Prospective randomized comparison of 50%/50% versus 65%/65% tilt biphasic waveform on defibrillation in humans

It is unknown if there is a single optimal biphasic waveform for defibrilla tion. Biphasic waveform tilt may be an important determinant of defibrillat ion efficacy. The purpose of this study was to compare acute defibrillation success with a three-electrode configuration in humans using 50%/50% versu s 65%/65% tilt truncated exponential, biphasic waveforms delivered through a 110-muF capacitor. Acute DFTs for biphasic waveforms with 50%/50% versus 65%/65% tilt were measured in random order in 60 patients using a binary se arch method. The electrode configuration consisted of a RV coil as the cath ode, and a SVC coil plus a pectoral active can emulator (CAN) as the anode. The waveforms were derived from an external voltage source with 110-muF ca pacitance, and the leading edge voltage of phase 2 was equal to the trailin g edge voltage of phase 2. Stored energy DFT (9.2 +/- 5.7 [50%/50%] vs 10.8 +/- 6.4 [65%/65%] J, P = 0.007), current DFT (10.9 +/- 4.0 [50%/50%] vs 12 .0 +/- 4.4 [65%/65%] A, P = 0.002) and voltage DFT (391 +/- 118 [50%/50%] v s 424 +/- 128 [65%/65%] V, P = 0.004) were significantly lower for the 50%/ 50% tilt waveform versus the 65%/65% tilt waveform using this three-electro de configuration and a 110-muF capacitor. For an RV (-)/SVC plus CAN (+) el ectrode configuration and a 110-muF capacitor, a 50%/50% tilt biphasic wave form results in a 15% reduction in energy DFT, 9% reduction in current DFT, and 8% reduction in voltage DFT versus a 65%/65% tilt biphasic waveform.