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Van Praagh R. Interatrial Communications. CONGENIT HEART DIS 2022. [DOI: 10.1016/b978-1-56053-368-9.00009-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Cerra MC, Imbrogno S. Phospholamban and cardiac function: a comparative perspective in vertebrates. Acta Physiol (Oxf) 2012; 205:9-25. [PMID: 22463608 DOI: 10.1111/j.1748-1716.2012.02389.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phospholamban (PLN) is a small phosphoprotein closely associated with the cardiac sarcoplasmic reticulum (SR). Dephosphorylated PLN tonically inhibits the SR Ca-ATPase (SERCA2a), while phosphorylation at Ser16 by PKA and Thr17 by Ca(2+) /calmodulin-dependent protein kinase (CaMKII) relieves the inhibition, and this increases SR Ca(2+) uptake. For this reason, PLN is one of the major determinants of cardiac contractility and relaxation. In this review, we attempted to highlight the functional significance of PLN in vertebrate cardiac physiology. We will refer to the huge literature on mammals in order to describe the molecular characteristics of this protein, its interaction with SERCA2a and its role in the regulation of the mechanic and the electric performance of the heart under basal conditions, in the presence of chemical and physical stresses, such as β-adrenergic stimulation, response to stretch, force-frequency relationship and intracellular acidosis. Our aim is to provide the basis to discuss the role of PLN also on the cardiac function of nonmammalian vertebrates, because so far this aspect has been almost neglected. Accordingly, when possible, the literature on PLN will be analysed taking into account the nonuniform cardiac structural and functional characteristics encountered in ectothermic vertebrates, such as the peculiar and variable organization of the SR, the large spectrum of response to stresses and the disaptive absence of crucial proteins (i.e. haemoglobinless and myoglobinless species).
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Affiliation(s)
| | - S. Imbrogno
- Department of Cell Biology; University of Calabria; Arcavacata di Rende (CS); Italy
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Cerra MC, Imbrogno S. Phospholamban and cardiac function: a comparative perspective in vertebrates. Acta Physiol (Oxf) 2012. [DOI: 10.1111/j.1748-1716.2011.02389.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - S. Imbrogno
- Department of Cell Biology; University of Calabria; Arcavacata di Rende (CS); Italy
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Al Ghamdi B, Hassan W. Atrial Remodeling And Atrial Fibrillation: Mechanistic Interactions And Clinical Implications. J Atr Fibrillation 2009; 2:125. [PMID: 28496625 DOI: 10.4022/jafib.125] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2008] [Revised: 12/19/2008] [Accepted: 04/14/2009] [Indexed: 01/13/2023]
Abstract
Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. The prevalence of AF increases dramatically with age and is seen in as high as 9% of individuals by the age of 80 years. In high-risk patients, the thromboembolic stroke risk can be as high as 9% per year and is associated with a 2-fold increase in mortality. Although the pathophysiological mechanism underlying the genesis of AF has been the focus of many studies, it remains only partially understood. Conventional theories focused on the presence of multiple re-entrant circuits originating in the atria that are asynchronous and conducted at various velocities through tissues with various refractory periods. Recently, rapidly firing atrial activity in the muscular sleeves at the pulmonary veins ostia or inside the pulmonary veins have been described as potential mechanism,. AF results from a complex interaction between various initiating triggers and development of abnormal atrial tissue substrate. The development of AF leads to structural and electrical changes in the atria, a process known as remodeling. To have effective surgical or catheter ablation of AF good understanding of the possible mechanism(s) is crucial.Once initiated, AF alters atrial electrical and structural properties that promote its maintenance and recurrence. The role of atrial remodeling (AR) in the development and maintenance of AF has been the subject of many animal and human studies over the past 10-15 years. This review will discuss the mechanisms of AR, the structural, electrophysiologic, and neurohormonal changes associated with AR and it is role in initiating and maintaining AF. We will also discuss briefly the role of inflammation in AR and AF initiation and maintenance, as well as, the possible therapeutic interventions to prevent AR, and hence AF, based on the current understanding of the interaction between AF and AR.
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Affiliation(s)
- Bandar Al Ghamdi
- King Faisal Specialist Hospital and research centre, Riyadh, Saudi Arabia
| | - Walid Hassan
- King Faisal Specialist Hospital and research centre, Riyadh, Saudi Arabia
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Schoonderwoerd BA, Van Gelder IC, Van Veldhuisen DJ, Van den Berg MP, Crijns HJGM. Electrical and Structural Remodeling: Role in the Genesis and Maintenance of Atrial Fibrillation. Prog Cardiovasc Dis 2005; 48:153-68. [PMID: 16271942 DOI: 10.1016/j.pcad.2005.06.014] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Atrial fibrillation (AF) and congestive heart failure (CHF) are 2 frequently encountered conditions in clinical practice. Both lead to changes in atrial function and structure, an array of processes known as atrial remodeling. This review provides an overview of ionic, electrical, contractile, neurohumoral, and structural atrial changes responsible for initiation and maintenance of AF. In the last decade, many studies have evaluated atrial remodeling due to AF or CHF. Both conditions often coexist, which makes it difficult to distinguish the contribution of each. Because of atrial stretch in the setting of hypertension or CHF, atrial remodeling frequently occurs long before AF arises. Alternatively, AF may lead to electrical remodeling, that is, shortening of refractoriness due to the high atrial rate itself. In many experimental AF or rapid atrial pacing studies, the ventricular rate was uncontrolled. In those studies, atrial stretch due to CHF may have interfered with the high atrial rate to produce a mixed type of electrical and structural remodeling. Other studies have dissected the individual role of AF or atrial tachycardia from the role CHF plays in atrial remodeling. Atrial fibrillation itself does not lead to structural remodeling, whereas this is frequently produced by hypertension or CHF, even in the absence of AF. Primary and secondary prevention programs should tailor treatment to the various types of remodeling.
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Affiliation(s)
- Bas A Schoonderwoerd
- Department of Cardiology, Thoraxcenter, University Medical Center Groningen, University of Groningen, RB Groningen, The Netherlands.
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Schoonderwoerd BA, Ausma J, Crijns HJGM, Van Veldhuisen DJ, Blaauw EH, Van Gelder IC. Atrial Ultrastructural Changes During Experimental Atrial Tachycardia Depend on High Ventricular Rate. J Cardiovasc Electrophysiol 2004; 15:1167-74. [PMID: 15485442 DOI: 10.1046/j.1540-8167.2004.03693.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Atrial structural and electrophysiologic changes occur during atrial tachycardia. The role of high ventricular rate in these processes remains to be established. METHODS AND RESULTS Six goats were subjected to 4 weeks of rapid atrioventricular (AV) pacing at an atrial and ventricular rate of 240 beats/min, resulting in development of congestive heart failure. In another five goats, AV block was created. These goats then were subjected to 4 weeks of atrial pacing, also at 240 beats/min while the ventricular rate was kept low and regular at 80 beats/min (A-paced). Pacing was interrupted only for measurement of atrial effective refractory period and right atrial diameter. The ultrastructure of both atria was examined by light and electron microscopy, including quantification of the percentage of atrial extracellular matrix (%ECM). A group of six goats served as controls. In the AV-paced group, severe structural remodeling occurred in the atria, including severe loss of sarcomeres, glycogen accumulation, disruption of sarcoplasmic reticulum, and appearance of numerous small mitochondria and nuclei with homogeneously distributed chromatin. In contrast, structural changes were virtually absent in the atria of A-paced goats. Only a redistribution of nuclear chromatin and the appearance of numerous mitochondria were observed. The ultrastructure was normal in control animals. The%ECM was increased in AV-paced goats (29%) compared to A-paced animals (18%) and controls (17%) (P < 0.05). Finally, right atrial diameter increased by 51% in AV-paced goats but was unchanged in A-paced goats (P < 0.05). In both experimental groups, atrial effective refractory period shortened during pacing. CONCLUSION Structural remodeling during chronic atrial tachycardia is related to the concomitant presence of a high ventricular rate and hence the occurrence of congestive heart failure rather than a high atrial rate. Electrical remodeling can occur in the absence of significant structural changes.
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Affiliation(s)
- Bas A Schoonderwoerd
- Department of Cardiology, Thoraxcenter, University Hospital Groningen, Groningen, The Netherlands.
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Tsubakihara M, Williams NK, Keogh A, dos Remedios CG. Comparison of gene expression between left atria and left ventricles from non-diseased humans. Proteomics 2003; 4:261-70. [PMID: 14730688 DOI: 10.1002/pmic.200300539] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We examine the reliability and accuracy of gene array technology in analyzing differences in gene expression between human non-diseased left atrium and left ventricle. We have used cDNA gene arrays and validated those data by carefully designed quantitative real-time polymerase chain reaction (PCR). We have identified pitfalls using cDNA gene array technology based on comparisons with other gene array studies and with changes reported for the levels of expression of the genes corresponding to these cDNAs. The high error rate reported here underscores the cautionary comments reported by others in this field.
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Affiliation(s)
- Masako Tsubakihara
- Institute for Biomedical Research, University of Sydney, Sydney, Australia.
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Boixel C, Fontaine V, Rücker-Martin C, Milliez P, Louedec L, Michel JB, Jacob MP, Hatem SN. Fibrosis of the left atria during progression of heart failure is associated with increased matrix metalloproteinases in the rat. J Am Coll Cardiol 2003; 42:336-44. [PMID: 12875773 DOI: 10.1016/s0735-1097(03)00578-3] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVES The purpose of this study was to determine the pathogenic factors and molecular mechanisms involved in fibrosis of the atria. BACKGROUND Fibrosis is an important component of the pathophysiology of atrial fibrillation, especially when the arrhythmia is associated with heart failure (HF) or atrial dilation. METHODS We used a rat model of myocardial infarction (MI) complicated by various degrees of left ventricular dysfunction and atrial dilation to study fibrosis and matrix metalloproteinase (MMP) activity in the left atrial (LA) myocardium by means of histologic, Western blot, zymographic, and immunohistologic techniques. RESULTS Three months after surgical ligature of the left coronary artery, 27 rats had a large MI, 12 were in mild HF, and 15 in severe HF. Both groups had LA enlargement at the echocardiography. Masson's trichrome and picrosirius staining of tissue sections revealed marked fibrosis at the periphery of trabeculae and also surrounding myolytic myocytes, in both mild and severe HF. In mild HF, the activity and expression of the matrilysin MMP-7 were increased (122%), whereas in severe HF, both MMP-7 (211%) and the gelatinase MMP-2 (187%) were up-regulated. There were no changes in the expression or activity of MMP inhibitors, TIMP-1, -2, and -4. Immunostaining of cryosections showed that MMP-2 was present in the interstitial spaces, whereas MMP-7 accumulated in myolytic myocytes. CONCLUSIONS Hemodynamic overload of the atria is an important pathogenic factor of fibrosis; MMP-7 appears to be involved in the early stage of this tissue remodeling process.
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Maier LS, Barckhausen P, Weisser J, Aleksic I, Baryalei M, Pieske B. Ca(2+) handling in isolated human atrial myocardium. Am J Physiol Heart Circ Physiol 2000; 279:H952-8. [PMID: 10993755 DOI: 10.1152/ajpheart.2000.279.3.h952] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Physiologically, human atrial and ventricular myocardium are coupled by an identical beating rate and rhythm. However, contractile behavior in atrial myocardium may be different from that in ventricular myocardium, and little is known about intracellular Ca(2+) handling in human atrium under physiological conditions. We used rapid cooling contractures (RCCs) to assess sarcoplasmic reticulum (SR) Ca(2+) content and the photoprotein aequorin to assess intracellular Ca(2+) transients in atrial and ventricular muscle strips isolated from nonfailing human hearts. In atrial myocardium (n = 19), isometric twitch force frequency dependently (0. 25-3 Hz) increased by 78 +/- 25% (at 3 Hz; P < 0.05). In parallel, aequorin light signals increased by 111 +/- 57% (P < 0.05) and RCC amplitudes by 49 +/- 13% (P < 0.05). Similar results were obtained in ventricular myocardium (n = 13). SR Ca(2+) uptake (relative to Na(+)/Ca(2+) exchange) frequency dependently increased in atrial and ventricular myocardium (P < 0.05). With increasing rest intervals (1-240 s), atrial myocardium (n = 7) exhibited a parallel decrease in postrest twitch force (at 240 s by 68 +/- 5%, P < 0.05) and RCCs (by 49 +/- 10%, P < 0.05). In contrast, postrest twitch force and RCCs significantly increased in ventricular myocardium (n = 6). We conclude that in human atrial and ventricular myocardium the positive force-frequency relation results from increased SR Ca(2+) turnover. In contrast, rest intervals in atrial myocardium are associated with depressed contractility and intracellular Ca(2+) handling, which may be due to rest-dependent SR Ca(2+) loss (Ca(2+) leak) and subsequent Ca(2+) extrusion via Na(+)/Ca(2+) exchange. Therefore, the influence of rate and rhythm on mechanical performance is not uniform in atrial and ventricular myocardium.
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Affiliation(s)
- L S Maier
- Abteilung Kardiologie und Pneumologie, Zentrum Innere Medizin, Georg-August-Universität Göttingen, 37075 Göttingen, Germany
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Aimé-Sempé C, Folliguet T, Rücker-Martin C, Krajewska M, Krajewska S, Heimburger M, Aubier M, Mercadier JJ, Reed JC, Hatem SN. Myocardial cell death in fibrillating and dilated human right atria. J Am Coll Cardiol 1999; 34:1577-86. [PMID: 10551709 DOI: 10.1016/s0735-1097(99)00382-4] [Citation(s) in RCA: 200] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
OBJECTIVES The aim of the present study was to determine if myocytes can die by apoptosis in fibrillating and dilated human atria. BACKGROUND The cellular remodeling that occurs during atrial fibrillation (AF) may reflect a degree of dedifferentiation of the atrial myocardium, a process that may be reversible. METHODS We examined human right atrial myocardium specimens (n = 50) for the presence of apoptotic myocytes. We used immunohistochemical and Western blotting analysis to examine the expression of a final effector of programmed cell death, caspase-3 (CASP-3) and of regulatory proteins from the BCL-2 family. RESULTS Sections from atria in AF contained a high percentage of large myocytes with a disrupted sarcomeric apparatus replaced by glycogen granules (64.4 +/- 6.3% vs. 12.2 +/- 5.8%). These abnormal myocytes, which also predominated in atria from hearts with decreased left ventricular ejection fraction (42.3 +/- 10.1%), contained large nuclei, most of which were TUNEL positive, indicating a degree of DNA breakage. None of these abnormal myocytes expressed the proliferative antigen Ki-67. A small percentage of the enlarged nuclei (4.2 +/- 0.8%) contained condensed chromatin and were strongly TUNEL positive. Both the pro- and activated forms of CASP-3 were detected in diseased myocardial samples, which also showed stronger CASP-3 expression than controls. Expression of the antiapoptotic BCL-2 protein was decreased in diseased atria, whereas that of the proapoptotic BAX protein remained unchanged. CONCLUSIONS In fibrillating and dilated atria, apoptotic death of myocytes with myolysis contributes to cellular remodeling, which may not be entirely reversible.
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Affiliation(s)
- C Aimé-Sempé
- INSERM U408, Faculté de Médecine, Xavier Bichat, Paris, France
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Ausma J, Wijffels M, Thoné F, Wouters L, Allessie M, Borgers M. Structural changes of atrial myocardium due to sustained atrial fibrillation in the goat. Circulation 1997; 96:3157-63. [PMID: 9386188 DOI: 10.1161/01.cir.96.9.3157] [Citation(s) in RCA: 474] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND After cardioversion of sustained atrial fibrillation (AF), the electrical and contractile functions of the atria are impaired, and recurrences of AF frequently occur. Whether remodeling of the structure of atrial myocardium is the basis for this problem is not known. METHODS AND RESULTS Sustained AF was induced by electrical pacing in 13 goats instrumented long-term. The goats were killed after 9 to 23 weeks, and the atrial myocardium was examined by light and electron microscopy. The changes were quantified in left and right atrial free walls, appendages, trabeculae, the interatrial septum, and the bundle of Bachmann. A substantial proportion of the atrial myocytes (up to 92%) revealed marked changes in their cellular substructures, such as loss of myofibrils, accumulation of glycogen, changes in mitochondrial shape and size, fragmentation of sarcoplasmic reticulum, and dispersion of nuclear chromatin. These changes were accompanied by an increase in size of the myocytes (up to 195%). There were virtually no signs of cellular degeneration, and the interstitial space remained unaltered. The duration of sustained AF did not significantly affect the degree of myolytic cell changes. CONCLUSIONS Sustained AF in goats leads to predominantly structural changes in the atrial myocytes similar to those seen in ventricular myocytes from chronic hibernating myocardium. These structural changes may explain the depressed contractile function of atrial myocardium after cardioversion. This goat model of AF offers a new approach to study the cascade of events leading to sustained AF and its maintenance.
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Affiliation(s)
- J Ausma
- Department of Molecular Cell Biology and Genetics, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands
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Hatem SN, Bénardeau A, Rücker-Martin C, Marty I, de Chamisso P, Villaz M, Mercadier JJ. Different compartments of sarcoplasmic reticulum participate in the excitation-contraction coupling process in human atrial myocytes. Circ Res 1997; 80:345-53. [PMID: 9048654 DOI: 10.1161/01.res.80.3.345] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The excitation-contraction coupling process of human atrial myocytes was studied in voltage-clamped myocytes isolated from right atrial appendages obtained during cardiac surgery. Intracellular Ca2+ transients (Cai transients) were monitored with 0.1 mmol/L indo 1 added to the internal dialyzing solution. Ryanodine receptors (RyRs) and sarcomeric alpha-actinin were stained with specific antibodies and visualized using plane and confocal microscopy. L-Type Ca2+ current (Ica) elicited a prolonged Cai transient, with an initial rapidly activating phase (slope 1, 23.6 +/- 1.2 s-1) followed by a slowly activating phase (slope 2, 5.8 +/- 0.4 s-1; P < .001 versus slope 1), resulting in a dome-shaped Cai transient. Ryanodine (100 mumol/L) inhibited 79 +/- 6% of the Cai transient, indicating that it was due essentially to sarcoplasmic reticulum Ca2+ release. During step depolarizations, maximal activation of the Cai transient or tail current (Itail) (in cells dialyzed with Ca2+ buffer-free internal solution) preceded that of Ica and did not follow its voltage dependence (n = 12). Test pulses lasting from 5 to 150 milliseconds elicited a similar time course of both Cai transient and Itail (n = 5). In a given cell, the two components of the Cai transient could be dissociated by altering the intracellular Ca2+ load, by increasing the stimulation rate from 0.1 to 1 Hz, or by varying the amplitude of Ica. Immunostaining of atrial sections and isolated myocytes showed that a large number of RyRs were located not only in a subsarcolemmal position but also deeper inside the cell, in a regularly spaced transverse band pattern at the level of Z lines. Together, our results indicate that, in human atrial myocytes, Ica only partially controls the activation of RyRs, with the prolonged and dome-shaped Cai transient of these cells probably reflecting the activation of RyRs not coupled to L-type Ca2+ channels.
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Affiliation(s)
- S N Hatem
- Laboratorie de Cardiologie Moléculaire et Cellulaire, Université de Paris XI-CNRS URA 1159, Hôpital Marie Lannelongue, Le Plessis Robinson, France
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Abstract
Ninety children, aged 1 day to 18 years (median 7 months), with electrocardiographic or echocardiographic evidence of left atrial (LA) enlargement were selected to determine if electrocardiographic criteria accurately reflected increased LA dimension as determined by echocardiography. Four cardiac defects known to produce LA enlargement were chosen: ventricular septal defect (24 patients), patient ductus arteriosus (25 patients), cardiomyopathy (27 patients) and mitral regurgitation (14 patients). Different electrocardiographic criteria for LA enlargement were assessed. The data indicated that the overall sensitivity and predictive value of the ECG to detect LA enlargement were 40 and 85%, respectively. The ECG and echocardiogram failed to agree in 62% of the patients. The most predictive variable for LA enlargement was the presence of a notched P wave in the limb leads with a large negative terminal deflection in lead V1. The sensitivity of ECG was highest in patients with chronic LA overload status, in mitral regurgitation (77%), cardiomyopathy (50%) and ventricular septal defect (54%). The results show that in the pediatric population, electrocardiographic criteria are moderately predictive for LA enlargement but not as sensitive as generally believed.
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Mary-Rabine L, Albert A, Pham TD, Hordof A, Fenoglio JJ, Malm JR, Rosen MR. The relationship of human atrial cellular electrophysiology to clinical function and ultrastructure. Circ Res 1983; 52:188-99. [PMID: 6218936 DOI: 10.1161/01.res.52.2.188] [Citation(s) in RCA: 130] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Although previous studies have described the electrophysiological and ultrastructural characteristics of human cardiac fibers, no attempt has been made as yet to describe quantitatively the relationship between the ultrastructural and cellular electrophysiological derangements occurring with cardiac disease, and their clinical manifestations. In this study, we used standard microelectrode techniques to record the action potential characteristics of human atrial fibers obtained during cardiac surgery and correlated the electrophysiological parameters with clinical and ultrastructural data. Ultrastructure was studied by optical and electron microscopy. We found a multiple linear regression among maximum diastolic potential, atrial size and pressure, P wave duration and ultrastructure changes. Proliferations of Z band material, widening of intercalated discs, and degenerative changes were quantified and correlated with electrophysiological and clinical data. These studies emphasize the relationship between hemodynamic anomalies and resultant changes in both human atrial fiber structure and electrical function. Finally, the likelihood of occurrence of arrhythmias can be predicted using the analytic method described.
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Abstract
We studied with ultrastructure techniques portions of right atrium resected at operation from 12 patients with chronic rheumatic heart disease and 6 patients with non-rheumatic valvular heart disease. The right atrial pressures, duration of symptoms and age of the patients were comparable in both groups. Ten of the 12 rheumatic and 4 of the 6 non-rheumatic patients had atrial fibrillation. In the 12 rheumatic patients we found severe interstitial fibrosis, extensive cellular degeneration (17% of cells studied) and marked cellular hypertrophy (average cell diameter 16 micrometers). The six non-rheumatic patients showed evidence of cellular hypertrophy (average cell diameter 15 micrometers) but minimal interstitial fibrosis or cellular degeneration. The degenerative changes in the rheumatic group did not correlate with the degree of hypertrophy or the extent of the hemodynamic alterations. Atrial fibrillation, present in both rheumatic and non-rheumatic patients, did not correlate with the presence of cellular degeneration. We conclude that the structural changes in atria of patients with chronic rheumatic heart disease may be part of the rheumatic process and are not entirely secondary to altered hemodynamics.
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