Late aneurysm formation is a well-described complication after surgical correction of aortic coarctation. Endovascular repair of such aneurysms avoids the morbidity of conventional reoperative thoracic surgery. We describe a unique case of antegrade endovascular repair of a distal coarctation-associated aneurysm with vascular access acquired through the aortic arch by an upper hemi-sternotomy.

Introduction:

Reoperative thoracic aortic surgery for aneurysm formation after aortic coarctation repair is a challenging procedure that carries significant operative morbidity and mortality. Endovascular stent grafting of such aneurysms has recently been applied to a small number of patients with promising midterm results. In certain cases of thoracic aneurysm stent grafting, the femoral or iliac vessels are either too small or too tortuous to allow the passage of the larger grafts required for repair of these aneurysms. We report the case of an endoluminal repair of a coarctation-associated thoracic aortic aneurysm with antegrade deployment of a stent graft through the aortic arch in a patient with hypoplastic abdominal vasculature.

Method:

A 74-year-old woman was referred to our institution for evaluation of a large thoracic aortic aneurysm detected on angiographic evaluation for claudication. The patient had undergone repair of a long-segment, low thoracic aortic coarctation with an 18-mm interposition graft at the age of 32. During the past 2 years her proximal hypertension had become difficult to control and she had 2 to 3 block claudication develop. Angiography revealed a 7-cm aneurysm in the region of the repair and a 60 mm Hg gradient across the distal anastomosis. The iliac arteries and the abdominal aorta were significantly hypoplastic from presumed longstanding recurrent coarctation, precluding retrograde vascular access for stent graft repair.

The patient's past medical history was significant for additional chest wall surgery including a left radical mastectomy and a subsequent right modified radical mastectomy, both for primary breast cancer. Because the abdominal vasculature could not accept an appropriate sized endograft, it was elected to approach the aneurysm endoluminally from above. The patient was taken to the operating room and a 6-cm upper hemi-sternotomy was made with partial sternal division into the right third interspace. After the administration of 5,000 units of heparin, a double pursestring was placed in the distal aortic arch, and a flexible guidewire was passed into the aorta through the pursestring. Under continuous fluoroscopy, the wire was advanced across the aneurysm and beyond the distal anastomotic stenosis. A guiding catheter was then used to exchange the flexible wire for a 0.035 Superstiff guidewire (Amplatz Superstiff [Meditech/Boston Scientific, Watertown, MA]). Then a 22 French introducer was passed over the wire and into the descending aorta. A 15-mm AneuRX stent graft (Medtronic, Minneapolis, MN) was then deployed under fluoroscopy in the distal aortic neck. A 22-mm AneuRX stent graft (Medtronic, Minneapolis, MN) was deployed within the 15-mm graft, across the aneurysm, and into the proximal neck.

Upon completion, an angiogram revealed total exclusion of the aneurysm; however, a residual stenosis remained at the old distal anastomotic site. Intraoperative angioplasty in this area enabled us to reduce the gradient to 30 mm Hg. The patient's postoperative course was uneventful. She was discharged home on postoperative day 3. At the 2-month follow-up, a computed tomographic scan revealed a well-healed endograft with no evidence of endoleak. Persistent proximal hypertension with a residual gradient across the distal endograft was treated with an uneventful axillo-bi-femoral bypass graft 2 months after the endoluminal aneurysm surgery.

Discussion:

Aneurysm formation after coarctation repair is most commonly associated with patch angioplasty, but it has been described with both end-to-end reconstruction and prosthetic graft interposition. Reoperative open repair of coarctation-associated aneurysms are associated with a high risk of laryngeal nerve and phrenic nerve palsies and carry a perioperative mortality of 5% to 15%. Because such aneurysms are localized to a limited portion of the descending thoracic aorta, they are frequently quite amenable to endovascular stent graft repair. Bell and colleagues have reported excellent midterm results with such repairs in 5 patients with coarctation-associated aneurysms. Stent-graft sizes for thoracic aortic repair can range anywhere from 24 to 36 mm in diameter and are typically selected by oversizing the diameter of the proximal and distal neck by 10% to 15%. These grafts are significantly larger than those used for conventional abdominal aortic aneurysm repair and require 24 French to 27 French introducer sheaths. Retrograde arterial access can be obtained through the femoral and iliac vessels or through a graft sewn to the abdominal aorta.

Contraindications to stent graft repair of thoracic aneurysms include severe stenosis or occlusion of the aorta, as well as severe tortuosity of either the iliac arteries or the abdominal aorta. The described technique of antegrade placement of thoracic aortic stent grafts is a novel procedure for performing endoluminal repair of thoracic aortic aneurysms when the retrograde femoral, iliac, and abdominal aortic vasculature will not accept an adequate sized introducer system. Cannulation of the distal aortic arch eliminates the risk of retrograde dissection and allows for the passage of significantly larger devices.

The risks of peripheral or cerebral embolization can be minimized with techniques that have long been applied to aortic cannulation for cardiopulmonary bypass, including careful intraoperative examination with transesophageal and epi-aortic echocardiography. Despite good midterm results with stent grafting of the thoracic aorta, long-term results remain unavailable. Therefore, careful lifelong follow-up is necessary for all patients undergoing this procedure. Currently we recommend computed tomographic scans at 6-month follow-up intervals for 2 years and then yearly if the repair is stable. Antegrade endoluminal stent graft deployment has been described through the open aorta under circulatory arrest as part of a single stage total aortic repair ("frozen elephant trunk"). However, this is the first description of its use on the beating heart through a minimally invasive sternal sparing incision. Given the complexities of thoracic aortic aneurysm repair, innovative hybrid approaches that use both open and endoluminal techniques promise to expand the minimally invasive possibilities for patients who previously had no other options.