Ectopic pacing at physiological rate improves postanoxic recovery of the developing heart.

Détails

ID Serval
serval:BIB_8F9F0B510314
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Ectopic pacing at physiological rate improves postanoxic recovery of the developing heart.
Périodique
American Journal of Physiology. Heart and Circulatory Physiology
Auteur(s)
Rosa A., Maury J.P., Terrand J., Lyon X., Kucera P., Kappenberger L., Raddatz E.
ISSN
0363-6135 (Print)
ISSN-L
0363-6135
Statut éditorial
Publié
Date de publication
2003
Peer-reviewed
Oui
Volume
284
Numéro
6
Pages
H2384-H2392
Langue
anglais
Résumé
Recently, rapid and transient cardiac pacing was shown to induce preconditioning in animal models. Whether the electrical stimulation per se or the concomitant myocardial ischemia affords such a protection remains unknown. We tested the hypothesis that chronic pacing of a cardiac preparation maintained in a normoxic condition can induce protection. Hearts of 4-day-old chick embryos were electrically paced in ovo over a 12-h period using asynchronous and intermittent ventricular stimulation (5 min on-10 min off) at 110% of the intrinsic rate. Sham (n = 6) and paced hearts (n = 6) were then excised, mounted in vitro, and subjected successively to 30 min of normoxia (20% O(2)), 30 min of anoxia (0% O(2)), and 60 min of reoxygenation (20% O(2)). Electrocardiogram and atrial and ventricular contractions were simultaneously recorded throughout the experiment. Reoxygenation-induced chrono-, dromo-, and inotropic disturbances, incidence of arrhythmias, and changes in electromechanical delay (EMD) in atria and ventricle were systematically investigated in sham and paced hearts. Under normoxia, the isolated heart beat spontaneously and regularly, and all baseline functional parameters were similar in sham and paced groups (means +/- SD): heart rate (190 +/- 36 beats/min), P-R interval (104 +/- 25 ms), mechanical atrioventricular propagation (20 +/- 4 mm/s), ventricular shortening velocity (1.7 +/- 1 mm/s), atrial EMD (17 +/- 4 ms), and ventricular EMD (16 +/- 2 ms). Under anoxia, cardiac function progressively collapsed, and sinoatrial activity finally stopped after approximately 9 min in both groups. During reoxygenation, paced hearts showed 1) a lower incidence of arrhythmias than sham hearts, 2) an increased rate of recovery of ventricular contractility compared with sham hearts, and 3) a faster return of ventricular EMD to basal value than sham hearts. However, recovery of heart rate, atrioventricular conduction, and atrial EMD was not improved by pacing. Activity of all hearts was fully restored at the end of reoxygenation. These findings suggest that chronic electrical stimulation of the ventricle at a near-physiological rate selectively alters some cellular functions within the heart and constitutes a nonischemic means to increase myocardial tolerance to a subsequent hypoxia-reoxygenation.
Mots-clé
Animals, Anoxia/physiopathology, Atrioventricular Node/physiology, Cardiac Pacing, Artificial, Chick Embryo, Electrocardiography, Electrophysiology, Glycogen/metabolism, Heart/growth & development, Heart/physiology, Heart Atria, Heart Rate/physiology, Ischemic Preconditioning, Myocardial, Myocardial Contraction/physiology, Myocardial Reperfusion Injury/prevention & control, Myocardium/metabolism, Oxygen Consumption/physiology, Proteins/metabolism, Ventricular Function
Pubmed
Web of science
Création de la notice
24/01/2008 14:19
Dernière modification de la notice
03/03/2018 19:22
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