Feasibility of measuring superior mesenteric artery blood flow during cardiac surgery under hypothermic cardiopulmonary bypass using transesophageal echocardiography: An observational study.

Background: Abdominal complications being rare but results in high mortality, commonly due to splanchnic organ hypoperfusion during the perioperative period of cardiac surgery. There are no feasible methods to monitor intraoperative superior mesenteric artery blood flow (SMABF). Hence, the aim of this study was to evaluate the feasibility and to measure SMABF using transesophageal echocardiography (TEE) during cardiac surgery under hypothermic cardiopulmonary bypass (CPB). Methodology: Thirty‑five patients undergoing elective cardiac surgery under CPB were enrolled. Heart rate, mean arterial pressure (MAP), cardiac output (CO), SMABF, superior mesenteric artery (SMA) diameter, superior mesentric artery blood flow over cardiac output (SMA/CO) ratio and arterial blood lactates were recorded at three time intervals. T0: before sternotomy, T1: 30 min after initiation of CPB and T2: after sternal closure. Results: SMA was demonstrated in 32 patients. SMABF, SMA diameter, SMA/CO, MAP and CO-decreased significantly (P < 0.0001) between T0 and T1, increased significantly (P ≤ 0.001) between T1 and T2 and no significant change (P > 0.05) between T0 and T2. Lactates increased progressively from T0 to T2. Conclusion: Study shows that there is decrease in SMABF during CPB and returns to baseline after CPB. Hence, it is feasible to measure SMABF using TEE in patients undergoing cardiac surgery under hypothermic CPB. TEE can be a promising tool in detecting and preventing splanchnic hypoperfusion during perioperative period.

Comparison of left internal mammary artery diameter before and after left stellate ganglion block.

Aims and Objectives: Left internal mammary artery (LIMA) is the preferred arterial conduit for coronary artery bypass grafting. Various pharmacological agents are known to increase LIMA blood flow. Sympathetic blockade mediated by stellate ganglion block (SGB) has been used to provide vasodilatation in the upper extremities and in the treatment of refractory angina. We investigated effect of left stellate ganglion block (LSGB) on LIMA diameter. Materials and Methods: In 30 diagnosed patients of triple vessel coronary artery disease, LSGB was given under fluoroscopic guidance by C6 transverse process approach using 10 ml of 1% lignocaine. LIMA diameter was measured before and 20 min after the block at 2nd, 3rd, 4th and at 5th rib level. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) were recorded before and 20 min after the block. Results: The LIMA diameter increased significantly at 2nd (2.56 ± 0.39 vs. 2.99 ± 0.40; P < 0.0001), 3rd (2.46 ± 0.38 vs. 2.90 ± 0.40; P < 0.0001), 4th (2.39 ± 0.38 vs. 2.84 ± 0.41; P < 0.0001) and 5th rib level (2.35 ± 0.38 vs. 2.78 ± 0.40; P < 0.0001). No statistically significant change occurred in HR, SBP, DBP and MAP before and 20 min after LSGB. Conclusions: LSGB significantly increased the LIMA diameter. The LSGB can be considered as an alternative to topical and systemic vasodilators for reducing vasospasm of LIMA.