Ultra-Hybrid Repair of Thoracoabdominal Aortic Aneurysm: A Good Option for Pan-Aorta Involvement

Treating extensive aortic aneurysm disease with descending thoracic aorta stent grafting followed by distal open completion — so-called staged ultra-hybrid repair — can yield outcomes comparable to those with open thoracoabdominal aortic aneurysm (TAAA) repair in a very high-risk population. So concludes an analysis of 92 patients who underwent completion of the hybrid procedure at Cleveland Clinic in the largest reported series to date, published in Seminars in Thoracic and Cardiovascular Surgery (2022;S1043-0679(22)00256-8).

“Patients selected for this strategy often have pan-aortic disease extending beyond a thoracoabdominal aneurysm, sometimes with a genetic syndrome leading to complex anatomies due to chronic dissection,” says the study’s senior author, Eric Roselli, MD, Chief of Adult Cardiac Surgery at Cleveland Clinic. “The majority of the patients underwent multiple stages of repair, including prior root, ascending and total arch replacements with a first-stage elephant trunk procedure followed again by stent grafting and then completion open repair. A hybrid approach eliminates the need for hypothermic circulatory arrest and limits left lung manipulation and spinal cord ischemia by breaking up a total aortic repair into additional stages.”

“Ultra-hybrid repair was born out of patients surviving so well after being treated for aortic dissection with a stent graft,” adds co-author Francis Caputo, MD, Vascular Surgery Director of Cleveland Clinic’s Aorta Center. “Those who develop progressive aneurysmal degeneration distal to the thoracic stent can benefit from a subsequent open operation to complete the repair.”

Combining complementary approaches

The ultra-hybrid approach consists of initial proximal thoracic aortic repair, descending thoracic aortic stent grafting and open distal repair across the thoracoabdominal segment at some point (days to years) afterwards. Compared with fully open repair — traditionally regarded as the “gold standard” — the hybrid approach may be associated with lower mortality and possibly a reduced risk of spinal cord injury.

Cleveland Clinic cardiac and vascular surgeons have increasingly adopted the ultra-hybrid strategy over the past 15 years, with numbers doubling from 2020 (19 cases) to 2021 (38 cases). The current series analysis shares their experience in terms of patient population, operative techniques and outcomes.

Study population and intervention strategies

The series included 92 adults (68% men; mean age, 58 ± 13 years) who completed a staged, hybrid TAAA repair between 2006 and 2020. Of these, 46% had a planned second stage, i.e., completion within six months of thoracic stent grafting. Over one-third of patients had a known or suspected heritable aortic condition.

Descending thoracic stent grafting was performed as a conventional thoracic endovascular aortic repair in 75% of cases and frozen elephant trunk in 5% of cases; another 20% had both, with the first-stage elephant trunk extended by thoracic endovascular aortic repair (TEVAR).

The median interval between stent grafting and open completion was 96 days in patients who underwent planned ultra-hybrid repair and 2.4 years in those who underwent delayed completion. At the time of open TAAA repair, aortic morphology included the following as the primary indication for completion:

• Chronic dissection (63%)
• Aneurysmal degeneration (30%)
• Endoleak (4%)
• Symptomatic acute type B dissection (2%)

Outcomes

After ultra-hybrid repair completion, survival was 80% at one year and 66% at five years. Hospital mortality was 7.6% (n = 7) and was associated with elevated blood urea nitrogen (> 20 mg/dL) and longer distance between the distal endograft edge and the most proximal patent visceral vessel (> 9 cm).

Complications included acute renal failure requiring dialysis (incidence of 20%), tracheostomy (8.7%), permanent paralysis (6.9%) and stroke (5.7%).

Freedom from aortic or iliac reoperation was 86% at one year and 66% at four years. Larger iliac diameter (> 2 cm) increased the risk of needing reoperation, often on the aortic bifurcation and iliac vessels.

Key takeaways

In their study report, the authors emphasize that the findings from their experience in these ultra-hybrid completion operations highlight the importance of multidisciplinary care and treatment strategies directed at a lifelong approach for aortic disease.

“A staged repair strategy for patients at risk for progressive aneurysmal degeneration can limit overall risk by minimizing the burden of trauma at any one stage,” says Dr. Roselli. He notes that the hybrid approach can be applied to those in need of repair distal to a preexisting thoracic endograft, as well as to patients with TAAAs deemed to be high risk for a single-stage operation or those not anatomically amenable to a purely endovascular repair. “This strategy also offers advantages to patients with moderate lung compromise and those who had previous open surgery in their left chest,” he adds, “as it limits the impact of open surgery to the more distal aorta.”

Drs. Roselli, Caputo and their co-authors provide the following insights from the Cleveland Clinic experience:

• The ultra-hybrid approach is feasible in a highly comorbid patient population. “Rates of hospital mortality, stroke and paralysis were reasonable, considering the extent of aorta that needed to be replaced,” notes Dr. Caputo.
• Spinal cord ischemia may be mitigated by a staged approach. Although first-stage thoracic stent grafting sacrifices segmental arteries, neovascularization of the spinal cord between stages may ameliorate ischemia. Incidence of permanent paraplegia in this study was comparable to or better than other published data on open repair.
• Patients with the most extensive disease may benefit from a proactive strategy. Those in whom a second stage was planned were weaned from ventilation more rapidly and had shorter ICU stays.

“The number of ultra-hybrid repairs we perform is steadily increasing as our referrals grow and the procedure becomes more standardized,” says Dr. Roselli. “We are constantly striving to improve results and are now refining graft design by adding a proximal cuff to better facilitate the endograft-to-surgical graft interface.”

Image at top: Successive stages of the ultra-hybrid approach to TAAA repair.