The Electrocardiographic T-Wave and its Relation with Ventricular Repolarization along Major Anatomical Axes
Background—The genesis of the electrocardiographic T-wave is incompletely understood and subject to controversy. We have correlated the ventricular repolarization sequence with simultaneously recorded T-waves.
Methods and Results—Nine pig hearts were Langendorff perfused (atrial pacing, cycle length 650 ms). Local activation and repolarization times (AT and RT) were derived from unipolar electrograms sampling the ventricular myocardium. Dispersion of RT (dRT; range) was determined along 4 anatomical axes: left-right, LV:apico-basal, LV:anterior-posterior, and LV:transmural. The heart was immersed in a fluid filled bucket containing 61 electrodes to determine Tp (Tpeak in lead of maximum integral), TpTe (Tp to Tend) and TpTe_total (first Tpeak in any lead to last Tend in any lead). Repolarization was nonlinearly distributed in time. RT25 (time at which 25% of sites were repolarized, 288±26 ms) concurred with Tp. TpTe was 38±8 ms and TpTe_total was 75±9 ms. TpTe_total correlated with dRT in the entire heart (73±18 ms), but not with dRTs along individual axes (LV-RV: 66±17 ms, LV:apico-basal: 51±18 ms, LV:anterior-posterior: 51±27 ms, mean LV:transmural: 14±7 ms, all n=9).
Conclusions—We provide a correlation between local repolarization and T-wave in a pseudo ECG. Repolarization differences along all anatomical axes contribute to the T-wave. TpTe_total represents total dispersion of repolarization. At Tp approximately 25% of ventricular sites have been repolarized.
- Received November 8, 2013.
- Revision received April 8, 2014.
- Accepted April 11, 2014.