Effects of implantable cardioverter defibrillator implantation and shock application on serum endothelin-1 and big-endothelin levels

The incidence of ventricular tachyarrhythmias in the early post-operative period following implantable cardioverter-defibrillator (ICD) implantation is relatively high compared with that in control periods. Since endothelin-1 (ET-1) has been proven to be an endogenous arrhythmogenic substance, we investigated the changes in serum ET-1 and big-ET levels in patients undergoing ICD implantation. Serum concentrations of ET-1 and big-ET were measured in 14 patients with various heart diseases before the operation, as well as 1min and 1h after the last shock therapy. Big-ET levels and the sum of ET-1 and big-ET levels were unchanged immediately after the operation, but had increased significantly by 1h after implantation (before, 1.57±0.61pmol/l; 1min, 1.86±0.87pmol/l; 1h, 4.29±1.65pmol/l for big-ET; before, 3.44±1.07pmol/l; 1min, 3.79±1.29pmol/l; 1h, 6.36±2.03pmol/l for big-ET+ET-1). There was a significant correlation between left ventricular ejection fraction and big-ET level measured 1h after the last shock delivery (r =-0.542, P<0.05). We conclude that the increased big-ET level observed 1h after the last induction and shock therapy of ventricular fibrillation might have a pathophysiological role in the increased incidence of post-operative spontaneous ventricular arrhythmias.