Objectives: This study was designed to elucidate the influence of cardiac sympathetic denervation on the sympathoexcitatory response to acute myocardial ischemia during balloon coronary occlusion (BCO) in humans.
Background: Alterations of cardiac sympathetic nerve function could modulate sympathetic reflexes originating from the ischemic area.
Methods: In 23 patients with angina pectoris, we quantified the baseline cardiac sympathetic denervation of the ischemia-related area by iodine-123 metaiodobenzylguanidine ((123)I-MIBG), and transient changes in sympathetic activity during BCO by wavelet analysis of RR interval variability.
Results: Balloon coronary occlusion resulted in a transient augmentation of low-frequency (LF: 0.04 to 0.14 Hz) spectral components of RR interval variability in 4 of 12 patients with cardiac denervation and in 8 of 11 patients without denervation (p < 0.01 by the chi-square test). Consequently, the increase in LF components was significantly less during BCO in patients with cardiac denervation (34%) than in those without denervation (273%) (interaction: p < 0.05). In seven patients with severe ischemia provoked by a fall of > or = 10% in the left ventricular ejection fraction, LF components increased by 506% during BCO, regardless of the condition of cardiac denervation. In contrast, in patients with mild ischemia provoked by a fall of <10% in the ejection fraction, changes of LF components during BCO were significantly less in patients with denervation than in those without denervation (84 vs. 344%, p < 0.05).
Conclusions: These findings suggest that if the provoked ischemia is not severe, cardiac sympathetic denervation could prevent ischemia-induced sympathoexcitation.