Effect of shock waveform on relationship between upper limit of vulnerability and defibrillation threshold

Charles D. Swerdlow, Robert M. Kass, Mark E. O'Connor, Peng-Sheng Chen

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

ULV-DFT Waveform. Introduction: The upper limit of vulnerability (ULV) correlates with the defibrillation threshold (DFT). The ULV can be determined with a single episode of ventricular fibrillation and is more reproducible than the single-point DFT. The critical-point hypothesis of defibrillation predicts that the relation between the ULV and the DFT is independent of shock waveform. The principal goal of this study was to test this prediction. Methods and Results: We studied 45 patients at implants of pectoral cardioverter defibrillators. In the monophasic-biphasic group (n = 15), DFT and ULV were determined for monophasic and biphasic pulses from a 120-μF capacitor. In the 60- to 110-μF group (n = 30), DFT and ULV were compared for a clinically used 110-μF waveform and a novel 60-μF waveform with 70% phase 1 tilt and 7-msec phase 2 duration. In the monophasic-biphasic group, all measures of ULV and DFT were greater for monophasic than biphasic waveforms (P <0.0001). In the 60- to 110-μF group, the current and voltage at the ULV and DFT were higher for the 60-μF waveform (P <0.0001), but stored energy was lower (ULV 17%, P <0.0001; DFT 19%, P = 0.03). There was a close correlation between ULV and DFT for both the monophasic-biphasic group (monophasic r2 = 0.75, P <0.001; biphasic r2 = 0.82, P <0.001) and the 60- to 110-μF group (60 μF r2 = 0.81 P <0.001; 110 μF r2 = 0.75, P <0.001). The ratio of ULV to DFT was not significantly different for monophasic versus biphasic pulses (1.17 ± 0.12 vs 1.14 ± 0.19, P = 0.19) or 60-μF versus 110-μF pulses (1.15 ± 0.16 vs 1.11 ± 0.14, P = 0.82). The slopes of the ULV versus DFT regression lines also were not significantly different (monophasic vs biphasic pulses, P = 0.46; 60-μF vs 110-μF pulses, P = 0.99). The sample sizes required to detect the observed differences between experimental conditions (P <0.05) were 4 for ULV versus 6 for DFT in the monophasic-biphasic group (95% power) and 11 for ULV versus 31 for DFT in the 60- to 110-μF group (75% power). Conclusion: The relation between ULV and DFT is independent of shock waveform. Fewer patients are required to detect a moderate difference in efficacy of defibrillation waveforms by ULV than by DFT. A small-capacitor biphasic waveform with a long second phase defibrillates with lower stored energy than a clinically used waveform.

Original languageEnglish (US)
Pages (from-to)339-349
Number of pages11
JournalJournal of Cardiovascular Electrophysiology
Volume9
Issue number4
StatePublished - 1998
Externally publishedYes

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Shock
Defibrillators
Ventricular Fibrillation
Sample Size

Keywords

  • Capacitor
  • Defibrillation
  • Defibrillation waveform
  • Implantable cardioverter defibrillator

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology

Cite this

Effect of shock waveform on relationship between upper limit of vulnerability and defibrillation threshold. / Swerdlow, Charles D.; Kass, Robert M.; O'Connor, Mark E.; Chen, Peng-Sheng.

In: Journal of Cardiovascular Electrophysiology, Vol. 9, No. 4, 1998, p. 339-349.

Research output: Contribution to journalArticle

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abstract = "ULV-DFT Waveform. Introduction: The upper limit of vulnerability (ULV) correlates with the defibrillation threshold (DFT). The ULV can be determined with a single episode of ventricular fibrillation and is more reproducible than the single-point DFT. The critical-point hypothesis of defibrillation predicts that the relation between the ULV and the DFT is independent of shock waveform. The principal goal of this study was to test this prediction. Methods and Results: We studied 45 patients at implants of pectoral cardioverter defibrillators. In the monophasic-biphasic group (n = 15), DFT and ULV were determined for monophasic and biphasic pulses from a 120-μF capacitor. In the 60- to 110-μF group (n = 30), DFT and ULV were compared for a clinically used 110-μF waveform and a novel 60-μF waveform with 70{\%} phase 1 tilt and 7-msec phase 2 duration. In the monophasic-biphasic group, all measures of ULV and DFT were greater for monophasic than biphasic waveforms (P <0.0001). In the 60- to 110-μF group, the current and voltage at the ULV and DFT were higher for the 60-μF waveform (P <0.0001), but stored energy was lower (ULV 17{\%}, P <0.0001; DFT 19{\%}, P = 0.03). There was a close correlation between ULV and DFT for both the monophasic-biphasic group (monophasic r2 = 0.75, P <0.001; biphasic r2 = 0.82, P <0.001) and the 60- to 110-μF group (60 μF r2 = 0.81 P <0.001; 110 μF r2 = 0.75, P <0.001). The ratio of ULV to DFT was not significantly different for monophasic versus biphasic pulses (1.17 ± 0.12 vs 1.14 ± 0.19, P = 0.19) or 60-μF versus 110-μF pulses (1.15 ± 0.16 vs 1.11 ± 0.14, P = 0.82). The slopes of the ULV versus DFT regression lines also were not significantly different (monophasic vs biphasic pulses, P = 0.46; 60-μF vs 110-μF pulses, P = 0.99). The sample sizes required to detect the observed differences between experimental conditions (P <0.05) were 4 for ULV versus 6 for DFT in the monophasic-biphasic group (95{\%} power) and 11 for ULV versus 31 for DFT in the 60- to 110-μF group (75{\%} power). Conclusion: The relation between ULV and DFT is independent of shock waveform. Fewer patients are required to detect a moderate difference in efficacy of defibrillation waveforms by ULV than by DFT. A small-capacitor biphasic waveform with a long second phase defibrillates with lower stored energy than a clinically used waveform.",
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T1 - Effect of shock waveform on relationship between upper limit of vulnerability and defibrillation threshold

AU - Swerdlow, Charles D.

AU - Kass, Robert M.

AU - O'Connor, Mark E.

AU - Chen, Peng-Sheng

PY - 1998

Y1 - 1998

N2 - ULV-DFT Waveform. Introduction: The upper limit of vulnerability (ULV) correlates with the defibrillation threshold (DFT). The ULV can be determined with a single episode of ventricular fibrillation and is more reproducible than the single-point DFT. The critical-point hypothesis of defibrillation predicts that the relation between the ULV and the DFT is independent of shock waveform. The principal goal of this study was to test this prediction. Methods and Results: We studied 45 patients at implants of pectoral cardioverter defibrillators. In the monophasic-biphasic group (n = 15), DFT and ULV were determined for monophasic and biphasic pulses from a 120-μF capacitor. In the 60- to 110-μF group (n = 30), DFT and ULV were compared for a clinically used 110-μF waveform and a novel 60-μF waveform with 70% phase 1 tilt and 7-msec phase 2 duration. In the monophasic-biphasic group, all measures of ULV and DFT were greater for monophasic than biphasic waveforms (P <0.0001). In the 60- to 110-μF group, the current and voltage at the ULV and DFT were higher for the 60-μF waveform (P <0.0001), but stored energy was lower (ULV 17%, P <0.0001; DFT 19%, P = 0.03). There was a close correlation between ULV and DFT for both the monophasic-biphasic group (monophasic r2 = 0.75, P <0.001; biphasic r2 = 0.82, P <0.001) and the 60- to 110-μF group (60 μF r2 = 0.81 P <0.001; 110 μF r2 = 0.75, P <0.001). The ratio of ULV to DFT was not significantly different for monophasic versus biphasic pulses (1.17 ± 0.12 vs 1.14 ± 0.19, P = 0.19) or 60-μF versus 110-μF pulses (1.15 ± 0.16 vs 1.11 ± 0.14, P = 0.82). The slopes of the ULV versus DFT regression lines also were not significantly different (monophasic vs biphasic pulses, P = 0.46; 60-μF vs 110-μF pulses, P = 0.99). The sample sizes required to detect the observed differences between experimental conditions (P <0.05) were 4 for ULV versus 6 for DFT in the monophasic-biphasic group (95% power) and 11 for ULV versus 31 for DFT in the 60- to 110-μF group (75% power). Conclusion: The relation between ULV and DFT is independent of shock waveform. Fewer patients are required to detect a moderate difference in efficacy of defibrillation waveforms by ULV than by DFT. A small-capacitor biphasic waveform with a long second phase defibrillates with lower stored energy than a clinically used waveform.

AB - ULV-DFT Waveform. Introduction: The upper limit of vulnerability (ULV) correlates with the defibrillation threshold (DFT). The ULV can be determined with a single episode of ventricular fibrillation and is more reproducible than the single-point DFT. The critical-point hypothesis of defibrillation predicts that the relation between the ULV and the DFT is independent of shock waveform. The principal goal of this study was to test this prediction. Methods and Results: We studied 45 patients at implants of pectoral cardioverter defibrillators. In the monophasic-biphasic group (n = 15), DFT and ULV were determined for monophasic and biphasic pulses from a 120-μF capacitor. In the 60- to 110-μF group (n = 30), DFT and ULV were compared for a clinically used 110-μF waveform and a novel 60-μF waveform with 70% phase 1 tilt and 7-msec phase 2 duration. In the monophasic-biphasic group, all measures of ULV and DFT were greater for monophasic than biphasic waveforms (P <0.0001). In the 60- to 110-μF group, the current and voltage at the ULV and DFT were higher for the 60-μF waveform (P <0.0001), but stored energy was lower (ULV 17%, P <0.0001; DFT 19%, P = 0.03). There was a close correlation between ULV and DFT for both the monophasic-biphasic group (monophasic r2 = 0.75, P <0.001; biphasic r2 = 0.82, P <0.001) and the 60- to 110-μF group (60 μF r2 = 0.81 P <0.001; 110 μF r2 = 0.75, P <0.001). The ratio of ULV to DFT was not significantly different for monophasic versus biphasic pulses (1.17 ± 0.12 vs 1.14 ± 0.19, P = 0.19) or 60-μF versus 110-μF pulses (1.15 ± 0.16 vs 1.11 ± 0.14, P = 0.82). The slopes of the ULV versus DFT regression lines also were not significantly different (monophasic vs biphasic pulses, P = 0.46; 60-μF vs 110-μF pulses, P = 0.99). The sample sizes required to detect the observed differences between experimental conditions (P <0.05) were 4 for ULV versus 6 for DFT in the monophasic-biphasic group (95% power) and 11 for ULV versus 31 for DFT in the 60- to 110-μF group (75% power). Conclusion: The relation between ULV and DFT is independent of shock waveform. Fewer patients are required to detect a moderate difference in efficacy of defibrillation waveforms by ULV than by DFT. A small-capacitor biphasic waveform with a long second phase defibrillates with lower stored energy than a clinically used waveform.

KW - Capacitor

KW - Defibrillation

KW - Defibrillation waveform

KW - Implantable cardioverter defibrillator

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