Changes in regional body blood volume caused by nitroglycerin.
Using a method of in vivo labeling of erythrocytes and subsequent whole-body scanning, we investigated the effect of nitroglycerin (NTG) on regional blood pooling in patients with chronic left heart failure (six men and two women). A group of eight patients with coronary heart disease who did not receive any NTG served as controls. These data were compared with the effects of NTG in ten male patients suffering from coronary artery disease. Up to 25 min after sublingual administration of 1.6 mg NTG we observed a significant decrease in radioactivity in the regions of heart, lung, and liver (maximal per hundred 6.0, 6.5, and 4.8 respectively) indicating the reduction in local blood volume. In the abdomen, the arms, and the legs we observed an increase in regional blood volume (maximum 9.7%, 8.3%, and 6.5% respectively). An overall significant change usually began approximately 5 min after NTG and lasted for about 20 min. In contrast to patients with left heart failure, patients with coronary artery disease did not show any significant difference in pulmonary and abdominal regions after NTG. The noninvasive method used allows an immediate determination of drug-induced regional blood volume pooling.