On-Pump Coronary Artery Bypass Grafting

Step 1

Surgical Anatomy

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  The named epicardial coronary arteries that serve as the distal anastomotic targets for coronary artery bypass grafting (CABG) are most commonly located just deep to the epicardial fat and superficial to the myocardium. The arteries, usually the left-sided vessels, may be located more deeply within the myocardium (intramyocardial). A straighter course on coronary angiography may suggest an intramyocardial location.

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  The left anterior descending (LAD) coronary artery courses superficially to the interventricular groove, providing diagonal branches to the anterior wall.

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  The ramus intermedius (RI) artery arises between the LAD and left circumflex artery (LCx) and can often be identified near the base of the left atrial appendage.

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  The LCx arises from the left main coronary artery as the left main artery bifurcates to give off the LAD in the atrioventricular groove. The LCx provides obtuse marginal branches that supply the lateral and inferolateral myocardium, usually terminating near the lateral margin of the left ventricle.

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  The right coronary artery (RCA) originates anteriorly from the aortic root and courses in the atrioventricular groove prior to crossing the acute margin of the heart and bifurcating into the posterior descending artery (PDA) and posterolateral ventricular branch (PLVB).

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  Right or left coronary dominance refers to the artery from the which the PDA originates.

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  The most commonly used conduits for CABG include the left and right internal mammary arteries (alternatively termed the internal thoracic artery ), radial artery, and reversed greater saphenous vein (GSV).

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  The left internal mammary artery (LIMA) originates from the proximal left subclavian artery opposite the thyrocervical trunk and courses approximately 1.5 cm lateral to the sternocostal junction. Proximally, the LIMA passes inferiorly and medially behind the subclavian vein, where the phrenic nerve usually crosses from lateral to medial as it courses to the pericardium. Care must be taken during proximal harvest of the LIMA to avoid phrenic nerve injury and resultant diaphragmatic dysfunction. The midportion of the LIMA is superficial, lying just deep to the endothoracic fascia, and can be visualized or palpated most easily in this location. Below the sixth rib, the transversus thoracis muscle covers the posterior aspect of the internal mammary artery (IMA). Near the junction of the xiphoid process and body of the sternum, the IMA bifurcates into the musculophrenic and superior epigastric arteries. The IMA is accompanied by paired internal mammary veins that combine to form a single vein proximally.

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  The radial artery originates from the brachial artery, coursing under the brachioradialis muscle proximally and in the lateral forearm deep to the distal deep fascia. From the antecubital fossa, the artery courses from medial to lateral. Care must be taken during harvest of the distal radial artery to avoid injury to the superficial radial nerve and lateral antebrachial cutaneous nerve.

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  The GSV is located on the medial side of the lower extremity, coursing superficial to the medial malleolus at the ankle and running deep to the subcutaneous fat as it courses more proximally. At its most proximal portion, the GSV drains into the common femoral vein at the saphenofemoral junction.

Step 2

Preoperative Considerations