Left ventricular function after repeated episodes of ventricular fibrillation and defibrillation assessed by transoesophageal echocardiography.

Abstract

Investigators studying the effects of cardioverter-defibrillators on left ventricular systolic function have given only minor attention to the diastolic effects. The purpose of this study was to investigate the impact of repeated episodes of ventricular fibrillation and defibrillation on systolic function and diastolic filling of the left ventricle during non-thoracotomy implantation of a cardioverter-defibrillator. Systolic function and diastolic filling of the left ventricle were assessed peri-operatively on a beat-by-beat basis using a transoesophageal echo-Doppler technique in 12 patients during > or = 4 episodes of ventricular fibrillation and defibrillation. Systolic function was assessed from the fractional area change and diastolic filling from the E/A ratio. Arterial blood pressure and the ECG were recorded continuously. Blood pressure and heart rate did not change significantly throughout the procedure. The systolic function, similarly, was not significantly affected; the only changes were seen in the first two beats after defibrillation when the mean fractional area increased from 0.2 +/- 0.01 to 0.4 +/- 0.02 and 0.3 +/- 0.02, respectively (P < 0.001). Diastolic filling was, however, impaired as reflected by a decrease in the E/A ratio from 2.6 +/- 0.5 before to 1.6 +/- 0.4 (P < 0.01) after repeated threshold tests. While the combined ischaemic and electrical trauma caused by repeated episodes of ventricular fibrillation and defibrillation during the implantation of a cardioverter-defibrillator did not cause any systolic dysfunction, diastolic filling was significantly impaired.