Chapter 58: Great Vessels Anatomy

The pulmonary trunk conveys deoxygenated blood from the right ventricle and is situated within the pericardium, where it is enclosed with the ascending aorta in a common sheath. The ascending aorta transitions into the aortic arch, which travels over the left lung hilum and subsequently descends as the thoracic aorta. Major branches arising from the aortic arch, from right to left, include the brachiocephalic trunk, the left common carotid artery, and the left subclavian artery. Key anatomical regions defined by these structures include the aortopulmonary window, a critical space containing structures such as the ligamentum arteriosum, the superficial cardiac plexus, and the left recurrent laryngeal nerve. Variations in aortic arch anatomy are common, ranging from a right-sided aortic arch, sometimes associated with visceral transposition, to abnormal branching patterns like the 'bovine arch,' or congenital anomalies such as a double aortic arch, which can result in a vascular ring entrapping the trachea and oesophagus. Pathologies associated with the aorta include coarctation, a congenital narrowing often distal to the left subclavian artery, necessitating extensive collateral circulation (e.g., intercostal arteries), which can cause rib notching. Aortic aneurysms and acute aortic dissection, classified by types like Stanford A/B, are typically associated with hypertension and medial degeneration, creating a dangerous false lumen. Furthermore, the chapter details congenital anomalies of the coronary arteries, defined as differences occurring in 1% or (lesser than) 1% of the population, including single coronary artery or the potentially fatal anomalous origin of the left coronary artery from the pulmonary trunk (ALCAPA or Bland-White-Garland syndrome). The venous system begins with the left and right brachiocephalic veins uniting to form the superior vena cava (SVC), which returns blood from above the respiratory diaphragm. Obstruction of the SVC, often due to underlying malignancy, is characterized by facial and neck oedema. The inferior vena cava (IVC) returns blood from infradiaphragmatic tissues and can exhibit variations such as duplication or absence, in which case the azygos and hemiazygos veins serve as essential collateral routes.