Respiratory effort during inspiration, expiration, and the Valsalva manoeuvre changes right ventricular preload and afterload. On inspiration these changes should improve systolic emptying of a larger end diastolic volume and so increase the ejection fraction, whereas on expiration the reverse should be true. The resting right ventricular ejection fraction was measured by first pass radionuclide angiography with gold-195m (half life 30.5 s) in 17 individuals at maximal inspiration and expiration and in eight at rest and during the strain phase (phase 2) of the Valsalva manoeuvre. The right ventricular ejection fraction was significantly lower during expiration than during inspiration. There were, however, no significant differences in bolus duration or right ventricular transit time. The Valsalva manoeuvre, in contrast, significantly increased the ejection fraction and also significantly prolonged both the bolus duration and right ventricular transit time. The conformation of the bolus curves during the Valsalva manoeuvre suggested the development of tricuspid regurgitation. These data suggest that relative influences of venous return, pulmonary arterial pressure, pulmonary vascular resistance, and possible functional tricuspid regurgitation vary during inspiration, expiration, and the Valsalva manoeuvre and can affect the right ventricular ejection fraction. Changes in right ventricular function on exercise assessed by first pass radionuclide angiography must be interpreted with caution because maximal respiratory effort may alter the right ventricular ejection fraction independently of ischaemia or other non-ischaemic factors.

Objective-To examine how exercise testing on background medical treatment affects the ability of the test to predict prognostically important patterns of coronary anatomy in patients with a high clinical probability of coronary artery disease but who are well controlled on medication. Design-Prospective study. Setting-Regional cardiothoracic centre and referring district general hospital. Patients-84 patients with a history of typical angina or definite myocardial infarction and mild symptoms who had been placed on the waiting list for prognostic angiography.

Silent myocardial ischaemia is readily detected by exercise radionuclide ventriculography in patients with coronary artery disease. In those who remain asymptomatic and event-free, it is not known whether silent ischaemia which is inducible despite anti-ischaemic medication exerts an insidious detrimental effect on left ventricular function. To study this, 34 medically treated patients (mean age 57; 26 men) underwent prospective measurement of left ventricular ejection fraction (LVEF) during rest and exercise radionuclide ventriculography without interruption of anti-ischaemic medication at baseline and 12 months later. There was no significant mean (standard deviation, 95% confidence interval) deterioration from baseline to 12 months in LVEF at rest (50% v 49%, SD 5; 95% CI = -3 to +1), peak exercise (44% v 45%, SD 8; 95% CI = -1 to +4) and the change in LVEF from rest to exercise (-6% v -4%, SD 7; 95% CI = -1 to +5). Thus, in coronary artery disease patients who remain asymptomatic and event-free on medical therapy, silent myocardial ischaemia which is readily inducible at baseline despite medication does not lead per se to deterioration of left ventricular systolic function at rest or exercise over 12 months.

SUMMARY Serial changes in left ventricular function on exercise were assessed by first pass radionuclide angiography with gold-195m (half life 30 5 s) in 25 men with known coronary anatomy. In the seven patients with three vessel disease, abnormalities of global left ventricular function and regional wall motion occurred earlier during exercise, were of greater extent at peak exercise, and persisted longer after exercise than in the 11 patients with one and two vessel disease or the seven with normal coronary arteries. Although there were significant differences between the groups in absolute change in ejection fraction and the rate of change in ejection fraction related to exercise duration and heart rate, a considerable overlap of values between groups precluded the accurate prediction of coronary anatomy in individuals.These data suggest that the amount of myocardium at risk from ischaemia in some patients with one and two vessel disease may resemble that in patients with three vessel disease. This study shows that an anatomical classification based solely on the number of diseased vessels will not predict the extent of the impairment of left ventricular function on exercise.

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