In vivo and in vitro effects of stellate ganglion blockade on radial and internal mammary arteries

Abstract

Objective: To investigate the effects of stellate ganglion blockade (SGB) on the internal mammary (IMA) and radial arteries (RA) in patients undergoing coronary artery bypass graft (CABG) surgery with in vivo and in vitro studies.

Design: Prospective, randomized trial.

Setting: University hospital.

Participants: Thirty-seven patients undergoing CABG surgery.

Interventions: SGB was performed on 19 patients before anesthesia induction. Another group of 18 patients underwent surgery without SGB. Diameters of proximal RA, distal RA, and IMA were determined by Doppler ultrasonography before (T1) and after (T2) anesthesia induction. Control or blocked IMA and RA segments were obtained. Norepinephrine (NE) was applied to determine the contractile force of IMA and RA rings in a concentration-dependent manner. The maximal contractile response and the sensitivity of the vessels were compared.

Measurements and main results: The diameters of IMA and distal RA were statistically larger in the SGB group than those in the control group at T2. NE-induced maximum contraction was higher in the blocked RA rings than those in the control RA and blocked IMA rings. The sensitivity of IMA segments to NE was higher than that of RA segments in the SGB group. The control and blocked IMA segments showed similar sensitivity to NE.

Conclusion: The present results show that SGB not only increases distal RA and IMA diameters but is also associated with in vitro differences, the mechanism of which remains to be elucidated. Therefore, SGB might be considered as an alternative to topical and systemic vasodilators for reducing vasospasm in patients undergoing CABG.