Does ventricular fibrillation cause myocardial stunning during defibrillator implantation?
Induction of ventricular fibrillation (VF) is an important part of the process of inserting implantable cardioverter defibrillators (ICDs), allowing the measurement of defibrillation thresholds. However, animal studies have revealed that repeated cycles of VF and defibrillation result in depressed left ventricular (LV) function and reduced cardiac output. Short intervals of VF do not affect myocardial contractility but longer periods produce heart failure. Induced VF was used in a canine model to study profound myocardial stunning leading to heart failure, as well as the therapeutic potential of the phosphodiesterase inhibitor, amrinone (combined with epinephrine and norepinephrine). Amrinone was found to significantly (p < 0.05) increase contractility when added to a stable preparation supported by epinephrine and norepinephrine infusion; amrinone or catecholamines alone had no effect. In the clinical setting, the following factors may affect LV contractility during ICD surgery: catec
