Effects of left circumflex coronary flow transducer implantation on posterior wall innervation

To determine whether dissection around a coronary artery and implantation of a flow transducer resulted in partial regional denervation of the heart, the effects of bilateral stimulation of the ansae subclaviae were evaluated on regional left ventricular (LV) wall thickening (WT) and tissue norepinephrine content in four groups of dogs following 1) sham operations (n = 6), 2) implantation of a Doppler flow transducer on the left circumflex coronary artery (n = 6), 3) selective circumflex coronary artery denervation with topical phenol application (n = 5), and 4) selective denervation of the posterior LV wall by extensive surgical stripping of the left circumflex coronary artery and local application of phenol (n = 6). One week later after anesthesia (chloralose 100 mg/kg) and a second thoracotomy for implantation of ultrasonic WT crystals, stimulation of the ansae subclaviae increased posterior WT by 67 ± 9% in the sham group, 71 ± 14% in the flow probe group, and did not increase systolic WT in the denervated group. In the posterior LV wall, norepinephrine levels were reduced (P<0.01) in the denervated group (6 ± 4 pg/ml) but not in the flow probe group (629 ± 4 pg/ml) compared with the sham group (589 ± 88 pg/ml). Selective left circumflex coronary artery denervation did not result in either diminished norepinephrine levels in the posterior LV wall nor diminished response of WT to sympathetic nerve stimulation. Thus chronic instrumentation applied properly to the left circumflex coronary artery does not result in significant regional denervation of the posterior myocardium.