Internal Mammary Arteries
The internal mammary arteries (IMAs), also known as internal thoracic arteries, are critical to the field of cardiac surgery, particularly in coronary artery bypass grafting (CABG). Their consistent blood flow and resistance to atherosclerosis make them ideal candidates for creating grafts that can bypass blocked coronary arteries.
Anatomy and Function of Internal Mammary Arteries
The internal mammary arteries are located bilaterally along the inside of the chest wall. They originate from the subclavian arteries and descend behind the ribs, supplying blood to the chest wall and the breasts. Each artery branches into a musculophrenic and a superior epigastric artery, which contribute to their robust blood supply to the thoracic and abdominal walls.
Utilization in Cardiac Surgery
In cardiac surgery, the IMAs are most commonly used for coronary artery bypass grafting due to their proximity to the heart and excellent long-term patency rates. Here are some specific ways they are utilized:
- Graft Preparation: The IMA is typically harvested in a "skeletonized" manner, meaning the artery is removed with little surrounding tissue, which preserves collateral blood flow to the sternum and decreases the risk of postoperative complications like sternal wound infections.
- Conduit for Bypass: The left internal mammary artery (LIMA) is preferred for grafting as it has been shown to have the best long-term results when grafted to the left anterior descending artery (LAD), a critical vessel commonly affected in coronary artery disease. The right internal mammary artery (RIMA) can also be used, either alone or in conjunction with the LIMA, especially in more complex grafting scenarios.
Advantages of Using IMAs in CABG
Using the internal mammary arteries in coronary bypass surgery offers several advantages:
- Patency: IMAs have a higher long-term patency rate than saphenous vein grafts. Studies show that over 90% of LIMA grafts remain open and functional at ten years post-surgery.
- Reduced Reintervention: Patients who receive IMA grafts generally require fewer reinterventions like reoperations or percutaneous interventions over their lifetimes.
- Improved Survival Rates: Numerous studies have demonstrated improved long-term survival rates in patients who receive IMA grafts, particularly those receiving LIMA to LAD grafts.
Conclusion
The use of internal mammary arteries in cardiac surgery, especially in CABG, represents a significant advancement in surgical treatment of coronary artery disease. Their robustness, durability, and accessibility make them an excellent choice for grafting, contributing significantly to improved patient outcomes in cardiac surgery.