Thoracic Endovascular Aortic Repair (TEVAR)

TEVAR treats disease of the descending thoracic aorta (beyond the left subclavian artery) from inside the vessel. It is used for aneurysms, complicated type B aortic dissections, penetrating ulcers and traumatic tears. Compared with open repair through a left thoracotomy with aortic cross-clamping, which carries high morbidity and months of recovery, TEVAR is done through the groin with a much shorter recovery. The stent graft is a fabric tube (polyester or PTFE) on a self-expanding metal frame, packed into a delivery system; examples are the Gore TAG, Medtronic Valiant Navion and Cook Zenith Alpha. Planning is done from a CT angiogram: the graft must land on at least about 2 cm of healthy aorta at each end ('landing zones'), it is oversized slightly, and the iliac and femoral arteries must be big enough for the delivery system (about 20 to 24 Fr sheaths for older devices; newer ones are smaller). Small or diseased access vessels may need a Dacron conduit sewn to the iliac artery through a small flank incision. If the graft must cover the left subclavian artery in a patient who depends on it (for example, with a left internal mammary bypass graft), a carotid-subclavian bypass is done first. More than one graft is often needed to cover the full length. The scrub person works mainly with long guidewires, catheters, sheaths and the delivery system, while keeping an open vascular tray ready for the groin and for emergencies. Risks include injury or rupture of the iliac artery (sudden low blood pressure when the sheath comes out), stroke, paralysis from poor blood flow to the spinal cord, endoleak (blood still entering the aneurysm), graft migration and bleeding. A spinal (lumbar) drain may be placed before surgery in high-risk patients, and blood pressure is kept up to protect the spinal cord.