Evaluation of Left Ventricular Function by Radionuclide Angiocardiography in Patients with Old Myocardial Infarction

To investigate the effect of vasodilator therapy on the cardiac function, the radionuclide angiocardiography by the first pass method was performed in patients with old myocardial infarction (OMI), using the computerized multicrystal gamma camera system 77. The ointment containning 12 mg of nitroglycerin (NTG-O) was applied on chest wall and abdominal skin of 23 patients and 10 mg of Nifedipine (NFP) was orally given to 20 patients.The changes of ejection fraction (EF), left ventricular end syst olic volume (LVESV), end diastolic volume (LVEDV) and cardiac output (CO) were assessed before and after the therapy. Moreover, the response to the drugs in patients with normal ventricular function (EF>45% group I) was compared with that in those with EF of 45% or less (group II ).Before the therapy, the patients in group II had larger LVEDV, as compared with that in group I, suggestive the maintenace of the left ventricular pump function in patients with decreased EF. LVEF in both groups was decreased after administration of NTG-O, because of preload reduction. NFP, which is known to reduce afterload, was decreased blood pressure and LVESV and increased EF and CO in all patients. In patients in group I, NTG-O reduced the preload, while NFP reduced the afterload.In contrast, in patients with group II, both NTG-O and NFP were decreased not only afterload but also preload.The fin ding suggest that vasodilators improved left ventricular performance by reduction of both preload and afterload of left ventricle.