Is every proximal anastomosis in coronary artery bypass grafting (CABG) created at the ascending aorta?

Proximal Anastomosis Sites in CABG

No, not every proximal anastomosis in CABG is created at the ascending aorta—while the ascending aorta is the standard and most common site, alternative locations including the innominate artery, subclavian artery, and axillary artery are used when the ascending aorta is severely diseased or calcified. 1, 2, 3

Standard Technique

The ascending aorta is the conventional and preferred site for proximal anastomoses in the vast majority of CABG procedures. 1, 4

• Most coronary bypass grafts are constructed with hand-sewn suture techniques for both proximal and distal anastomoses, with the proximal anastomoses typically created on the ascending aorta using continuous polypropylene suture. 1, 4
• This standard approach involves partial clamping of the ascending aorta to create a bloodless field for the proximal anastomosis. 1

Alternative Sites for Proximal Anastomoses

When Alternative Sites Are Necessary

Severely atherosclerotic or calcified ("porcelain") ascending aorta necessitates alternative proximal anastomotic sites to avoid catastrophic atheroembolism. 2, 3

Three maneuvers during standard CABG can cause atheromatous embolism from diseased ascending aorta:

• Aortic cannulation 2
• Cross-clamping 2
• Partial clamping for proximal anastomosis construction 2

Specific Alternative Locations

The innominate artery serves as the primary alternative site for proximal anastomoses when the ascending aorta is unsuitable. 3

• In a series of 16 patients with calcific atheromatous plaques, 25 proximal anastomoses were successfully performed on the innominate artery with only one cerebrovascular complication (6.2% mortality). 3
• Other viable alternative sites include the right axillary artery, right subclavian artery, and sequential grafting from the internal mammary artery or other saphenous vein grafts. 2, 3

Technical Modifications

Connector devices enable proximal anastomosis creation with minimal aortic manipulation in patients with diseased ascending aortas. 1

• These devices allow construction of proximal anastomoses without aortic cross-clamping, potentially reducing embolization of debris and neurological complications. 1
• A clampless technique using a Foley catheter and polypropylene suture has been described for calcified ascending aorta, achieving 93% graft patency at mean 1.6-year follow-up. 5
• Patch aortoplasty with bovine pericardial patch reconstruction represents another option when focal aortic disease is present. 6

Clinical Outcomes with Alternative Approaches

Extra-anatomic CABG procedures demonstrate safety and efficacy comparable to standard techniques when properly selected for patients with porcelain aorta. 2

• In 8 patients undergoing extra-anatomic CABG with alternative proximal anastomotic sites, no cerebrovascular or visceral organ injury from atheroemboli occurred. 2
• Operations can be performed on the beating heart or with cardiopulmonary bypass support, with arterial cannulation through the femoral artery when necessary. 2

Critical Pitfalls to Avoid

Intraoperative detection of severe aortic calcification requires immediate modification of the surgical plan to prevent stroke. 3

• Epiaortic ultrasound imaging allows visualization of the ascending aorta's "blind spot" (caused by tracheal interposition), identifying friable atheroma at the site of aortic cannulation—a major stroke risk factor. 1
• When calcific atheromatous plaques are detected intraoperatively, conversion to off-pump surgery with alternative proximal anastomotic sites should be strongly considered. 3
• Sequential grafting techniques (using LITA or SVG as the inflow source for additional grafts) can minimize the number of proximal anastomoses required on diseased vessels. 3