Understanding Potential Complications of EVAR and TEVAR
Endovascular Aneurysm Repair (EVAR) and Thoracic Endovascular Aneurysm Repair (TEVAR) have revolutionized the treatment of aortic aneurysms, offering less invasive alternatives to traditional open surgical repair. While these procedures have significantly improved patient outcomes, they are not without potential complications. A comprehensive understanding of these risks is crucial for both medical professionals and patients considering these interventions. This article aims to provide an academic overview of the potential complications associated with EVAR and TEVAR, drawing upon current medical literature.
Complications of Thoracic Endovascular Aortic Repair (TEVAR)
TEVAR, primarily used for thoracic aortic aneurysms, has demonstrated reduced early morbidity and mortality compared to open surgical repair. However, despite continuous advancements in endovascular techniques and devices, certain complications persist [1]. Key complications include:
Spinal Cord Ischemia (SCI)
Spinal cord ischemia remains a significant concern after TEVAR, with reported incidences ranging from 2% to 10% [1]. The pathophysiology involves inadequate collateral blood supply to the spinal cord, often due to decreased blood flow or atheroembolism from aortic plaques via segmental arteries. Risk factors include extensive aortic coverage (especially >200mm), coverage of the left subclavian artery (LSA) or hypogastric artery, and prolonged procedure duration [1]. Strategies to mitigate SCI risk include maintaining elevated mean arterial pressure (MAP), judicious graft coverage, and cerebrospinal fluid (CSF) drainage [1].
Stroke
Stroke is another major complication of TEVAR, with reported incidences between 1.2% and 8.2% [1]. While TEVAR avoids the embolism risk associated with aortic cross-clamping, manipulation of the diseased aortic arch and great vessels with wires and catheters can lead to embolization. Risk factors include acute aortic dissections, significant atherosclerotic burden in the aortic arch, hypertension, and pre-existing cerebrovascular disease [1]. Preoperative LSA revascularization and the use of fenestrated grafts are being explored as preventive measures [1].
Endoleaks
Endoleaks are defined as persistent blood flow and pressurization within the excluded aortic segment after endograft placement [1]. Although the incidence has decreased with modern devices, endoleaks remain a common complication. They are classified into several types, each with distinct mechanisms and management strategies [1]:
- **Type I:** Sealing failure at the graft attachment sites (proximal or distal). These are high-pressure leaks with a greater risk of rupture and typically require intervention [1].
- **Type II:** Retrograde flow into the perigraft space via collateral vessels. This is the most common type, often managed with observation, but intervention is needed if the aneurysm expands [1].
- **Type III:** Device failure due to component dysfunction or graft fabric tears. These are also high-pressure leaks requiring intervention [1].
- **Type IV:** Blood passage through graft porosity. This type has become very uncommon with advanced graft materials [1].
- **Type V (Endotension):** Continued aneurysm sac expansion without a demonstrable leak. Management often involves observation or open repair if expansion persists [1].
Endograft Collapse
Endograft collapse is a rare but serious complication, often associated with off-label use in trauma patients or excessive graft oversizing [1]. It can lead to significant morbidity and mortality, often necessitating emergent re-intervention [1].
Vascular Access and Device Delivery Injuries
These complications arise from the insertion and manipulation of devices, particularly in patients with peripheral vascular disease or tortuous vessels. Early complications include arterial dissection, iliac artery rupture, arterial perforation, and distal thromboemboli [1]. Late complications can include lower limb ischemia [1].
Renal Failure
Acute kidney injury (AKI) is a common complication after TEVAR, with incidence rates varying widely (1% to 34%) due to differing definitions [1]. Risk factors include pre-existing hypertension and chronic renal failure, as well as the use of iodinated contrast media during the procedure [1].
Complications of Endovascular Aneurysm Repair (EVAR)
EVAR, primarily used for abdominal aortic aneurysms, is also associated with a range of complications, some of which overlap with TEVAR, while others are specific to the abdominal anatomy [2].
Endoleaks
Similar to TEVAR, endoleaks are the most frequent complication after EVAR [2]. The classification and management principles are largely the same as described for TEVAR, with Type II endoleaks being the most common [2].
Contrast Nephropathy
Contrast-induced nephropathy, leading to acute renal failure, occurs in approximately 6.7% of EVAR cases [2]. This is primarily due to the use of iodinated contrast medium during the procedure. Preventive strategies include adequate preoperative hydration and, in some cases, the use of carbon dioxide as an alternative contrast agent [2].
Ischemic Complications
Ischemic complications immediately after EVAR can result from clot formation or embolization into aortic side branches, or inadvertent coverage of these branches by the stent graft [2]. These can include:
- **Colonic Ischemia:** Occurs in 1% to 3% of cases, with a high mortality rate. The mechanism often involves microemboli from thrombotic deposits or atheroma dislodged during graft deployment [2].
- **Spinal Cord Ischemia:** While rare after EVAR for abdominal aortic aneurysms (0.21% incidence), it can occur due to atheromatous embolization and interruption of collateral circulation from lumbar and internal iliac arteries [2].
- **Renal Artery Occlusion:** Inadvertent coverage of one or both renal arteries can occur in less than 5% of cases, potentially leading to renal dysfunction [2].
Surgical Complications
Local wound complications at the groin access site, such as hematoma, infection, or lymphocele, occur in 1% to 10% of cases [2]. Access artery injuries, including thrombosis, dissection, or pseudoaneurysm formation, can occur in up to 3% of EVAR procedures, often related to the large catheter systems used and pre-existing vascular disease [2].
Conclusion
Both EVAR and TEVAR represent significant advancements in the treatment of aortic aneurysms, offering less invasive options with improved early outcomes. However, a thorough understanding of their potential complications is essential for effective patient management. These complications, ranging from endoleaks and ischemic events to access site injuries and renal dysfunction, necessitate careful patient selection, meticulous procedural technique, and vigilant postoperative surveillance. Continued research and technological innovation aim to further minimize these risks and enhance the long-term durability and safety of endovascular aortic repair.
References
[1] Chen, S. W., Lee, K. B., Napolitano, M. A., Murillo-Berlioz, A. E., Sattah, A. P., Sarin, S., & Trachiotis, G. (2020). Complications and Management of the Thoracic Endovascular Aortic Repair. *Aorta (Stamford)*, *8*(3), 49–58. [https://pmc.ncbi.nlm.nih.gov/articles/PMC7644296/](https://pmc.ncbi.nlm.nih.gov/articles/PMC7644296/)
[2] Maleux, G., Koolen, M., & Heye, S. (2009). Complications after Endovascular Aneurysm Repair. *Seminars in Interventional Radiology*, *26*(1), 3–9. [https://pmc.ncbi.nlm.nih.gov/articles/PMC3036452/](https://pmc.ncbi.nlm.nih.gov/articles/PMC3036452/)