Effect of Stellate Ganglion Block on Internal Mammary Artery Dynamics: A Randomized Controlled Clinical Trial

The left internal mammary artery (LIMA) is commonly selected as the graft of choice for coronary artery bypass procedures. Various pharmacological agents have been used to enhance LIMA blood flow. Left stellate ganglion block (LSGB) has been utilized to achieve sympathetic blockade, promote vasodilation in the upper extremities, and manage refractory angina. This randomized controlled clinical trial aimed to evaluate the effect of preoperative LSGB on LIMA blood flow in patients undergoing elective coronary artery bypass grafting (CABG). Seventy patients (aged 18-80 years, of both genders) scheduled for elective CABG were equally divided into two groups: the LSGB group and the control group. Patients in the intervention group received an ultrasound-guided LSGB using 8 mL of 0.25% bupivacaine. Both groups received topical nitroglycerin during LIMA harvesting. LIMA diameter was measured at baseline and again after an equal time interval before the induction of anaesthesia. Additionally, LIMA free flow after harvesting and mean graft flow were measured using a transit time flow metre (TTFM). LIMA free blood flow was significantly increased in the LSGB group (50.57 ± 5.79 mL/min) compared to the control group (46.86 ± 8.32 mL/min), with a P-value = 0.034. Similarly, the LIMA diameter was significantly greater in the LSGB group (2.38 ± 0.17 mm) than in the control group (2.31 ± 0.14 mm), with a P-value = 0.04, suggesting that preoperative LSGB significantly enhances LIMA blood flow and diameter in patients undergoing CABG.