الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Surgical myocardial revascularization still remains as one of the most effective, and long-lasting modalities in the treatment of coronary artery disease (CAD), especially in more complex anatomies, diabetics and the wider use of arterial conduits.
Complete Revascularization, and arterial grafting are recognized with improved long-term outcomes. Therefore, there has been an upsurge in the use of arterial conduits; especially Bilateral internal mammary artery (BIMA) grafts, and their composite configurations; based on their excellent patency rates compared with saphenous vein grafts (SVG). This was emphasized in the recent EACTS guidelines in 2014 that give a class I for the use of arterial conduits on the left coronary artery (LCA), and Class IIa for their use in patients less than 70 years old.
It is increasingly important to focus on the optimization of the outcomes of CABG, and to early detect, and reduce the associated technical errors, morbidity, and mortality. Graft patency verification is a highly valued procedure. The incidence of intraoperative graft failure has been estimated to be approximately 5% for IMA grafts, and 11% for vein grafts. Therefore, the EACTS gives a class IIa indication for the routine intraoperative assessment of graft patency.
Several modalities are described: Imaging technologies include coronary angiography, thermal angiography (TCA), and intraoperative fluorescence imaging (IFI). Ultrasound technologies include transit-time flow measurement (TTFM), epicardial color Doppler, dual beam Doppler flowmeter, combined high resolution epicardial ultrasonography (HR-ECUS) with (TTFM), and finally trans-esophageal echocardiography (TEE).
As experience with TTFM grew, a number of pitfalls in CABG became clear. Thus, it is the most widely used easy, instant, and reproducible technique for intraoperative graft patency assessment.
This prospective study aimed to address the TTFM readings in composite BIMA Y grafts compared to the conventional single mammary graft group, and their correlation to postoperative major adverse cardiac events (MACEs). It included 230 consecutive patients who were treated with a total of (677; 45% arterial) coronary grafts via isolated on-pump CABG through median sternotomy over a single year period.
Patients were assigned into two groups according to the surgical technique. Group A comprised 165 patients (474 grafts; 35% arterial), who underwent conventional CABG. Group B consisted of 65 patients treated with the BIMA composite Y grafts (203 grafts; 66% arterial). Medistim’s TTFM equipment was used to measure mean flow (MGF), diastolic fraction (DF%), and pulsatility index (PI) in all of the single, sequential and composite grafts.
Grafts targeted to the LCA system demonstrated diastolic dominant pattern in all grafts, more marked diastolic component, higher MGF, lower PI, and more back flow when compared with grafts on the RCA.
Flow in composite grafts was found to be equivalent to the sum of the MGF of the targeted branches, while the DF% in the inflow source was equivalent to the mean of both limbs. Our data confirms an intraoperative adaptation of the LIMA that has 1.57-fold increase in the flow if bypassed to multiple targets.
The LIMA inflow source of the Y graft had significantly higher MGF, and less PI compared to LIMA–LAD in group A. The LIMA-LAD targeted branch of the Y graft had significantly less MGF, and higher PI compared to corresponding measurements group A. Flow in sequential grafts was found to be satisfactory. No statistical significance between skeletonized and pedicled IMA based anastomoses could be found.
Suboptimal readings were found in (28/677, 4.1%) grafts. Competitive flow was diagnosed in 4 grafts (0.59%) and only 1 was revised. In group A, (7/17, 1.5%) of total grafts were revised. While in group B, (3/11, 1.4%) grafts were revised. Findings of graft revision reviled: competitive flow, graft tension, conduit spasm, and dissection.
Seven patients required Intraaortic balloon pump support. Five patients had myocardial infarction (All in group A). Mortality following non-emergent surgery (7/230, 3.04%) was significantly higher in patients with LIMA-LAD graft where PI >5, while flow and DF% were not predictive of outcomes after multivariate analysis.
We interpret these findings as being yet another piece of compelling evidence supporting satisfactory use of multiple arterial conduits in CABG, mainly on the left coronary system. We recommend that grafts with these readings; especially PI >5; should be re-assessed and that revision may be appropriate.