The Flow And Clinical Assessment Of Sequential Left Internal Mammary Artery Grafting In Off-pump Coronary Bypass Graft

BackgroundsThe internal mammary artery(IMA)has become the first choice in myocardiac revascularization due to its higher long-term patency rate.The expanded use of this ideal conduit for seqential grafting has enhanced its application.The objective of this study was to assesse the flow of sequential and non-sequential left internal mammary artery(LIMA)grafting in off-pump coronary artery bypass grafting(OPCABG),and present the objective evidence for the clinical using.Methods:Between Mar.2006 and Feb.2008,72 consecutive patients underwent OPCABG with LIMA bypass grafts were included in the study,there were 40 men and 32 women,a mean age of 65(52～78)years old,mean weight was 66.5(50～83) Kilograms.Grafts with at least one sequential anastomosis,named group A,The other 36 patients underwent myocardial revascularization with LIMAs only grafted to the left anterior descending branch.All patients were diagnosed as coronary artery desease(CAD)with 3 branches stenosis by coronary angiography(CAG)before cardiac surgery,29(40.3%) patients had the main left coronary artery stenosis among them.Angina was presented in the total 72 patients and 33(45.8%)were in Canada Heart Association ClassⅢ,29(40.3%)in classⅣ.The anesthesia method of inhalation combine with vein injection were used.Maintained the mean blood pressure(BP)65～80mmHg and heart rate(HR)50-55 bpm,and Nitroglycerin(0.2ug/kg.min)was administrated during the procedure.The LIMA combined with the radial artery(RA)or saphenous vein were used as bypass grafts.LIMA's blood flow at 4^threb level was meassured,when the hemodynamics stabilized after the grafts finishing using Medi-stim Butterfly Flowmeter(2002,Oslo,Norway).In Group A:meassurement of the main LIMAs' blood flow after the first anastomosis has been performed and recorded as F_A1,PI_A1,and then it has been performed and recorded as F_A2,PI_A2after the rest of one or two anastomosis finished;In Group B:the main LIMAs' blood flow has been meassured after finishing LIMA-LAD end to side anastomosis,and recorded as F_B,PI_B.Statistic analysis was used with SPSS10.0 statistic software to analyze the all patients' data.Results:①There were no statistically difference between the two groups.②In Group A,there were a total of 178 coronary artery grafts,mean 4.95±0.17 gratis per-patient and 76 sequential LIMA anastomosis,mean 2.11±0.07 per-patient.LIMA bypass grafts with 3 sequential anastomosis were performed in 4 patients,and in 2 LIMA to 2 diagnal branches and LAD,the other 2 LIMA to the diagnal,middle and proxmal LAD.In Group B:A total of 176 coronary artery grafts,mean 4.88±0.32 grafts per-patient and 36 sequential LIMA anastomosed were performed with LIMA-LAD grafts.③The LIMAs' mean flow and PI were significant differencs between LIMA sequential anastomosis in Group A and Non-sequential grafts in Group B:31±5.6ml/min versus PI 2.0±0.3 and 21±2.8ml/min versus PI 2.7±0.4 respectively(P＜0.01).There were also significant differences in LIMAs' mean flow and PI just pre and post LIMA-LAD anastomosis(31±5.6ml/min and 2.0±0.3 VS 18±3.1 ml/min and 2.8±0.3).But LIMAs' mean flow and PI shown no differences between pre LIMA-LAD anastomosis in Group A and Group B.TTFM show diastolic-dominated waves in LIMAs of both groups.④The levels of CK-MB were nomal in both groups and no patients experienced hospital complication,such as ventical arrhythmia,peri-operative myocardial infarction and low cardiac output Syndrome.Conclusions①Sequential LIMA grafting can promote the LIMA flow in OPCAB,and there is a trend of the flow of LIMA are related to the number of sequential grafts of LIMA.②Multiple sequential LIMA bypass grafts are feasible,with a higher long-term patency rate and better clinical outcome.③The LIMA can provide adequate volume flow to myocardium surplied by diagnal,intermediat remus,LAD even more areas.It also expanded use of more arterial conduits for myocardial revasculization.