The use of flowmetry during coronary bypass surgery in patients with diffuse coronary bed lesion

Abstract

Introduction . In recent decades, the number of patients with coronary artery disease and diffuse coronary artery disease has significantly increased. Performing the full volume of myocardial revascularization in such patients is not always possible due to the nature of the lesion of the coronary bed, and the risk of shunt dysfunction in the early postoperative period remains high. Therefore, the use of ultrasound intraoperative flowmetry in coronary bypass surgery is especially necessary, but the issues of optimal indicators of graft patency remain unresolved. The Objective was to evaluate the possibilities of using intraoperative ultrasound flowmetry in patients with diffuse coronary bed lesion. Methods and Materials . The study included 188 patients with diffuse coronary bed lesion who underwent coronary bypass surgery at the St. George Thoracic and Cardiovascular Surgery Clinic, Pirogov National Medical and Surgical Center and the Center for Cardiology and Cardiovascular Surgery, Rostov-on-Don. Ultrasound Doppler flowmetry was performed in all patients, the following indicators were evaluated: the average volumetric blood flow rate (MGF – mean graft flow), the pulsation index (PI – pulsation index) and the percentage of diastolic volume filling (DF – diastolic filling). Coronaroshuntography was performed in 29 patients in the early postoperative period (within 2–6 hours after surgery). The comparison of angiographic data (slowing of blood flow through the shunt, stenosis, occlusion) with intraoperative parameters of ultrasound flowmetry was carried out. Results . 405 primary intraoperative flowmetry samples were analyzed in 188 patients with diffuse coronary lesion. It was found that 19.7 % of intraoperative flowmetry indicators were less than the recommended values: 9.3 % of autoarterial and 25 % of autovenous shunts to the anterior descending artery; 20.8 % of autovenous shunts to the diagonal artery; 33.3 % – to the envelope and 21.9 % – to the right coronary artery. In 21 % of the observations, technical problems were identified (defect of proximal or distal anastomoses; bend of the conduit; dissection of the autoarterial shunt), which were eliminated; in other cases, no technical problems were identified. When comparing the data of intraoperative ultrasound flowmetry and shuntography in the early postoperative period, statistical differences were revealed in patients with normal patency of venous shunts and their dysfunction: MGF 53±18 (46–59) vs. 38±15 (29–47), p=0.014; PI: 3±1 (2–3) vs. 7±1 (6–8), p≤0.001; DF: 79±15 (64–91) vs. 48±17 (41–60), p=0.005. There are differences in the flowmetry of autoarterial shunts depending on the risk of their dysfunction: MGF 32±11 (28–44) vs. 20±5 (13–24), p=0.005; PI: 2±1 (1–4) vs. 7±2 (5–9), p≤0.001; DF: 70±12 (61–85) vs. 50±15 (45–64), p=0.005. Conclusion . Intraoperative ultrasound flowmetry is a safe and effective tool for assessing blood flow through conduits during coronary bypass surgery in patients with coronary artery disease and diffuse coronary bed lesions. According to our study, to predict the normal patency of shunts in the early postoperative period, it is advisable to use targets MGF above 28 ml/min for internal thoracic artery and 65 ml/min for venous shunts, PI less than 5.0 for all types of conduits, DF above 60 % for autoarterial shunt, and more than 68 % for autovenous graft.