I-123 METAIODOBENZYLGUANIDINE MYOCARDIAL IMAGING IN PATIENTS WITH PULMONARY-HYPERTENSION

Iodine-123-metaiodobenzylguanidine (I-123-MIBG) has been used to evalu ate the cardiac sympathetic nervous system. We evaluated the effect of pulmonary hypertension on the sympathetic neuronal function of the le ft ventricle in patients with pulmonary hypertension. We studied 20 pa tients with either chronic lung disease or pulmonary vascular disease. The patients were divided into a pulmonary hypertensive group and a c ontrol group. Single photon emission tomography was performed in the r esting state 15 min and 4 h after administration of I-123-MIBG. Region s of interest (ROI) were set in the left ventricular (LV) free wall, t he interventricular septum (IVS) and outside the LV free wall on short -axis images. The washout rate and the ROI/LV uptake ratio were calcul ated in each ROI. The IVS:LV uptake ratio was significantly lower in t he pulmonary hypertensive group than in the control group. Our results suggest that left heart sympathetic neuronal dysfunction initially oc curs in the IVS before it involves the LV free wall subsequently.