MYOCARDIAL BLOOD-FLOW RATE AND CAPILLARY-PERMEABILITY FOR TC-99M-DTPAIN PATIENTS WITH ANGIOGRAPHICALLY NORMAL CORONARY-ARTERIES - EVALUATION OF THE SINGLE-INJECTION, RESIDUE DETECTION METHOD WITH INTRACORONARY INDICATOR BOLUS INJECTION AND THE USE OF A MOBILE GAMMA-CAMERA

The aims of the present study were to quantitate myocardial perfusion and capillary permeability in the human heart by means of the single-i njection, residue detection method using a mobile gamma camera. With t his method, the intravascular mean transit time and the capillary extr action fraction (E) can be determined in one experiment and in the sam e myocardial region. Eighteen patients with a history of chest pain ep isodes and angiographically normal coronary arteries were studied afte r intracoronary bolus injections of Tc-99m-DTPA during elective corona ry angiography. Two measurements were performed at a 15-min interval d uring resting conditions, and a third measurement was made during atri al pacing. Regions of interest were drawn in the left anterior descend ing (LAD) and the circumflex (CX) coronary artery perfusion beds. Sour ces of variation in plasma flow rate (f(pl)), E, and the calculated ca pillary permeability area product (PS) were determined. Spontaneous 15 min variations (mean of two values) for the LAD and the CX territory, respectively, gave a mean f(pl)(LAD) of 74.2 (measurement 1) and 77.8 ml.(100 g.min)(-1) (measurement 2) (SD of the difference 7.5 ml.(100 g .min)(-1)) and f(pl)(CX) of 82.7 and 92.1 ml. (100 g.min)(-1), respe ctively (SD of the difference 16.1 ml.(100 g.min)(-1)), and E(LAD) was 51.0 and 55.7%, respectively (SD of the difference 8.4%), and E(CX) w as 52.9 and 50.4%, respectively (SD of the difference 5.9%). During at rial pacing, the rate-pressure product increased by 97%, and in the LA D area f(pl) increased by 46% (p < 0.05), E decreased by 6% (NS), and PS increased by 39% (NS), whereas in the CX region flow increased by o nly 9% (p < 0.01), E decreased by 15% (p < 0.05), and PS decreased by 15% (NS) compared with baseline values. Both the spontaneous variation and the observer variation are low. The reduced vasodilator response in the CX region in combination with the decrease in E, which reduce t he supply of nutrients, may play a role in the symptoms of these patie nts.