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Defibrillation causes immediate cardiac dilation in humans

Erin Sylvester1, Eric Johnson, Paul Hess

  • 1The University of Memphis, Memphis, Tennessee 38152, USA.

Journal of Cardiovascular Electrophysiology
|August 2, 2003
PubMed

Insights

Defibrillation causes immediate ventricular dilation in humans, indicating a rapid relaxation of the heart muscle. This study provides the first evidence of this mechanical response following defibrillation.

Area of Science:

  • Cardiology
  • Cardiac Electrophysiology
  • Medical Imaging

Background:

  • Previous research on isolated heart tissue identified excitation and deexcitation as key defibrillation mechanisms.
  • This study investigates the mechanical response of the human heart to defibrillation.

Purpose of the Study:

  • To provide the first evidence in humans of cardiac deexcitation immediately following defibrillation.
  • To track the heart's mechanical response to defibrillation using echocardiography.

Main Methods:

  • Seven human subjects receiving an implantable cardioverter defibrillator (ICD) were studied.
  • Two-dimensional echocardiography was used to measure ventricular chamber geometry before and after defibrillation.
  • Ventricular fibrillation and defibrillation were induced approximately three times per subject.

Main Results:

  • Immediately after defibrillation, both right and left ventricular chambers showed significant dilation.
  • Fractional area increase was observed in the right ventricle (1.58 +/- 0.25) and left ventricle (1.10 +/- 0.06).
  • Peak dilation occurred at 194 +/- 114 milliseconds post-defibrillation.

Conclusions:

  • Defibrillation induces a rapid increase in ventricular chamber area due to myocardial relaxation.
  • This suggests that defibrillation synchronizes cardiac cells to a deexcited state in humans.
Abstract

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