[Regional myocardial blood flow measurements in resting and dipyridamole induced vasodilative state by Xenon-133 clearance method].

Myocardial imaging with Xenon-133 and a gamma camera was employed to evaluate the relationship between angiographically demonstrated coronary artery stenosis and regional myocardial blood flow (r-MBF) in 22 patients with ischemic heart disease and 9 control subjects. After a left anterior oblique cineangiogram was obtained, the cinecamera was replaced by the mobile gamma camera in the same plane and location over the pericardium of patients. Then, 370 MBq (10 mCi) of 133Xe was injected into the left coronary artery as a bolus. After the first measurement of r-MBF in resting state, a second injection was made 3 minutes after intravenous injection of 0.56 mg/kg of dipyridamole for 4 minutes. The r-MBF in different regions of the heart was calculated by Kety formula. Coronary flow reserve (CFR) was defined the rMBF ratio between resting and dipyridamole induced vasodilative state. In the resting state, good correlation (r = 0.711) was observed between pressure rate product and the r-MBF at the areas perfused by non stenotic vessels. The r-MBF of the areas perfused by severe stenotic vessels (greater than 90%) was smaller than that of the areas perfused by non stenotic vessels, however there was overlapping of flow. In the dipyridamole induced vasodilative state, the r-MBF of the areas perfused by intact vessels increased approximately 2.4 times of the resting state, and showed good correlation with pressure rate product. In contrast, the r-MBF of the areas perfused by stenotic vessels did not correlate with pressure rate product, but depended on the degrees of coronary stenosis (50-75% stenosis; 1.9 times, greater than 90% stenosis; 1.3 times, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)