## Truncation

The voltage of capacitive-discharge waveforms approach zero asymptotically, and the earliest capacitive-discharge defibrillation waveforms were not truncated.15'16 Schuder and Stoeckle17 first reported that transthoracic defibrillation was much more effective with truncated waveforms. Subsequently, the effect of truncation on defibrillation efficacy of ICD waveforms has been studied extensively.18-20 By definition, truncation of phase I is required to produce a single capacitor biphasic waveform.

Figure 2: (a) Effect of capacitance value on the discharge waveform. Note (horizontal double arrow) that the time to decay to a given voltage is tripled for the 150 versus the 50 |F waveform. Capacitor is initially charged to 100 V and the pathway resistance is 50 Q. (b) Effect of load resistance value on discharge waveform. Capacitor (110 | F) is initially charged to 100 V. Note (horizontal double arrow) that the time to decay to a given voltage is tripled for the 90 versus the 30 Q load. In both cases, the capacitor is initially charged to 100 V

Figure 2: (a) Effect of capacitance value on the discharge waveform. Note (horizontal double arrow) that the time to decay to a given voltage is tripled for the 150 versus the 50 |F waveform. Capacitor is initially charged to 100 V and the pathway resistance is 50 Q. (b) Effect of load resistance value on discharge waveform. Capacitor (110 | F) is initially charged to 100 V. Note (horizontal double arrow) that the time to decay to a given voltage is tripled for the 90 versus the 30 Q load. In both cases, the capacitor is initially charged to 100 V

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