CORRELATION BETWEEN SCINTIGRAPHIC EVIDENCE OF REGIONAL SYMPATHETIC NEURONAL DYSFUNCTION AND VENTRICULAR REFRACTORINESS IN THE HUMAN HEART

Background. Denervation supersensitivity has been proposed as a mechan ism for the relation between ventricular arrhythmias and the sympathet ic nervous system. Evaluation of this phenomenon in humans has become feasible only recently with the development of noninvasive scintigraph ic methods for evaluating the pattern of sympathetic innervation. The purpose of this study was to determine if scintigraphic evidence of sy mpathetic neuronal dysfunction correlates with measurements of ventric ular refractoriness and to evaluate the phenomenon of denervation supe rsensitivity in humans. Methods and Results. Eleven patients with a hi story of sustained ventricular tachycardia or sudden cardiac death who were referred for placement of an implantable defibrillator participa ted in this study (seven men and four women; age, 51+/-18 years). Preo perative scintigraphic evaluation of the pattern of sympathetic innerv ation was performed with C-11-hydroxyephedrine in conjunction with pos itron emission tomography. At the time of surgery, ventricular refract oriness was determined in regions of myocardium demonstrating normal a nd reduced C-11-hydroxyephedrine retention in the baseline state and d uring an infusion of norepinephrine. Scintigraphic evaluation demonstr ated regions of reduced C-11-hydroxyephedrine retention in each patien t. The effective refractory period in areas of myocardium that demonst rated reduced C-11-hydroxyephedrine retention was significantly longer than in areas of myocardium demonstrating normal C-11-hydroxyephedrin e retention (273+/-32 versus 243+/-32 msec, p<0.001). Norepinephrine s hortened the effective refractory period in regions of myocardium demo nstrating normal and reduced C-11-hydroxyephedrine retention to a simi lar degree. Conclusions. There is a correlation between scintigraphic evidence of sympathetic neuronal dysfunction and ventricular refractor iness in the human heart. These observations help validate the use of scintigraphic techniques for evaluation of sympathetic innervation and may assist in the further evaluation of the relation between the symp athetic nervous system and ventricular arrhythmias.