Use of myocardial tomo-scintigraphy by 123I - MIBG in right ventricle arrhythmia-gen dysplasia

The dysfunction of myocardial sympathetic system was implied in occurrence of ventricular arrhythmias in patients with a right ventricle arrhythmia-gen dysplasia (RVAD). The goal of this study is to evaluate the myocardial pre-synaptic adrenergic regional function by using the cardiac tomo-scintigraphy with 123I - meta-iodo-benzyl-guanidine (MIBG). Fourteen patients (12 M, 2 F, age: 46± 13) in whom the disease's diagnosis was done on the basis of the parameters of European Task Force (electric, angiographic, histologic), were studied. Six healthy subjects (32 ± 12 years) were at the same time studied as control group. Each patient benefited by an at-rest tomo-scintigraphy by 201Tl to eliminate any hypo-perfusion which could hinder the interpretation of MIBG fixation. A 48 h delay was necessary between the two isotopic examinations. After blocking the thyroid by Lugol fort, an at-rest tomo-scintigraphy by 123I - MIBG was effected 4 h after the injection IV of 259 MBq of tracer following a classical acquisition of a myocardial tomography with a tracer-adopted collimator (Elscint camera). Global and regional evaluations of the cardiac adrenergic neuronal function were effected by using the cardio-mediastinal ratio (CMR) and the circumferential profile, respectively, for the localization, extension and amplitude of regional adrenergic defects. The CMR is within the normal limits (236 ± 39% vs 234 ± 14% in healthy subjects). The adrenergic defects are present in 11/14 patients (a reduction of 50% of capture of MIBG as compared with the control group, < average - 2 ET) in the anterior and lateral regions of left ventricle. In conclusion, the tomo-scintigraphy by 123I - MIBG allows the detecting of presence of a sympathetic dys-innervation of left ventricle in patients afflicted with RVAD