Role of flowmetry in tactics of bypass grafting for myocardial bridge of the anterior descending artery. / Rol' floumetrii v taktike shuntirovaniia miokardial'nogo mosta perednei niskhodiashchei arterii.

The purpose of the study was to analyse the remote results of bypass grafting for myocardial bridges. Our retrospective single-centre study included a total of 17 patients subjected to coronary bypass grafting of the anterior descending artery (ADA) in connection with a detected myocardial bridge (MB). All patients underwent assessment of the coronary bypass grafts (CBG) by means of intraoperative flowmetry - transit time flow measurement (TTFM), as well as angiographic control of the CBGs in the remote period. The duration of follow up amounted to 72 months. Six patients were found to have pronounced retrograde blood flow accompanied by an elevated index of peripheral resistance (Pi) and decreased mean volumetric blood flow velocity (Qmean) below the threshold values. Compression of the ADA proximal to the anastomosis appeared to be followed by improvement of blood flow parameters, in connection with which the shunted artery was ligated with monofilament polypropylene suture 4/0. According to the findings of coronary bypass angiography (CBA) the following results were obtained: 4 occluded grafts were revealed in the group of patients in whom ligation of the ADA was not performed. In patients subjected to ADA ligation in connection with pronounced retrograde blood flow, all bypass grafts were competent. The cumulative probability of freedom from graft occlusion was significantly higher in the group of patients subjected ADA ligation proximal to the anastomosis (Log Rank=0.032).

[Flowmetric and angiographic predictors of occlusion of coronary bypass grafts]. / Floumetricheskie i angiograficheskie prediktory okkliuzii koronarnykh shuntov.

OBJECTIVE: The study was aimed at assessing remote (up to 42 months) results of coronary artery bypass grafting (CABG) and revealing flowmetric and angiographic predictors of coronary bypass graft occlusion. PATIENTS AND METHODS: Our retrospective single-centre study included a total of 141 patients undergoing coronary artery bypass grafting (CABG). All patients were subjected to assessment of coronary bypass grafts by means of transit-time flowmetry (TTFM), as well as angiographic control of coronary bypass grafts in the remote period. The duration of follow up amounted to 42 months. We performed flowmetric assessment of blood flow by the following parameters: mean volumetric blood flow velocity (Qmean), peripheral resistance (PR), as well as studied angiographic parameters such as: the degree of proximal stenosis of the bypassed coronary artery (CA), the diameter of the bypassed CA. Competence of bypass grafts after carried out coronaroshuntography (CSG) was determined according to the classification of Fitzgibbon. RESULTS: We performed flowmetric and angiographic assessment of 235 autoarterial and 117 autovenous bypass grafts. During the follow-up period of up to 42 months we revealed 33 (14%) occluded arterial conduits and 30 (25.6%) venous ones. The Kaplan-Meier analysis demonstrated that the probability of the lack of occlusions of venous grafts amounted to 74.4±5.8%, with that of arterial grafts equalling 86±3.3%, i. e. during the follow-up period of up to 42 months, the probability of occlusion of venous grafts was reliably higher than that of arterial ones (Log Rank=0.006). The Cox regression analysis made it possible to reveal that occlusion of grafts was influenced by an increase in the peripheral resistance index (p=0.033, HR=1.374), a decrease of volumetric blood flow velocity in the graft (Qmean) (p=0.005; HR=0.981), and by the type of the graft (venous) (p=0.001; HR=2.587). CONCLUSIONS: 1) arterial grafts appeared to yield better results of myocardial revascularisation within the terms up to 42 months as compared with venous coronary artery bypass grafting; 2) using a vein increases the risk for the development of graft occlusion 2.5-fold each month after the operation; 3) an increase in the peripheral resistance index (PR) by 1 unit elevates the risk of occlusion of the coronary graft 1.3-fold with each month after the operation; 4) a decrease in the volumetric blood flow velocity (Q) by 1 ml leads to an increase in the risk of graft occlusion by 2% with each month after the operation.

[Risk factors for progression of atherosclerosis of the shunted coronary artery in the remote postoperative period]. / Faktory riska progressirovaniia ateroskleroza shuntiruemoi koronarnoi arterii v otdalennom periode.

The study was aimed at revealing risk factors for progression of atherosclerosis in the shunted coronary artery in the remote period following coronary artery bypass grafting. Our prospective study included a total of 292 patients having endured coronary artery bypass grafting. All patients were divided in two groups depending on the type of the bypass grafts used: either autoarterial shunts (Group 1) or autovenous grafts (Group 2). We thus assessed a total of 516 autoarterial grafts and 257 autovenous grafts, as well as the coronary arteries shunted thereby. The long-term results were evaluated by means of coronaroshuntography performed not earlier than 12 months after surgery. The average duration of follow up amounted to 53.4±26.5 months. Analysing the cumulative risk for progression of atherosclerosis in the arteries shunted demonstrated that for autoarterial grafts the rate of the development of proximal stenosis of the coronary artery (CA) shunted was lower compared with autovenous grafts (p≤0.001). The Cox regression model showed that an autovein used as a graft increased the risk for the development of occlusion of the shunted CA by 43% from the baseline each postoperative month. The presence of proximal stenosis of the shunted coronary artery amounting to or exceeding 90% increases the risk of occlusion by 68% per month. Also, for the patients with the SYNTAX scoring ≥ 32 points the risk of coronary artery occlusion increases 2.2-fold each month after the operation. Such factors as the patient's gender, the diameter of the shunted artery, diabetes mellitus, tobacco smoking, multifocal atherosclerosis by the findings of the study exerted no influence on the progression of proximal stenosis of the shunted coronary artery.

[Indices of intraoperative flowmetry, determining patency of grafts in the remote period after revascularization of the right coronary artery].

The authors studied the threshold values of ultrasound flowmetry concerning composite T-grafts, combined I-grafts, and autovenous shunts during revascularization of the right coronary artery (RCA), determining high risk for the development of shunt occlusion in the remote postoperative period. The retrospective study included a total of 223 patients subjected to revascularization of the RCA's basin with the help of composite T-grafts, combined I-grafts, and autovenous shunts. Depending on the method of bypass grafting of the RCA and its branches, all patients were subdivided into 3 groups: Group 1 was composed of 65 patients in whom the RCA basin was revascularized by a branch of the composite T-graft, Group 2 comprised 112 patients who endured autovenous aortocoronary bypass grafting, and Group 3 consisted of 46 patients in whom the RCA basin was shunted by a combined mammarovenous I-graft. The groups had no statistically significant differences on the main clinical and demographic parameters. Intraoperative assessment of the blood flow through the coronary shunts was carried out by means of ultrasound flowmetry. The remote results were evaluated based on the findings of the control coronaroshuntography which was carried out in all patients within the terms varying from 16 to 43 months. In the remote period in Group 1 patients (T-graft), 59 (90%) mammary shunts were patent, in Group 2 - 99 (88.4%) autovenous shunts, and in Group 3 (I-graft) 42 (95.5%) shunt were patent. Cumulative probability of freedom from shunt occlusion within the terms up to 3 years after surgery in Group 1 amounted to 82±0.5%, in Group 2 to 58±2.1%, and in Group 3 to 86±1.9%, with the differences between Group 2 and other groups being statistically significant (p=0.01). The Poisson regression analysis showed that the risk for graft occlusion increased by 10% with the resistance index in the branch of the T-graft from 4.0; by 8% with the resistance index in the autovein from 2.9; and by 3% with the index of resistance in the I-graft from 3.2. The conclusion was made that composite T-grafts and combined I-grafts demonstrated similar results of patency within the terms up to 3 years, possessing advantages over autovenous conduits while shunting the RCA basin. The optimal index of peripheral resistance for the autovein during revascularization of the RCA basin is up to 2.9; for the combined T-graft - up to 3.2, and for the composite T-graft - up to 4.0. Probability of shunt occlusion in the remote period does not depend upon the average volumetric blood velocity (Qmean) but is directly proportional to the value of the pulsatility index (Pi) which reflects the state of the distal bed.

[Flowmetric assessment of coronary bypass grafts in the conditions of artificial circulation and on the beating heart].

Advantages and shortcomings of aortocoronary bypass grafting on the beating heart and in the conditions of artificial circulation (AC) have long been discussed. The data on patency of bypass grafts in the remote period are indicative of comparable results of operations with and without AC or advantages of using AC. In order to determine benefits of each method it is necessary to reveal intraoperative predictors of bypass grafts occlusion in the remote period. We analyzed the results of ultrasound flowmetry of the blood flow through the left internal thoracic artery during bypass grafting of the anterior descending artery with the use of AC and on the beating heart. A retrospective study included a total of 352 patients subdivided into 2 groups: Group One was composed of 120 patients undergoing surgery in the conditions of AC and Group Two comprised 232 patients subjected to similar operations on the beating heart. Blood flow was measured with the help of flowmeter VeryQ MediStim® after termination of AC and inactivation of heparin by protamine, with systolic pressure of 100-110 mm Hg. There were no statistically significant differences between the groups by the diameter and degree of stenosis of the anterior descending artery, diameter of the left internal thoracic artery. The mean volumetric blood flow velocity (Qmean) along the shunts in Group One was higher (p=0.01). No statistically significant differences by the pulsatility index (PI) between the groups were revealed (p=0.2). A conclusion was drawn that coronary bypass grafting of the anterior descending artery by the left internal thoracic artery in the conditions of artificial circulation made it possible to achieve higher volumetric velocity of blood flow through the conduit as compared with operations on the beating heart, with similar resistance index. The immediate results of the operations with the use of the both techniques did not differ.

[Prosthesis of mitral valve in mesenchimal dysplasia: anatomo-morphological aspects and technical specificities].

Pathomorphological aspects of acquired mitral defects of the heart caused by manifestations of mesenchimal dysplasia were studied in 100 patients. Special attention is given to important features of surgical strategy when performing mitral valve prosthesis in such patients unlike similar procedures for mitral defects of another etiology.

[Morphological characteristics of the right gastroepiploic artery and its use in myocardial revascularization]. / Morfologicheskaia kharakteristika pravoi zheludochno-sal'nikovoi arterii i ee ispol'zovanie pri revaskuliarizatsii miokarda.

The results of morphological and morphometrical investigation of the biopsy and autopsy material from 35 right gastroepiploic arteries were analyzed. Histological and histochemical methods were used. The anatomo-topographic and morphometrical characteristics of the right gastroepiploic artery allow it to be used for gastro-coronary shunting. It makes the possibilities of the aorto-arterial revascularization of the myocardium substantially wider.