Heterogeneity of the human myocardial sympathetic innervation: in vivo demonstration by iodine 123-labeled meta-iodobenzylguanidine scintigraphy

Abstract

The normal pattern of the myocardial sympathetic innervation was studied in 15 subjects using single photon emission computed tomography (SPECT) gamma scintigraphy with iodine 123-labeled meta-iodobenzylguanidine (I123MIBG). Seven young subjects (mean age 29.4 +/- 7.5 years SD) with supraventricular tachycardia and eight older patients (mean age 53.0 +/- 5.1 years SD) with normal coronary arteries at cardiac catheterization and normal thallium-201 scintigrams were studied. MIBG uptake in the hearts of six patients with complete cardiac denervation after orthotopic cardiac transplantation was also studied. MIBG scintigrams were reconstructed into bull's-eye target plots and divided into eight equal sectors. Within each sector, four areas representing the apical, two midventricular, and basal regions were defined. There was a reduction in counts in the older group of subjects with normal coronary anatomy (1218.2 +/- 198.4) as compared with younger subjects with supraventricular tachycardia (1124.4 +/- 317.6), (F = 15.0, df = 1, p < 0.001). The difference was lost after adjustment for age (p = 0.2) by means of analysis of covariance. There was a difference in counts within different sectors of the scan (F = 5.7, df = 7, p < 0.001), with lateral and anterior sectors having higher counts than septal and inferior sectors. There was no difference in the counts within areas of the scan (F = 0.04, df = 3, not significant [NS]) or different areas within the sectors (F = 1.1, df = 21, NS). A small diminution of counts (approximately 10%) in the 10 o'clock region of the bull's-eye target plot was observed in some scans.(ABSTRACT TRUNCATED AT 250 WORDS)