Cardiac dynamics during supine exercise in cyclosporine-treated orthotopic heart transplant recipients: assessment by radionuclide angiography.

The mechanisms by which the denervated heart responds to supine exercise were assessed by equilibrium gated radionuclide angiography in 18 cardiac transplant recipients 1 to 25 months (mean 11) after surgery. Results were compared with those in 15 normal subjects. Exercise duration among transplant recipients did not differ significantly from that in normal subjects. The heart rate at rest in transplant patients was 30% higher than in normal volunteers. Heart rate increased only 3% between rest and the first stage of exercise in transplant recipients compared with a 37% increase in the normal group (p less than 0.001). Cardiac output at rest was similar in both groups although the rate of rise of cardiac output and peak cardiac output were significantly lower among the transplant recipients. In early exercise, the means by which cardiac output increased in the transplant patients differed significantly from normal. In the transplant recipients, the left ventricular end-diastolic volume index increased 14% compared with a decrease of 2% in normal subjects (p less than 0.001) during the first stage of exercise. At the same time, the end-systolic volume index increased 6% in the transplant group but decreased 11% in normal subjects (p less than 0.001). These changes resulted in an overall increase in stroke volume by 20% in the transplant group compared with only a slight increase (+3%) in normal subjects (p less than 0.001) during the first stage of exercise. Among transplant recipients, the stroke volume index plateaued after the first stage of exercise, which, in combination with the blunted chronotropic response, resulted in a peak cardiac index 25% lower than that in normal subjects (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of bepridil with nadolol for angina pectoris.

Bepridil hydrochloride is a unique calcium channel-blocking drug with anti-ischemic and type 1 antiarrhythmic properties. With a half-life of more than 40 hours, once-daily therapy is possible. Twenty-four patients (22 men, 2 women), mean age 58 years (range 43 to 72), with stable exertional angina were assigned to therapy with bepridil and nadolol in a randomized, double-blind, crossover trial. Antianginal efficacy was assessed by a diary of angina frequency and nitroglycerin consumption as well as by treadmill exercise testing. The effect of therapy on ventricular function was assessed by symptom-limited equilibrium gated exercise radionuclide angiography. During therapy with both nadolol and bepridil, the number of episodes of angina per week was significantly reduced and nitroglycerin consumption decreased compared with baseline evaluation. Exercise duration was prolonged by both therapies (baseline 281 +/- 122 seconds, nadolol 377 +/- 96 seconds, bepridil 400 +/- 109 seconds; p less than 0.005 for nadolol and bepridil vs baseline). Time to the onset of angina was similarly prolonged, 50% by nadolol and 65% by bepridil (p less than 0.005). Bepridil had no effect on PR and QRS durations, although QTc was significantly prolonged (baseline 0.43 +/- 0.03, nadolol 0.42 +/- 0.03, bepridil 0.45 +/- 0.04; p less than 0.005 for bepridil vs baseline and nadolol). By radionuclide angiography, neither nadolol nor bepridil had an adverse effect on left ventricular function at rest or during exercise. Bepridil therefore provides effective therapy for angina without adverse effects on left ventricular function, comparable to the effects of beta blockade with nadolol.

Left ventricular volume response to exercise in normal and coronary artery disease patients.

The left ventricular (LV) volume response to supine exercise (EX) was studied in 15 normal volunteers (mean age 44, asymptomatic, with normal resting ECG and treadmill stress test) and 28 coronary artery disease patients (CAD, documented by cardiac catheterization) with no previous myocardial infarction. Each individual underwent stress gated equilibrium radionuclide angiography (RNA) and was on no medication. A nongeometric count based LV volume programme developed in our laboratory (correlation to biplane cineangiography R = .98), was used to calculate end diastolic volume index (EDI), end systolic volume index (ESI), stroke volume index (SVI), cardiac index (CI), and ejection fraction (EF). In normal individuals, end diastolic volume did not change from rest to exercise, while end systolic volume decreased by an average of 16%. In the patients with coronary artery disease, however, both end diastolic volume and end systolic volume increased (14% and 15% respectively). Furthermore, our preliminary data suggest that the extent of the changes may be dependent upon the extent of the underlying CAD. While all the CAD patients had an increase in their end diastolic volumes, there was no change in the end systolic volume in those with single vessel disease, an 11% increase in patients with double vessel disease and a 19% in patients with triple vessel disease.

Arrhythmogenic right ventricular dysplasia: detection by radionuclide ventriculography.

A 35 year old female patient was referred for investigation and treatment of recurrent ventricular tachycardia. Cardiac examination and the echocardiogram were normal. Equilibrium radionuclide ventriculography demonstrated a reduction in right ventricular ejection fraction (rest and exercise) while left ventricular ejection fraction was normal. It is proposed that radionuclide ventriculography may be the noninvasive study of choice to screen patients for arrhythmogenic right ventricular dysplasia. The right ventricular response to exercise may provide additional evidence for right ventricular dysfunction based on relative changes compared to the left ventricle. The diagnosis of arrhythmogenic right ventricular dysplasia may be subsequently confirmed by right ventricular angiography or endomyocardial biopsy, both of which are techniques which may not be performed during routine cardiac catheterization in the absence of the radionuclide ventriculography findings to suggest right ventricular dysfunction.

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.

Retrograde coronary sinus versus aortic root perfusion with cold cardioplegia: randomized study of levels of cardiac enzymes in 40 patients.

Myocardial injury was assessed with the use of enzyme indexes in 40 patients randomly assigned to one of two groups undergoing coronary artery bypass surgery. Twenty patients received cold cardioplegia delivered by retrograde coronary sinus perfusion and 20 received cardioplegic solution by anterograde aortic root perfusion. Creatine kinase isoenzyme MB and lactate dehydrogenese isoenzyme 1 and isoenzyme 2 assays were carried out on blood samples obtained from the coronary sinus before aortic cross-clamping and 0, 5, and 30 min after aortic unclamping. Levels of these enzymes were also obtained from venous blood samples before aortic cross-clamping and 3, 8, 14, and 20 hr after aortic unclamping and 2, 3, 4, and 5 days after surgery. Preoperative and postoperative hemodynamic measurements (Swan-Ganz catheter) and radionuclide wall motion studies were also obtained for comparison. There was no overall significant difference between the two groups postoperatively in terms of enzyme indexes, hemodynamic measurements, or results of wall motion studies. We conclude that retrograde coronary sinus perfusion is an alternative to aortic root perfusion in delivering cold cardioplegia. More studies are required to determine which subgroup of patients with coronary artery disease may benefit from retrograde coronary perfusion.