Double Transposition and Physician-Modified Endografting for Complex Arch Aneurysm

Abstract

Hybrid repair of complex aortic arch disease typically requires aortic debranching to create a proximal landing zone for completion arch endografting. Despite advances in endograft technology, physician-modified endografting may be required to customize a prosthesis for challenging anatomy. We present a case of a complex distal arch aneurysm after a prior coarctation repair with a pediatric interposition graft several decades earlier, treated with hybrid repair by double transposition for arch debranching and physician-modified arch endografting for complete aneurysm exclusion.

Complex arch aneurysms frequently require a staged approach for repair. In the era of thoracic endovascular aortic repair (TEVAR), minimally invasive hybrid approaches to complex arch aneurysms have been developed to avoid major thoracic aortic procedures requiring hypothermic circulatory arrest, particularly in frail patients with cardiopulmonary or renal dysfunction. In planning a staged hybrid approach for complex distal arch aneurysm repair, additional consideration of the proximal and distal landing zones as well as of endograft sizing is critical for success. We present a case of double transposition through ministernotomy and physician-modified TEVAR to repair a complex distal arch aneurysm.

The patient is a 68-year-old woman with a history of aortic coarctation repaired at the age of 9 years with an interposition graft through left thoracotomy. She was frail, with comorbid scoliosis and hypertension. Magnetic resonance imaging for evaluation of her spine incidentally revealed a 6.1-cm complex distal arch aneurysm involving the left subclavian ostium. The aneurysm was bilobed, located immediately proximal to the site of her prior coarctation repair with an interposition graft (Figure 1). The interposition graft was narrowed to 10 mm in diameter, with circumferential calcification and well-developed arterial collaterals.

Figure 1.

Arch aneurysm in (A) sagittal and (B) coronal views.

Technique

The conventional treatment of this aneurysm was open arch and proximal descending replacement by redo left thoracotomy requiring deep hypothermic circulatory arrest. Given the patient’s age and comorbidities, we proceeded with an alternative minimally invasive hybrid repair consisting of a “double transposition” (left carotid to brachiocephalic, left subclavian to left carotid) and subsequent TEVAR. The Video outlines our technique. Key monitoring for the double transposition procedure included electroencephalography, somatosensory evoked potentials, and right radial arterial line.

The supra-aortic vessels were exposed through a 6-cm upper ministernotomy. The innominate and left carotid were isolated for several centimeters, with care taken to identify and to protect the left vagus nerve. The left carotid transposition anastomosis was oriented at the leftward aspect of the innominate, which is critical to avoid tension or twisting. After giving 10,000 units of heparin, we placed a side-biting clamp on the innominate artery and confirmed the absence of any electroencephalographic or somatosensory evoked potential changes. The right radial arterial line pressure was also unaffected. The left carotid was transposed without changes in neurologic monitoring and deaired before restoration of full cerebral perfusion. With the left carotid transposed, the left subclavian was isolated almost directly posterior in our field, which could be palpated arising from the aneurysm sac within the neck. Once isolated, we clamped the subclavian artery proximally and distally, distal to the vertebral artery ostium, which was controlled separately. A key technical aspect is to make the arteriotomy for subclavian transposition on the inferolateral aspect of the left carotid to prevent any tension or kinking of this anastomosis (Figure 2). After completion and deairing, distal unclamping was performed first on the subclavian, followed by the carotid to flush any microdebris to the arm rather than to the left side of the brain. The sternum was closed, and the patient was extubated in the operating room, neurologically intact.

Figure 2.

Completed double transposition, with labeling.

After about 1 week of recovery, the patient was brought to our hybrid operating room for second-stage repair, involving physician-modified TEVAR of the distal arch and proximal descending thoracic aorta. Before skin incision, based on preoperative measurements, we selected a 28 × 150-mm thoracic endoprosthesis, opened on the back table. Using a CV-2 polytetrafluoroethylene suture and a 10-mm angioplasty balloon, we placed constraining sutures for a length of 5 cm in the midportion of the stent graft. The sutures were placed around a metal ring of the endograft frame and tied down loosely over the inflated 10-mm balloon. This created a 5-cm-long segment of stent graft to be deployed inside our patient’s prior surgical interposition graft, which would be uniformly constrained at 10-mm-diameter and therefore avoid uncontrolled infolding of the endograft and any further narrowing of the treated proximal descending aorta. Of note, the modified TEVAR graft did not necessarily need to overexpand the previous interposition graft to accommodate all cardiac output in the setting of well-developed arterial collaterals. After bilateral common femoral artery access was obtained, intravascular ultrasound was used to mark the precise location of the previous surgical graft. We then exchanged for a 0.035-inch system and advanced our wire and then catheter around the arch into the ascending aorta, allowing exchange with a double-curved stiff Lunderquist wire. We then advanced a 20F sheath through the right femoral artery, ultimately positioning it within the arch, with our catheter from the left common femoral artery positioned for aortography. After lowering of the systolic blood pressure below 100 mm Hg, we deployed the modified endograft beginning at the distal aspect of the innominate artery. Completion aortography showed a small type 1A endoleak, which persisted after balloon aortoplasty of the proximal landing zone. Through our large-bore sheath, we advanced a steerable endoanchor system and deployed 3 endoanchors along the lesser curve of the aorta to eliminate bird-beaking and to seal the previous type 1A endoleak (Figure 3). Completion aortography showed immediate resolution of the endoleak, and the procedure was complete. After all devices were removed and our access sites hemostatic, the patient was extubated in the operating room neurologically intact. At 6 months, computed tomography angiography demonstrated successful endovascular repair of the aneurysm with no evidence of endoleak.

Figure 3.

Completion of arch endografting, without endoleak, demonstrated on (A) aortography and postoperative computed tomography angiography (B) axial, (C) coronal, and (D) sagittal views.

Comment

Complex distal arch aneurysms, classically repaired through the left side of the chest with full cardiopulmonary bypass and circulatory arrest, carry attendant significant morbidity and mortality, including a risk of stroke approaching 10%, even at other aortic reference centers.1, 2, 3 In considering distal arch aneurysms in frail patients and those with significant cardiopulmonary, renal, or other comorbidity, hybrid approaches using various open methods for arch debranching with subsequent endovascular aneurysm exclusion represent a viable alternative with reduced short-term morbidity and mortality.^2,4 The technique of double transposition for arch debranching, as previously reported by Desai and colleagues,⁵ is additionally advantageous as it avoids the use of any prosthetic material and concerns about long-term graft patency, avoids any aortic clamping, and can be completed through a less invasive upper ministernotomy. After construction of a suitable proximal landing zone, second-stage endografting was completed with a single device, avoiding a requirement for parallel or fenestrated arch endografting, each with its own risk for endoleaks and other modes of long-term failure.⁶ Use of physician-modified endografting with constraining sutures served to create a bespoke endograft to achieve both aneurysm exclusion and uniform endograft expansion throughout the stented segment, including the calcified and narrowed prior coarctation interposition graft.

Collectively, our approach served to minimize morbidity and avoided open redo thoracotomy with arch and descending thoracic aortic replacement under deep hypothermic circulatory arrest while yielding technical success and rapid recovery.