[Assessment of myocardial perfusion and cardiac sympathetic nerve dysfunction in patients with sick sinus syndrome--evaluation of coronary hemodynamics and 201TlCl/123I-MIBG myocardial SPECT].

To clarify the coronary hemodynamics, myocardial perfusion and cardiac sympathetic nerve function in patients with sick sinus syndrome (SSS), we performed left coronary digital subtraction angiography (DSA) in 41 patients, exercise 201TlCl-myocardial scintigraphy (planar and SPECT) in 69 patients, and 201TlCl/123I-MIBG myocardial dual SPECT in 13 patients without significant organic coronary stenosis. Coronary artery spasm was documented on coronary angiography in 25/43 (58%) patients with SSS by ergonovine provocation test. Compared with normals, patients with SSS demonstrated prolongation of left coronary circulation time (CCT) on own heart beats and right atrial pacing. We suspected that prolonged CCT may be induced by increased peripheral coronary vascular resistance and impaired coronary microcirculation in patients with SSS. Forty-two patients (60.9%) developed exercise-induced 201Tl-myocardial perfusion defect on SPECT images. On myocardial dual SPECT images, 11/13 (85%) patients showed localized myocardial low uptake in 123I-MIBG-SPECT images. In eight patients with normal findings on 201Tl-SPECT, six patients showed abnormality on 123I-MIBG-SPECT. We suspected that coronary vasospasm, impaired coronary micro-circulation and cardiac sympathetic nerve dysfunction are taken a part of pathophysiology in SSS (decreased beta-adrenergic receptor of peripheral coronary arteries?).