Radionuclide-Determined Change in Pulmonary Blood Volume with Exercise

To assess the clinical usefulness of radionuclide-determined changes in pulmonary blood volume in patients with or without substantial coronary-artery disease, we determined the ratio of pulmonary blood volume at rest as compared with that during exercise. We used multigated blood-pool images obtained at rest and during supine exercise to determine the blood-volume ratio in patients subsequently undergoing coronary arteriography for evaluation of chest pain. Exercise tests were performed by use of a submaximal-workload protocol, although all tests were limited according to each patient's symptoms. The mean exercise/rest pulmonary-blood-volume ratios were lower for persons without coronary-artery disease (0.94 +/- 0.06 [S.D.], 10 patients) and for those with disease confined to the right coronary artery (0.99 +/- 0.12, five patients), as compared with all others with coronary-artery disease (1.14 +/- 0.15, 37 patients) (P less than 0.01). A pulmonary-blood-volume ratio equal to or greater than 1.06 had a sensitivity of 79 per cent. Patients with coronary-artery disease not confined to the right coronary artery usually show an increase in pulmonary blood volume during supine exercise. No such change occurs in persons without coronary-artery disease.