Interventional therapy of aortic diseases by stent-graft placement
(7 September 2005: VIDYYA MEDICAL NEWS SERVICE) -- Endovascular stent grafting has been successfully used in patients with abdominal and thoracic aneurysms and has been explored as a less invasive alternative in patients with stable type B aortic dissection. Furthermore, stent-graft placement and/or fenestration have also been applied to treat aortic branch occlusions resulting from malperfusion syndromes in both type A and type B acute aortic dissections. Aims of treatment include reconstruction of the thoracic aortic segment containing the entry tear, induction of thrombosis of the false lumen and reestablishing the true lumen and side branch flow.
The exact role of percutaneous fenestration and stent placement in acute aortic dissection is still evolving. Patients with acute aortic dissection may have life threatening complications manifested by end organ ischemia. The mortality rate of patients with renal ischemia is 50% to 70% and as high as 87% in mesenteric ischemia. Although the surgical success rate at reversing peripheral pulse deficits is high, the surgical in-hospital mortality rates in the setting of end organ ischemia remain as high as 89%. As such, percutaneous management of this complication has emerged as a viable therapy before or after definitive surgical management if needed. In 384 patients with acute type B aortic dissections in the IRAD registry, 46 (12%) were managed with endovascular stent grafting which was similar to the number of patients treated with surgery (56, 15%). Only three (6.5%) died during the initial hospitalization.
Nienaber et al. compared the outcome of stent grafting with surgery in a nonrandomized evaluation of 24 patients with chronic type B aortic dissection with at least one indication for surgery. Stent graft placement resulted in no morbidity or mortality, whereas surgery for type B dissection was associated with four deaths (33%) and five serious adverse events within 12 months. Dake et al. studied the placement of endovascular stent grafts across the primary entry tear in 19 patients with acute aortic dissection (four patients with type A and 15 with type B). Dissections involved aortic branches in 14 of the 19 patients (74%) and symptomatic compromise of multiple branch vessels was observed in seven patients (37%). Placement of stent graft across the primary tear was technically successful in all 19 patients. Complete thrombosis of the false lumen was achieved in 15 patients (79%). Revascularization of ischemic branch vessel was successful in 76% of the obstructed branches. Three of 19 (16%) patients died at 30 days without further death during the subsequent average follow up of 13 months.
The European Society of Cardiology Task force on acute aortic dissection released its recommendations for the indications for stent graft and/or fenestration in 2001. Additionally, in high risk patients not suitable for surgery because of age, comorbid conditions, or personal preference, endovascular repair offers palliative treatment to those who otherwise would have been left to follow the natural history of the disease.
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