Left ventricular function at rest and during bicycle exercise in normal subjects: Assessment by ECG-gated myocardial perfusion SPET with Tc-99(m)-tetrofosmin

Tc-99(m)-labelled myocardial perfusion tracers allow simultaneous assessmen t of myocardial perfusion and left ventricular function using EGG-gated SPE T. The aim of this study was to evaluate left ventricular performance durin g exercise by means of EGG-gated myocardial perfusion SPET. After the admin istration of Tc-99(m)-tetrofosmin (555-740 MBq), eight healthy volunteers a ged 27-49 years underwent ECG-gated myocardial perfusion SPET at rest and d uring supine submaximal exercise (75 and 125 W), for 3 min each. Using EGG- gated SPET data, left ventricular end-diastolic volume (LVEDV) demonstrated a biphasic response during exercise (from 106.4 +/- 17.5 to 119.9 +/- 19.9 to 108.1 +/- 19.2 ml). In contrast, left ventricular end-systolic volume d ecreased gradually and significantly during exercise (from 47.1 +/- 11.9 to 41.5 +/- 8.9 to 36.1 +/- 10.1 ml, P < 0.05), and left ventricular ejection fraction continued to increase at higher workloads (from 56.1 +/- 6.0 to 6 3.0 +/- 2.7 to 67.0 +/- 4.3; P < 0.01) despite a fall in LVEDV. There was a progressive increase in cardiac output during exercise, which reached a pe ak of 7.2 +/- 0.9 l.min(-1). We conclude that EGG-gated myocardial perfusio n SPET can assess left ventricular function during exercise and may provide useful information for the evaluation of patients with ischaemic heart dis ease. ((C) 1999 Lippincott Williams & Wilkins).