Fluxometria intraoperatória do enxerto composto de artéria torácica interna esquerda e veia safena magna

Abstract

Composite graft of left internal thoracic artery (LITA) and great saphenous vein (GSV) in the revascularization of two or more arteries of the left coronary system (LCS) is a technique described in literature since the 1980s. Despite recent studies demonstrating that LITA is capable of providing adequate blood flow for two or more LCS arteries, both in basal condition and under stress, deeper studies must be developed to improve this knowledge. The objective of this study was to analyze blood flow dynamics in this kind of composite graft, specially in what concerns to LITA adaptability and to the influence of GSV segment on LITA flow. In 23 patients, a LITA and GVS composite Y-graft was realized to the anterior interventricular artery (AIA) and to another LCS branch, respectively, without extracorporeal circulation. Mean blood flow, as well as parameters of graft patency (diastolic fraction and pulsatile index) and coronary flow reserve (CFR) were evaluated through transit time flowmetry (TTFM) in all segments of the composite graft, which are LITA proximal and distal segments, and GSV segment. The measures were realized in basal condition and after dobutamine-induced pharmacological stress, as well as without and with non-traumatic temporary clamping of the distal segments of composite graft. Pharmacological stress resulted in increased values of blood flow in all analyzed segments (p<0,05). Non-traumatic temporary clamping of GSV segments did not cause statistically significant changes in mean blood flow of LITA distal segment, as much in basal situation as under pharmacological stress, without modification of the CFR. Likewise, non-traumatic temporary clamping of LITA distal segment did not cause statistically significant changes in mean blood flow of GSV segment, as much in basal situation as under pharmacological stress, without modification of the CFR. In conclusion, evaluation through TTFM of mean blood flow, diastolic fraction, pulsatile index and coronary flow reserve in LITA and GSV composite graft to revascularize AIA and another LCS branch, respectively, evidenced blood flow dynamics with physiologic adaptability in all segments, both in basal situation and under stress, in other words, in accordance to the flow demand. The presence of GSV segment in the composite graft refereed pattern did not change physiological dynamics of blood flow in LITA distal segment.