Functionality of mammary-coronary bypass grafts according to the data of intraoperative flowmetry

Abstract

Improvement of surgical treatment for ischaemic heart disease is one of the main trends in modern medicine. After the operation of coronary bypass grafting, further functioning of blood flow in the grafts largely depends upon its domination over the native blood flow in the target coronary arteries. Therefore, intraoperative diagnosis of functional competence of coronary bypass grafts by means of flowmetry is currently of special importance. The purpose of this study was flowmetric quantitative assessment of the curves of blood flow through the coronary bypass grafts, depending on the degree of stenosis of the target coronary arteries. A total of 135 patients were examined during our study. We evaluated the curves of blood flow through the bypass grafts from the left internal thoracic artery to the anterior descending artery. The bypass grafts were divided into three groups: the 1st group (n=47) with moderate stenosis of the coronary arteries (from 50 to 75%); the 2nd group (n=42) with a more pronounced lesion of the target vessel (from 75 to 99%), and the 3rd group (n = 46) with occluded coronary arteries (100%). It was revealed that the flow rate (Q, ml/min) in group one was lower (17±3.1) than in group two (33±5.3) and group three (45±3.4). Also, differences were revealed in the resistance index of the grafts: it turned out to be higher in group one (5.2±1.1) and group two (4.5±0.9) as compared with group three (1.8±0.5). However, there was no between-group difference in diastolic filling of the grafts, which amounted to 58±13, 61±10 and 64±9% for groups one, two and three, respectively. By the shape of the curve, we assessed the reverse systolic peak whose presence prevailed in the grafts of group one (15 of 47; 31.9%) and group two (11 of 42; 26.2%) as compared with that in the grafts of group three (5 of 46; 10.8%). The obtained findings confirm higher frequency of the presence of competitive blood flow in the grafts used on non-occluded coronary arteries.