HEART-RATE-VARIABILITY IN ISOLATED RABBIT HEARTS

The presence of heart rate variability (HRV) in patients with cardiac denervation after heart transplantation raised our interest in HRV of isolated, denervated hearts. Hearts from seven adult white ELCO rabbit s were transferred to a perfusion apparatus. All hearts were perfused in the working mode and in the Langendorff mode for 20 minutes each. H RV was analyzed in the frequency domain. A computer simulated test ECG at a constant rate of 2 Hz was used for error estimation of the syste m. In the isolated, denervated heart, HRV was of random, broad-band fl uctuations, different from the well-characterized oscillations at spec ific frequencies in intact animals. Mean NN was 423 +/- 51 ms in the L angendorff mode, 406 +/- 33 ms in the working heart mode, and 500 ms i n the test EGG. Total power was 663 +/- 207 ms(2), 817 +/- 318 ms(2), and 3.7 ms(2), respectively There was no significant difference in any measure of HRV between Langendorff and working heart modes. The data provide evidence for the presence of HRV in isolated denervated rabbit hearts. Left atrial and ventricular filling, i.e., the working heart mode, did not alter HRV, indicating that left atrial or ventricular st retch did not influence the sinus nodal discharge rate.