OPTIMIZATION OF BIPHASIC WAVE-FORMS FOR HUMAN NONTHORACOTOMY DEFIBRILLATION

Citation
Jf. Swartz et al., OPTIMIZATION OF BIPHASIC WAVE-FORMS FOR HUMAN NONTHORACOTOMY DEFIBRILLATION, Circulation, 88(6), 1993, pp. 2646-2654
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cardiac & Cardiovascular System",Hematology
Journal title
ISSN journal
0009-7322
Volume
88
Issue
6
Year of publication
1993
Pages
2646 - 2654
Database
ISI
SICI code
0009-7322(1993)88:6<2646:OOBWFH>2.0.ZU;2-9
Abstract
Background. Biphasic waveforms reduce defibrillation threshold (DFT) i n a wide variety of models. Although there are several human studies o f long-duration, high-tilt biphasic waveform defibrillation, the speci fic biphasic waveform shape required to achieve optimal DFT reduction is unknown. Methods and Results. This study tested the effect of singl e capacitor biphasic waveform tilt modification on DFT using a paired study design in 18 patients undergoing nonthoracotomy defibrillator im plantation. Baseline DPT was obtained using a 65% tilt, simultaneous p ulse, bidirectional monophasic shock from a right ventricular cathode to a coronary sinus or superior vena cava lead and a subscapular patch . The single-capacitor biphasic waveform shocks, delivered over the sa me pathways, consisted of either both phases at 65% tilt (65/65 biphas ic waveform) to produce an overall tilt of 88% and a delivered energy 11% greater than monophasic shock or both phases at 42% tilt (42/42 bi phasic waveform) to produce an overall tilt of 66% and delivered energ y equal to monophasic shock. The 65/65 biphasic waveform reduced store d energy DFT 25%, from 16.2+/-4.4 J with monophasic shock to 12.1+/-5. 3 J (P<.02); however, it did not significantly reduce the delivered en ergy DET. In contrast, the 42/42 biphasic waveform required 49% less s tored energy (16.2+/-4.4 J, monophasic shock, vs 8.3+/-3.3 J, biphasic waveform; P<.001) and 49% less delivered energy (14.2+/-3.8 J, monoph asic shock, vs 7.3+/-2.9 J, biphasic waveform; P<.001) than monophasic shock for successful defibrillation. The 42/42 biphasic waveform deli vered energy DFT was 4.6+/-5.2 J (39%) less than 65/65 biphasic wavefo rm DFT (P<.002). Conclusions. DET reduction is an inherent electrophys iological property of biphasic waveforms that is independent of delive red energy. Overall biphasic waveform tilt and the relative amplitudes of the waveform phases are important factors in defibrillation effica cy. Defibrillation with a 42/42 biphasic waveform is more efficacious than 65/65 biphasic waveform defibrillation; however, the optimal biph asic waveform remains unknown.