Key result
Sequential pulses were not associated with lower energies for internal defibrillation compared to single pulses delivered through the same pathways.
Why the study?
Does sequential pulse defibrillation reduce the energy required for internal defibrillation compared to single shocks in dogs?
Does sequential pulse defibrillation reduce the energy required for internal defibrillation compared to single shocks in dogs?
In a canine model, sequential pulses were not associated with lower energies than single pulses delivered through the same pathways, indicating temporal summation is comparable to a single shock for internal defibrillation.
Answers are grounded in this paper and cite their sources.
No support for sequential-pulse energy savings in dogs; leaves open clinical translation to human internal defibrillation.
Sequential pulse defibrillation using two current pathways was compared with single shocks simultaneously utilizing both pathways in 16 dogs to assess the effects of temporal summation. A cardioverter‐defibrillator catheter was positioned via the external jugular vein with the distal 4 cm2 shocking electrode located in the right ventricular apex and the proximal 8 cm2 electrode located in the superior vena cava. Three electrode configurations were tested(1) single pulse, distal electrode (cathode) to proximal electrode and chest wall patch (common anode), (2) sequential 5 ms pulses with 1 ms interpulse delay, distal electrode (cathode] to proximal electrode (anode) followed by distal electrode (cathode) to chest wall patch (anode), and (3] sequential 10 ms pulses with I ms interpulse delay using same current pathways described for configuration 2. The lowest energies resulting in termination of AC induced ventricular fibrillation on four trials were 27.9. 26.6, and 42.3 joules respectively for configurations 1, 2, and 3. The mean energy levels were not significantly different for configurations 1 and 2, both of which were significantly lower than that for configuration 3. The lowest peak voltages terminating ventricular fibrillation on four trials were 595 ± 176, 521 ± 134 and 579 ± 171 volts for configuration 1, 2, and 3. The mean voltage level for configuration 2 was significantly lower than that for configurations 1 and 3, which were not significantly different. The mean calculated impedance for the pathway utilizing the catheter was 74.6 ±13.7 ohms, for the pathway utilizing the distal catheter electrode to the chest wall electrode was 102.9 ± 19.7 ohms, and for simultaneous discharge employing both current pathways was 65.0 ±11.3 ohms. In conclusion, for the lead system tested, sequential pulses were not associated with lower energies than single pulses delivered through the same pathways and therefore, temporal summation is comparable to a single shock for internal defibrillation.
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Wetherbee et al. (1988) studied Ventricular fibrillation (n=16). Sequential pulse defibrillation vs. Single pulse defibrillation was evaluated on Lowest energies resulting in termination of ventricular fibrillation. Sequential pulses were not associated with lower energies for internal defibrillation compared to single pulses delivered through the same pathways.
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