Results of flowmetric assessment of composite Y-grafts and autovenous coronary artery bypass grafts.

Abstract

The purpose of the study was to perform intraoperative assessment of blood flow in coronary bypass grafts of the 'first' and 'third' order according to Calafiore A.M. with the help of the TTFM technique and to compare the obtained results. This retrospective, single-centre study enrolled a total of 222 patients subjected to coronary artery bypass grafting (CABG) from January to November 2017. Depending on the type of bypass grafting of the posterior interventricular artery (PIVA), the patients were divided into 2 groups. Group One consisted of 108 patients undergoing bypass grafting of the PIVA with the help of combined Y-grafts from the right internal thoracic artery (RTIA). Group Two was composed of 114 patients subjected to autovenous coronary artery bypass grafting of the PIVA. Blood flow was assessed with the help of the VeriQ MediStim® flowmeter after termination of extracorporeal circulation (ECC), at systolic pressure of 100-110 mm Hg. The parameters of blood flow were assessed using the 1.5- and 2-mm probes. In a specially designed protocol we registered the type of the shunt, the bypassed artery, and values of flowmetry parameters. We also evaluated the pattern of the flowmetric curve according to Takemi Handa et al. RESULTS: The obtained findings revealed a statistically significant difference in the values of Qmean (p=0.001), with the PI values in the groups not statistically differing (p=0.14). Thus, in patients with similar parameters influencing the volumetric velocity of blood flow (the degree of proximal stenosis, diameter of the bypassed artery, mean systolic AP and HR) the value of Qmean was higher in the group with coronary artery bypass grafting (CABG), i. e., in the group of the 'first-order' conduits. Therefore, an autovein directly anastomosed to the aorta experiences grater haemodynamic overload, which completely confirms the theory of Calafiore A.M. First-order conduits (CABG) appear to experience greater wall strain because of greater haemodynamic overload as compared with third-order conduits (Y-grafts). A composite Y-graft may be an alternative technique of bypass grafting of the basin of the right coronary artery (RCA). A composite Y-graft has greater resistance to wall shear stress than an autovein anastomosed to the aorta.