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NEW YORK -- The morbidity and mortality associated with hybrid repair of thoracoabdominal aortic aneurysms in high-risk patients remain substantial, according to data from four vascular centers.

The hybrid procedure, which involves combined visceral/renal debranching and endovascular exclusion, is intended to be a less invasive approach for patients who are considered high risk for open surgery, the clinical standard. However, even though aortic cross-clamping, extracorporal perfusion, thoracotomy, and single-lung ventilation are avoided, "hybrid procedures may not be so benign, even in centers of excellence," said Dr. Dittmar Böckler at the Veith symposium on vascular medicine sponsored by the Cleveland Clinic.

In the initial report of 29 patients who underwent the hybrid procedure, there were three deaths and no cases of paraplegia (a complication seen with open surgery). The authors described their results as "encouraging" (J. Vasc. Surg. 2006;43:1081-9).

Subsequent experience has been less promising, however. "Because the numbers in published series are small, we pooled data from three centers, in Heidelberg, Munich, and London," said Dr. Böckler of the University of Heidelberg (Germany).

Among the 87 patients who were included in the analysis, most were male, 24 had chronic expanding dissections, 3 had mycotic aneurysms, and 8 had Marfan syndrome or a connective tissue disease. Mean aneurysm diameter was 74 mm. Previous aortic procedures were common among the patients, all of whom were considered high risk.

"Analysis revealed that, at 30 days, mortality was 13%, paraplegia was 8%, dialysis and renal insufficiency was 3%, graft occlusion resulting in gut resection was 2%, and overall graft occlusion was 6%," Dr. Böckler said.

At 1 year, the overall mortality was 25%, and rates of paraplegia, dialysis, and graft occlusion remained the same as at 30 days. The endoleakage rate was 11%. There were eight type I endoleaks, which were treated with proximal extension in six patients; two patients had spontaneous sealing of the endoleaks. Five patients had type III endoleaks that were treated endovascularly.

Many questions about the hybrid procedure remain, Dr. Böckler said. "Should it be simultaneous or staged? What about cerebrospinal fluid drainage? We don't know about long-term results, and we don't know if it's a good option for patients with [Marfan syndrome] and chronic dissection," he said.

"In conclusion, hybrid procedures are technically feasible, and are an alternative for repair of types I-III degenerative thoracoabdominal aortic aneurysms in very select high-risk patients who are not considered fit for open surgery. But mortality and paraplegia rates are still too high, which is disappointing," Dr. Böckler said.

Similar experience was reported at the symposium by Dr. Richard P. Cambria of the division of vascular and endovascular surgery, Massachusetts General Hospital and Harvard Medical School, Boston.

Between June 2005 and December 2007, 23 high-risk patients with thoracoabdominal aneurysms underwent mesenteric and renal debranching and subsequent placement of a thoracic stent graft, whereas 77 underwent open repair.

The hybrid and open groups had similar mean ages (77 and 73 years, respectively) and mean aneurysm size (6.5 cm in both groups). The mean Society for Vascular Surgery (SVS) risk score was 9 in the hybrid group and 6 in the open group, and more patients in the hybrid group than in the open group had oxygen-dependent chronic obstructive pulmonary disease and prior thoracic or thoracoabdominal repairs. "Composite mortality and/or paraplegia was doubled in the hybrid group, at 22%, compared with 12% in the open group," Dr. Cambria said.

Similarly, the rate of any type of reoperation was 39% in the hybrid group, compared with 21% in the open group. Actuarial survival rates at 1 year were 74% and 72% in the hybrid and open groups, respectively. "While touted as an operation of limited extent, the hybrid repair in high-risk patients has substantial morbidity, and to really clarify its role, a prospective study in equivalent risk patients would be needed," he concluded.

When asked to comment on this article, Dr. Frank Pomposelli, chief, division of vascular and endovascular surgery, Beth Israel Deaconess Medical Center, Boston, stated: "In spite of the many advances brought about since Crawford's development of the graft inclusion technique for thoraco-abdominal aortic aneurysm repair, it remains a formidable procedure with a significant morbidity and mortality even in the hands of experts in centers with large clinical experiences. The so-called visceral debranching procedure has been touted as a less morbid approach to this difficult problem, and on balance is attractive since it avoids direct surgery on the aorta, does not require thoracotomy, and can occasionally be done through a retroperitoneal incision. Our practice has been to stage the procedure, performing the thoracic stent graft at a later date.

"As outlined in the article, the visceral debranching procedure is in and of itself a morbid procedure in many patients and perhaps more so than the conventional approach since this procedure is usually performed in patients in whom the surgeon feels direct aortic repair is too risky. The take home message for me is that if a patient is unable to withstand a thoraco-abdominal repair, they are equally likely to suffer significant complications with the hybrid procedure. Is that really so surprising?

"The dissection required for this procedure is extensive. The blood loss and fluid shifts are often substantial. And as outlined above, paraplegia rates are not improved and may actually be worse, as is the need for re-operation.

"I personally feel that the utility of this operation in high-risk patients with thoraco-abdominal aneurysms is highly questionable and echoes the opinion that a prospective study is needed prior to expanding its use in these difficult patients." Dr. Pomposelli concluded.