Regional myocardial sympathetic dysinnervation in arrhythmogenic right ventricular cardiomyopathy. An analysis using 123I-meta-iodobenzylguanidine scintigraphy.

Abstract

In patients with ARVC, regional abnormalities of sympathetic innervation are frequent and can be demonstrated by 123I-MIBG scintigraphy. Sympathetic denervation appears to be the underlying mechanism of reduced 123I-MIBG uptake and may be related to frequent provocation of ventricular arrhythmias by exercise or catecholamine exposure in ARVC. Therefore, in patients with ARVC, the noninvasive detection of localized sympathetic denervation by 123I-MIBG imaging may have implications for the early diagnosis and for the choice of antiarrhythmic drugs in the treatment of arrhythmias.

Abnormalities of Cardiac Sympathetic Innervation in Arrhythmogenic Right Ventricular Cardiomyopathy

“…[1][2][3] Because sympathetic nerve fibers travel in the subepicardium, localized presynaptic sympathetic denervation may occur early in the course of the disease process before functional abnormalities become apparent. 2,7 However, the findings of the present study do not support the presence of such a denervation process underlying sympathetic dysinnervation in ARVC. Analysis of the tracer clearance rate from the myocardium revealed substantially higher blood flow-corrected k 2 values (ie, k 2 /MBF) for the 4 subjects who had a reduced V d for 11 C-HED (subjects 1, 4, 6, and 7), whereas this parameter was normal for the 4 subjects with normal or high values of V d .…”

“…Regional abnormalities of presynaptic adrenergic function were not as extensive as previously reported in studies using 123 I-MIBG SPECT 7 and were found in only 4 patients with ARVC in the present study. This may be explained by patient selection, which was not based on the results of preceding 123 I-MIBG scanning but rather on the absence of previous treatment with antiadrenergic drugs.…”

“…Although abnormalities of the presynaptic function (V d of 11 C-HED) were not significant in the limited number of patients included in the present study, the results confirm and extend our previous observations by radionuclide studies performed with 123 I-MIBG-SPECT, which consistently demonstrated regional reduction of transporter-mediated neuronal catecholamine reuptake (uptake-1) in ARVC. 7 …”

“…7 On the basis of these studies, we hypothesized that abnormalities of myocardial sympathetic function are present and may contribute to the arrhythmogenesis in ARVC. Reduced presynaptic uptake of radionuclide tracers may result from increased neuronal firing rates or impaired function of the presynaptic norepinephrine transporter (uptake-1).…”

Heterogeneous Atrial Denervation Creates Substrate for Sustained Atrial Fibrillation

“…[1][2][3][4][5][6] Although the importance of the autonomic nervous system in atrial fibrillation (AF) has been suggested by both experimental and clinical observations, its role in the initiation and perpetuation of AF has not been determined. The autonomic tone before the onset of AF has been used to identify so-called vagal AF in humans.…”