HEART-RATE-VARIABILITY DURING REPEATED ARTERIAL-OCCLUSION IN CORONARYANGIOPLASTY

Acute coronary occlusion may cause severe autonomic reactions that can modify the clinical presentation of acute ischemic events. To evaluat e whether adaptation in these autonomic reactions exists during repeat ed short coronary occlusions, heart rate (HR) and its variability in t he time and frequency domains were analyzed in 70 patients with signif icant (50% to 95%) coronary artery stenosis immediately before and dur ing 2 identical balloon occlusions of the vessel (mean 110 seconds). R eactions were compared with the range of nonspecific changes formed by analyzing a control group (n = 13) with no ischemia during balloon in flation in a totally occluded coronary artery. Thus, neither occlusion caused significant changes in HR or HR variability in 29 patients (41 %). Vagal activation, as seen by an abnormal increase in HR variabilit y or brady-cardia, or both, was observed in 24 patients (34%). HR reac tions in this group (p <0.05) were significantly attenuated during the second occlusion. An opposite reaction (i.e., abnormal decrease in HR variability or tachycardia, or both) was observed in 17 patients (24% ). A nonsignificant tendency for attenuation of the reactions was air, seen in this group. Severity of chest pain, frequency of ST-segment s hifts, or narrowing of pulse pressure were comparable during the 2 occ lusions. Thus, a preceding short vessel occlusion-reperfusion cycle se ems to attenuate autonomic HR reactions, especially vagal reactions, d uring subsequent coronary occlusion. Alleviation of extreme autonomic reactions may modify the clinical outcome of coronary occlusion in a b eneficial way.