Defibrillation causes immediate cardiac dilation in humans

TitleDefibrillation causes immediate cardiac dilation in humans
Publication TypeJournal Article
Year of Publication2003
AuthorsSylvester E, Hoffmeister B, Johnson E, Hess P, Malkin R
JournalJournal of Cardiovascular Electrophysiology
Start Page832
Pagination832 - 836
Date Published01/2003

Introduction: Prior studies in isolated heart tissue have shown both excitation and deexcitation to be the primary mechanism of defibrillation. This article presents the first evidence in man of deexcitation immediately following defibrillation by tracking the heart's mechanical response. Methods and Results: The geometric changes of the ventricular chambers were measured before and after defibrillation in seven human subjects receiving an implantable cardioverter defibrillator (ICD). The ICD was used to produce approximately three episodes of ventricular fibrillation and defibrillation in each subject. Twenty-two two-dimensional echocardiographic images of the right ventricle (RV) and 11 images of the left ventricle (LV) were recorded and analyzed at 30 frames per second. Just over 2 seconds of each episode were digitized, beginning half a second before the defibrillation shock. Individual frames were analyzed to yield cross-sectional, ventricular chamber area as a function of time. Immediately following defibrillation, ventricular chambers dilated with significant fractional area increase (RV: 1.58 ± 0.25, LV: 1.10 ± 0.06), with peak dilation at 194 ± 114 msec. Conclusion: Defibrillation causes a rapid increase in ventricular chamber area due to relaxation of the myocardium, suggesting that defibrillation synchronizes the cardiac cells to the deexcited state in man.

Short TitleJournal of Cardiovascular Electrophysiology