Effects of electrophysiologic testing of the automatic implantable cardioverter-defibrillator on left ventricular systolic function and diastolic filling.

We investigated the effects of electrophysiologic testing of the automatic implantable cardioverter-defibrillator (AICD) on left ventricular systolic function and diastolic filling in 12 patients. Ventricular tachycardia or ventricular fibrillation was induced by programmed electrical stimulation and alternating-current, respectively. Patients were studied before and immediately after, 10 minutes after, and 1 hour after defibrillation by the AICD using M-mode, two-dimensional, and pulsed Doppler echocardiography. Immediately after defibrillation, increases were found in the peak early filling velocity (70 +/- 10 cm/sec to 84 +/- 24 cm/sec, p less than 0.01), peak early-to-atrial filling velocity ratio (1.05 +/- 0.21 to 1.29 +/- 0.26, p less than 0.005), and maximum rate of diastolic chamber enlargement (82 +/- 26 mm/sec to 102 +/- 44 mm/sec, p less than 0.05). These changes were not evident at 10 minutes and 1 hour. Cardiac output and ejection fraction were unchanged after defibrillation. Heart rate and diastolic filling time were unchanged. We conclude that electrophysiologic testing of the AICD does not impair left ventricular function in the immediate to 1-hour period after defibrillation. Left ventricular systolic function is unchanged and diastolic filling is enhanced.