Neurally mediated depressor hemodynamic response induced by intracoronary catheter balloon inflation in pigs.

OBJECTIVES: To assess whether intracoronary catheter balloon inflation triggers a neurally mediated hemodynamic response that interacts with the ischemia-induced myocardial dysfunction.

METHODS: Forty-eight chloralose anesthetized pigs underwent a 60 s intraluminal catheter balloon inflation of the proximal left anterior descending (LAD) coronary artery before and after one of these treatments: disruption of LAD pericoronary nerves with phenol (n=6), bilateral stellectomy (n=8), bilateral cervical vagotomy (n=6), atropine (n=5), and ganglionic blockade with hexamethonium (n=10). In 13 other pigs, we assessed the reproducibility of two balloon inflations spaced 15 min (n=6) or 60 min (n=7). The ECG, left ventricular (LV) pressure, and LV dP/dt were recorded during each intervention. Right ventricular (RV) pressure, RV dP/dt, and aortic blood flow were also measured in a subset of pigs.

RESULTS: Balloon inflation induced an early (10 s) and reproducible (ANOVA, P<0.001) drop in systolic pressure and peak dP/dt; a decrease in aortic blood flow; a rise in end-diastolic pressure; and elevation of the ST segment. Pericoronary denervation, stellectomy and ganglionic blockade attenuated (P<0.001) the drop in LV parameters during coronary inflation, but atropine and vagotomy did not.

CONCLUSIONS: A depressor hemodynamic response subserved by pericoronary nerves worsens the LV dysfunction induced by brief coronary catheter balloon inflation in anesthetized pigs. Cholinergic fibers do not appear to play a major role.