh
- MedStar Heart and Vascular Institute at MedStar Union Memorial Hospital and MedStar Good Samaritan Hospital, Baltimore, MD, USA
| | - Manasvi Gupta
- Department of Internal Medicine, UConn Health, University of Connecticut, Farmington, CT, USA
| | - Yoshihito Saijo
- Section of Cardiovascular Imaging, Robert and Suzanne Tomsich, Department of Cardiovascular Medicine, Sydell and Arnold Miller Family Heart, Vascular and Thoracic Institute, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Agam Bansal
- Department of Internal Medicine, Cleveland Clinic, Cleveland, OH, USA
| | - Medhat Farwati
- Department of Internal Medicine, Cleveland Clinic, Cleveland, OH, USA
| | - Rachel Marcus
- MedStar Heart and Vascular Institute at MedStar Union Memorial Hospital and MedStar Good Samaritan Hospital, Baltimore, MD, USA
| | - Allan Klein
- Section of Cardiovascular Imaging, Robert and Suzanne Tomsich, Department of Cardiovascular Medicine, Sydell and Arnold Miller Family Heart, Vascular and Thoracic Institute, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Bo Xu
- Section of Cardiovascular Imaging, Robert and Suzanne Tomsich, Department of Cardiovascular Medicine, Sydell and Arnold Miller Family Heart, Vascular and Thoracic Institute, Cleveland Clinic Foundation, Cleveland, OH, USA
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Alpha and beta myosin isoforms and human atrial and ventricular contraction. Cell Mol Life Sci 2021; 78:7309-7337. [PMID: 34704115 PMCID: PMC8629898 DOI: 10.1007/s00018-021-03971-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 10/03/2021] [Accepted: 10/08/2021] [Indexed: 01/15/2023]
Abstract
Human atrial and ventricular contractions have distinct mechanical characteristics including speed of contraction, volume of blood delivered and the range of pressure generated. Notably, the ventricle expresses predominantly β-cardiac myosin while the atrium expresses mostly the α-isoform. In recent years exploration of the properties of pure α- & β-myosin isoforms have been possible in solution, in isolated myocytes and myofibrils. This allows us to consider the extent to which the atrial vs ventricular mechanical characteristics are defined by the myosin isoform expressed, and how the isoform properties are matched to their physiological roles. To do this we Outline the essential feature of atrial and ventricular contraction; Explore the molecular structural and functional characteristics of the two myosin isoforms; Describe the contractile behaviour of myocytes and myofibrils expressing a single myosin isoform; Finally we outline the outstanding problems in defining the differences between the atria and ventricles. This allowed us consider what features of contraction can and cannot be ascribed to the myosin isoforms present in the atria and ventricles.
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Dermlim A, Osuga T, Nakamura K, Morita T, Nisa K, Sasaoka K, Leela-Arporn R, Nagata N, Tamura M, Sasaki N, Ohta H, Takiguchi M. Effect of acute volume loading on left atrial strain values derived from two-dimensional speckle tracking echocardiography in dogs. J Vet Med Sci 2019; 81:949-957. [PMID: 31092763 PMCID: PMC6656807 DOI: 10.1292/jvms.19-0012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose of this study was to evaluate the cardiac acute volume loading effect on left atrial (LA) strain and strain rate (SR) parameters derived from two-dimensional speckle tracking
echocardiography (2D-STE) in healthy dogs. Six healthy beagles were anesthetized and subjected to increase cardiac preload by intravenous infusion with lactated Ringer solution at 150
ml/kg/hr for 90 min. A Swan-Ganz catheter was placed to directly measure the mean pulmonary capillary wedge pressure (PCWP). Echocardiography was performed before
(baseline) and at 15, 30, 45, 60, 75, and 90 min after acute volume loading began. Apical 4-chamber images focused on the LA were digitally recorded for later strain and SR analysis via
2D-STE. Acute volume loading significantly increased from baseline during LA strain and SR as assessed by the speckle tracking–based technique during reservoir and conduit function at 15 to
90 min after volume load began, and strain indices representing booster pump function were enhanced at 45 to 90 min. In addition, acute volume loading resulted in a significantly greater
PCWP after fluid infusion. On multiple regression analysis, quadratic regression analysis was a better fit for the relationship between PCWP and all LA functional indices. Our findings
indicated that LA function analyzed by strain and SR was enhanced during cardiac acute volume loading in healthy dogs. The change in strain and SR during acute volume loading should be
interpreted with caution during the diagnosis of heart diseases related to volume overload.
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Affiliation(s)
- Angkhana Dermlim
- Laboratory of Veterinary Internal Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 006-0818, Japan
| | - Tatsuyuki Osuga
- Laboratory of Veterinary Internal Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 006-0818, Japan
| | - Kensuke Nakamura
- Laboratory of Internal Medicine, Organization for Promotion of Tenure Track, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Tomoya Morita
- Laboratory of Veterinary Internal Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 006-0818, Japan
| | - Khoirun Nisa
- Laboratory of Veterinary Internal Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 006-0818, Japan
| | - Kazuyoshi Sasaoka
- Laboratory of Veterinary Internal Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 006-0818, Japan
| | - Rommaneeya Leela-Arporn
- Laboratory of Veterinary Internal Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 006-0818, Japan
| | - Noriyuki Nagata
- Laboratory of Veterinary Internal Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 006-0818, Japan
| | - Masahiro Tamura
- Laboratory of Veterinary Internal Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 006-0818, Japan
| | - Noboru Sasaki
- Laboratory of Veterinary Internal Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 006-0818, Japan
| | - Hiroshi Ohta
- Laboratory of Veterinary Internal Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 006-0818, Japan
| | - Mitsuyoshi Takiguchi
- Laboratory of Veterinary Internal Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 006-0818, Japan
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Benussi S, de Maat GE. Atrial remodelling and function: implications for atrial fibrillation surgery. Eur J Cardiothorac Surg 2019; 53:i2-i8. [PMID: 29590384 DOI: 10.1093/ejcts/ezx340] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Accepted: 08/11/2017] [Indexed: 12/15/2022] Open
Abstract
The exact mechanism of atrial fibrillation (AF) is still incompletely understood. A number of alterations that impact focal electrical discharge, the atrial substrate and modulating factors contribute to its pathogenesis. Atrial remodelling (resulting in atrial cardiomyopathy) sets the stage for AF development. Once present, AF results in the loss of synchronized atrial contraction, which affects ventricular filling and atrial reservoir and conduit functions. Passive atrial function is particularly important in patients with left ventricular diastolic dysfunction. AF can cause tachycardiomyopathy, a mostly reversible cardiac alteration induced by tachycardia. At a structural level, atrial support is also instrumental to the function of atrioventricular valves. All of these functions can be recovered to variable degrees via rhythm control strategies. Surgical and hybrid ablation show very promising results, especially in patients with a more advanced disease substrate. This review highlights the pathophysiological aspects of AF related to left atrial function and their practical implications for surgical rhythm management.
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Affiliation(s)
- Stefano Benussi
- Division of Cardiac Surgery, University Hospital Zurich, Zurich, Switzerland
| | - Gijs E de Maat
- Department of Cardiothoracic Surgery, University Medical Centre Groningen, Groningen, Netherlands
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Buhl R, Carstensen H, Hesselkilde EZ, Klein BZ, Hougaard KM, Ravn KB, Loft-Andersen AV, Fenner MF, Pipper C, Jespersen T. Effect of induced chronic atrial fibrillation on exercise performance in Standardbred trotters. J Vet Intern Med 2018; 32:1410-1419. [PMID: 29749082 PMCID: PMC6060327 DOI: 10.1111/jvim.15137] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 03/14/2018] [Accepted: 03/27/2018] [Indexed: 11/29/2022] Open
Abstract
Background Atrial fibrillation (AF) is the most common arrhythmia affecting performance in horses. However, no previous studies have quantified the performance reduction in horses suffering from AF. Objectives To quantify the effect of AF on maximum velocity (Vmax), maximum heart rate (HRmax), heart rate recovery (T100), hematologic parameters and development of abnormal QRS complexes. Animals Nine Standardbred trotters. Methods Two‐arm controlled trial. Six horses had AF induced by means of a pacemaker and 3 served as sham‐operated controls. All horses were subjected to an exercise test to fatigue before (SET1) and after (SET2) 2 months of AF or sham. The Vmax and HRmax were assessed using a linear mixed normal model. Abnormal QRS complexes were counted manually on surface ECGs. Results Atrial fibrillation resulted in a 1.56 m/sec decrease in Vmax (P < .0001). In the AF group, HRmax ± SD increased from 226 ± 11 bpm at SET1 to 311 ± 27 bpm at SET 2. The AF group had higher HRmax at SET2 compared with controls (P < .0001), whereas no difference between the control and AF groups was observed at SET1 (P = .96). Several episodes of wide complex tachycardia were observed during exercise in 3 of the AF horses during SET2. Conclusions and Clinical Importance Atrial fibrillation resulted in a significant reduction in performance, an increase in HR and development of abnormal QRS complexes during exercise, which may be a risk factor for collapse or sudden cardiac death.
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Affiliation(s)
- Rikke Buhl
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | - Helena Carstensen
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | - Eva Zander Hesselkilde
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | - Bjørg Zinkernagel Klein
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | - Karen Margrethe Hougaard
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | - Kirsten Bomberg Ravn
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | | | - Merle Friederike Fenner
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | - Christian Pipper
- Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Jespersen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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Abstract
BACKGROUND This study evaluated the early postoperative benefits of laparoscopic sleeve gastrectomy (LSG) on the left ventricular (LV) function and left atrial (LA) structural, mechanical, and electrical functions in severely obese patients. METHODS Thirty-two patients with severe obesity who were consecutively scheduled for LSG and 30 healthy controls were included in the study. LV global longitudinal strain (LGS), peak atrial longitudinal strain (PALS), and strain rates (S-Sr, E-Sr, and A-Sr) of the lateral and septal LA walls, and intra- and interatrial dyssynchrony periods for all subjects were evaluated using strain echocardiography. The measurements were repeated in patients 1 month after surgery. RESULTS LGS of the LV was significantly depressed in the patient group compared with the control group (p < 0.001). LA peak septal and lateral wall strain values were significantly lower in patients than in controls (both p values <0.001). LA intra- and interatrial dyssynchrony periods were longer in patients than in controls (p = 0.012 and p = 0.004, respectively). LGS significantly improved after LSG (p < 0.001). Significant reductions were noted in the LA antero-posterior diameter (p < 0.001), LA volume index (LAVI, p = 0.001), and in the mitral velocity to the early diastolic velocity of the mitral annulus ratio (E/e' ratio, p = 0.046). The PALS of the septal and lateral LA walls significantly increased (p = 0.001 and p < 0.001, respectively). S-Sr, E-Sr, and A-Sr values of the septal LA wall (p = 0.049, p < 0.001, and p = 0.001, respectively) and the lateral LA wall (p = 0.009, p = 0.007, and p = 0.002, respectively) significantly improved postoperatively. Intra- and interatrial dyssynchrony significantly decreased (p = 0.001 and p < 0.001, respectively). Weight loss positively correlated with changes in LGS (R = 0.39, p = 0.039), LAVI (R = 0.39, p = 0.034), intra-atrial dyssynchrony (R = 0.45, p = 0.021), interatrial dyssynchrony (R = 0.42, p = 0.038), septal LA wall peak strain (R = 0.44, p = 0.027), lateral LA wall peak strain (R = 0.46, p = 0.017), septal LA wall A-Sr (R = 0.43, p = 0.028), and lateral LA wall A-Sr (R = 0.46, p = 0.019). The comparison of postoperative findings of the patients with controls revealed that the LA diameter, both LA volume and volume index (LAVI), E/e' ratio, S-Sr and E-Sr of both lateral and septal LA walls, intra- and interatrial LA dyssynchrony of the patient group became similar to the control group (all p value >0.05). Postoperative A-Sr values of both LA walls (both p value <0.001) were higher in patients than controls. CONCLUSION The benefits of LSG on LV and LA function may be observed even in the early postoperative phase. The resulting weight loss correlates with LV and LA reverse remodeling in severely obese patients.
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Inoue K, Asanuma T, Masuda K, Sakurai D, Higaki J, Nakatani S. Compensatory increase of left atrial external work to left ventricular dysfunction caused by afterload increase. Am J Physiol Heart Circ Physiol 2015; 308:H904-12. [DOI: 10.1152/ajpheart.00530.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 01/29/2015] [Indexed: 11/22/2022]
Abstract
Afterload mismatch can cause acute decompensation leading to an occurrence of acute heart failure. We investigated how the left atrium (LA) and left ventricle (LV) react to acute increases in afterload using speckle tracking echocardiography (STE). LA strain and volume were obtained by STE in 10 dogs during banding of descending aorta (AoB). Simultaneously, LA pressure was measured by a micromanometer-tipped catheter. LA peak negative strain during LA contraction, strain change during LA relaxation (early reservoir strain), and that during LA dilatation (late reservoir strain) were obtained from LA longitudinal strain-volume curves. From pressure-strain curves, the areas of A-loop and V-loops were computed as the work during active contraction and relaxation (A-work) and that during passive filling and emptying (V-work). AoB increased LV systolic pressure (105 ± 15 vs. 163 ± 12 mmHg, P < 0.01) and mean LA pressure (3.8 ± 1.2 vs. 7.1 ± 2.0 mmHg, P < 0.01). LV global circumferential strain decreased (−18.8 ± 3.5 vs. −13.2 ± 3.5%, P < 0.01), but LV stroke volume was maintained (8.4 ± 2.3 vs. 9.6 ± 3.6 ml). LA peak negative strain (−2.9 ± 2.3 vs. −9.8 ± 4.0%, P < 0.01) and early reservoir strain (4.5 ± 2.1 vs. 7.7 ± 2.4%, P < 0.05) increased by AoB, but late reservoir strain did not change (8.9 ± 3.4 vs. 6.1 ± 3.4%). A-work significantly increased (3.2 ± 2.0 vs. 19.2 ± 15.1 mmHg %, P < 0.01), whereas V-work did not change (13.3 ± 7.1 vs. 13.1 ± 7.7 mmHg %). In conclusion, LA external work during active contraction and relaxation increased as compensation for LV dysfunction during aortic banding. Atrial dysfunction may lead failure of this mechanism and hemodynamic decompensation.
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Affiliation(s)
- Katsuji Inoue
- Department of Cardiology, Pulmonology, Hypertension and Nephrology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan; and
| | - Toshihiko Asanuma
- Division of Functional Diagnostics, Department of Health Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Kasumi Masuda
- Division of Functional Diagnostics, Department of Health Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Daisuke Sakurai
- Division of Functional Diagnostics, Department of Health Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Jitsuo Higaki
- Department of Cardiology, Pulmonology, Hypertension and Nephrology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan; and
| | - Satoshi Nakatani
- Division of Functional Diagnostics, Department of Health Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
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Bois JP, Lin G, Brady PA, Ammash NM. Development of left atrial thrombus and subsequent cardioembolic stroke in a 21-year-old man with ebstein anomaly who previously underwent pulmonary vein isolation ablation and Cox maze III procedure: significance of left atrial mechanical function. Circulation 2015; 131:1110-8. [PMID: 25802257 DOI: 10.1161/circulationaha.115.015340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- John P Bois
- From Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, MN
| | - Grace Lin
- From Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, MN
| | - Peter A Brady
- From Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, MN
| | - Naser M Ammash
- From Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, MN.
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Lai HC, Chien WC, Chung CH, Lee WL, Wang KY, Liu CN, Liu TJ. Atrial fibrillation increases medical cost and complicates hospital outcome of traffic accident-related physical trauma--a nationwide population-based study. Int J Cardiol 2014; 177:964-9. [PMID: 25449508 DOI: 10.1016/j.ijcard.2014.09.190] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 09/01/2014] [Accepted: 09/28/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND Traffic accidents account substantially for premature disability and deaths in the modern world. Whether atrial fibrillation complicates the outcome of traffic injury remains under-investigated. METHODS From 1998 to 2010, all inpatient records stored in the Taiwan National Health Insurance database were screened. Those related with traffic accidents were aggregated to individuals and enrolled. The medical expenses and hospital outcomes were compared between patients with atrial fibrillation (AF group) and either the rest patients (No-AF group) or the propensity-matched patients without atrial fibrillation (No-AF-matched group). Prognostic predictive variables for adverse in-hospital events were further identified by multivariate regression analysis. RESULTS Within the 13-year time span, of the 776,620 individuals ever admitted for traffic accidents, there were 1233 patients with AF. Compared with No-AF and No-AF-matched groups respectively, AF patients stayed longer in hospital (10.9 ± 10.6 vs. 6.8 ± 7.2 and vs. 8.2 ± 8.7 days, both p < 0.001), more often required surgical operations (73.2% vs. 69.5%, p = 0.006 and vs. 68.9%, p = 0.021), and consumed larger medical expenses (US$ 2384 ± 3174 vs. 1246 ± 2024, or 91.3% higher; and vs. 1406 ± 2172, or 69.6% higher, both p < 0.001), yet developed more postoperative complications (8.8% vs. 1.2% and vs. 3.2%, both p<0.001) and deaths (2.5% vs. 0.9%, p < 0.001 and vs. 1.6%, p = 0.015). Identified by regression analysis, CHA2DS2-VASC score and representative demographic/injury-related variables predict in-hospital adverse events in these AF group patients. CONCLUSIONS For patients suffering traffic accidents, those with AF consume more surgical resources and medical expenses yet end up with poorer hospital outcome, especially those with higher CHA2DS2-VASC scores and other relevant variables.
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Affiliation(s)
- Hui-Chin Lai
- Department of Anesthesiology, Taichung Veterans General Hospital, Taichung, Taiwan; Department of Critical Care, Taichung Veterans General Hospital, Taichung, Taiwan; Department of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan; Department of Surgery, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Wu-Chien Chien
- Graduate School of Public Health, National Defense Medical Center, Taipei, Taiwan
| | - Chi-Hsiang Chung
- Taiwanese Injury Prevention and Safety Promotion Association, Taipei, Taiwan
| | - Wen-Lieng Lee
- Department of Anesthesiology, Taichung Veterans General Hospital, Taichung, Taiwan; Department of Critical Care, Taichung Veterans General Hospital, Taichung, Taiwan; Department of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan; Department of Surgery, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Kuo-Yang Wang
- Department of Anesthesiology, Taichung Veterans General Hospital, Taichung, Taiwan; Department of Medicine, Chung-Shan Medical University School of Medicine, Taichung, Taiwan
| | | | - Tsun-Jui Liu
- Department of Anesthesiology, Taichung Veterans General Hospital, Taichung, Taiwan; Department of Critical Care, Taichung Veterans General Hospital, Taichung, Taiwan; Department of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan; Department of Surgery, National Yang-Ming University School of Medicine, Taipei, Taiwan.
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Mehrzad R, Rajab M, Spodick DH. The three integrated phases of left atrial macrophysiology and their interactions. Int J Mol Sci 2014; 15:15146-60. [PMID: 25167138 PMCID: PMC4200839 DOI: 10.3390/ijms150915146] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 08/17/2014] [Accepted: 08/21/2014] [Indexed: 11/24/2022] Open
Abstract
Our understanding of the left atrium is growing, although there are many aspects that are still poorly understood. The left atrium size as an imaging biomarker has been consistently shown to be a powerful predictor of outcomes and of different cardiovascular disorders, such as, but not limited to, atrial fibrillation, congestive heart failure, mitral regurgitation and stroke. Left atrial function has been conventionally divided into three integrated phases: reservoir, conduit and booster-pump. The highly dynamic left atrium and its response to the stretch and secretion of atrial neuropeptides leaves the left atrium far from being a simple transport chamber. The aim of this review is to provide an understanding of the left atrial physiology and its relation to disorders within the heart.
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Affiliation(s)
- Raman Mehrzad
- Department of Medicine, Steward Carney Hospital, Tufts University School of Medicine, 2100 Dorchester Avenue, Boston, MA 02124, USA.
| | - Mohammad Rajab
- Department of Medicine, Division of Cardiology, Virginia Commonwealth University Medical Center, Richmond, VA 23298, USA.
| | - David H Spodick
- Department of Medicine, Division of Cardiology, St. Vincent Hospital, University of Massachusetts Medical School, Worcester, MA 02124, USA.
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15
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Multimodality imaging for patient evaluation and guidance of catheter ablation for atrial fibrillation — Current status and future perspective. Int J Cardiol 2014; 175:400-8. [DOI: 10.1016/j.ijcard.2014.06.047] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 05/12/2014] [Accepted: 06/24/2014] [Indexed: 11/17/2022]
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Freiermuth D, Skarvan K, Filipovic M, Seeberger M, Bolliger D. Volatile anaesthetics and positive pressure ventilation reduce left atrial performance: a transthoracic echocardiographic study in young healthy adults. Br J Anaesth 2014; 112:1032-41. [DOI: 10.1093/bja/aet583] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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17
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Rubaj A, Rucinski P, Kutarski A, Dabrowska-Kugacka A, Oleszczak K, Zimon B, Trojnar M, Zapolski T, Drozd J, Tarkowski A, Wysokinski A. Cardiac hemodynamics and proinflammatory cytokines during biatrial and right atrial appendage pacing in patients with interatrial block. J Interv Card Electrophysiol 2013; 37:147-54. [PMID: 23625090 PMCID: PMC3698432 DOI: 10.1007/s10840-013-9792-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 02/12/2013] [Indexed: 11/10/2022]
Abstract
Purpose Interatrial block (IAB) frequently coexists with sinus node disease and is considered a risk factor of left atrial dysfunction, atrial arrhythmias, and heart failure development. Conventional right atrial appendage (RAA) pacing impairs intra- and interatrial conductions and consequently prolongs P wave duration. Biatrial (BiA) pacing helps correct IAB, but its advantageous influence remains controversial. The aim of the study was to compare the effects of BiA and RAA pacing on cardiac hemodynamics and serum concentrations of inflammatory markers and neuropeptides. Methods Twenty-eight patients with IAB and preserved atrio-ventricular conduction treated with BiA pacing were studied. Standard invasive hemodynamic measurements were performed during BiA and RAA pacings. Furthermore, the influence of 1 week of BiA and RAA pacing on neuropeptides: atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) and markers of inflammation: high sensitivity C-reactive protein (hs-CRP), interleukin 6 (IL-6), and neopterin was examined. Results BiA pacing resulted in significant increase of cardiac output (CO) and reduction of pulmonary capillary wedge pressure. We demonstrated significantly lower concentrations of ANP, hs-CRP, IL-6, and neopterin after 1 week of BiA in comparison to RAA pacing. BNP levels remained unchanged. Conclusions BiA pacing in comparison to RAA pacing improves hemodynamic performance in patients with IAB and preserved atrio-ventricular conduction. BiA pacing is associated with reduction of ANP and markers of inflammation (hs-CRP, IL-6, and neopterin).
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Affiliation(s)
- Andrzej Rubaj
- Department of Cardiology, Medical University of Lublin, 8 Jaczewskiego Str, Lublin, Poland
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Weimar T, Watanabe Y, Kazui T, Lee US, Moon MR, Schuessler RB, Damiano RJ. Differential impact of short periods of rapid atrial pacing on left and right atrial mechanical function. Am J Physiol Heart Circ Physiol 2012; 302:H2583-91. [PMID: 22505644 DOI: 10.1152/ajpheart.01170.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Current techniques to describe atrial function are limited by their load dependency and hence do not accurately reflect intrinsic mechanical properties. To assess the impact of atrial fibrillation on atrial function, combined pressure-volume relationships (PVR) measured by conductance catheters were used to evaluate the right (RA) and left (LA) atrium in 12 isoflurane-anesthetized pigs. Biatrial PVR were recorded over a wide range of volumes during transient caval occlusion at baseline sinus rhythm (SR), after onset of rapid atrial pacing (RAP), after 1 h of RAP, after conversion to SR, and after 1 h of recovery. Cardiac output decreased by 16% (P = 0.008) with onset of RAP. Mean LA and RA pressures increased by 21 and 40% (P < 0.001), respectively, and remained elevated during the entire recovery period. RA reservoir function increased from 51 to 58% and significantly dropped to 43% after resumption of SR (P = 0.017). Immediately after RAP, a right shift of LA end-systolic PVR-intercept for end-systolic volume required to generate an atrial end-systolic pressure of 10 mmHg (24.4 ± 4.9 to 28.1 ± 5.2 ml, P = 0.005) indicated impaired contractility compared with baseline. Active LA emptying fraction dropped from 17.6 ± 7.5 to 11.7 ± 3.7% (P < 0.001), LA stroke volume and ΔP/Δt(max)/P declined by 22% (P = 0.038 and 0.026, respectively), while there was only a trend to impaired RA systolic function. Stiffness quantified by the ratio of pressure to volume at end-diastole was increased immediately after RAP only in the RA (P = 0.020), but end-diastolic PVR shifted rightward in both atria (P = 0.011 LA, P = 0.045 RA). These data suggest that even short periods of RAP have a differential impact on RA and LA function, which was sustained for 1 h after conversion to SR.
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Affiliation(s)
- Timo Weimar
- Division of Cardiothoracic Surgery, Washington University School of Medicine, Barnes-Jewish Hospital, St. Louis, Missouri 63110, USA
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Echocardiography signs of early cardiac impairment in patients with breast cancer and trastuzumab therapy. Clin Res Cardiol 2012; 101:415-26. [PMID: 22249492 DOI: 10.1007/s00392-011-0406-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 12/23/2011] [Indexed: 01/05/2023]
Abstract
OBJECTIVE Recent studies in breast cancer patients and Trastuzumab therapy (Herceptin) showed a development of a toxic cardiomyopathy as a severe complication. The aim of this study was to discover early changes in cardiac function and morphology. METHODS We studied 42 female patients with Her-2/-neu over-expression in breast cancer by echocardiography before, 3, and 6 months after start of the adjuvant Herceptin therapy. All values were mean value ± standard deviation. RESULTS After 3 or 6 months of a trastuzumab therapy we discovered significant increases in the diastolic and systolic left ventricle volume indices (LV-DVI 32.4 ± 8.5 vs. 38.5 ± 8.7 vs. 40.3 ± 10.3 ml/m², p < 0.001 and LV-SVI 12.6 ± 4.0 vs. 15.7 ± 4.7 vs. 17.2 ± 6.8 ml/m², p < 0.001), an increase of the end-diastolic and end-systolic LV diameter (LVEDD 46.8 ± 4.2 vs. 48.0 ± 4.7 vs. 49.7 ± 4.5 ml/m², p < 0.01; LVESD 28.3 ± 4.2 vs. 31.0 ± 4.7 vs. 32.3 ± 4.9 mm, p < 0.001), a reduced systolic ventricle function determined by the tissue Doppler imaging (TDI) velocity (9.2 ± 2.5 vs. 8.0 ± 1,7 vs. 7.7 ± 1.5 cm/s, p < 0.001), fractional shortening (39,6 ± 7.5 vs. 35.4 ± 7.4 vs. 35.2 ± 7.0%, p < 0.01), and the LV-EF Simpson biplane [62.0 ± 5.1 vs. 60.1 ± 6.3 (p = ns) vs. 58.4 ± 7.9%, p < 0.01] compared to pretreatment values. There was also an increase of the left atrial volume index (21.4 ± 6.2 vs. 26.2 ± 7.9 vs. 29.7 ± 8.8 ml/m², p < 0.001), a decrease of the median TDI atrial velocities (11.9 ± 2.4 vs. 10.5 ± 2.8 vs. 10.1 ± 2.1 cm/s, p < 0.01), an increase of the peak early diastolic filling velocities (73.1 ± 15.4 vs. 83.1 ± 16.4 vs. 82.2 ± 19.4 cm/s, p < 0.05), and an increase of the median mitral valve insufficiency degree (0.64 ± 0.65 vs. 1.03 ± 0.76 vs. 1.11 ± 0.73°, p < 0.001). We could not detect a significant increase in diastolic dysfunction. Also right heart diameters and function did not change significantly. Most patients stayed in an asymptomatic stage of cardiac disease. CONCLUSION The blockade of Her2/-neu receptors with trastuzumab in patients with breast cancer led to measurable alterations of left ventricular volume, left atrial volume, and systolic function as early as 3 months after start of treatment.
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Kaminski M, Steel K, Jerosch-Herold M, Khin M, Tsang S, Hauser T, Kwong RY. Strong cardiovascular prognostic implication of quantitative left atrial contractile function assessed by cardiac magnetic resonance imaging in patients with chronic hypertension. J Cardiovasc Magn Reson 2011; 13:42. [PMID: 21843343 PMCID: PMC3195715 DOI: 10.1186/1532-429x-13-42] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 08/15/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Progressive left ventricular (LV) diastolic dysfunction due to hypertension (HTN) alters left atrial (LA) contractile function in a predictable manner. While increased LA size is a marker of LV diastolic dysfunction and has been shown to be predictive of adverse cardiovascular outcomes, the prognostic significance of altered LA contractile function is unknown. METHODS A consecutive group of patients with chronic hypertension but without significant valvular disease or prior MI underwent clinically-indicated CMR for assessment of left ventricular (LV) function, myocardial ischemia, or viability. Calculation of LA volumes used in determining LA emptying functions was performed using the biplane area-length method. RESULTS Two-hundred and ten patients were included in this study. During a median follow-up of 19 months, 48 patients experienced major adverse cardiac events (MACE), including 24 deaths. Decreased LA contractile function (LAEF(Contractile)) demonstrated strong unadjusted associations with patient mortality, non-fatal events, and all MACE. For every 10% reduction of LAEF(Contractile), unadjusted hazards to MACE, all-cause mortality, and non-fatal events increased by 1.8, 1.5, and 1.4-folds, respectively. In addition, preservation of the proportional contribution from LA contraction to total diastolic filling (Contractile/Total ratio) was strongly associated with lower MACE and patient mortality. By multivariable analyses, LAEF(Contractile) was the strongest predictor in each of the best overall models of MACE, all-cause mortality, and non-fatal events. Even after adjustment for age, gender, left atrial volume, and LVEF, LAEF(Contractile) maintained strong independent associations with MACE (p < 0.0004), all-cause mortality (p < 0.0004), and non-fatal events (p < 0.0004). CONCLUSIONS In hypertensive patients at risk for left ventricular diastolic dysfunction, a decreased contribution of LA contractile function to ventricular filling during diastole is strongly predictive of adverse cardiac events and death.
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Affiliation(s)
- Matthew Kaminski
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Kevin Steel
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | | | - Maung Khin
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Sui Tsang
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Thomas Hauser
- Cardiovascular Division, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Raymond Y Kwong
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
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Yaniv Y, Juhaszova M, Wang S, Fishbein KW, Zorov DB, Sollott SJ. Analysis of mitochondrial 3D-deformation in cardiomyocytes during active contraction reveals passive structural anisotropy of orthogonal short axes. PLoS One 2011; 6:e21985. [PMID: 21779362 PMCID: PMC3136939 DOI: 10.1371/journal.pone.0021985] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 06/13/2011] [Indexed: 11/19/2022] Open
Abstract
The cardiomyocyte cytoskeleton, composed of rigid and elastic elements, maintains the isolated cell in an elongated cylindrical shape with an elliptical cross-section, even during contraction-relaxation cycles. Cardiomyocyte mitochondria are micron-sized, fluid-filled passive spheres distributed throughout the cell in a crystal-like lattice, arranged in pairs sandwiched between the sarcomere contractile machinery, both longitudinally and radially. Their shape represents the extant 3-dimensional (3D) force-balance. We developed a novel method to examine mitochondrial 3D-deformation in response to contraction and relaxation to understand how dynamic forces are balanced inside cardiomyocytes. The variation in transmitted light intensity induced by the periodic lattice of myofilaments alternating with mitochondrial rows can be analyzed by Fourier transformation along a given cardiomyocyte axis to measure mitochondrial deformation along that axis. This technique enables precise detection of changes in dimension of ∼1% in ∼1 µm (long-axis) structures with 8 ms time-resolution. During active contraction (1 Hz stimulation), mitochondria deform along the length- and width-axes of the cell with similar deformation kinetics in both sarcomere and mitochondrial structures. However, significant deformation anisotropy (without hysteresis) was observed between the orthogonal short-axes (i.e., width and depth) of mitochondria during electrical stimulation. The same degree of deformation anisotropy was also found between the myocyte orthogonal short-axes during electrical stimulation. Therefore, the deformation of the mitochondria reflects the overall deformation of the cell, and the apparent stiffness and stress/strain characteristics of the cytoskeleton differ appreciably between the two cardiomyocyte orthogonal short-axes. This method may be applied to obtaining a better understanding of the dynamic force-balance inside cardiomyocytes and of changes in the spatial stiffness characteristics of the cytoskeleton that may accompany aging or pathological conditions.
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Affiliation(s)
- Yael Yaniv
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Su Wang
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Kenneth W. Fishbein
- Laboratory of Clinical Investigation, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Dmitry B. Zorov
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Steven J. Sollott
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
- * E-mail:
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Blume GG, Mcleod CJ, Barnes ME, Seward JB, Pellikka PA, Bastiansen PM, Tsang TSM. Left atrial function: physiology, assessment, and clinical implications. EUROPEAN JOURNAL OF ECHOCARDIOGRAPHY 2011; 12:421-30. [PMID: 21565866 DOI: 10.1093/ejechocard/jeq175] [Citation(s) in RCA: 328] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The interest in the left atrium (LA) has resurged over the recent years. In the early 1980s, multiple studies were conducted to determine the normal values of LA size. Over the past decade, LA size as an imaging biomarker has been consistently shown to be a powerful predictor of outcomes, including major public health problems such as atrial fibrillation, heart failure, stroke, and death. More recently, functional assessment of the LA has been shown to be, at least as, if not more robust, a marker of cardiovascular outcomes. Current available data suggest that the combined evaluation of LA size and LA function will augment prognostication. The aim of this review is to provide a critical appraisal of current echocardiographic techniques for the assessment of LA function and the implications of such assessment for prediction and disease prevention.
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Affiliation(s)
- Gustavo G Blume
- Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, MN, USA
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Crawford T. Left atrial diastolic dysfunction: a new complication after catheter ablation for atrial fibrillation? Heart Rhythm 2011; 8:1372-3. [PMID: 21402171 DOI: 10.1016/j.hrthm.2011.03.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Indexed: 01/15/2023]
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Left Atrial Function: Doppler and Strain. CURRENT CARDIOVASCULAR IMAGING REPORTS 2010. [DOI: 10.1007/s12410-010-9041-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Palecek T, Lubanda JC, Trckova R, Linhart A. Left atrial flow propagation velocity: a new approach for assessment of left atrial reservoir function. Int J Cardiovasc Imaging 2010; 27:75-82. [PMID: 20571873 DOI: 10.1007/s10554-010-9660-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2010] [Accepted: 06/11/2010] [Indexed: 01/11/2023]
Abstract
To assess the feasibility of left atrial flow propagation velocity (LAFPV) measurement and to evaluate the influence of preload alterations on this new parameter of left atrial (LA) reservoir function as compared to conventional echocardiographic indices. 30 healthy volunteers (26 ± 5 years, 20 males) underwent echocardiographic examination at rest, during passive leg lifting and after sublingual administration of nitroglycerine with subsequent Valsalva maneuver. LA reservoir function was assessed by conventional indices including LA expansion index, peak velocity and velocity-time integral of pulmonary venous systolic flow. As well, LAFPV was measured by color M-mode in an apical 4-chamber view as the slope of the transatrial flow wave during LA reservoir phase. LAFPV measurement was feasible in 25 subjects (83%). All conventional parameters of LA reservoir function were significantly altered from resting values by both load-modifying conditions. However, LAPFV was not significantly altered by such maneuvers (228 ± 28 cm s⁻¹ at rest vs. 238 ± 3 cm s⁻¹ during leg lifting, P = NS, vs. 218 ± 38 cm s(-1) after nitroglycerin with Valsalva maneuver, P = NS vs. rest, P < 0.01 vs. leg lifting). LAFPV can be measured in a majority of subjects and represents a new, less load-dependent index of LA reservoir function that may more appropriately reflect LA compliance.
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Affiliation(s)
- Tomas Palecek
- 2nd Department of Medicine - Department of Cardiovascular Medicine, First Faculty of Medicine, Charles University of Prague and General University Hospital in Prague, Prague 2, Czech Republic.
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Affiliation(s)
- Queenie Lo
- Liverpool HospitalDepartment of CardiologySydneyNew South Wales2170Australia
| | - Liza Thomas
- Liverpool HospitalDepartment of CardiologySydneyNew South Wales2170Australia
- The University of New South WalesSydneyNew South Wales2052Australia
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Aune E, Baekkevar M, Roislien J, Rodevand O, Otterstad JE. Normal reference ranges for left and right atrial volume indexes and ejection fractions obtained with real-time three-dimensional echocardiography. EUROPEAN JOURNAL OF ECHOCARDIOGRAPHY 2009; 10:738-44. [PMID: 19435735 DOI: 10.1093/ejechocard/jep054] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
AIMS The aim of this study was to obtain normal reference ranges and intra-observer reproducibility for left (L) and right (R) atrial (A) volume indexes (VI, corrected for body surface area) and ejection fractions (EF) with real-time three-dimensional echocardiography. METHODS AND RESULTS One hundred and sixty-six participants, 79 males and 87 females, aged 29-79 years considered free from clinical and subclinical cardiovascular disease, were included. Normal ranges are defined as 95% reference values for atrial dimensions and reproducibility as coefficients of variations (CVs) for repeated measurements. Upper normal reference values were 41 mL/m(2) for maximum (max) LAVI and 19 mL/m(2) for minimum (min) LAVI. The lower normal reference value was 45% for LAEF. The respective values for RA were 47 mL/m(2), 20 mL/m(2), and 46%. The only relevant gender difference was a higher upper normal max RAVI among males vs. females. The CVs for repeated measurements were 9% for max LAVI, 8% for max RAVI, 13% for LAEF, and 14% for RAEF. CONCLUSION The present study provides normal ranges for atrial dimensions and contractility with a new, fast, and reproducible technique that can be used bedside without offline analysis.
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Affiliation(s)
- Erlend Aune
- Department of Cardiology, Vestfold Hospital Trust, NO-3103 Toensberg, Norway.
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Ostermaier RH, Lampert S, Dalla Vecchia L, Ravid S. The effect of atrial fibrillation and the ventricular rate control on exercise capacity. Clin Cardiol 2009; 20:23-7. [PMID: 8994734 PMCID: PMC6656193 DOI: 10.1002/clc.4960200107] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Atrial fibrillation (AF) is a common cardiac arrhythmia, affecting approximately 1.5 million patients in the United States. HYPOTHESIS This study was designed to determine the effect of AF and the ventricular rate control during AF on cardiovascular performance as measured by exercise endurance on a standard Bruce protocol. METHODS Sixty-three patients with AF who underwent exercise stress testing during both sinus rhythm and AF were analyzed. Heart rate, blood pressure, heart rate acceleration, exercise duration, and left ventricular (LV) systolic function were measured. RESULTS Atrial fibrillation resulted in a small but statistically significant decrease in exercise endurance (426 +/- 180 vs. 402 +/- 168 s, p < 0.05). The drop in exercise tolerance was consistent regardless of the underlying heart condition or adequate ventricular rate control during AF. Heart rate in AF was consistently faster than in sinus rhythm, at rest, and at peak exercise (63 vs. 79 beats/min and 125 vs. 149 beats/min, respectively, p < 0.001). CONCLUSION Our analyses indicated that (1) the loss of atrioventricular synchrony had minimal effect on cardiovascular performance in patients with preserved LV function, (2) the decrease in cardiovascular performance was related to loss of atrioventricular synchrony but not to underlying heart disease or ventricular rate control, and (3) compensation for the loss of the atrial contribution was provided by consistently faster heart rate during AF.
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Antoniou A, Milonas D, Kanakakis J, Rokas S, Sideris DA. Contraction-excitation feedback in human atrial fibrillation. Clin Cardiol 2009; 20:473-6. [PMID: 9134280 PMCID: PMC6655574 DOI: 10.1002/clc.4960200514] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Contraction-excitation feedback, that is, electrophysiologic changes that are caused or preceded by mechanical changes of the myocardium, has been extensively studied in the ventricles. The role of contraction-excitation feedback in the atria, and more particularly in the genesis and maintenance of atrial fibrillation, has been less adequately investigated. HYPOTHESIS The aim of the present study was to determine whether increased right atrial pressure (RAP) facilitates the induction of atrial fibrillation (AF) in patients with a history of lone AF. METHODS Sixteen patients with a history of paroxysmal AF but without structural heart disease were included in the study. All patients underwent electrophysiologic study at both a lower (3.1 +/- 2.0 mmHg) and (in 13 cases) a higher (6.4 +/- 2.5 mmHg) RAP. "Higher" was considered the pressure following rapid (in about 30 min) intravenous administration of normal saline or before the administration of a diuretic. RESULTS Rapid atrial pacing induced AF in 19 of 29 attempts. At a lower pressure, rapid pacing induced brief (3 s to 3 min) AF in 3 of 16 patients, long-lasting (> 3 min) AF in 3 of 16 patients, and no AF in 10 of 16 patients. At a higher pressure, brief AF was induced in 3 of 10 patients in whom no AF could be induced at a lower pressure, and long-lasting AF in 10 patients in whom either brief AF (3 cases) or no AF (7 cases) was induced at a lower pressure. In 11 patients, in whom Wenckebach periodicity was determined at both higher and lower pressure, the critical cycle length at which atrioventricular block appeared was significantly (p < 0.001, paired t-test) longer (349.1 +/- 44.4 ms, i.e., +15.5 +/- 11.3 ms) at higher than at lower atrial pressure (333.6 +/- 41.0 ms). In nine patients, in whom Wenckebach periodicity was determined and two rhythms occurred at different pressures, the critical cycle length was 332.2 +/- 45.8 ms when associated with sinus rhythm, and significantly (p < 0.01) longer (344.4 +/- 48.0 ms, i.e., +12.2 +/- 8.3 ms) when associated with induction of AF. CONCLUSION In patients with lone atrial fibrillation, modest increases in atrial pressure may facilitate the induction of atrial fibrillation.
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Affiliation(s)
- A Antoniou
- Department of Clinical Therapeutics, Medical School of Athens University, Greece
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Del Colle S, Milan A, De Castro S, Pandian N, Veglio F. WITHDRAWN: Left atrial function and arterial hypertension. J Hum Hypertens 2008:jhh200896. [PMID: 18701925 DOI: 10.1038/jhh.2008.96] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 06/10/2008] [Accepted: 07/04/2008] [Indexed: 11/08/2022]
Abstract
Left atrial enlargement is frequently observed in many cardiac diseases. One of the main determinants of left atrial size is ventricular diastolic function. It has recently been suggested that left atrial volume might be the morphophysiologic expression of long-term modifications induced by diastolic function. Furthermore, left ventricular remodelling, such as it happens in hypertensive patients, is another important determinant of atrial volume. All the volumetric modifications of the left atrium, during cardiac cycle, are involved in hypertensive damage. Therefore, left atrial function impairment represents the result of morphological and haemodynamic alterations observed in hypertension. Actually, many techniques, invasive and non-invasive, are available with the purpose to investigate the real atrial dimensions and provide a suitable assessment of atrial function. Recently, it has been demonstrated that the degree of left atrial enlargement is associated with adverse prognosis in different clinical setting. The predictive value of left atrial volume seems to be independent of left ventricular systolic and diastolic function, but the use of left atrial volume for risk stratification is yet an evolving science: more data are required with respect to the natural history of left atrial remodelling in disease, the degree of left atrial modifiability with therapy and whether regression of left atrial size translates into improved cardiovascular outcome.Journal of Human Hypertension advance online publication, 14 August 2008; doi:10.1038/jhh.2008.96.
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Affiliation(s)
- S Del Colle
- 1Division of Internal Medicine and Hypertension, Department of Medicine and Experimental Oncology, University of Torino, Torino, Italy
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32
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Attaran RR, Baweja G, Foster L, Butman S, Sorrell VL. Lower patent foramen ovale detection with transthoracic echocardiography in atrial fibrillation. Int J Cardiovasc Imaging 2008; 24:819-24. [DOI: 10.1007/s10554-008-9334-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2008] [Accepted: 06/17/2008] [Indexed: 11/28/2022]
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Abhayaratna WP, Seward JB, Appleton CP, Douglas PS, Oh JK, Tajik AJ, Tsang TSM. Left Atrial Size. J Am Coll Cardiol 2006; 47:2357-63. [PMID: 16781359 DOI: 10.1016/j.jacc.2006.02.048] [Citation(s) in RCA: 818] [Impact Index Per Article: 45.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2005] [Revised: 01/27/2006] [Accepted: 02/07/2006] [Indexed: 01/01/2023]
Abstract
Left atrial (LA) enlargement has been proposed as a barometer of diastolic burden and a predictor of common cardiovascular outcomes such as atrial fibrillation, stroke, congestive heart failure, and cardiovascular death. It has been shown that advancing age alone does not independently contribute to LA enlargement, and the impact of gender on LA volume can largely be accounted for by the differences in body surface area between men and women. Therefore, enlargement of the left atrium reflects remodeling associated with pathophysiologic processes. In this review, we discuss the normal size and phasic function of the left atrium. Further, we outline the clinically important aspects and pitfalls of evaluating LA size, and the methods for assessing LA function using echocardiography. Finally, we review the determinants of LA size and remodeling, and we describe the evidence regarding the prognostic value of LA size. The use of LA volume for risk stratification is an evolving science. More data are required with respect to the natural history of LA remodeling in disease, the degree of LA modifiability with therapy, and whether regression of LA size translates into improved cardiovascular outcomes.
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Affiliation(s)
- Walter P Abhayaratna
- Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA
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Salukhe TV, Dob D, Sutton R. Pacemakers and defibrillators: anaesthetic implications. Br J Anaesth 2004; 93:95-104. [PMID: 15169736 DOI: 10.1093/bja/aeh170] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- T V Salukhe
- National Heart Lung Institute, Royal Brompton Hospital, Sydney Street, London SW3 6NP, UK.
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35
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Zhang Y, Mowrey KA, Zhuang S, Wallick DW, Popović ZB, Mazgalev TN. Optimal ventricular rate slowing during atrial fibrillation by feedback AV nodal-selective vagal stimulation. Am J Physiol Heart Circ Physiol 2002; 282:H1102-10. [PMID: 11834509 DOI: 10.1152/ajpheart.00738.2001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although the beneficial effects of ventricular rate (VR) slowing during atrial fibrillation (AF) are axiomatic, the precise relationship between VR and hemodynamics has not been determined. We hypothesized that selective atrioventricular node (AVN) vagal stimulation (AVN-VS) by varying the nerve stimulation intensity could achieve precise graded slowing and permit evaluation of an optimal VR during AF. The aims of the present study were the following: 1) to develop a method for computerized vagally controlled VR slowing during AF, 2) to determine the hemodynamic changes at each level of VR slowing, and 3) to establish the optimal anterograde VR during AF. AVN-VS was delivered to the epicardial fat pad that projects parasympathetic nerve fibers to the AVN in 14 dogs. Four target average VR levels, corresponding to 75%, 100%, 125%, and 150% of the sinus cycle length (SCL), were achieved by computer feedback algorithm. VR slowing resulted in improved hemodynamics and polynomial fit analysis found an optimum for the cardiac output at VR slowing of 87% SCL. We conclude that this novel method can be used to maintain slow anterograde conduction with best hemodynamics during AF.
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Affiliation(s)
- Youhua Zhang
- Department of Cardiovascular Medicine, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
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36
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Bauer EP, Szalay ZA, Brandt RR, Pitschner HF, Bachmann G, Brunner-La Rocca HP, Klövekorn WP. Predictors for atrial transport function after mini-maze operation. Ann Thorac Surg 2001; 72:1251-4; discussion 1255. [PMID: 11603445 DOI: 10.1016/s0003-4975(01)02977-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Restoration of atrial transport function (ATF) is a major goal of the maze procedure. This prospective study was undertaken to evaluate predictors of left atrial transport function in patients undergoing a mini-variant of the maze III procedure 3 and 12 months postoperatively. METHODS Mini-maze operation was performed in 72 patients with a mean age of 64 +/- 8.7 years during a 5-year period. Seventy of 72 (97%) had combined procedures. Clinical and electrophysiologic examination was carried out before surgery, and 3 and 12 months postoperatively. RESULTS Early mortality was 1.4% (1 of 72 patients) and late death occurred in 5.6% (4 of 71 patients). After 3 months, 54 of 68 (80%) patients showed sinus rhythm, and 48 of 60 (80%) after 12 months. ATF was restored in 87% (echocardiography) and 82% (magnetic resonance imaging) after 3 months, and in 86% (echocardiography) and 78% (magnetic resonance imaging) after 12 months. Independent predictors for ATF restoration after 12 months were better preoperative left ventricular function (p = 0.02), and smaller preoperative left atrial diameter (p = 0.005). Correlation between echocardiography and magnetic resonance imaging was 80% after 12 months. CONCLUSIONS Restoration of ATF after mini-maze procedure is achieved in over 80%. Independent predictors for ATF restoration are smaller preoperative left atrial diameter and better preoperative left ventricular ejection fraction.
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Affiliation(s)
- E P Bauer
- Department of Cardiothoracic Surgery, Kerckhoff-Clinic Foundation, Bad Nauheim, Germany.
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37
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Hoit BD, Gabel M. Influence of left ventricular dysfunction on the role of atrial contraction: an echocardiographic-hemodynamic study in dogs. J Am Coll Cardiol 2000; 36:1713-9. [PMID: 11079681 DOI: 10.1016/s0735-1097(00)00922-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES The purpose of this study was to understand the significance of an effective atrial systole and the interactions between atrial and ventricular function. BACKGROUND The significance of atrial function is controversial, particularly in the setting of left ventricular (LV) dysfunction. METHODS Serial, rapid pacing in five dogs that had undergone radiofrequency ablation and implantation of right atrial and ventricular pacemakers produced reversible atrial and ventricular dysfunction (alone and in combination). Atrial function (echocardiograph-determined transmitral diastolic flow, left atrial appendage emptying, and pulmonary venous flow), cardiac output, and right heart pressures were measured at matched paced heart rates of 80 beats/min. RESULTS Isolated rapid atrial pacing (LV ejection fraction approximately 60%) decreased atrial booster pump in the body and appendage of the left atrium, but increased the conduit function of the left atrium. Isolated LV dysfunction (LV ejection fraction approximately 34%) increased atrial booster pump function. The decreased atrial booster pump function in animals with combined atrial and ventricular dysfunction was incompletely compensated by the redistribution of the reservoir and conduit functions of the left atrium. As a result, cardiac output decreased and right heart pressures increased only after superimposed pacing. CONCLUSIONS In the presence of a normal left ventricle (LV), atrial failure has little effect on cardiac output and right heart pressures because of compensatory conduit function, but when early LV dysfunction coexists, changes in reservoir and conduit functions are insufficient to compensate for an impairment of atrial contraction.
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Affiliation(s)
- B D Hoit
- Department of Medicine, Case Western Reserve University, University Hospitals of Cleveland, Ohio 44106, USA.
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Moreyra AE, Wilson AC, Deac R, Suciu C, Kostis JB, Ortan F, Kovacs T, Mahalingham B. Factors associated with atrial fibrillation in patients with mitral stenosis: a cardiac catheterization study. Am Heart J 1998; 135:138-45. [PMID: 9453533 DOI: 10.1016/s0002-8703(98)70354-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Atrial fibrillation (AF) is frequently found in association with rheumatic mitral valve disease. To study the interrelation of factors contributing to the risk of AF in patients with mitral stenosis, we examined a cardiac catheterization database of a series of 314 patients. Patients with AF were older, 53.4 +/- 6.1 years versus 51.7 +/- 7.2 years (p = 0.03), and had a lower cardiac index, 2.3 +/- 0.6 L/min/m2 versus 2.6 +/- 0.7 L/min/m2 (p = 0.0002), than patients in sinus rhythm at catheterization. The mitral valve area was significantly smaller in patients with AF than in patients in sinus rhythm, 1.2 +/- 0.5 cm2 versus 1.6 +/- 0.7 cm2 (odds ratio 1.40/0.25 cm2 decrease; p = 0.0001) as was mitral valve index. The pressure-AF association with the highest statistical significance was seen with mean right atrial pressure, 10.6 +/- 4.9 mm Hg versus 7.6 +/- 3.8 mm Hg (odds ratio 2.24; p < 0.0001). Other variables with significant positive associations by univariate analysis were pulmonary artery wedge pressure, pulmonary artery mean pressure, and pulmonary resistance. When stepwise logistic multiple regression analysis was performed, the results indicated that both severity of mitral stenosis and increased right atrial pressure were independently associated with AF in this population with mitral stenosis. After adjustment was performed for these variables, age was not independently associated with AF.
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Affiliation(s)
- A E Moreyra
- Department of Medicine, UMDNJ-Robert Wood Johnson Medical School, New Brunswick, NJ 08903-0019, USA
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Sideris DA, Toumanidis ST, Tselepatiotis E, Kostopoulos K, Stringli T, Kitsiou T, Moulopoulos SD. Atrial pressure and experimental atrial fibrillation. Pacing Clin Electrophysiol 1995; 18:1679-85. [PMID: 7491311 DOI: 10.1111/j.1540-8159.1995.tb06989.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A possible profibrillatory effect on the atria of an elevated atrial pressure and the site of atrial stimulation was examined. In 15 anesthetized dogs, right or left atrial or biatrial pacing was applied at a high rate (300-600/min) for 5 seconds at double threshold intensity under a wide range of atrial pressures achieved by venous or arterial transfusion or bleeding. Induction of atrial fibrillation in 236 of 1,971 pacing runs was associated with a significantly higher (P < 0.001) atrial pressure (21.6 +/- 12.2 mmHg, mean +/- SD) than maintenance of sinus rhythm (16.8 +/- 11.1 mmHg in 1,735 of 1,971 pacing runs). Stimulation of the right atrium resulted in atrial fibrillation more frequently than left atrial or biatrial stimulation, with biatrial stimulation less frequent than right or left atrial stimulation. The induction of atrial fibrillation was related to the atrial pressure and to the site of stimulation but not to the pacing rate or the prepacing heart rate. The prepacing heart rate, associated with failure to induce sustained atrial fibrillation, was higher than that associated with atrial fibrillation in 12 of 15 experiments (significantly in 6) and not significantly lower in 3 of 15. Atrial fibrillation lasting 1 minute or more was more frequently associated with simultaneous stimulation of both atria than of either atrium alone. Thus, an elevated atrial pressure may facilitate the induction of atrial fibrillation. The site of stimulation also plays an important role for both the induction and maintenance of atrial fibrillation in this model.
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Affiliation(s)
- D A Sideris
- Department of Clinical Therapeutics, Medical School of Athens University, Greece
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40
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Liau CS, Chen MF, Lin FY, Tsai CH, Lee YT. Relationship between ventricular rate and cardiac output in mimic experimental atrial fibrillation. J Electrocardiol 1994; 27:163-8. [PMID: 8201300 DOI: 10.1016/s0022-0736(05)80100-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In treating atrial fibrillation (AF) the goal of ventricular rate reduction is still not determined. An animal model of AF was developed in which the relationship between ventricular rate and the parameters of cardiac function in AF can be studied. To simulate AF, complete heart block was chemically produced on open-chest dogs. Then, assisted by a portable computer, the ventricles were paced with a series of grossly irregular stimuli of predetermined rates, while atria were paced rapidly (500 beats/min). The resulting electrocardiogram and pressure were indistinguishable from the naturally occurring AF. It was found that in AF with ventricular rates that were lower than that of the control state, cardiac output was decreased. Cardiac output increased and reached a plateau when the ventricular rate increased to the level of the control state and then kept stable up to a rate of 320 beats/min. There was a discrepancy between the effective ventricular rate (rate of beats with pulse pressures > or = 25 mmHg in the femoral artery) and the electrical ventricular rate. When the electrical ventricular rate increased over the control ventricular rate the effective ventricular rate did not increase in a parallel manner. Rather, the effective ventricular rate leveled off at the control ventricular rate. This discrepancy may explain the parallel relationship between the effective ventricular rate and cardiac output.
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Affiliation(s)
- C S Liau
- Department of Internal Medicine, College of Medicine, National Taiwan University, Taipei, R.O.C
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41
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Hoit BD, Shao Y, Gabel M, Walsh RA. In vivo assessment of left atrial contractile performance in normal and pathological conditions using a time-varying elastance model. Circulation 1994; 89:1829-38. [PMID: 8149549 DOI: 10.1161/01.cir.89.4.1829] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND Contractile function of the ex vivo, isolated left atrium (LA) has been described by a time-varying elastance, but this atrial chamber property has not been shown in vivo. METHODS AND RESULTS Instantaneous LA pressure-volume (P-V) relations were studied in 12 anesthetized, autonomically blocked, atrially paced dogs. LA volume was calculated from orthogonal sonomicrometer pairs using a cast-validated formula. Data were collected during increases in LA pressure produced by a phenylephrine bolus (200 to 400 micrograms IV). Isochronal P-V points from 5 beats, representing a wide range of atrial pressures, were fitted by linear regression analysis (range of R2, .92 to .99). There were significant time-dependent increases in the slopes [E(t)] and small but statistically insignificant decreases in the volume axis intercepts [VO(t)] of the instantaneous LA P-V relations during atrial contraction; maximal elastance (Emax) occurred 29 +/- 16 milliseconds before atrial end systole (minimal LA volume). Emax was not significantly different than the slopes of either the nonisochronal end-systolic P-V relation (Ees) or the nonisochronal maximal P-to-V relation (EmaxPV): 5.5 +/- 2.8, 4.3 +/- 1.5, and 5.4 +/- 4.2 mm Hg/mL, respectively. In 7 dogs, data were collected both before and after a rapid infusion of calcium gluconate (1 to 2 g IV). Emax increased significantly with a calcium-induced increase in inotropic state (4.5 +/- 1.6 to 5.7 +/- 1.8 mm Hg/mL, P < .01), but the volume axis intercept was unchanged (3.6 +/- 0.7 versus 3.4 +/- 1.9, P = NS). In 4 additional dogs with heart failure (mean LA pressure, 26 +/- 6 mm Hg) produced by 3 weeks of rapid right ventricular pacing, LA stroke volume was significantly greater than and elastance determinations were similar to those of normal dogs. However, the effects of calcium infusion on LA function were attenuated in these animals. CONCLUSIONS We conclude that (1) in the intact heart, LA contraction may be approximated by time-varying elastance with time-dependent changes in E(t) and that (2) LA systolic P-V relations using either the nonisochronal maximum P-to-V ratio or end systole may be useful as an estimate of Emax, are highly linear and sensitive to calcium-induced changes in inotropic state, and may be useful in identifying LA chamber adaptation to chronic hemodynamic loads.
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Affiliation(s)
- B D Hoit
- Department of Internal Medicine, University of Cincinnati Medical Center, OH 45267-0542
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42
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Jordaens L, Missault L, Germonpré E, Callens B, Adang L, Vandenbogaerde J, Clement DL. Delayed restoration of atrial function after conversion of atrial flutter by pacing or electrical cardioversion. Am J Cardiol 1993; 71:63-7. [PMID: 8420237 DOI: 10.1016/0002-9149(93)90711-k] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
It is often suggested but never proven that atrial function is not affected during atrial flutter, nor after its conversion to normal sinus rhythm. To evaluate this hypothesis, a prospective study was performed in 22 patients (age range 20 to 88 years) with atrial flutter. Diastolic transmitral flow was analyzed with echo-Doppler before and after conversion. After randomization, conversion was attempted with overdrive pacing or up to two 50 J shocks. If the initial method was unsuccessful, a 200 J shock was administered. All patients were converted to sinus rhythm with this protocol. Shortly after conversion (at 1 and 6 hours), atrial contribution to ventricular filling was absent in 4 of 22 patients. In the remaining 18 patients, atrial contribution to ventricular filling was small. Atrial contribution to transmitral flow improved from 20 to 27% within 24 hours (p < 0.01) and increased further to 38% at 6 weeks (p < 0.005). Peak velocity of late diastolic filling increased from 0.28 m/s after 1 hour to 0.39 m/s after 24 hours (p < 0.0001) and improved even further during later follow-up. In 1 patient, an effective atrial systole was not observed until the 14th day. Cardiac output did not change significantly during the study period. No differences were observed between the conversion modalities. In conclusion, atrial dysfunction is present immediately after conversion of atrial flutter to normal sinus rhythm. This dysfunction occurs also after overdrive pacing and can last > 1 week. The findings suggest that stasis in the atria can remain temporarily present after successful conversion of atrial flutter to sinus rhythm.
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Affiliation(s)
- L Jordaens
- Department of Cardiology, University Hospital Ghent, Belgium
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43
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Janosik AL, Pearson AC, Labovitz AJ. Applications of Doppler echocardiography in cardiac pacing. Echocardiography 1991; 8:45-63. [PMID: 10149244 DOI: 10.1111/j.1540-8175.1991.tb01403.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The purpose of this article is to review the use of Doppler echocardiography for assessing responses during cardiac pacing. Doppler techniques allow the physician to select the optimal mode pacemaker and pacemaker settings with regard to heart rate and atrioventricular delay, at rest and during exercise. Doppler parameters can be used to predict the relative hemodynamic advantage of dual chamber or rate adaptive pacing over fixed rate pacing. This valuable noninvasive modality may enhance the benefit of pacemaker therapy.
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Affiliation(s)
- A L Janosik
- Division of Cardiology, St. Louis University Hospital, MO 63110
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Janosik DL, Pearson AC, Buckingham TA, Labovitz AJ, Redd RM. The hemodynamic benefit of differential atrioventricular delay intervals for sensed and paced atrial events during physiologic pacing. J Am Coll Cardiol 1989; 14:499-507. [PMID: 2754135 DOI: 10.1016/0735-1097(89)90208-8] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The ability to program different atrioventricular (AV) delay intervals for paced and sensed atrial events is incorporated in the design of some newer dual chamber pacemakers. However, little is known regarding the hemodynamic benefit of differential AV delay intervals or the magnitude of difference between optimal AV delay intervals for paced and sensed P waves in individual patients. In this study, Doppler-derived cardiac output was used to examine the optimal timing of paced and sensed atrial events in 24 patients with a permanent dual chamber pacemaker. The hemodynamic effect of utilizing separate optimal delay intervals for sensed and paced events compared with utilizing the same fixed AV delay interval for both was determined. The optimal delay interval during DVI (AV sequential) pacing and VDD (atrial triggered, ventricular inhibited) pacing at similar heart rates was 176 +/- 44 and 144 +/- 48 ms (p less than 0.002), respectively. The mean difference between the optimal AV delay intervals for sensed (VDD) and paced (DVI) P waves was 32 ms and was up to 100 ms in some individuals. The difference between optimal AV delay intervals for sensed and paced atrial events was similar in patients with complete heart block and those with intact AV node conduction. At the respective optimal AV delay intervals for sensed and paced P waves, there was no significant difference in the cardiac output during VDD compared with DVI pacing. However, cardiac output significant declined during VDD pacing at the optimal AV delay interval for a paced event and during DVI pacing at the optimal interval for a sensed event.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D L Janosik
- Department of Internal Medicine, St. Louis University Medical Center, Missouri 63110
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45
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Rydén L, Karlsson O, Kristensson BE. The importance of different atrioventricular intervals for exercise capacity. Pacing Clin Electrophysiol 1988; 11:1051-62. [PMID: 2457884 DOI: 10.1111/j.1540-8159.1988.tb03951.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In order to determine whether different atrioventricular intervals influence the maximal exercise capacity, 15 patients with second degree or complete atrioventricular block and no signs of left ventricular failure were studied. They all had atrioventricular synchronous pacemakers. Maximal exercise tests (sitting bicycle ergometry) were performed at four different atrioventricular intervals (50, 100, 150, and 200 ms) and during rate-matched asynchronous ventricular pacing. The patients thereby served as their own controls. Ventricular rate, maximal oxygen uptake and minute ventilation were measured and perceived exertion estimated every minute. Different atrioventricular intervals did not affect the maximal exercise capacity, the maximal oxygen uptake, the perceived exertion or minute ventilation. Since the results were similar during atrioventricular synchronous pacing at various atrioventricular intervals and on rate-matched asynchronous ventricular pacing, this study supports previous findings that the important factor for maximal physical performance is not a preserved atrioventricular synchronization but the ability to increase the ventricular rate.
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Affiliation(s)
- L Rydén
- Department of Cardiology, Central Hospital, Skövde, Sweden
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Keren G, Etzion T, Sherez J, Zelcer AA, Megidish R, Miller HI, Laniado S. Atrial fibrillation and atrial enlargement in patients with mitral stenosis. Am Heart J 1987; 114:1146-55. [PMID: 2960225 DOI: 10.1016/0002-8703(87)90190-6] [Citation(s) in RCA: 93] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The present study was designed to assess the relative contribution of atrial fibrillation and left atrial pressure to changes in the size of the left and right atria in patients with mitral stenosis. The study included 155 subjects, 102 of whom underwent prospective echocardiography and Doppler cardiography, and 69 of whom underwent cardiac catheterization. The size of the atria was determined by two-dimensional echocardiography. There were no significant hemodynamic differences between patients with mitral stenosis who were in either sinus rhythm or atrial fibrillation. The left atrium was larger (p less than 0.001) in patients with mitral stenosis and atrial fibrillation (37.6 +/- 10.8 cm2) than in patients in sinus rhythm (27.8 +/- 7.7 cm2) or normal subjects (15 +/- 3.3 cm2). The size of the right atrium was larger (p less than 0.001) in patients with mitral stenosis and atrial fibrillation (21.7 +/- 5.2 cm2) than in patients in sinus rhythm (13.4 +/- 3.9 cm2) or normal subjects (13.8 +/- 3.7 cm2). Multiple regression analysis showed that the severity of mitral stenosis accounted for 38%, age for 7%, and atrial fibrillation for 11% of the change in the size of the left atrium. Atrial fibrillation accounted for 24%, age for 11, and mitral valve area for 3% of the change in the size of the right atrium. The analysis suggests that the onset of left atrial dilatation in mitral stenosis is the result of an early increase in left atrial pressure. Atrial fibrillation, which develops irrespective of the severity of the mitral stenosis, contributes to a further enlargement of the left and right atria.
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Affiliation(s)
- G Keren
- Department of Cardiology, Ichilov Hospital, Tel Aviv Medical Center, Israel
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Labovitz AJ, Williams GA, Redd RM, Kennedy HL. Noninvasive assessment of pacemaker hemodynamics by Doppler echocardiography: importance of left atrial size. J Am Coll Cardiol 1985; 6:196-200. [PMID: 4008774 DOI: 10.1016/s0735-1097(85)80274-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The relative decrease in cardiac output with ventricular pacing versus "physiologic" modes was measured noninvasively using Doppler echocardiography in 26 patients. Standard echocardiographic measurements of left ventricular size (diastolic diameter), left ventricular function (shortening fraction) and left atrial size were examined to determine which of these variables might best identify patients more likely to benefit from maintenance of atrioventricular (AV) synchrony. Decreases in relative cardiac output, expressed as reduction in the Doppler-derived flow velocity integral, with loss of AV synchrony ranged from 0 to 43% (mean decrease 21%). There was no correlation between left ventricular size or function and effect of pacing mode on relative cardiac output. There was, however, correlation between left atrial size and sensitivity to pacing mode. Patients with normal left atrial size were significantly more sensitive to loss of AV synchrony. In this subgroup, the decrease in flow velocity integral with ventricular pacing was 32 +/- 11% compared with only 11 +/- 13% in patients with left atrial enlargement. Thus, Doppler echocardiography is useful in assessing optimal pacing mode in the individual patient. Echocardiographically measured left atrial size may identify patients in whom physiologic pacing may be major benefit.
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Unverferth DV, Fertel RH, Unverferth BJ, Leier CV. Atrial fibrillation in mitral stenosis: histologic, hemodynamic and metabolic factors. Int J Cardiol 1984; 5:143-54. [PMID: 6321366 DOI: 10.1016/0167-5273(84)90137-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We examined the histologic, hemodynamic and metabolic factors associated with rheumatic mitral stenosis. Eighteen patients comprised three groups: Group I - 7 patients in sinus rhythm; Group II - 5 patients in intermittent atrial fibrillation; Group III - 6 patients in chronic atrial fibrillation. The left atrial dimension was determined by echocardiography. Left atrial pressure, mitral valve gradient, mitral valve area and the presence or absence of calcium in the mitral valve were determined at catheterization. The left atrial appendage was removed during open heart surgery and the tissue was analyzed for cell size, percent fibrosis and content of cyclic AMP and GMP. There was no difference between the groups in pulmonary capillary wedge pressure, mitral valve gradient, mitral valve area or the presence of calcium. The Group I left atrial dimension (51 +/- 2 mm, means +/- SE) was significantly smaller than that of Group III (56 +/- 2 mm, P less than 0.05). Group II was not different from Groups I or III. Although the concentration of cyclic AMP did not differ among the groups, the cyclic GMP was significantly depressed in Group III (0.15 +/- 0.02 fmol/microgram protein) when compared to Group I (0.24 +/- 0.05 fmol/microgram protein, P less than 0.01). Group II had intermediate values which did not differ from Groups I or III. The percent fibrosis was greatest in Group III (34.8 +/- 1.8%) and least in Group I (27.2 +/- 2.8%, P less than 0.05). There was no difference in cell size among the groups. Although atrial fibrillation may lead to some of these irregularities, a depressed cyclic GMP, increased fibrosis and increased left atrial dimension may play a role in the pathogenesis of irreversible atrial fibrillation.
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Abstract
The authors look at the use of pacemakers in three groups of patients: one with previously implanted cardiac pacemakers, one requiring temporary pacing systems for reasons related to their heart, and one in whom indications exist for permanent pacemaker implantation, but because of a surgical emergency, cannot have a permanent unit implanted before the noncardiac operation.
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