Rest and exercise left ventricular ejection and filling characteristics following orthotopic cardiac transplantation.

High temporal resolution radionuclide angiography was performed in 24 normal volunteers and 31 healthy cardiac transplant recipients two to 43 months (mean 13 +/- 14 months) postoperatively in order to obtain cardiac volumes and parameters of left ventricular ejection and filling at rest and during supine exercise. The peak left ventricular ejection rate was significantly higher in transplant patients at rest (2.73 +/- 0.62 versus 1.98 +/- 0.29, P less than 0.0001). During submaximal exercise, however, in contrast to normal subjects, peak ejection rate increased in transplant recipients only during later exercise, corresponding to an increase in heart rate. Peak left ventricular filling rate was also significantly higher among transplant recipients at rest (3.52 +/- 0.96 versus 2.36 +/- 0.45, P less than 0.0001) and during submaximal exercise. Peak filling rate increased in transplant patients on initiation of exercise, associated with an increase in the end diastolic volume in the absence of an increase in heart rate. In 13 patients studied more than one year post cardiac transplantation, the peak ejection rate and peak filling rates did not differ from those studied less than one year post transplant. Therefore, in transplant patients, no defect of myocardial filling was apparent either at rest or during exercise. Systolic performance improved in later exercise, presumably as levels of circulating catecholamines and heart rate increased.