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Gender and Seasonally Related Differences in Myocardial Recovery and Susceptibility to Sotalol‐Induced Arrhythmias in Isolated Rabbit Hearts
Author(s) -
SPEAR JOSEPH F.,
MOORE E. NEIL
Publication year - 2000
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/j.1540-8167.2000.tb00067.x
Subject(s) - medicine , sotalol , cardiology , incidence (geometry) , qt interval , repolarization , afterdepolarization , electrophysiology , electrocardiography , anesthesia , atrial fibrillation , physics , optics
Gender and Seasonal Differences in Rabbit Hearts. Introduction : Gender differences and seasonal variations in cardiac electrophysiology and susceptibility to arrhythmias have been described clinically. The present study was undertaken to determine if there are similar gender and seasonally related differences in the electrophysiology of the rabbit heart. Methods and Results: We analyzed epicardial electrograms, left ventricular endocardial monophasic action potentials (MAPs), and simulated X and Y lead ECGs from 145 isolated rabbit hearts studied over a period of 41 months. Hearts from males had seasonal increases in the duration of myocardial recovery. During the months of June to September compared with October to January and February to May, epicardial activation‐recovery intervals (231.6 ± 23.4 vs 215.6 ± 19.2 and 213.5 ± 18.8 msec, P = 0.003), MAP durations (256.5 ± 25.4 vs 237.0 ± 19.6 and 230.7 ± 26.4 msec, P < 0.001), and QT intervals (278.3 ± 25.6 vs 267.3 ± 11.8 and 261.3 ± 13.0 msec, P = 0.03) were longer. Overall, hearts from females had shorter QT intervals than males (257.7 ± 15.7 vs 270.1 ± 20.3 msec, P < 0.001), and this difference was reflected in their shorter epicardial activationrecovery intervals and MAP durations. However, hearts from females showed a greater prolongation of epicardial recovery (P = 0.007) and greater incidence of arrhythmias (P < 0.001) with sotalol than males. Also, the incidence of arrhythmias was greater in the winter months October to May (P < 0.001). Conclusion : The isolated rabbit heart provides a spontaneous model of gender and seasonally related differences in cardiac electrophysiology and arrhythmia susceptibility. These differences may be related to variation in the expression of or regulation of the membrane ion channels mediating repolarization.