Continuous Cardiac Magnetic Resonance Imaging During Untreated Ventricular Fibrillation
Cardiac magnetic resonance imaging (CMR) was performed in 6 swine after the induction of ventricular fibrillation (VF). With use of a 1.5-T GE Signa NV-CV/i scanner (GE Medical Systems), data were acquired with a steady-state, free-precession pulse sequence (repetition time=3.7 ms, echo time=1.6 ms, α=45°, matrix=224×224, field of view=36×27 cm2, slice thickness=6 mm, slice gap=0 mm). During VF, the pulse sequence was set to acquire ungated data (ie, data at a single cardiac phase). Data collection started immediately after the initiation of VF and continued every 30 seconds for 30 minutes. Images were analyzed offline (CMR Tools), and the comprehensive volumetric data were published in Circulation as a companion article (Circulation. 2005;111:1136–1140). The midcardiac slice from 1 swine is graphically displayed as a time-elapsed image (Figure and corresponding Movie). This provides an immediate visual appreciation of the right and left ventricular response to VF that is consistent with the volumetric data presented in the companion article. In this closed-chest, intact-pericardium swine model of untreated VF, the evolution from immediate right ventricular dilation (first minute) to early left ventricular dilation and wall thinning (5 minutes) and finally left ventricular ischemic contracture (“stone” heart at 20 to 30 minutes) was consistently seen in all 6 animals.
The Data Supplement Movie is available with this article at http://circ.ahajournals.org/cgi/content/full/111/19/e294/DC1.