Thoracic Aortic Aneurysm and Thoracic Endovascular Aortic Repair

23.1Definition and presentation

A descending thoracic aortic aneurysm is enlargement of the descending aorta; it is not synonymous with aortic dissection, in which blood separates layers of the aortic wall and creates a false lumen. An aneurysm can occur without dissection, and chronic dissection can subsequently develop aneurysmal dilatation. This chapter addresses descending thoracic aneurysm and its repair. Acute dissection, intramural hematoma, and penetrating aortic ulcer require their own diagnostic and treatment pathways, discussed in Chapter 25. Aneurysm diameter, growth, symptoms, morphology, heritable disease, and procedural risk determine the repair decision ACC/AHA 2022 · ESVS 2026.

Most aneurysms are asymptomatic. Symptomatic disease behaves as an impending complication rather than stable disease and is an indication for repair regardless of absolute diameter. Symptomatic presenting features include:

• Back pain mapping to the aneurysm.
• New hoarseness.
• Embolic events.

23.2Repair threshold and treatment decision

Guideline thresholds should be identified rather than merged into a single 5.5–6.0 cm rule. ACC/AHA 2022 recommends repair of an intact descending thoracic aneurysm at ≥5.5 cm (Class I, B-NR); repair below that diameter may be considered with rupture-risk features, including growth ≥0.5 cm/year, symptoms, saccular morphology, or heritable thoracic aortic disease (Class IIb, B-NR). Increased procedural risk can justify a higher threshold. ESVS 2026 recommends considering repair of descending thoracic or thoraco-abdominal aneurysm at ≥6.0 cm (Recommendation 61, Class IIa, C), and allows consideration at ≥5.5 cm in selected patients according to indexed size or significant growth (Recommendation 62, Class IIb, C). These are distinct recommendations with different strengths, not interchangeable cut-offs ACC/AHA 2022 · ESVS 2026. For genetic aortopathies, the specific syndrome and family history determine the applicable threshold rather than a single universal diameter. Baseline medical management applies to all patients regardless of the repair decision: impulse and blood-pressure control (beta-blockade or an equivalent agent to reduce aortic wall stress, with an ARB or ACE inhibitor layered to target), a statin, and smoking cessation ESVS 2017.

The treatment decision follows a stepwise logic:

1. Decide surveillance versus repair: Below threshold, surveillance is maintained. Confirmed enlargement, threshold criteria, or symptoms transition the patient to intervention planning. A deliberate no-intervention pathway is established for patients with prohibitive operative risk or limited life expectancy.
2. Decide endovascular versus open repair: Thoracic endovascular aortic repair (TEVAR) is favored for older patients, suitable endovascular anatomy, and those lacking physiological reserve for a thoracotomy. Open repair is reserved for younger fit patients, hostile anatomy, connective-tissue disease where a seal in a fragile aorta lacks durability, proximal arch involvement that exceeds branched-device capability at the local center, and chronic dissection necessitating eventual thoracoabdominal replacement.
3. Plan access strategy: Access logistics are finalized prior to the procedure. Older patients and women frequently require femoral cut-down, an iliac conduit, or percutaneous closure with a large-bore device.
4. Adjust for emergency: Symptomatic disease permits a short delay for evaluation, whereas overt rupture or contained leak demands immediate intervention outside the elective framework.

In the Gore TAG pivotal trial and a 2014 meta-analysis, TEVAR gave lower 30-day mortality and shorter hospital stays than open repair, with broadly comparable mid-term aneurysm-related survival Cheng 2010 · TAG Investigators 2008. Long-term outcomes for TEVAR are dominated by seal-zone integrity and reintervention for endoleak or device migration. A durable seal needs at least 2 cm of adequately sized, non-aneurysmal, non-dissected aorta in both the proximal and distal landing zones; inadequate seal-zone length is a primary driver of type I endoleak ESVS 2017. High-volume aortic centers demonstrate better risk-adjusted outcomes for both modalities.

23.3Left subclavian artery coverage and revascularization

Left subclavian artery (LSA) coverage is required when the proximal seal must extend across its origin, typically for a zone 2 landing; it is not required for every descending thoracic repair. ACC/AHA 2022 recommends LSA revascularization before TEVAR when coverage is planned for descending thoracic aneurysm (Class I, B-NR). ESVS 2026 advises considering revascularization in elective TEVAR with planned coverage (Recommendation 21, Class IIa, B) and individualising the open or endovascular method (Recommendation 22, Class IIa, C) ACC/AHA 2022 · ESVS 2026.

Carotid-subclavian bypass and subclavian-to-carotid transposition remain established options. The reconstruction must maintain essential branch perfusion and address retrograde flow from the covered subclavian origin when it could perfuse the excluded aneurysm ESVS 2017 · ESVS 2026.

Single-branch TEVAR and related techniques

A thoracic branch endoprosthesis can preserve LSA flow through an integrated side branch while extending the aortic seal into zone 2. It is distinct from a parallel chimney graft, which lies alongside the aortic endograft and introduces a potential gutter. Device selection requires assessment of the aortic landing zone, branch geometry, access, and the applicable instructions for use; clinical feasibility is not equivalent to eligibility for every device. The GORE TAG Thoracic Branch Endoprosthesis received US FDA approval in 2022 for specified descending thoracic applications preserving the LSA. FDA supplement P210032/S015, approved on 11 April 2025, extended the indication to aortic arch and descending thoracic lesions while maintaining one arch branch in appropriately selected anatomy. Thus the initial 2022 indication should not be presented as the complete current US label GORE 2025 · GORE 2022.

Device studies and regulatory evaluations concern selected anatomy and defined endpoints; they do not establish superiority over bypass or transposition. Parallel grafts and physician-modified or in situ fenestrations are not interchangeable with a purpose-built branch device. Their gutter, alignment, branch-patency, and governance issues require separate assessment. Zone 0 or 1 reconstruction, multiple arch branches, and extensive hybrid arch procedures are discussed in Chapter 24; their evidence should not be extrapolated from single-branch zone 2 repair ESVS 2026.

23.4Spinal cord protection and complications

Spinal cord ischemia can occur during extensive TEVAR or develop after the procedure. Risk assessment includes coverage length, prior aortic repair, pelvic and subclavian collateral supply, and hypotension. Prevention combines preservation of collateral flow, staged extensive repair when feasible, adequate perfusion and oxygen delivery, and early serial neurological examination ESVS 2026.

CSF drainage is not a routine requirement for every TEVAR. ESVS 2026 permits a reactive rescue-drain strategy in preference to routine prophylactic drainage for extensive endovascular thoracic repair (Recommendation 26, Class IIb, C). Its recommendation for prophylactic drainage during open thoracic or thoraco-abdominal repair is different (Recommendation 25, Class I, A) and should not be transferred to TEVAR. Selective prophylactic drainage remains an individual protocol decision balancing ischemic risk against intracranial, spinal, and catheter-related bleeding. Coverage beyond 20 cm or previous AAA surgery contributes to risk assessment but is not an automatic drain indication ESVS 2026.

A new motor or sensory deficit requires immediate escalation: restore systemic perfusion and oxygen delivery, assess collateral and branch perfusion, and consider rescue drainage when appropriate. Blood-pressure and drainage targets belong to a monitored spinal-protection protocol; a drain-pressure number without limits on drainage and neurological monitoring is not a complete protocol. Further discussion of selective and rescue drainage is provided in Chapter 22 ESVS 2026.

Retrograde type A dissection is a rare but high-mortality complication occurring when an intimal tear in the ascending aorta propagates retrograde from the stent edge. Risk factors include proximal arch landing (zone 0 and 1), aggressive proximal oversizing, post-deployment ballooning over a fragile arch, and underlying genetic aortopathy or chronic dissection ESVS 2017 · Chen 2017 · Coselli 2016 · Lee 2015 · Canaud 2014. Avoidance strategies mandate conservative device oversizing at the lower end of the manufacturer-recommended range, elimination of unnecessary proximal ballooning, and a lower threshold for open repair when zone 0 or 1 landing is required in a fragile aorta.

23.5Post-TEVAR imaging surveillance

Surveillance after TEVAR follows a structured cadence to detect endoleak, assess sac size, and verify device position. Acceptance of lifelong imaging and possible reintervention is an inherent part of the TEVAR pathway. Loss to follow-up is the single most common preventable cause of late TEVAR failure, so the surveillance plan (next study date, imaging site, and responsible team) is agreed and documented before discharge.

If the graft is stable with a shrinking or unchanged sac at 12 months, imaging intervals are often extended based on center protocol; absolute intervals for extended surveillance beyond 12 months are not uniformly established. Conversely, an unstable seal, type Ia endoleak, or distal sac growth shortens the surveillance interval and triggers evaluation for reintervention.

23.6Areas of controversy

Several aspects of descending thoracic aortic aneurysm management remain unsettled:

• Spinal drain utilization: The choice between routine versus selective cerebrospinal fluid drainage remains a center-level protocol decision rather than a universal standard, balancing ischemia protection against bleeding and catheter-related risks ESVS 2017.
• Subclavian revascularization staging: Whether left subclavian revascularization is performed as a staged prior operation or concurrently on the day of TEVAR varies by center logistics and patient physiological reserve ESVS 2017.
• Branched endografting: Emerging branched and fenestrated thoracic devices that preserve subclavian flow without extra-anatomic bypass represent an active area of practice shift at specialized centers, potentially altering standard coverage algorithms in the future.

Further reading

• Endovascular aortic repair versus open surgical repair for descending thoracic aortic disease a systematic review and meta-analysis of comparative studies. (2010). Historical TEVAR-versus-open comparative evidence in descending thoracic disease; not a current selection rule. Cheng 2010
• Retrograde Type A Aortic Dissection After Thoracic Endovascular Aortic Repair: A Systematic Review and Meta-Analysis. (2017). Retrograde type A dissection after TEVAR. Chen 2017