Hybrid Repair With Antegrade Visceral Artery Debranching: The Preferred Treatment Option for Thoracoabdominal Aneurysms in High-Risk Patients

ACR Appropriateness Criteria® Thoracoabdominal Aortic Aneurysm or Dissection: Treatment Planning and Follow-Up

As the incidence of thoracoabdominal aortic pathology (aneurysm and dissection) rises and the complexity of endovascular and surgical treatment options increases, imaging follow-up of patients remains crucial. Patients with thoracoabdominal aortic pathology without intervention should be monitored carefully for changes in aortic size or morphology that could portend rupture or other complication. Patients who are post endovascular or open surgical aortic repair should undergo follow-up imaging to evaluate for complications, endoleak, or recurrent pathology. Considering the quality of diagnostic data, CT angiography and MR angiography are the preferred imaging modalities for follow-up of thoracoabdominal aortic pathology for most patients. The extent of thoracoabdominal aortic pathology and its potential complications involve multiple regions of the body requiring imaging of the chest, abdomen, and pelvis in most patients. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Debranching aortic surgery

Conventional open surgery still remains as the gold standard of care for aortic arch and thoracoabdominal pathology. In centers of excellence, open repair of the arch has been performed with 5% immediate mortality and a low rate of complications; however overall mortality rates are around 15%, being up to 40% of all patients rejected for treatment due to their age or comorbidities. For thoracoabdominal aortic pathology, data reported from centers of excellence show immediate mortality rates from 5% to 19%, spinal cord ischemia from 2.7% to 13.2%, and renal failure needing dialysis from 4.6% to 5.6%. For these reasons, different alternatives that use endovascular techniques, including debranching procedures, have been developed. The reported results for hybrid debranching procedures are controversial and difficult to interpret because series are retrospective, heterogenic and including a small number of patients. Clearly, an important selection bias exists: debranching procedures are performed in elderly patients with more comorbidities and with thoracoabdominal aortic aneurysms that have more complex and extensive disease. Considering this fact, debranching procedures still remain a useful alternative: for aortic arch pathology debranching techniques can avoid or reduce the time of extracorporeal circulation (ECC) or cardiac arrest which may be beneficial in high-risk patients that otherwise would be rejected for treatment. And compared to pure endovascular techniques, they can be used in emergency cases with applicability in a wide range of anatomies. For thoracoabdominal aortic aneurysms, they are mainly useful when other lesser invasive endovascular options are not feasible due to anatomical limitations or when they are not available in cases where delaying the intervention is not an option.

Three-Year Outcomes With the Multilayer Flow Modulator for Repair of Thoracoabdominal Aneurysms

Purpose: To evaluate midterm outcomes of endovascular repair of types II and III thoracoabdominal aortic aneurysms (TAAA) using the Multilayer Flow Modulator (MFM) in patients unsuitable for open surgery or fenestrated stent-grafts. Methods: In the prospective, multicenter, nonrandomized STRATO trial (EudraCT registration: 2009-013678-42; ClinicalTrials.gov identifier NCT01756911), 23 patients (mean age 75.8 years; 19 men) with Crawford type II and III TAAA (mean diameter 6.5 cm) were implanted between April 2010 and February 2011. Outcomes included all-cause mortality and stable aneurysm thrombosis with associated branch vessel patency. Results: Through 36 months, there were 7 deaths (none confirmed as aneurysm-related), and no cases of spinal cord injury, device migration or fracture, or respiratory, renal, or peripheral complications. Three patients were lost to follow-up and 2 devices were explanted. The device was patent in the 11 remaining patients at 3 years. Stable aneurysm thrombosis was achieved for 15 of 20 patients at 12 months, 12 of 13 at 24 months, and 10 of 11 at 36 months. The rate of branch patency was 96% at 12 months (primary patency), 100% at 24 months, and 97% at 36 months. Nine patients suffered from endoleaks (attachment site or device overlap); 9 patients underwent 11 reinterventions (3 surgical). Maximum aneurysm diameter was stable for 18 of 20 patients at 12 months, 11 of 13 at 24 months, and 9 of 11 at 36 months. For 10 patients with computed tomography at 36 months, the mean ratio of aneurysm flow volume to total volume had decreased by 83%; the mean ratio of thrombus volume to total volume increased by 159%. Conclusion: Through 3 years, endovascular repair with the MFM appears to be safe and effective while successfully maintaining branch vessel patency.

A computational simulation of the effect of hybrid treatment for thoracoabdominal aortic aneurysm on the hemodynamics of abdominal aorta

Hybrid visceral-renal debranching procedures with endovascular repair have been proposed as an appealing technique to treat conventional thoracoabdominal aortic aneurysm (TAAA). This approach, however, still remained controversial because of the non-physiological blood flow direction of its retrograde visceral revascularization (RVR) which is generally constructed from the aortic bifurcation or common iliac artery. The current study carried out the numerical simulation to investigate the effect of RVR on the hemodynamics of abdominal aorta. The results indicated that the inflow sites for the RVR have great impact on the hemodynamic performance. When RVR was from the distal aorta, the perfusion to visceral organs were adequate but the flow flux to the iliac artery significantly decreased and a complex disturbed flow field developed at the distal aorta, which endangered the aorta at high risk of aneurysm development. When RVR was from the right iliac artery, the abdominal aorta was not troubled with low WSS or disturbed flow, but the inadequate perfusion to the visceral organs reached up to 40% and low WSS and flow velocity predominated appeared at the right iliac artery and the grafts, which may result in the stenosis in grafts and aneurysm growth on the host iliac artery.

Clinical outcomes of single versus staged hybrid repair for thoracoabdominal aortic aneurysm

OBJECTIVE

We investigated the outcomes of hybrid repair of thoracoabdominal aortic aneurysms and performed meta-analyses and meta-regressions to assess whether the number of stages during hybrid repair is associated with mortality.

METHODS

Review methods were according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The primary outcome was 30-day mortality. Secondary outcomes of procedural and clinical success were reported descriptively. Meta-analyses, meta-regressions, and logistic regressions were performed to estimate the odds ratio (OR) describing the association between the staging of the operation and in-hospital death.

RESULTS

We included 19 studies of 660 patients. Procedures were single-staged in 288 patients and staged in 372. Perioperative mortality ranged from 0% to 44.4%, and spinal cord ischemia ranged from 0% to 15.3%. After a mean follow-up of 26 months (range, 6-88.5 months), the overall mortality was 20.8%. The meta-regression of all studies' summary data (OR, 0.64; 95% confidence interval [CI], 0.19-2.16; P = .45; I(2) = 0.42) and a meta-regression where mortality rates in four studies were stratified by operative staging (OR, 0.57; 95% CI, 0.24-1.36; P = .19; I(2) = 0.38) supported a two-stage procedure but failed to reach statistical significance. Logistic regressions of individual patient data from a single center demonstrated evidence that a staged procedure was safer (adjusted OR, 0.04; 95% CI, 0.00-0.96; P < .05).

CONCLUSIONS

Hybrid repair of thoracoabdominal aortic aneurysms may reduce early morbidity and mortality even in a group considered high risk for open surgery but still carries risks of perioperative complications. This study suggested advantages to a staged procedure, but statistically significant evidence is lacking. Prospective data are still needed to optimize hybrid repair and best define its role.