Neurocardiac Responses to Acute Coronary Balloon Occlusion in Humans

Both cardioinhibitory and sympathoexcitutory responses to transient coronary artery occlusion have been ascribed to activation of cardiac sensory receptors. Using autoregressive modeling, the power spectrum of heart rate variability was determined from continuous ECG records before, during (120 sec) and following coronary balloon occlusion in 17 patients with isolated single vessel coronary artery stenosis; 11 with left anterior descending (LAD) stenoses and 6 with either right coronary artery (RCA; n = 3) or circumflex (Cfx; n = 3) stenoses. There were no significant changes in heart rate or its variance either during balloon occlusion or following releuse for both the LAD and RCA/Cfx groups. However, during LAD occlusion there was a significant 27% increase in the low frequency (LF) power (60.5 ± 15.1 to 82.3 ± 25.4 b/min 2 /Hz; P < 0.05) and a 37% decrease in the high frequency (HF) power (28.9 ± 13.2 to 18.3 ± 9.7 b/min 2 /Hz;P < 0.05). An insignificant, but directionally opposite, trend was seen for the LF power during RCA/Cfx occlusions. Neither the presence nor absence of intracoronary collaterds, beta blockade, inflation induced ischemia, or history of previous myocardial infarction appeared to influence the effect of balloon inflation on either LF or HF values. The autospectral changes seen during transient LAD occlusion had not returned to control values within 30 minutes of balloon release. Thus, transient occlusion of an LAD artery stenosis elicits a shift in cardio‐sympathovagal balance towards heightened sympathetic modulation of sinus node activity.