Radioisotope scintigraphy for the study of dynamics of amine regulation by the human lung.

CHEST 71: 2, FEBRUARY, 1977 SUPPLEMENT RVEF, cardiac index (CI), and mean pulmonary artery pressure (PAP) were measured before and 30 minutes after intravenous ouabain (0.01 mgkg) in 11 patients with severe CAO and DCP. Control RVEF (46.9 ± 3.4%), CI (2.79 0.15 L/min/M2) and PAP (30 ± 2 mm Hg) were not significantly altered by ouabain (48.5 ± 2.9%, 2.82 ± 0.14 L/min/M2, 31 ± 1 mm Hg respectively) even in 6 patients with depressed RVEF (38.5 ± 3.0% to 43.0 ± 3.2%). RVEF, CI, and PAP were measured before and after 6 months of continuous lowflow oxygen therapy in 6 patients. There was a significant decrease (P <0.05) in PAP (40 ± 5 to 30 ± 3 mm Hg) and pulmonary arteriolar resistance index (990 ± 134 to 631 ± 65 dynes.cm-’), and a significant increase (P ( 0.05) in RVEF (38.5 ± 4.8 to 55.7 ± 3.1%) after oxygen. For correlation of RVEF with PAP, 35 patients with severe CAO were studied. In 14 normal men, radionuclide-determined RVEF averaged 57% with a normal range (2SD) of 51 to 64%, and systolic PAP averaged 17 mm Hg (12 to 22 mm Hg). In patients with severe CAO, RVEF did not correlate with systolic or mean PAP (y = -0.44 and 0.32 respectively). Fourteen patients (40%) had depressed RVEF (37 ± 2%), and the systolic PAP in this group (51 ± 4 mm Hg) was significantly higher (P < 0.001) than the systolic PAP (40 ± 2 mm Hg) in those with normal RVEF (58 ± 1%). Results suggest that in severe CAO, RVEF is depressed in most patients with a history of DCP and RVEF is normal without a history of DCP. Ouabain fails to alter significantly RV performance even when RVEF is depressed, whereas chronic low-flow oxygen therapy increases RVEF probably by decreasing RV afterload. RVEF does not correlate with PAP.