Raflo, Charles P.

SUMMARY Results of systolic time interval recordings obtained serially on 104 female New Zealand White rabbits were analyzed for reproducibility, variation with respect to changes in heart rate (hr), and interrelationship of the various systolic time intervals. A table of values for systolic time intervals in the healthy rabbit was constructed. The preejection period (pep), left ventricular ejection time (lvet), and pep/lvet ratio were 0.040 ± 0.008 s, 0.119 ± 0.014 s, and 0.337 ± 0.066 respectively. The major systolic time intervals, pep and lvet, varied with respect to hr according to the regression equations: pep = 0.057 − 0.000078 hr and lvet = 0.175 − 0.000251 hr. The QS2 interval, S1S2 interval and isovolumic contraction time also varied with changes in hr.

SUMMARY Systolic time interval recordings were performed serially on 104 healthy female New Zealand White rabbits and 51 rabbits with congestive heart failure (chf) induced by chronic anthracycline drug therapy. The results were analyzed and the comparisons were made with studies of systolic time interval recordings of chf in persons. In the rabbit, chf is manifested by prolongation of the isovolumic contraction time, the preejection period (pep), and by shortening of the left ventricular ejection time (lvet). The ratio of pep/lvet was a sensitive indicator of left ventricular failure, with values in excess of 0.466 reflecting significant cardiac dysfunction at the 95% confidence level. The mean pep/lvet = 0.337 ± 0.66 in healthy rabbits and pep/lvet = 0.502 ± 0.075 in rabbits with chf. The pep index increased from 0.057 ± 0.007 in healthy rabbits to 0.074 ± 0.007 in rabbits with heart failure. The lvet index decreased from 0.173 ± 0.007 in healthy rabbits to 0.166 ± 0.010 in rabbits with chf.