Left ventricular geometry immediately following defibrillation: shock-induced relaxation.

TitleLeft ventricular geometry immediately following defibrillation: shock-induced relaxation.
Publication TypeJournal Article
Year of Publication2003
AuthorsDe Jongh AL, Ramanathan V, Hoffmeister BK, Malkin RA
JournalAmerican journal of physiology. Heart and circulatory physiology
Volume284
Issue3
Start PageH815
PaginationH815 - H819
Date Published03/2003
Abstract

A previous two-dimensional (2D) ultrasound study suggested that there is relaxation of the myocardium after defibrillation. The 2D study could not measure activity occurring within the first 33 ms after the shock, a period that may be critical for discriminating between shock- and excitation-induced relaxation. The objective of our study was to determine the left ventricular (LV) geometry during the first 33 ms after defibrillation. Biphasic defibrillation shocks were delivered 5-50 s after the induction of ventricular fibrillation in each of the seven dogs. One-dimensional, short-axis ultrasound images of the LV cavity were acquired at a rate of 250 samples/s. The LV cavity diameter was computed from 32 ms before to 32 ms after the shock. Preshock and postshock percent changes in LV diameter were analyzed as a function of time with the use of regression analysis. The normalized mean pre- and postshock slopes (0.2 +/- 2.2 and 3.3 +/- 7.9\% per 10 ms) were significantly different (P

DOI10.1152/ajpheart.00093.2002
Short TitleAmerican journal of physiology. Heart and circulatory physiology