951
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Sato T, Mitamura H, Kurita Y, Takeshita A, Shinagawa K, Miyoshi S, Kanki H, Hara M, Ogawa S. Electropharmacologic effects of pilsicainide, a pure sodium channel blocker, on the remodeled atrium subjected to chronic rapid pacing. J Cardiovasc Pharmacol 2001; 38:812-20. [PMID: 11707684 DOI: 10.1097/00005344-200112000-00002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Clinical experience suggests that sodium channel blockers are effective in converting atrial fibrillation of recent onset but not chronic atrial fibrillation. We investigated changes in the electrophysiologic effects of pilsicainide, a pure sodium channel blocker, on the canine atrium during chronic rapid pacing (400/min). Three pairs of bipolar electrodes were sutured to the right atrial appendage in six dogs. Five days later, rapid atrial pacing was started after baseline measurements of the effective refractory period (ERP), the intra-atrial conduction velocity, the atrial wavelength, and the inducibility of atrial fibrillation. These studies were repeated at 2, 7, and 14 days of pacing, both before and after pilsicainide administration. Before pacing, pilsicainide increased ERP more than it decreased conduction velocity, causing an increase of wavelength, particularly at faster rates. However, this use-dependent prolongation of ERP disappeared after 2 days of pacing. Thus, pilsicainide failed to prolong ERP during chronic pacing, allowing progressive shortening of wavelength in the remodeled atrium. The effect of sodium channel blockers on atrial refractoriness may decline as rapid atrial excitation persists, limiting the usefulness of these agents for the treatment of chronic atrial fibrillation.
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Affiliation(s)
- T Sato
- Cardiopulmonary Division, Department of Medicine, Keio University, School of Medicine, Tokyo, Japan.
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952
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Ausma J, Litjens N, Lenders MH, Duimel H, Mast F, Wouters L, Ramaekers F, Allessie M, Borgers M. Time course of atrial fibrillation-induced cellular structural remodeling in atria of the goat. J Mol Cell Cardiol 2001; 33:2083-94. [PMID: 11735256 DOI: 10.1006/jmcc.2001.1472] [Citation(s) in RCA: 157] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Previously we documented cellular structural changes of a non-degenerative nature in atrial myocytes after atrial fibrillation (AF) in the goat. The time course of these changes was not studied. METHODS AND RESULTS Cellular structural changes were studied by light- and electron microscopy and immunohistochemistry in goat atria after 0-16 weeks AF. The first sign of cellular structural remodeling was a more homogeneous chromatin distribution, at 1 week of AF. Sub-structural changes in mitochondria and sarcoplasmic reticulum occurred gradually. Cellular degeneration was absent. The degree of myolysis and glycogen accumulation increased till 8 weeks of AF and did not increase further from thereon. After 16 weeks of AF, 42% of the myocytes in the right atrial free wall were affected by myolysis. The diameter of the atrial myocytes increased. Dedifferentiation of the atrial myocytes was suggested by altered expression patterns of structural proteins, such as the disappearance of cardiotin (1 week), the A-I junctional part of titin (4 weeks), desmin at the intercalated disk (ID) (8 weeks) and a gradual re-expression of alpha-smooth muscle actin. CONCLUSION Remodeling of the cellular ultrastructure in atrial myocardium of the goat develops progressively during AF. Re-expression of fetal proteins indicate dedifferentiation of atrial myocytes, analogous to observations in hibernating myocardium of the ventricle.
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Affiliation(s)
- J Ausma
- Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands.
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953
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Fuster V, Rydén LE, Asinger RW, Cannom DS, Crijns HJ, Frye RL, Halperin JL, Kay GN, Klein WW, Lévy S, McNamara RL, Prystowsky EN, Wann LS, Wyse DG, Gibbons RJ, Antman EM, Alpert JS, Faxon DP, Fuster V, Gregoratos G, Hiratzka LF, Jacobs AK, Russell RO, Smith SC, Klein WW, Alonso-Garcia A, Blomström-Lundqvist C, De Backer G, Flather M, Hradec J, Oto A, Parkhomenko A, Silber S, Torbicki A. ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation: executive summary. A Report of the American College of Cardiology/ American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines and Policy Conferences (Committee to Develop Guidelines for the Management of Patients With Atrial Fibrillation): developed in Collaboration With the North American Society of Pacing and Electrophysiology. J Am Coll Cardiol 2001; 38:1231-66. [PMID: 11583910 DOI: 10.1016/s0735-1097(01)01587-x] [Citation(s) in RCA: 486] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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954
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Fuster V, Rydén LE, Asinger RW, Cannom DS, Crijns HJ, Frye RL, Halperin JL, Kay G, Klein WW, Lévy S, McNamara RL, Prystowsky EN, Wann L, Wyse D, Gibbons RJ, Antman EM, Alpert JS, Faxon DP, Fuster V, Gregoratos G, Hiratzka LF, Jacobs AK, Russell RO, Smith SC, Klein WW, Alonso-Garcia A, Blomström-Lundqvist C, De Backer G, Flather M, Hradec J, Oto A, Parkhomenko A, Silber S, Torbicki A. ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation31This document was approved by the American College of Cardiology Board of Trustees in August 2001, the American Heart Association Science Advisory and Coordinating Committee in August 2001, and the European Society of Cardiology Board and Committee for Practice Guidelines and Policy Conferences in August 2001.32When citing this document, the American College of Cardiology, the American Heart Association, and the European Society of Cardiology would appreciate the following citation format: Fuster V, Rydén LE, Asinger RW, Cannom DS, Crijns HJ, Frye RL, Halperin JL, Kay GN, Klein WW, Lévy S, McNamara RL, Prystowsky EN, Wann LS, Wyse DG. ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines and Policy Conferences (Committee to Develop Guidelines for the Management of Patients With Atrial Fibrillation). J Am Coll Cardiol 2001;38:XX-XX.33This document is available on the World Wide Web sites of the American College of Cardiology (www.acc.org), the American Heart Association (www.americanheart.org), the European Society of Cardiology (www.escardio.org), and the North American Society of Pacing and Electrophysiology (www.naspe.org). Single reprints of this document (the complete Guidelines) to be published in the mid-October issue of the European Heart Journal are available by calling +44.207.424.4200 or +44.207.424.4389, faxing +44.207.424.4433, or writing Harcourt Publishers Ltd, European Heart Journal, ESC Guidelines – Reprints, 32 Jamestown Road, London, NW1 7BY, United Kingdom. Single reprints of the shorter version (Executive Summary and Summary of Recommendations) published in the October issue of the Journal of the American College of Cardiology and the October issue of Circulation, are available for $5.00 each by calling 800-253-4636 (US only) or by writing the Resource Center, American College of Cardiology, 9111 Old Georgetown Road, Bethesda, Maryland 20814. To purchase bulk reprints specify version and reprint number (Executive Summary 71-0208; full text 71-0209) up to 999 copies, call 800-611-6083 (US only) or fax 413-665-2671; 1000 or more copies, call 214-706-1466, fax 214-691-6342; or E-mail: pubauth@heart.org. J Am Coll Cardiol 2001. [DOI: 10.1016/s0735-1097(01)01586-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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955
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Hung MJ, Wang CH, Kuo LT, Cherng WJ. Coronary artery spasm-induced paroxysmal atrial fibrillation--a case report. Angiology 2001; 52:559-62. [PMID: 11512696 DOI: 10.1177/000331970105200809] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Paroxysmal atrial fibrillation is described in a patient that was consistent with the clinical history developed after induction of coronary artery spasm. The mechanism appeared to be sinus node artery spasm inducing sinus node ischemia. Coronary artery spasm can be a cause of paroxysmal atrial fibrillation.
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Affiliation(s)
- M J Hung
- Department of Medicine, Chang Gung Memorial Hospital, Keelung, Taiwan
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956
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Sato T, Mitamura H, Kurita Y, Takeshita A, Shinagawa K, Miyoshi S, Kanki H, Hara M, Takatsuki S, Soejima K, Ogawa S. Recovery of electrophysiological parameters after conversion of atrial fibrillation. Int J Cardiol 2001; 79:183-9. [PMID: 11461740 DOI: 10.1016/s0167-5273(01)00419-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We investigated the recovery of electrophysiological parameters from electrical remodeling after conversion of chronic lone atrial fibrillation in humans. Clinical studies have shown that the longer atrial fibrillation lasts, the more difficult it becomes to maintain the sinus rhythm after cardioversion. To explore the effects of the duration of atrial fibrillation on changes of electrophysiological parameters after conversion, we determined the atrial effective refractory period and P wave duration during right atrial pacing at 1 and 24 h after electrical cardioversion in 15 patients with chronic lone atrial fibrillation (median duration, 6 months). By 24 h after cardioversion, the effective refractory period at a pacing cycle length of 600 ms increased from 225+/-19 to 254+/-27 ms. However, the P wave duration did not decrease significantly 24 h after conversion. As the duration of atrial fibrillation became longer, the prolongation of effective refractory period was more delayed (P<0. 001, r=0.82), and the shortening of P wave duration was significantly smaller within 24 h after cardioversion (P<0. 001, r=0.67). After cardioversion of chronic lone atrial fibrillation, the recovery of shortened atrial refractoriness and prolonged intraatrial conduction time is dependent on the duration of preexisting atrial fibrillation.
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Affiliation(s)
- T Sato
- Cardiopulmonary Division, Department of Medicine, Keio University School of Medicine, 35 Shinanomachi Shinjuku-ku, Tokyo 160-8582, Japan.
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957
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Santoni-Rugiu F, Verma R, Mehta D, Gopal A, Chan EK, Pe E, Gomes JA. Signal-averaged P-wave ECG discriminates between persistent and paroxysmal atrial fibrillation. J Electrocardiol 2001; 34:189-95. [PMID: 11455508 DOI: 10.1054/jelc.2001.25133] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Atrial fibrillation (Afib) has been associated with abnormal signal-averaged P wave (SAPW) parameters but whether SAPW is associated with the time course of these arrhythmias (persistent vs. paroxysmal, frequent vs. rare episodes) remains unknown. This article assesses the significance of SAPW duration in distinguishing patients with paroxysmal from those with persistent Afib. SAPW electrocardiogram was performed with a "double triggering" software system for acquisition and analysis of data. SAPW total duration (TD), X, Y, and Z leads magnitudes and vector signal magnitudes were measured offline. Optimal cutoff value between control and patient groups was determined by using a receiver operator characteristic curve. Data were analyzed to compare controls with patients groups and between patient groups according to time course of the arrhythmic history. Fifteen age-matched patients without a history of Afib and 55 patients with a history of Afib (33 with paroxysmal and 22 with persistent arrhythmia) were studied off antiarrhythmic drugs. Patients with history of persistent arrhythmia were studied within 2 days after electrical cardioversion to sinus rhythm. SAPW TD was the only parameter consistently associated with Afib. SAPW TD was 98 +/- 6 ms (mean +/- SD) in the control group, 127 +/- 19 ms in the pooled patients group (P =.0001); 122 +/- 20 ms for paroxysmal and 133 +/- 17 ms for the persistent Afib group (P =.04). Analysis of other SAPW parameters were not statistically significant. SAPW duration is a simple method to identify patients with history of Afib. A significantly longer SAPW TD characterizes patients with a history of persistent as opposed to paroxysmal Afib. Prolongation of SAPW TD possibly reflects more advanced electrophysiological changes, creating a more stable substrate that leads to persistence of the arrhythmia.
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Affiliation(s)
- F Santoni-Rugiu
- Electrophysiology Section of the Zena and Micheal Wiener Cardiovascular Institute, Department of Medicine, The Mount Sinai Medical Center and The Mount Sinai School of Medicine of NYU, New York, NY 10029, USA.
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958
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Lendeckel U, Arndt M, Wrenger S, Nepple K, Huth C, Ansorge S, Klein HU, Goette A. Expression and activity of ectopeptidases in fibrillating human atria. J Mol Cell Cardiol 2001; 33:1273-81. [PMID: 11444929 DOI: 10.1006/jmcc.2001.1389] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent studies have demonstrated that atrial fibrillation (AF) occurs in the presence of degenerative changes of atrial tissue. In contrast, bradykinin (BK) appears to have cardioprotective effects diminishing myocardial hypertrophy and fibrosis. It is unknown, however, whether AF has direct effects on BK metabolism. Therefore, the purpose of this study was to determine the atrial expression of the membrane-bound peptidases, also referred to as ectopeptidases, carboxypeptidase M (CPM), dipeptidyl peptidase IV (DPIV), and alanyl-aminopeptidase (APN) in patients with and without AF. Atrial tissue samples of 35 patients undergoing open heart surgery were examined. Seventeen patients had chronic persistent AF (> or = 6 months; CAF), the remaining 18 patients (controls) had no history of AF. Peptidase expression was analyzed at the mRNA (quantitative RT-PCR) level and apparent changes were confirmed at the protein level. In case of unaltered mRNA levels, enzyme activity was determined. Reduced amounts of CPM-mRNA were found in patients with CAF (41.3+/-9.7 U nu controls: 86.1+/-17.5 U P<0.05). CPM protein was decreased to 47.5% in patients with CAF compared with controls (P<0.01). DPIV and APN mRNA amounts were similar in both groups. DPIV activity, however, was increased during CAF (219.6+/-30 pkat/mg protein v controls: 195.8+/-21.8 pkat/mg P<0.05). APN activity was unchanged. In conclusion, atrial bradykinin metabolizing activities are significantly altered during AF in humans. The observed alterations in ectopeptidase expression/activity may play a role in the structural remodeling of fibrillating atria.
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Affiliation(s)
- U Lendeckel
- Institute of Experimental Internal Medicine, University Hospital Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany.
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959
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Affiliation(s)
- R H Falk
- Section of Cardiology, Boston Medical Center, MA 02118, USA.
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960
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Lin JL, Lai LP, Tseng YZ, Lien WP, Huang SK. Global distribution of atrial ectopic foci triggering recurrence of atrial tachyarrhythmia after electrical cardioversion of long-standing atrial fibrillation: a bi-atrial basket mapping study. J Am Coll Cardiol 2001; 37:904-10. [PMID: 11693769 DOI: 10.1016/s0735-1097(00)01192-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES The objective of this study was to assess the spatial distribution of atrial ectopic foci potentially triggering recurrent atrial tachyarrhythmias after electrical cardioversion of long-standing atrial fibrillation (AF). BACKGROUND It remains unknown whether targeted ablation of atrial ectopic foci concentrated in the pulmonary veins is feasible in patients with long-standin
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Affiliation(s)
- J L Lin
- Department of Internal Medicine, National Taiwan University Hospital, Taipei.
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961
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Abstract
Atrial fibrillation is a common cardiac arrhythmia with significant sequela. The goals of treating atrial fibrillation are rate control, prevention of thromboembolism, and maintenance of sinus rhythm. The epidemiology and pathophysiology of atrial fibrillation is reviewed, as well as strategies and recommendations for achieving therapeutic goals. The authors also review investigational therapeutic options using nonpharmacologic modalities.
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Affiliation(s)
- F Pelosi
- Division of Cardiology, University of Michigan Health System, Ann Arbor, Michigan, USA.
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962
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Connelly JH, Clubb FJ, Vaughn W, Duncan M. Morphological changes in atrial appendages removed during the maze procedure: a comparison with autopsy controls. Cardiovasc Pathol 2001; 10:39-42. [PMID: 11343994 DOI: 10.1016/s1054-8807(01)00057-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Atrial fibrillation (AF) is commonly encountered in clinical practice and typically it is treated with pharmacological agents. Some patients whose arrhythmias are resistant to pharmacological therapy undergo the maze procedure, which is a surgical treatment. The atrial appendages are removed as part of the surgical procedure. These appendages often demonstrate mycocyte hypertrophy, vacuolar degeneration and other changes that may be seen in cardiomyopathies. We examined 19 of these appendages and compared them with 17 autopsy controls, 12 of whom had documented coronary atherosclerotic disease and 5 of whom did not. We semiquantitatively measured the amount of vacuolar degeneration, interstitial fibrosis, myocyte hypertrophy and intramyocardial adipose tissue. Univariate and multivariate analysis was performed and revealed that vacuolar degeneration were significantly more common in appendages of patients with arrhythmias than the autopsy controls (P<.0004). The other three histological features studied were not significantly different in the three groups. Ultrastructural studies on atrial tissue excised during the maze procedure, retrieved from the paraffin blocks, revealed degenerative changes similar to cardiomyopathic myocardial tissue. Vacuolar degeneration is commonly seen in atrial appendages removed in patients with chronic AF. Myocyte hypertrophy is a nonspecific finding and may occur in patients with arrhthymias and coronary artery disease.
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Affiliation(s)
- J H Connelly
- Department of Pathology, St. Luke's Episcopal Hospital and Texas Heart Institute, Houston, TX 77030, USA.
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963
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Goette A, Staack T, Röcken C, Arndt M, Geller JC, Huth C, Ansorge S, Klein HU, Lendeckel U. Increased expression of extracellular signal-regulated kinase and angiotensin-converting enzyme in human atria during atrial fibrillation. J Am Coll Cardiol 2000; 35:1669-77. [PMID: 10807475 DOI: 10.1016/s0735-1097(00)00611-2] [Citation(s) in RCA: 393] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVES The purpose of this study was to determine whether atrial expression of the extracellular signal-regulated kinases Erk1/Erk2 and of the angiotensin-converting enzyme (ACE) is altered in patients with atrial fibrillation (AF). BACKGROUND Recent studies have demonstrated that atrial fibrosis can provide a pathophysiologic substrate for AF. However, the molecular mechanisms responsible for the development of atrial fibrosis are unclear. METHODS Atrial tissue samples of 43 patients undergoing open heart surgery were examined. Seventeen patients had chronic persistent AF (> or =6 months; CAF), 8 patients had paroxysmal AF (PAF) and 18 patients had no history of AF. Erk expression was analyzed at the mRNA (quantitative reverse transcription polymerase chain reaction), the protein (immunoblot techniques) and atrial tissue (immunohistochemistry) levels. Erk-activating kinases (MEK1/2) and ACE were analyzed by immunoblot techniques. RESULTS Increased amounts of Erk2-mRNA were found in patients with CAF (75 +/- 20 U vs. sinus rhythm: 31 +/- 25 U; p < 0.05). Activated Erk1/Erk2 and MEK1/2 were increased to more than 150% in patients with AF compared to patients with sinus rhythm. No differences between CAF and PAF were found. The expression of ACE was three-fold increased during CAF. Amounts of activated Erk1/Erk2 were reduced in patients treated with ACE inhibitors. Patients with AF showed an increased expression of Erk1/Erk2 in interstitial cells and marked atrial fibrosis. CONCLUSIONS An ACE-dependent increase in the amounts of activated Erk1/Erk2 in atrial interstitial cells may contribute as a molecular mechanism for the development of atrial fibrosis in patients with AF. These findings may have important impact on the treatment of AF.
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Affiliation(s)
- A Goette
- University Hospital Magdeburg, Department of Internal Medicine, Germany
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964
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Rossi A, Enriquez-Sarano M, Burnett JC, Lerman A, Abel MD, Seward JB. Natriuretic peptide levels in atrial fibrillation: a prospective hormonal and Doppler-echocardiographic study. J Am Coll Cardiol 2000; 35:1256-62. [PMID: 10758968 DOI: 10.1016/s0735-1097(00)00515-5] [Citation(s) in RCA: 168] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES The objective was to determine the independent association between atrial fibrillation (A-Fib) and activation of natriuretic peptides. BACKGROUND The association of A-Fib with activation of N-terminal atrial and brain natriuretic peptides (N-ANPs and BNPs, respectively) is uncertain but of great importance for the diagnostic utilization of natriuretic peptides. This uncertainty is related to the lack of appropriate controls, with left ventricular (LV) and atrial overload similar to A-Fib. METHODS We prospectively measured N-terminal atrial and BNPs and endothelin-1 levels in 100 patients and 14 age- and gender-matched control subjects. The 32 patients with A-Fib were compared with 68 patients in sinus rhythm and similar LV and atrial overload (due to mitral regurgitation or LV dysfunction) measured simultaneously with hormonal levels with comprehensive Doppler echocardiography. RESULTS Patients with A-Fib compared with those in sinus rhythm had similar symptoms, comorbid conditions, cardioactive medications, pulmonary pressure, left atrial volume, and LV ejection fraction and filling characteristics but demonstrated higher N-ANP levels (2,613 +/- 1,681 vs. 1,654 +/- 1,323 pg/ml, p = 0.007) even after adjustment for the underlying cardiac disease (p < 0.0001). Conversely, BNP levels were similar in both groups (165 +/- 163 vs. 160 +/- 269 pg/ml, p = 0.9). In multivariate analysis, a higher N-ANP level was associated with A-Fib (p = 0.0003), symptom class (p < 0.0001) and endothelin-1 level (p = 0.032) independently of left atrial volume and LV ejection fraction. Conversely, BNP showed no independent association with and was most strongly associated with LV ejection fraction (p < 0.0001). CONCLUSIONS Atrial fibrillation is an independent determinant of higher N-ANP levels and blurs its association with LV dysfunction. Conversely, the BNP is not independently associated with A-Fib and is strongly determined by LV dysfunction, for which it is an independent marker.
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Affiliation(s)
- A Rossi
- Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and Mayo Foundation, Rochester, Minnesota, USA
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965
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Understanding the Pathophysiology of Atrial Fibrillation from Clinical Observations. DEVELOPMENTS IN CARDIOVASCULAR MEDICINE 2000. [DOI: 10.1007/978-0-585-28007-3_2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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966
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Thijssen VL, Ausma J, Liu GS, Allessie MA, van Eys GJ, Borgers M. Structural changes of atrial myocardium during chronic atrial fibrillation. Cardiovasc Pathol 2000; 9:17-28. [PMID: 10739903 DOI: 10.1016/s1054-8807(99)00038-1] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Of all known arrhythmia's, atrial fibrillation (AF) is the most often met in the clinical setting and it is associated with an increase in mortality risk. Several risk factors for AF have been described and several mechanisms of induction and maintenance have been proposed. Studies in patients with AF have shown that structural changes occur in the atria, but the relationship between the structural remodelling and the chronicity of the arrhythmia are not well understood. The changes mainly concern adaptive (dedifferentiation of cardiomyocytes) and maladaptive (degeneration of cells with replacement fibrosis) features. In order to characterise the time course of the structural remodelling the need for animal models which adequately mimic chronic atrial fibrillation in humans is felt essential. In this review, the structural changes that are observed during prolonged sustained AF in patients and animal models, are described. Furthermore, the time course and potential mechanisms of structural remodelling are discussed and methods for elucidation of the underlying molecular mechanisms are presented.
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Affiliation(s)
- V L Thijssen
- Department of Molecular Cell Biology & Genetics, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands
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967
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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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968
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Gaspo R. The tachycardia-induced dog model of atrial fibrillation. clinical relevance and comparison with other models. J Pharmacol Toxicol Methods 1999; 42:11-20. [PMID: 10715599 DOI: 10.1016/s1056-8719(99)00042-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In the past, investigators have relied extensively on acute in vivo models of atrial fibrillation (AF), in which AF was induced either pharmacologicly or by vagal stimulation. More recently, there is a need and desire for more clinically relevant models that can only be achieved with the use of chronically instrumented animals. One of these models is the atrial tachycardia-induced AF dog model, which is the main focus of this review. The model produces a persistent AF in 80% of animals paced at 400 beats/min for 6 weeks. Atrial tachycardia also induces various pathophysiologic and ultrastructural changes that often resemble electrical remodeling of atria in patients that have a high susceptibility to AF. This model can also be used to evaluate drug efficacy with respect to attenuation of AF duration or conversion of AF to sinus rhythm. The model may therefore be used to provide further insights into the discovery of new therapeutic approaches to modifying this atrial arrhythmic disorder in man.
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Affiliation(s)
- R Gaspo
- Department of Pharmacology, Centre for Therapeutic Research, Merck Frosst Canada, 16711 Trans Canada Hwy., Kirkland, Quebec, Canada.
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969
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970
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Ciotti R, Belotti G, Facchi E, Cantù A, D'Amico A, Gatti C. Sudden cardio-pulmonary toxicity following a single infusion of gemcitabine. Ann Oncol 1999; 10:997. [PMID: 10509166 DOI: 10.1023/a:1008305716918] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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971
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Warraich RS, Dunn MJ, Yacoub MH. Subclass specificity of autoantibodies against myosin in patients with idiopathic dilated cardiomyopathy: pro-inflammatory antibodies in DCM patients. Biochem Biophys Res Commun 1999; 259:255-61. [PMID: 10362496 DOI: 10.1006/bbrc.1999.0761] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Detection of antimyosin antibodies in non-inflammatory cardiac disease undermines their disease specificity as a sensitive marker of damage in dilated cardiomyopathy (DCM) patients. Antibody subclass specificity could provide a more sensitive marker of disease and possibly discriminate the humoral autoimmune responses in different cardiac diseases. Frequency and reactivity of autoantibodies against alpha- and beta-isoforms of myosin heavy chain (mhc) were evaluated by ELISA for IgG, IgM, and subclasses IgG1, IgG2, and IgG3 in patients with DCM (NYHA III/IV, n = 82), end stage ischemic heart disease (E-IHD: NYHA III/IV, n = 62), mild ischemic heart disease (NYHA I/II, n = 27), and controls (n = 54). Autoantibodies against atrial and ventricular myosin were raised in heart failure patients compared to mild-IHD and controls but with different antigen affinities. Reactivity in E-IHD was significantly raised against (ventricular) beta-mhc compared with only mild-IHD patients, suggesting a relative increase in ventricular specific antibodies in IHD patients with a higher NYHA class. IgG subclass analysis for IgG1, IgG2, and IgG3 against alpha- and beta-mhc showed statistically raised levels of IgG3 only in DCM patients and a significantly higher reactivity of IgG2 in heart failure patients versus controls. The results demonstrate immunological heterogeneity of antimyosin antibodies developed in different clinical entities. Pro-inflammatory characteristics of IgG3 antibodies in a select group of patients with DCM may contribute to autoimmune mechanisms of injury in these patients.
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Affiliation(s)
- R S Warraich
- National Heart and Lung Institute, Harefield Hospital, Harefield, Middlesex, UB9 6JH, United Kingdom
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972
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Abstract
Atrial fibrillation remains one of the most challenging arrhythmias in cardiology. Despite the overall advance in the treatment of patients with cardiac dysrhythmias with the introduction of radiofrequency ablation, therapeutic options in atrial fibrillation have remained largely unchanged and aimed at controlling the heart rate and anticoagulation. New surgical and ablation compartmentalization techniques are being developed that are promising, but to date these techniques are still extremely laborious and available only to a handful of patients. Advances in genetics and molecular biology will likely give new insights into the development of the disease. Molecular biology research is presently focused into two main fields: 1) identification of the genes that cause familial forms of the disease, and 2) altered gene expression during the disease state. These studies are aimed at identifying not only the triggering factors in the acute form but also those that prolong the arrhythmia and convert it into a chronic form.
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Affiliation(s)
- R Brugada
- Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
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973
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Abstract
INTRODUCTION With few exceptions, acquired heart disease is the result of gradual changes in the heart, progressing during several months or years. This also includes certain cardiac arrhythmias, as for instance atrial fibrillation (AF). In spite of the important role of slowly progressing pathologic processes, most of our knowledge about mechanisms of cardiac arrhythmias is based on acute experiments. Only recently, the attention also is more focused on long-term adaptation processes like cardiac memory, electrical remodeling, and tachycardia-induced cardiomyopathy. In experimental animal models, it has been shown that AF induces a vicious circle of electrophysiologic and structural changes that inevitably leads to "domestication" of the arrhythmia ("AF begets AF"). In this article, the studies on AF-induced electrophysiologic and cellular remodeling are discussed.
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Affiliation(s)
- M A Allessie
- Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands
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974
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Abstract
Atrial fibrillation (AF) is an arrhythmia associated with a wide variety of cardiac conditions, and it carries a risk of thromboembolism which varies with the underlying disease. The prevalence of AF increases markedly with age, and a review of histopathologic studies reveals that normal aging produces histologic changes in atrial conduction that may lead to the development of atrial arrhythmias. The diverse pathologic causes of AF also result in histologic abnormalities, and an examination of the relation of the etiology of the arrhythmia to pathologic changes suggests a possible reason for the varying risk of thrombus formation. The interaction between the histologic abnormalities and the presence of triggers of AF may also play an important role in the onset and maintenance of this common condition.
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Affiliation(s)
- R H Falk
- Boston Medical Center, Massachusetts 02118, USA.
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975
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Maixent JM, Paganelli F, Scaglione J, Lévy S. Antibodies against myosin in sera of patients with idiopathic paroxysmal atrial fibrillation. J Cardiovasc Electrophysiol 1998; 9:612-7. [PMID: 9654226 DOI: 10.1111/j.1540-8167.1998.tb00942.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Circulating autoantibodies against myosin heavy chain have been detected in patients with ventricular myocarditis and in patients with dilated cardiomyopathy. This study investigated the presence of antibodies against myosin in sera of healthy control persons as compared with patients with idiopathic paroxysmal atrial fibrillation refractory to antiarrhythmic therapy. METHODS AND RESULTS An SDS-PAGE (sodium dodecylsulfate polyacrylamide gel electrophoresis) procedure, followed by Western blotting with homogenates and membrane fractions of human left ventricular and atrial specimen as antigens, was used to analyze sera of 10 patients with idiopathic paroxysmal atrial fibrillation and 10 age-matched healthy control subjects. Circulating immunoglobulin G reactivity against cardiac myosin heavy chain was detected in 6 patients (60%) as compared with 1 control subject (10%). This difference was statistically significant (P < 0.05). All patients with idiopathic paroxysmal atrial fibrillation who showed reactivity against myosin heavy chain also had specific reactivity in their sera that exhibited reactivities to both ventricular and atrial cardiac myosin heavy chain isoforms. CONCLUSION This study demonstrates the presence of circulating autoantibodies against myosin heavy chain in a significant percentage of patients with idiopathic paroxysmal atrial fibrillation and raises the possibility of an autoimmune process in some patients with paroxysmal atrial fibrillation.
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Affiliation(s)
- J M Maixent
- Division of Cardiology, University of Marseille, School of Medicine, Centre Hospitalo Universitaire Nord and Institut Fédératif Jean Roche, Marseille, France
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