title: Tracking cardiac electrical instability by computing interlead heterogeneity of T-wave morphology.
abstract: Oscillations in T-wave morphology, particularly T-wave alternans (TWA), have been fundamentally linked to increased susceptibility to ventricular fibrillation (VF). We investigated whether the escalation in complexity of T-wave oscillations before VF is attributable to increased spatial heterogeneity of repolarization. Peak interlead T-wave heterogeneity (TWH) was measured by second central moment analysis of T-wave morphology in epicardial electrograms in dogs during left anterior descending coronary artery occlusion. TWH differentiated cases in which myocardial ischemia provoked VF from those without VF (563 +/- 56 vs. 139 +/- 36 microV, P < 0.01). In the former group, progressive, significant increases in TWH above preocclusion baseline (70 +/- 8 microV) began at 2.25 min after the start of occlusion and were associated successively with TWA (at 155 +/- 19 microV), T-wave multupling (at 386 +/- 100 microV), complex oscillatory T-wave forms (at 560 +/- 76 microV), discordant TWA (at 572 +/- 98 microV), and VF at 4.36 +/- 0.14 min. TWH in precordial ECGs in 12 pigs during angioplasty-balloon-induced myocardial ischemia also discriminated animals that experienced VF (from 90 +/- 14 at baseline to 382 +/- 39 microV, P < 0.05) from those without VF (from 96 +/- 17 at baseline to 199 +/- 61 microV, NS). Ischemia-induced changes in ST segment and T-wave amplitude did not predict VF. Heightened spatial heterogeneity of repolarization, as assessed by second central moment analysis of TWH, underlies TWA and increased risk for ischemia-induced VF. Monitoring spatial TWH from precordial leads could prove useful in stratifying risk for life-threatening arrhythmias.
authors.affiliation: Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Nearing
authors.forename: Richard L
authors.initials: RL
authors.lastname: Verrier
mesh_terms: D000465:Algorithms; D015906:Angioplasty, Balloon, Coronary; D000818:Animals; D003327:Coronary Disease / Q000503:physiopathology; D004285:Dogs; D004562:Electrocardiography / Q000295:instrumentation / Q000379:methods*; D004594:Electrophysiology; D005260:Female; D006321:Heart / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D009200:Myocardial Contraction / Q000502:physiology; D010496:Pericardium / Q000502:physiology; D013552:Swine; D014693:Ventricular Fibrillation / Q000503:physiopathology