The thoracic aorta is divided into four segments: the aortic root (including the sinuses of Valsalva and coronary artery origins); the ascending aorta (from the sinotubular junction to the innominate artery origin); the aortic arch (giving off the innominate, left common carotid, and left subclavian arteries); and the descending thoracic aorta (from the left subclavian to the diaphragm at T12). Each segment has distinct anatomy, pathology, and surgical approach.
Thoracic aortic aneurysm classification by segment guides surgical planning: root aneurysms (Marfan, bicuspid aortic valve) require Bentall procedure; ascending aneurysms require supracoronary tube graft; arch aneurysms require hypothermic circulatory arrest with antegrade cerebral perfusion; descending aneurysms are treated by thoracic endovascular aortic repair (TEVAR). Aortic dissection (type A involves ascending, type B starts beyond the left subclavian) dictates urgency and approach. The critical aortic zones for TEVAR landing are standardised (zones 0-9) based on branch vessel coverage.
Intimal tear in the ascending aorta propagates retrogradely to the aortic root and pericardium and anterogradely through the arch and descending aorta; type A dissection is a surgical emergency requiring aortic root and ascending aorta replacement under cardiopulmonary bypass to prevent death from aortic regurgitation, coronary malperfusion, or pericardial tamponade.
