Defibrillator shocks >9 J delivered during baseline rhythm or defibrillation testing resulted in a 10% to 15% reduction in cardiac index (P=0.001 for 27-34 J), proportional to shock strength.
Observational (n=17)
Do ventricular defibrillator shocks adversely affect cardiac hemodynamics in patients undergoing defibrillator implantation?
High-energy defibrillator shocks (>9 J) cause a transient, dose-dependent reduction in cardiac index, suggesting a hemodynamic benefit to using lower-energy defibrillation when possible.
Absolute Event Rate: 2.14% vs 2.3%
p-value: p=0.001
INTRODUCTION: The effect of implantable defibrillator shocks on cardiac hemodynamics is poorly understood. The purpose of this study was to test the hypothesis that ventricular defibrillator shocks adversely effect cardiac hemodynamics. METHODS AND RESULTS: The cardiac index was determined by calculating the mitral valve inflow with transesophogeal Doppler during nonthoracotomy defibrillator implantation in 17 patients. The cardiac index was determined before, and immediately, 1 minute, 2 minutes, and 4 minutes after shocks were delivered during defibrillation energy requirement testing with 27- to 34-, 15-, 10-, 5-, 3-, or 1-J shocks. The cardiac index was also measured at the same time points after 27- to 34-, and 1-J shocks delivered during the baseline rhythm. The cardiac index decreased from 2.30 +/- 0.40 L/min per m2 before a 27- to 34-J shock during defibrillation energy requirement testing to 2.14 +/- 0.45 L/min per m2 immediately afterwards (P = 0.001). This effect persisted for > 4 minutes. An adverse hemodynamic effect of similar magnitude occurred after 15 J (P = 0.003) and 10-J shocks (P = 0.01), but dissipated after 4 minutes and within 2 minutes, respectively. There was a significant correlation between shock strength and the percent change in cardiac index (r = 0.3, P = 0.03). The cardiac index decreased 14% after a 27- to 34-J shock during the baseline rhythm (P 9 J delivered during the baseline rhythm or during defibrillation energy requirement testing result in a 10% to 15% reduction in cardiac index, whereas smaller energy shocks do not affect cardiac hemodynamics. The duration and extent of the adverse effect are proportional to the shock strength. Shock strength, and not ventricular fibrillation, appears to be most responsible for this effect. Therefore, the detrimental hemodynamic effects of high-energy shocks may be avoided when low-energy defibrillation is used.
Tokano et al. (Sat,) conducted a observational in Patients undergoing nonthoracotomy defibrillator implantation (n=17). Ventricular defibrillator shocks vs. Before shock was evaluated on Cardiac index (p=0.001). Defibrillator shocks >9 J delivered during baseline rhythm or defibrillation testing resulted in a 10% to 15% reduction in cardiac index (P=0.001 for 27-34 J), proportional to shock strength.