We examined conventional radionuclide ventriculograms of 19 heart transplant patients and 12 control patients. R-to-R intervals were shorter in heart transplant patients (630 +/- 95 msec) than in controls (781 +/- 204 msec, p less than 0.01). The elevated heart rate is associated with a decreased left ventricular ejection fraction (56.7 +/- 10.3% vs 67.4 +/- 6.1%, p less than 0.005) and decreased emptying time (225 +/- 21 msec vs 270 +/- 47 msec, p less than 0.01), a shorter interval from the R wave to end systole (311 +/- 28 msec for heart transplant patients vs 349 +/- 48 msec in controls, p less than 0.01) and decreased filling time (262 +/- 61 msec vs 340 +/- 123 msec, p less than 0.01). The maximal filling rate is significantly increased (4.3 +/- 1.4 end diastolic volume/sec in heart transplant patients) compared with controls (3.0 +/- 1.1 end diastolic volume/sec, p less than 0.01, Student's t test). In those patients for whom the interval between the transplant procedure and the radionuclide ventriculogram study was greater than 360 days, the filling time (231 +/- 34 vs 296 +/- 67 msec) and emptying time (216 +/- 18 vs 235 +/- 20 msec, p less than 0.05) were significantly less than for those transplants in place less than 1 year. Other parameters were not significantly different. Those heart transplant patients having had two or more documented rejection episodes had no significant difference in hemodynamic function when compared with patients with one or no rejection episodes; no measure of the severity of rejection was used in this analysis.(ABSTRACT TRUNCATED AT 250 WORDS)