Action potential duration gradients in the heart ventricles and the cardiac electric field during ventricular repolarization (a model study)

- The contribution of APD gradients and activation to the T-vector was simulated.
- All the gradients except the transmural produced one-dimensional T-vectors.
- The transmural gradient produced both transversal and apicobasal T-vectors.
- The transmural and the apicobasal gradients produced similar cardiac electric field.
- Activation sequence was an important contributor to repolarization electric field.

BackgroundWe simulated contributions of transmural, apicobasal, anteroposterior and interventricular action potential duration (APD) gradients to the body surface potential distribution (BSPD) with constant or varied magnitudes of the transmural and apicobasal gradients.MethodsSimulations were done in the framework of the discrete computer model of the rabbit heart ventricles on the basis of realistic activation sequence and APDs. The APD gradients were set constant at 20 ms or varied in the range of ± 80 ms.ResultsThe apicobasal, transmural and interventricular APD gradients of 20 ms produced similar BSPDs, whereas the BSPD inversion was caused by the inverted apicobasal or transmural 80 ms gradients. The transmural APD gradient produced transversal and mainly apicobasal T-wave vectors due to wall curvature and cancellation effects. The “normal” transversal and apicobasal repolarization gradients were decreased and increased by activation sequence, respectively.ConclusionThe different APD gradients contributed consistently to the development of BSPD.