Internal Thoracic ArteryEdit

The internal thoracic artery (ITA), also called the internal mammary artery, is a prominent vessel of the chest wall that plays a central role in modern cardiovascular surgery as well as in routine thoracic vascular anatomy. It arises from the subclavian artery and descends about 1 to 2 cm lateral to the sternum, giving off perforating branches to the intercostal spaces and other thoracic structures before bifurcating near the sixth intercostal space into the superior epigastric and musculophrenic arteries. Its exceptional long-term patency and reliable flow characteristics have made the ITA a preferred conduit for bypass procedures, particularly in the coronary circulation, and it remains a subject of ongoing anatomical and surgical study Subclavian artery Superior epigastric artery Musculophrenic artery.

Introductory overview The left internal thoracic artery (LITA) and the right internal thoracic artery (RITA) are the two major branches that supply the anterior chest wall. The LITA, in particular, is widely regarded as the gold standard graft for connecting to the left anterior descending artery in coronary artery bypass grafting (CABG) due to its superior patency and durability relative to other conduits such as saphenous vein grafts. The ITA’s resistance to atherosclerosis, its robust endothelium, and its ability to adapt to arterial pressure contribute to its favorable long-term performance in revascularization procedures. In addition to its use in CABG, the ITA can be employed in other vascular reconstructions and reconstructive operations that require durable arterial inflow CABG Graft patency.

Anatomy and variants - Origin and course: The ITA typically stems from the posterior aspect of the subclavian artery and travels downward behind the upper six costal cartilages, just lateral to the sternum, before giving off anterior intercostal branches and eventually terminating as the superior epigastric and musculophrenic arteries. Its proximity to the sternum makes it an attractive conduit in heart surgery but also means its harvest must be carefully managed to preserve chest wall perfusion Subclavian artery. - Diameter and length: The ITA is a small-to-medium sized artery, generally measuring about 2 to 3 mm in diameter and extending roughly 20 centimeters, though these dimensions vary among individuals and with age. - Laterality and variations: The LITA and RITA are mirror images in their basic course, but anatomical variations can occur, including aberrant origins or accessory ITAs. In some cases, more than one arterial branch can supply the chest wall, and certain congenital or acquired conditions may influence its usability as a graft Left internal thoracic artery Right internal thoracic artery. - Termination: The ITA bifurcates near the sixth intercostal space into the superior epigastric and musculophrenic arteries, which continue to supply the anterior thorax and the upper abdominal wall, respectively Musculophrenic artery.

Clinical significance and physiology The ITA’s vascular properties contribute to high graft patency and resilience to atherogenesis. Its native endothelium produces nitric oxide and other factors that promote vasodilation and inhibit thrombosis, contributing to durable flow even when exposed to arterial pressures post-grafting. These properties help explain why ITA grafts to coronary targets—especially the left anterior descending artery—often outperform venous grafts over the long term. Beyond its use in CABG, the ITA can be mobilized for other arterial reconstructions or as a source of vascular inflow for complex thoracic procedures Endothelium.

Use in cardiovascular surgery - Left ITA to LAD grafting: The LITA-to-LAD graft is the archetype of durable arterial revascularization and has become a cornerstone of modern CABG. Long-term studies consistently show superior patency and survival with LITA-LAD grafts compared with many alternative conduits, contributing to improved outcomes for patients requiring extensive myocardial revascularization Coronary artery bypass grafting. - Right ITA and bilateral ITA use: The RITA can be used alone or in combination with the LITA (BITA grafting). BITA strategies may offer additional long-term benefits but involve greater technical demands and potential risks, including sternal wound complications in some patient populations Right internal thoracic artery. - Other uses: The ITA can be used as a free graft in complex revascularization or in certain reconstructive contexts where durable arterial inflow is required. In some cases, it also serves as a donor artery for neurovascular or head-and-neck reconstructions, though such uses are less common than cardiac applications Free graft.

Harvesting techniques and their implications - Pedicled vs skeletonized harvest: A pedicled harvest preserves more surrounding tissue and may maintain collateral chest wall perfusion, but it can be associated with greater sternal devascularization. Skeletonization, in which the ITA is harvested with minimal surrounding tissue, tends to preserve sternal blood supply more effectively and is associated with reduced rates of sternal wound infection and mediastinitis in high-risk patients, though it requires surgical expertise to maintain vessel integrity Skeletonization (surgical technique). - Patient-specific considerations: Factors such as diabetes, obesity, prior chest radiation, obesity, and prior sternotomy influence the risk profile for ITA harvest and postoperative complications. Decision-making about which ITA (left, right, or bilateral) to use, and how to harvest, involves weighing long-term graft patency against potential short-term risks and complications Diabetes mellitus Sternal wound infection. - Graft patency and outcomes: When used as a graft, the ITA generally demonstrates superior long-term patency compared with saphenous vein grafts, contributing to better long-term freedom from angina and reduced need for repeat revascularization in many cohorts. Comparative data vary by patient population and operative strategy, but the general trend supports arterial grafts for durable outcomes Graft patency.

Controversies and debates - BITA versus single ITA grafting: Proponents of using both ITAs report enhanced long-term survival and reduced adverse cardiac events, particularly in younger, healthier patients with good conduit options. Critics point to a higher risk of deep sternal wound infection and mediastinitis in some subsets, especially diabetics or those with obesity, and emphasize the need for meticulous technique and patient selection. The balance between long-term benefits and short-term risks remains a topic of ongoing clinical debate and varies with surgical expertise and institutional protocols Deep sternal wound infection. - Harvest technique: The choice between pedicled and skeletonized ITA harvest continues to be refined. Evidence suggests skeletonization lowers local complications in many cases, but some surgeons prioritize speed or lymphatic preservation in specific scenarios. The optimal approach may be patient- and procedure-specific, rather than one-size-fits-all Skeletonization (surgical technique). - Graft selection and sequencing: Decisions about which arteries to graft, and whether to use ITA grafts for non-LAD targets or in a staged fashion, reflect evolving guidelines and surgeon experience. While LITA-LAD is consistently favored, the strategic use of the RITA or additional ITA grafts depends on patient anatomy, comorbidity, and the anticipated durability of repair Coronary artery bypass grafting.

See also - Left internal thoracic artery - Right internal thoracic artery - Coronary artery bypass grafting - Mediastinitis - Sternal wound infection - Graft patency - Endothelium