PMC

Calcium transients from selected pixels after 4 minutes of ischemia in a blood-perfused heart showing pairs of pixels where alternans is out of phase.

Spectral Method TWA output in a patient with nonischemic cardiomyopathy with a positive test. Note the high TWA level in precordial leads V3 (22μV) and V4 (24μV).

Progression of T-wave complexity in electrograms monitored from a 4-electrode plaque preceding ventricular fibrillation is paralleled by the increasing magnitude of T-wave heterogeneity, assessed by analysis of second central moment, a measure of variance in T-wave morphology among the electrodes.

Top: Representative ECG tracing (left upper panel) and high-resolution QRS-aligned superimposed waveforms with baseline wander removal and noise filtering (right upper panel) illustrating exercise-induced TWA of 124μV in lead V4 in a patient from the Finnish Cardiovascular Study (FINCAVAS) who experienced cardiovascular death at 12 months following the exercise stress test. The bidirectional arrow refers to the point of maximum TWA. Bottom: Representative rhythm strip (left lower panel) and QRS-aligned superimposed MMA waveforms (right lower panel) for the maximum TWA (65μV) in lead V3 from a patient enrolled in the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS) study. Note the lack of separation between the superimposed beats in the isoelectric PQRS complex, indicating the low level of noise. The ABAB separation is concentrated within the JT segment, as observed experimentally.,