Ventricular fibrillation in myopathic human hearts:: mechanistic insights from in vivo global endocardial and epicardial mapping

Ventricular fibrillation in myopathic human hearts: mechanistic insights from in vivo global endocardial and epicardial mapping. Am J Physiol Heart Circ Physiol 292: H2589-H2597, 2007. First published January 26. 2007: doi: 10.1152/ajpheart.01336.2006. - Ventricular fibrillation (VF) is an important cause Of Sudden cardiac death and cardiovascular mortality in patients with cardiomyopathy. Although it was generally believed that chaotic reentrant wavefronts underlie VF in humans, there is emerging evidence of spatiotemporal organization during, early VF. The mechanism of this organization of electrical activity in early VF is unknown in myopathic hearts. We Studied early VF in vivo. intraoperatively in five cardiomyopathic patients. Simultaneous electrograms were obtained from the epicardium and endocardium in left ventricular cardiomyopathy and from the endocardium in right ventricular myopathy. The Hilbert transform was used to derive the phase of the electrograms. Rotors were identified by isolating phase singularity points. Rotors were present in all of the myopathic hearts studied during VF and cumulatively lasted a mean of 3.2 +/- 2.0 s of the 7.0 +/- 4.0 s of the VF segments analyzed. For each Surface mapped. 3.6 +/- 2.9 rotors were identified for the duration mapped. The average number of cycles completed by these rotors was 4.9 +/- 4.9. The lon2est rotor lasted 10.2 +/- 6.2 rotations and lasted 2.0 +/- 1.2 s. The rotors on the endocardium had a cycle length of 192 33 Ins compared with 220 +/- 15 rus oil the epicardium (P = 0.08). There is centrifugal activation of electrical activity from these rotors. and they Live rise to domains that activate at faster rates with evidence of conduction block at the border with slower domains. These rotors frequently, localized to border regions of myocardium with bipolar electrogram amplitude of <0.5 mV. The organization of electrical activity during early VF in myopathic human hearts is characterized by wavefronts emanating from a few rotors.