QT Interval Heterogeneities Induced Through Local Epicardial Warming/Cooling. An Experimental Study
2014
A B S T R A C T Introduction and objectives: Abnormal QT interval durations and dispersions have been associated with increased risk of ventricular arrhythmias. The present study examines the possible arrhythmogenic effect of inducing QT interval variations through local epicardial cooling and warming. Methods: In 10 isolated rabbit hearts, the temperatures of epicardial regions of the left ventricle were modified in a stepwise manner (from 22 8C to 42 8C) with simultaneous electrogram recording in these regions and in others of the same ventricle. QT and activation-recovery intervals were determined during sinus rhythm, whereas conduction velocity and ventricular arrhythmia induction were determined during programmed stimulation. Results: In the area modified from baseline temperature (37 8C), the QT (standard deviation) was prolonged with maximum hypothermia (195 (47) vs 149 (12) ms; P .34). Conclusions: In the experimental model employed, local variations in the epicardial temperature modulate the QT interval, activation-recovery interval, and conduction velocity. Induction of heterogeneities did not promote ventricular arrhythmia occurrence.
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