title: Radionuclide angiocardiographic assessment of pulmonary vascular reactivity in patients with left to right shunt and pulmonary hypertension.
abstract: Radionuclide angiocardiography was used to assess pulmonary vascular reactivity in eight patients (nine studies) with a large, relatively unrestrictive intracardiac defect and pulmonary arterial hypertension. Radionuclide angiocardiograms, using technetium-99m pertechnetate, were performed first with the patient breathing room air and then after 10 minutes of breathing a mixture containing 90 percent or more of oxygen. The pulmonary to systemic flow ratios obtained by gamma variate analysis of the radionuclide time-activity curves were compared with those calculated with the Fick principle at the time of cardiac catheterization. There was a good correlation between the two methods both in room air studies (r = 0.88) and in those obtained with 90 percent or more of oxygen (r = 0.94). All six studies (in five patients) with a reactive pulmonary vasculature (judged by a pulmonary vascular resistance at cardiac catheterization of less than 6 units/m2 with oxygen or after tolazoline) had a radionuclide pulmonary to systemic flow ratio of 3.0 or greater with oxygen. The three patients with a nonreactive pulmonary vasculature had a radionuclide pulmonary to systemic flow ratio of 2.3 or less with oxygen, a value that was unchanged from the room air value. These data suggest that radionuclide angiocardiography may be a useful, relatively noninvasive method of assessing pulmonary vascular reactivity in patients with a large, relatively unrestrictive intracardiac defect.
mesh_terms: D000790:Angiocardiography; D006328:Cardiac Catheterization; D002675:Child, Preschool; D006330:Heart Defects, Congenital / Q000000981:diagnostic imaging*; D006345:Heart Septal Defects, Ventricular / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D006976:Hypertension, Pulmonary / Q000000981:diagnostic imaging* / Q000503:physiopathology; D007223:Infant; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D011652:Pulmonary Circulation; D011877:Radionuclide Imaging; D013670:Sodium Pertechnetate Tc 99m; D013667:Technetium; D014655:Vascular Resistance
chemical_list: D013667:Technetium; D013670:Sodium Pertechnetate Tc 99m