MEASUREMENT OF HUMAN PULMONARY ARTERIAL VOLUME INVIVO

  • 1 January 1979
    • journal article
    • research article
    • Vol. 15  (5) , 925-934
Abstract
A method of measuring pulmonary arterial transit time (PATT), from the pulmonary valve to the precapillary vessels, using the .gamma.-emitting isotope 99mTc and external counting probes, was applied in patients during cardiac catheterization. The method was successfully applied in 36 of 39 patients. The dose of 99Tc for a single determination was 1 mCi. Agreement between right and left lung transit times was good; average difference between the 2 lungs was less than 7% of mean PATT. Reproducibility between duplicate injections was 9.4 .+-. 1.2% (SEM [standard error of the mean]). Pulmonary arterial volume (PAV) was calculated as the product of PATT and flow. In 11 normal patients average PAV was 92 ml .cntdot. m-2 and constituted 30% of total pulmonary blood volume (PBV). In 10 patients with pulmonary hypertension secondary to lung disease average PAV was 129 ml .cntdot. m-2, constituting 38% of PBV, while, in 7 patients with left ventricular disease and a similar degree of pulmonary hypertension, PAV was also 129 ml .cntdot. m-2, but constituted only 29% of PBV. In pulmonary hypertension secondary to lung disease the pulmonary arteries are enlarged out of proportion to the remainder of the pulmonary vascular bed. In 7 patients with lung carcinoma, in whom 1 main branch of the pulmonary artery was occluded with a balloon catheter, PAV fell significantly less than was predicted, indicating a distension of the unoccluded portion of the arterial tree. Distensibility in the unoccluded part of the arterial tree was calculated to be 4.5%/cmH2O pressure.