Cardiac electric activity in rats with experimental pulmonary hypertension during ventricular repolarization

Cardiac electric activity of Wistar rats with experimentally induced pulmonary arterial hypertension (PAH) in the period of ventricular repolarization was in- vestigated by the methods of electrocardiography and multichannel surface mapping. Pulmonary arterial hypertension was induced by a single subcutaneous injection of monocrotaline (MCT) (60 mg/kg, Sigma-Aldrich, Germany). Cardioelectric potentials were recorded from 64 electrodes evenly distributed around the rat's body, synchronously with the ECG in the leads from the extremities before and 4 weeks after the MCT injection. In the ECG in the second lead from the extremities the duration of the R-R interval, QT and T-wave intervals: J-Tpeak (from the J point to the T-wave peak), Tpeak-Tend (from the T-wave peak to its end) and J-Tpeak (from the J point to the end of the T-wave) - was measured in three cardiocycles. Heart rate was calculated based on the average value of R-R interval. ECG analysis in the second lead from the extremities revealed significant decrease in heart rate, prolongation of QT-, Tpeak-Tend, J-Tend intervals in rats with experimentally induced pulmonary hypertension. In rats, 4 weeks after the injection of MCT, right ventricular hypertrophy develops, leading to significant increase in the duration of cardiac ventricular repolarization due to its final period and reliable changes in the amplitude-temporal parameters of the cardiac electric field on the body surface compared to the initial state.