@entity384 . 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 @entity1 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 @entity1 subjects receiving an @entity737 ( @entity737 ). The @entity737 was used to produce approximately three episodes of @entity2224 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 @entity1 .

Defibrillation causes immediate @entity384 in XXXX .

@entity1 :: ('9606', 'Species') :: ['human', 'man'] @entity384 :: ('MESH:D002311', 'Disease') :: ['Defibrillation Causes Dilation'] @entity737 :: ('MESH:D057873', 'Disease') :: ['ICD', 'implantable cardioverter defibrillator'] @entity2224 :: ('MESH:D014693', 'Disease') :: ['ventricular fibrillation']
@entity1 :: (9606,Species) :: ['humans']
