Combined Ascending Aortic Stent-Graft and Inner Branched Arch Device for Type A Aortic Dissection

Investigational Devices

The custom-made Zenith Ascend stent-graft is a single-component tubular or tapering stent-graft constructed of woven polyester fabric sewn to self-expanding nitinol stents with braided polyester and monofilament polypropylene suture. Uncovered stents are incorporated on both the proximal and distal ends to improve alignment and fixation; the lack of hooks and barbs reduces the risk for iatrogenic dissection at the interface between the proximal stent and the wall of the ascending aorta. ⁵ Four radiopaque markers are placed within 1 mm of the graft fabric edge proximally and distally. The device is currently produced with proximal diameters of 28 to 50 mm.

The custom-made Zenith inner branched arch stent-graft is composed of a woven polyester fabric sewn to stainless steel and nitinol stents. Two inner branches are used to attach bridging covered stents coming from the targeted supra-aortic vessels, most commonly the innominate and left common carotid arteries. ¹¹ The device is currently manufactured with proximal diameters of 34 to 46 mm.

Planning and Operative Technique

All elective patients were discussed by a multidisciplinary team consisting of a cardiologist, a cardiothoracic surgeon, a vascular surgeon, and an anesthetist. Endovascular repair was offered when open surgery was not indicated owing to patient comorbidities. Patients were informed that the investigational devices were being used on a compassionate basis and gave written informed consent.

Thin-slice, arterial-phase computed tomography angiography (CTA) scans were analyzed with the Aquarius iNtuition workstation (TeraRecon Inc, San Mateo, CA, USA) to provide dimensions for stent-graft customization. To apply this technique, the beginning of the entry tear in the ascending aorta must be at least 2 cm from any coronary orifice to allow a sufficient proximal landing zone. The ascending stent-graft can be in tubular or tapering configuration depending on the size of the ascending aorta. The outer wall to outer wall diameter should not measure >40 mm or <24 mm. Adequate oversizing of 15% to 30% is required due to marked pulsatility of the ascending aorta. The branched arch device is designed to accommodate the distal diameter of the ascending stent-graft, its own distal landing zone, and the diameters, lengths, and clock position of the supra-aortic vessels. Overlap between the ascending stent-graft and the branched device is preferably 2 full stents or more. Distal aortic extension stent-grafts as well as false lumen occlusion devices are used as necessary.

Cervical debranching in the form of left carotid–subclavian bypass was undertaken in a staged or simultaneous setting depending on the urgency of the condition. Endovascular procedures were performed under general anesthesia in a hybrid theatre with fixed fluoroscopy and 3-dimensional fusion imaging (Allura Xper and AlluraClarity; Philips Healthcare, Best, the Netherlands). The stent-grafts were preflushed with CO₂ before saline flushing to reduce the amount of trapped air in the sheath. ¹² The main access was transfemoral, while supra-aortic vessels were accessed through a right common carotid artery cutdown and a percutaneous left brachial artery puncture. A double-curved extended Lunderquist extra-stiff wire (Cook Medical Europe) was positioned in the left ventricle. An occlusion balloon in the inferior vena cava was inflated to reduce cardiac output as the Ascend stent-graft was deployed distal to all coronary orifices and proximal to the innominate trunk. The branched device was then placed with sufficient overlap of the proximal stent-graft and alignment of the branch markers to the targeted supra-aortic vessels. Cannulation and bridging of the supra-aortic branches from the inner branches were performed as previously described. ¹¹

Postoperatively, patients were monitored in an intensive care setting before being transferred to the general ward. An early CTA was arranged before hospital discharge; in the absence of endoleaks, the surveillance CTA scans were scheduled for annually thereafter.

Patient Outcomes

All patients underwent left carotid–subclavian bypass, with the inner branches targeting the innominate trunk and left common carotid artery. Spinal drainage was employed for the 3 elective procedures. Mean operating time was 292±83 minutes (range 200–380) and mean fluoroscopy time was 35±19 minutes (range 15–65), with a dose area product of 599±469 Gy·cm² (range 136–1193). Technical success (no type I or III endoleak and successful revascularization of all supra-aortic vessels) was achieved in all patients. Median intensive care unit stay was 5 days (range 4–23) and the median hospital stay was 16 days (range 8–25).

One patient with acute dissection and disseminated breast cancer died of pneumonia on day 23. Other perioperative complications included individual cases of major stroke, systemic inflammatory response syndrome, and groin lymphatic leakage. The major stroke was a cerebellar hemorrhage, likely due to the combined effect of systemic anticoagulation and spinal drainage. This patient required surgical external ventricular drainage for decompression of hydrocephalus; he recovered without neurological deficit. The other patient with acute dissection died at 5 months. The 3 elective patients were followed for 7, 13, and 19 months, respectively. All had false lumen thrombosis (Figure 1) with either reduced or stable aneurysm diameters.

OPEN IN VIEWER

Figure 1.

A 52-year-old man (patient 5) with chronic type A dissection and a saccular false lumen ascending aortic aneurysm measuring 62 mm. (A) The dissection extended to the abdominal aorta. (B) He was treated with modular ascending and inner branched arch stent-grafts and false lumen occlusion. (C) The ascending stent-graft landed just distal to the coronary ostia. (D) The false lumen was completely thrombosed, and the aneurysm shrank after the operation.