Iodine-123-BMIPP myocardial washout and cardiac work during exercise in normal and ischemic hearts.

Abstract

Iodine-123-BMIPP washout at rest and after exercise was investigated in relation to cardiac work in normal and ischemic myocardium. Sixteen healthy volunteers and 10 patients with ischemic heart disease were examined. After injection of 111 MBq of 123I-BMIPP, successive SPECT imaging was performed to evaluate washout ratio (WR) at rest and after mild and maximal exercise. In the healthy volunteers, the mean WR was 3.3 +/- 3.5% after 1 hr of rest and increased during both mild and maximal exercise. The WR showed a better correlation with net pressure rate product (PRP) than with the peak PRP. After maximal exercise, the WR showed a distinct correlation with the net PRP in the range from 200-300 x 10(3) mmHg/min and then showed a plateau greater than 10%. In five ischemic heart disease patients with the net PRP > or = 300 x 10(3) mmHg/min, the exercise WR values were significantly elevated in normal segments relative to ischemic segments. BMIPP washout increased with the increase in cardiac work during exercise in normal myocardium but not in ischemic myocardium. A certain amount of exercise is necessary to evaluate fatty acid metabolism in normal and ischemic myocardium.