Left Upper Extremity Ischemia

Aneurysms involving the aortic arch pose a significant risk to cerebral and upper extremity blood flow with endovascular repair. Intentional coverage of the LSCA with the endovascular graft can occur in approximately 50% of thoracic endograft implants. Most patients can tolerate LSCA coverage without left upper extremity ischemia. However, if the right subclavian and vertebral arteries are not patent, ischemia can ensue. Additionally, the patient can experience decreased blood flow to the left internal mammary artery, leading to significant myocardial ischemia to a prior coronary artery bypass graft. If left upper extremity ischemia occurs, an LSCA bypass should be performed postoperatively.

Stroke

Intravascular wires and endografts that are introduced into the atherosclerotic aorta can come in contact with mobile thrombi in the arch and brachiocephalic vessels, leading to cerebral ischemia. Iatrogenic dissection of the carotid or vertebral arteries and retrograde dissection of the aorta have been described as devastating complications. If the LSCA is covered during endograft deployment, cerebral ischemia can develop due to decreased flow from the left vertebral artery. A left carotid to left subclavian bypass graft should first be placed if the left subclavian will be covered by the graft. The incidence of stroke after TEVAR ranges from 2% to 8%. Risk factors for perioperative stroke include severe atheromatous aortic disease (grade IV or V aortic disease on TEE), endovascular coverage of aortic arch vessels, history of prior stroke, long extent of aortic coverage, preexisting CAD, longer procedure duration, and female sex.

Spinal Cord Ischemia

Spinal cord ischemia is also a possible complication of endovascular treatment of TAAAs, although with less incidence than after open repair. Intercostal arteries are intentionally covered during endovascular stent placement of a TAAA, possibly compromising spinal cord perfusion by obliterating the collateral circulation. Endovascular coverage of the LSCA can compromise spinal cord perfusion in patients with a left-dominant vertebral artery, solitary vertebral artery, carotid artery disease, or an incomplete circle of Willis. Spinal cord injury after TAAA repair is a heterogeneous syndrome manifesting as a spectrum of impairments that varies depending on the severity and extent of ischemia. Additionally, delayed-onset neurologic deficits, like those seen after open repair, can also be seen after endovascular treatment. Delayed-onset deficits are thought to be due to postoperative events such as hypotension, thrombosis, hematoma, embolization, and elevated CSF pressure. Injury to the spinal cord is directly related to the extent of the aorta that is involved and is highest with Crawford type II repairs. Risk factors for spinal cord injury after TEVAR include LSCA coverage without revascularization, concomitant open abdominal aortic surgery, and the use of three or more stent grafts.

Renal Failure

Similar to open repair of TAAAs, renal insufficiency can develop after endovascular repair with an incidence rate of 14%. Deployment of the endograft in a diseased, atherosclerotic aorta can lead to embolic showers and occlusion of mesenteric, splenic, or renal arteries. This phenomenon contributes to the development of renal insufficiency. Risk factors for postoperative renal dysfunction after TEVAR include preoperative chronic renal insufficiency, perioperative blood transfusions, and the thoracoabdominal extent of the aneurysm.

Postimplantation Syndrome

This commonly observed phenomenon consisting of fever, leukocytosis, and an elevation in inflammatory markers normally occurs in the early postoperative period, although it occasionally has a delayed presentation. It is usually mild and self-limiting, responding to conservative management with nonsteroidal anti-inflammatory drugs.

Endograft Collapse

Endograft collapse is a rare but serious complication after TEVAR, typically presenting in the first 3 months after endovascular repair. Endograft collapse can present asymptomatically or can present with diminished or absent femoral pulses, abdominal pain, or multiorgan failure. Excessive oversizing of the endograft and poor apposition of the proximal endograft to the aortic wall are the primary causes of endograft collapse. Maldeployment of the endograft and progression of the aortic disease are rare causes of endograft collapse.

Endoleaks

An endoleak is a leakage of blood into an aneurysm sac previously excluded during TEVAR. Endoleaks after TEVAR occur in 5% to 30% of patients. Endoleak is a complication unique to the endovascular approach to aortic repair, and there are four types:

• Type I endoleak is caused by incomplete seal at the end of the graft, leading to blood flow into the aneurysm sac.

• Type II endoleak is caused by leaking of blood into the aneurysm from collateral vessels excluded during the repair.

• Type III endoleak is caused by inadequate sealing of overlapping graft joints or rupture of graft fabric, leading to blood flow into the aneurysm sac.

• Type IV endoleak is caused by the direct leakage of blood through a porous graft.

Management includes aggressive endovascular repair of type I and III endoleaks, with observation of type II endoleaks. Type IV endoleaks are of historical interest because new graft material has virtually eliminated the incidence of this complication. Risk factors for the development of endoleaks include larger preoperative aneurysm sac diameter, greater length of stent coverage, and the use of multiple stent grafts.

References

• Diamond KR, Simons JP, et al. Effect of thoracoabdominal aortic aneurysm extent on outcomes in patients undergoing fenestrated/branched endovascular aneurysm repair. J Vasc Surg. 2021;74:833-842.e2.
• Harik L, Lau C. Open and endovascular repair of thoracoabdominal aortic aneurysm-a narrative review. J Thorac Dis. 2023;15:3984-3997.
• Isselbacher EM, Preventza O, Hamilton Black J 3rd, et al; Peer Review Committee Members. 2022 ACC/AHA guideline for the diagnosis and management of aortic disease: a report of the American Heart Association/American College of Cardiology Joint Committee on clinical practice guidelines. Circulation. 2022;146:e334-e482.