Feasibility of Perioperative Stellate Ganglion Blocks in Cardiac Surgery

Based upon Northern New England Cardiovascular Study Group data, the rate of post operative atrial fibrillation (POAF) requiring treatment following coronary artery bypass grafting (CABG) at Maine Medical Center (MMC) is currently 30%. Nationally, POAF occurs in up to 40% of patients post CABG, 50% of patients after valve surgery, 64% of patients post mitral valve and CABG and 49% after aortic valve replacement. Atrial fibrillation worsens a patient's hemodynamic status and increases the risk of congestive heart failure (CHF), embolic events and longer ICU stays leading to increased patient morbidity and strain on financial resources. In the U.S., POAF carries a higher risk of stroke (37% OR 2.0 in-hospital mortality (OR = 1.7), worsened survival (74% versus 87%), and an additional 4.9 days and $10,000-$11,500 in hospital stay costs. Atrial fibrillation requires both an initiation trigger and favorable environment for maintenance and the sympathetic and parasympathetic nervous systems play important roles in this regard. Unfortunately, the precise mechanisms of POAF are still being investigated. This postoperative complication has persisted in spite of efforts to mitigate it pharmacologically with beta blockers and amiodarone, an experience shared by most other cardiac surgery centers. The stellate ganglion is formed by the fusion of the inferior cervical sympathetic ganglion and first thoracic sympathetic ganglion. By modulating the sympathetic component of the autonomic nervous system, stellate ganglion stimulation has been shown to facilitate induction of atrial fibrillation while ablation may reduce or prevent episodes. Human studies have further supported this model. Preliminary studies of perioperative stellate ganglion block (SGB) in cardiac surgery suggest that this technique may reduce or prevent episodes of POAF requiring treatment. The investigator's ultimate goal is to determine whether SGB reduces the incidence of POAF in specific cardiac surgery populations at MMC. First, however, the investigator proposes to test the hypothesis that SGB, performed perioperatively by cardiac anesthesiologists in a population of patients undergoing cardiac surgery, is both safe and clinically feasible.