Follow These 10 Commandments for Successful Multiarterial Grafting in CABG

The use of at least two arterial grafts improves outcomes of coronary artery bypass grafting (CABG) for multivessel disease, yet more than 93% of patients undergoing CABG in the U.S. receive only a single graft and over 80% of conduits are saphenous vein grafts. That’s despite recent Society of Thoracic Surgeons guidelines urging use of additional internal thoracic artery (ITA) and/or radial artery grafts as a supplement to the ITA-to-LAD (left anterior descending artery) graft in patients with multivessel disease.

What’s holding surgeons back from further adoption of multiarterial grafting? Greater technical complexity, longer operative time, wound healing concerns in patients with diabetes, and latency in survival gains are among the reasons, according to a recent editorial in Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery by Cleveland Clinic cardiothoracic surgeons Faisal Bakaeen, MD, and Rami Akhrass, MD. To help close this practice gap and optimize success in this underutilized approach, the editorialists offer what they dub “The 10 Commandments for Multiarterial Grafting.”

“Multiarterial grafting may not be appropriate for all patients undergoing CABG, but it should be part of any revascularization strategy discussion,” says Dr. Bakaeen. “Adhering to a few guiding principles helps ensure good early and late outcomes.”

The 10 “commandments” are summarized below.

1) Use the left ITA to bypass the LAD

The left ITA-LAD graft is the mainstay of a CABG operation around which the remaining grafts are planned. The ITA is an ideal conduit: compared with the saphenous vein, it is rarely affected by intimal hyperplasia or atherosclerosis. And the LAD is the ideal recipient, usually supplying more than half of the mass of the left ventricle.

2) Choose a second arterial conduit for the second most important target

Make use of the ITAs carefully, with the aim of maximizing the amount of myocardium supplied by the grafts. Important target vessels are those that reach more than 75% toward the apex of the heart or supply a large territory via secondary branches. A variety of configurations are possible depending on patient anatomy and disease, but the overall strategy should be to use bilateral ITA and radial artery conduits for the largest territories at risk.

3) Harvest the ITAs as a skeletonized graft

Carefully harvesting the ITAs as a skeletonized rather than pedicled graft is associated with better sternal healing and fewer wound complications. Sternal healing — and the decision whether to use both ITA conduits — is of particular concern in patients with diabetes, radiation exposure, use of steroids or immunosuppression, and poor nutritional status.

4) Assess graft patency intraoperatively

Intraoperative transit time flow measurement can help verify graft patency, providing the opportunity to promptly correct any problems. This is especially important for arterial conduits, which are more delicate than veins and susceptible to dissections and hematomas. The following thresholds indicate acceptable patency:

• Flow > 15 to 20 mL/min
• Pulsatility index < 3
• Back flow < 3%
• Diastolic filling 60%-70% for left coronary targets, 50%-60% for right coronary targets

“False-negative and -positive test results commonly occur for a variety of reasons,” warns Dr. Bakaeen, who also co-authored an invited expert opinion in JTCVS Techniques earlier this year devoted to intraoperative graft patency measurement. “Ultimately, surgical judgment must be the primary driver of decisions about graft revisions.”

5) Don’t settle for a short or bad conduit

A good conduit is essential to optimal perioperative outcomes and long-term graft patency. Whichever blood vessel is chosen for a conduit, it should not be accepted if it has poor flow or is small, fragile or dissected. Short grafts under tension are liable to spasm, deformity and obstruction of native coronary flow. Radial arteries need particular attention, as about 25% are inadequate for grafting.

6) Avoid competitive flow

Attention is needed to avoid situations in which competitive flow may develop, resulting in a “string sign” on imaging. Competitive native flow can occur when grafting a coronary target that is not severely stenotic. Index flow reserve measurement can help determine whether a vessel needs to be grafted and which conduit would be appropriate. Radial arteries in particular tend to suffer from competitive flow and should not be used when the native target vessel is less than 90% stenotic. Competitive vein graft flow can also develop if a vein graft is placed close to an arterial graft with no significant disease between them.

7) Avoid steal

Either coronary-subclavian or coronary-coronary steal can lead to reversal of flow and worsening cardiac ischemia. Careful preoperative planning with bilateral arm blood pressure measurements and chest CT scans, as well as intraoperative flow measurements, can help avoid or detect such situations.

8) Go with parallel side-to-side anastomosis in sequential grafting

But beware sequential grafting with intramyocardial coronary vessels, where the myocardial tissue has a tendency to kink at the toe and heel, creating a “seagull deformity.” It may be best to use a composite graft in such situations.

9) Perform CABG on-pump

Off-pump CABG should be reserved for procedures where minimal or no aortic manipulation is desired and for patients who have significant aortic calcification or are at increased risk from cardiopulmonary bypass.

10) Build volume-based experience

“Higher volumes of multiarterial grafting translate into better short- and long-term outcomes,” says Dr. Bakaeen. “Experience should be built up in a stepwise fashion so it can become part of daily routine practice.”

Read the full “10 Commandments” here.