Rate-dependence of atrial tachycardia effects on atrial refractoriness and atrial fibrillation maintenance. 2009

Akiko Shiroshita-Takeshita, and Hideo Mitamura, and Satoshi Ogawa, and Stanley Nattel
Department of Medicine and Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger Street, Montreal, Quebec, Canada.

OBJECTIVE Although atrial-tachycardia remodelling is a significant atrial fibrillation (AF) promoting factor, little information is available about how atrial-tachycardia rate determines remodelling effects. This study assessed the effects of atrial tachypacing (ATP) over a range of clinically relevant rates on atrial electrophysiology and AF. RESULTS Chronically instrumented dogs underwent sequential 7 day ATP at 400, 300, 200, and 160 bpm in random order with 2 day recovery intervals between periods of ATP. ATP at 400, 300, and 200 bpm significantly decreased atrial effective refractory period (ERP) by 41 +/- 2, 37 +/- 3, and 7 +/- 1 ms, respectively, with no significant effects at 160 bpm. Mean duration of induced AF was increased by 400 and 300 bpm ATP (404 +/- 284 and 410 +/- 283 s on day 4, respectively, vs. 12 +/- 4 s at baseline, P < 0.01), but not by 200 or 160 bpm ATP. ATP effects developed slowly with 200 bpm pacing, so we studied 5 week ATP at 200 and 160 bpm in additional dogs. ERP shortened gradually over 3 weeks at 200 bpm (131 +/- 5 ms baseline vs. 112 +/- 4 and 105 +/- 4 ms at 2 and 3 weeks, respectively), but no decrease occurred thereafter (5-week value: 104 +/- 3 ms) and AF duration was not significantly affected. No change in ERP or AF duration occurred at 160 bpm. Because of the limited effects of 200 bpm ATP on AF duration despite significant effects on ERP, we tested 200 bpm ATP effects in the presence of AF substrates. When 200 bpm ATP was induced in the presence of a fibrotic AF substrate induced by 2 weeks of ventricular tachypacing followed by 1 week recovery, no change in AF duration or atrial vulnerability occurred. However, when 200 bpm ATP was followed by 400 bpm ATP, the onset of remodelling and AF duration increases was accelerated. CONCLUSIONS There is a non-linear relationship between atrial rate and the extent of atrial electrical remodelling. Remodelling at rates equivalent to paroxysmal supraventricular tachycardias in man is insufficient to promote AF alone or in the presence of an atrial fibrotic substrate, but can accelerate the remodelling and stabilization of AF when followed by faster atrial tachyarrhythmias.

UI MeSH Term Description Entries
D002304 Cardiac Pacing, Artificial Regulation of the rate of contraction of the heart muscles by an artificial pacemaker. Pacing, Cardiac, Artificial,Artificial Cardiac Pacing,Artificial Cardiac Pacings,Cardiac Pacings, Artificial,Pacing, Artificial Cardiac,Pacings, Artificial Cardiac
D004195 Disease Models, Animal Naturally-occurring or experimentally-induced animal diseases with pathological processes analogous to human diseases. Animal Disease Model,Animal Disease Models,Disease Model, Animal
D004285 Dogs The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065) Canis familiaris,Dog
D006325 Heart Atria The chambers of the heart, to which the BLOOD returns from the circulation. Heart Atrium,Left Atrium,Right Atrium,Atria, Heart,Atrium, Heart,Atrium, Left,Atrium, Right
D006339 Heart Rate The number of times the HEART VENTRICLES contract per unit of time, usually per minute. Cardiac Rate,Chronotropism, Cardiac,Heart Rate Control,Heartbeat,Pulse Rate,Cardiac Chronotropy,Cardiac Chronotropism,Cardiac Rates,Chronotropy, Cardiac,Control, Heart Rate,Heart Rates,Heartbeats,Pulse Rates,Rate Control, Heart,Rate, Cardiac,Rate, Heart,Rate, Pulse
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001281 Atrial Fibrillation Abnormal cardiac rhythm that is characterized by rapid, uncoordinated firing of electrical impulses in the upper chambers of the heart (HEART ATRIA). In such case, blood cannot be effectively pumped into the lower chambers of the heart (HEART VENTRICLES). It is caused by abnormal impulse generation. Auricular Fibrillation,Familial Atrial Fibrillation,Paroxysmal Atrial Fibrillation,Persistent Atrial Fibrillation,Atrial Fibrillation, Familial,Atrial Fibrillation, Paroxysmal,Atrial Fibrillation, Persistent,Atrial Fibrillations,Atrial Fibrillations, Familial,Atrial Fibrillations, Paroxysmal,Atrial Fibrillations, Persistent,Auricular Fibrillations,Familial Atrial Fibrillations,Fibrillation, Atrial,Fibrillation, Auricular,Fibrillation, Familial Atrial,Fibrillation, Paroxysmal Atrial,Fibrillation, Persistent Atrial,Fibrillations, Atrial,Fibrillations, Auricular,Fibrillations, Familial Atrial,Fibrillations, Paroxysmal Atrial,Fibrillations, Persistent Atrial,Paroxysmal Atrial Fibrillations,Persistent Atrial Fibrillations
D013612 Tachycardia, Ectopic Atrial Abnormally rapid heartbeats originating from one or more automatic foci (nonsinus pacemakers) in the HEART ATRIUM but away from the SINOATRIAL NODE. Unlike the reentry mechanism, automatic tachycardia speeds up and slows down gradually. The episode is characterized by a HEART RATE between 135 to less than 200 beats per minute and lasting 30 seconds or longer. Atrial Ectopic Tachycardia,Ectopic Atrial Tachycardia,Atrial Ectopic Tachycardias,Atrial Tachycardia, Ectopic,Atrial Tachycardias, Ectopic,Ectopic Atrial Tachycardias,Ectopic Tachycardia, Atrial,Ectopic Tachycardias, Atrial,Tachycardia, Atrial Ectopic,Tachycardias, Atrial Ectopic,Tachycardias, Ectopic Atrial
D013617 Tachycardia, Supraventricular A generic expression for any tachycardia that originates above the BUNDLE OF HIS. Supraventricular Tachycardia,Supraventricular Tachycardias,Tachycardias, Supraventricular
D022062 Electrophysiologic Techniques, Cardiac Methods to induce and measure electrical activities at specific sites in the heart to diagnose and treat problems with the heart's electrical system. Cardiac Electrophysiologic Techniques,Electrophysiologic Study, Cardiac,Atrial Electrogram,Bundle of His Electrogram,Cardiac Electrophysiologic Technics,Cardiac Electrophysiological Techniques,Electrophysiologic Techniques, Intracardiac,Electrophysiological Techniques, Cardiac,Electrophysiological Techniques, Intracardiac,His Bundle Electrogram,Intra-Atrial Electrogram,Intracardiac Electrogram,Intracardiac Electrophysiologic Techniques,Intracardiac Electrophysiological Technics,Intracardiac Electrophysiological Techniques,Programmed Electrostimulation, Cardiac,Transesophageal Electrophysiologic Study,Transesophageal Electrophysiological Study,Atrial Electrograms,Bundle Electrogram, His,Bundle Electrograms, His,Cardiac Electrophysiologic Studies,Cardiac Electrophysiologic Study,Cardiac Electrophysiologic Technic,Cardiac Electrophysiologic Technique,Cardiac Electrophysiological Technique,Cardiac Programmed Electrostimulation,Cardiac Programmed Electrostimulations,Electrogram Bundle, His,Electrogram Bundles, His,Electrogram, Atrial,Electrogram, His Bundle,Electrogram, Intra-Atrial,Electrogram, Intracardiac,Electrograms, Atrial,Electrograms, His Bundle,Electrograms, Intra-Atrial,Electrograms, Intracardiac,Electrophysiologic Studies, Cardiac,Electrophysiologic Studies, Transesophageal,Electrophysiologic Study, Transesophageal,Electrophysiologic Technic, Cardiac,Electrophysiologic Technics, Cardiac,Electrophysiologic Technique, Cardiac,Electrophysiologic Technique, Intracardiac,Electrophysiological Studies, Transesophageal,Electrophysiological Study, Transesophageal,Electrophysiological Technic, Intracardiac,Electrophysiological Technics, Intracardiac,Electrophysiological Technique, Cardiac,Electrophysiological Technique, Intracardiac,Electrostimulation, Cardiac Programmed,Electrostimulations, Cardiac Programmed,His Bundle Electrograms,His Electrogram Bundle,His Electrogram Bundles,Intra Atrial Electrogram,Intra-Atrial Electrograms,Intracardiac Electrograms,Intracardiac Electrophysiologic Technique,Intracardiac Electrophysiological Technic,Intracardiac Electrophysiological Technique,Programmed Electrostimulations, Cardiac,Studies, Cardiac Electrophysiologic,Studies, Transesophageal Electrophysiologic,Studies, Transesophageal Electrophysiological,Study, Cardiac Electrophysiologic,Study, Transesophageal Electrophysiologic,Study, Transesophageal Electrophysiological,Technic, Cardiac Electrophysiologic,Technic, Intracardiac Electrophysiological,Technics, Cardiac Electrophysiologic,Technics, Intracardiac Electrophysiological,Technique, Cardiac Electrophysiologic,Technique, Cardiac Electrophysiological,Technique, Intracardiac Electrophysiologic,Technique, Intracardiac Electrophysiological,Techniques, Cardiac Electrophysiologic,Techniques, Cardiac Electrophysiological,Techniques, Intracardiac Electrophysiologic,Techniques, Intracardiac Electrophysiological,Transesophageal Electrophysiologic Studies,Transesophageal Electrophysiological Studies

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