Why Blocked Coronary Arteries Are Not Removed During CABG
The surgeon does not remove the blocked coronary artery during CABG because the native vessel continues to supply blood flow distal to the blockage through collateral circulation and provides the essential anatomic pathway for the bypass graft to restore perfusion—removing it would eliminate the target vessel needed for revascularization and destroy viable myocardial blood supply. 1
Fundamental Surgical Principle of CABG
The core concept of coronary artery bypass grafting is to bypass the blockage, not remove it. The procedure works by creating an alternative route for blood flow around the stenotic segment while preserving the native coronary anatomy. 2
Why the Native Artery Must Remain
The distal coronary artery beyond the blockage serves as the target for the bypass graft anastomosis—surgeons create the distal anastomosis on the native coronary artery beyond the stenosis, requiring the vessel to remain intact. 1
Native coronary arteries often maintain some antegrade flow and extensive collateral circulation that continues to perfuse myocardium, even with severe stenosis—removing the artery would eliminate this residual perfusion. 3
The coronary arteries are embedded within the myocardium and removing them would cause extensive myocardial damage, hemorrhage, and loss of viable heart muscle. 4
Technical Aspects of Bypass Construction
The surgical technique specifically depends on the native vessel remaining in place:
Proximal anastomoses are created on the ascending aorta, while distal anastomoses are created on the target coronary arteries beyond the stenosis—this requires the native artery to be present and patent distal to the blockage. 1
The bypass graft (typically left internal mammary artery to LAD, with >90% patency at 10-15 years) is sewn directly to the native coronary artery using hand-sewn continuous polypropylene suture techniques. 1, 5
The native vessel provides the anatomic conduit that distributes blood flow to the myocardial territory—the graft simply provides a new inflow source to this existing distribution system. 4
Clinical Outcomes Support This Approach
The bypass strategy (rather than removal) has proven highly effective:
CABG demonstrates superior outcomes to percutaneous coronary intervention for complex three-vessel disease and left main coronary artery disease by preserving native anatomy while restoring perfusion. 2
Long-term graft patency directly correlates with symptom relief and survival—internal mammary arteries maintain >90% patency at 10 years specifically because they augment rather than replace the native circulation. 4
Common Misconception
A critical pitfall is misunderstanding that coronary artery disease involves atherosclerotic plaque within the vessel wall, not a removable obstruction. The plaque is integrated into the arterial structure itself—attempting removal would necessitate removing the entire arterial segment, which would be technically impossible given the coronary arteries' intramyocardial course and would result in massive myocardial infarction. 4