Mechanism Linking T-Wave Alternans to the Genesis of Cardiac Fibrillation

• DOI: 10.1161/01.cir.99.10.1385
• Publication Date: 2012-06-12T00:42:29Z
• Authors: Joseph M. Pastore; Steven D. Girouard; Kenneth R. Laurita; Fadi G. Akar; David S. Rosenbaum
• Keywords: T wave alternans; Reentry; Fibrillation

Background —Although T-wave alternans has been closely associated with vulnerability to ventricular arrhythmias, the cellular processes underlying and their role, if any, in mechanism of reentry remain unclear. Methods Results —T-wave on surface ECG was elicited 8 Langendorff-perfused guinea pig hearts during fixed-rate pacing while action potentials were recorded simultaneously from 128 epicardial sites voltage-sensitive dyes. Alternans repolarization phase potential observed above a critical threshold heart rate (HR) (209±46 bpm) that significantly lower (by 57±36 than HR for alternation depolarization. The magnitude (range, 2.7 47.0 mV) 171 272 varied substantially between cells across surface. explained primarily by beat-to-beat time course repolarization. Above HR, membrane alternated opposite neighboring (ie, discordant alternans), creating large spatial gradients In presence alternans, small acceleration cycle length produced characteristic sequence events: (1) unidirectional block an impulse propagating against steep repolarization, (2) reentrant propagation, (3) initiation fibrillation. Conclusions —Repolarization at level single cell accounts ECG. Discordant produces sufficient cause These data establish linking pathogenesis sudden cardiac death.