Complication With Medtronic Thoracic Stent Endograft

Introduction and Background

The introduction of thoracic stent grafts into clinical practice over the past two decades and the ability to image the thoracic aorta in high definition have offered a paradigm shift in the way we have been able to diagnose and to treat thoracic aortic pathologies. Looking at national registry data from 2002–2012, Wang et al. described a majority shift toward endovascular treatment of thoracic aortic aneurysms and dissections. Given the number of products available to date to treat thoracic pathology, it is increasingly important that the vascular surgeon understands the capabilities and limitations for each device used. In 2009, Medtronic introduced the Valiant thoracic stent graft with Captivia delivery system to the US market. In 2018, Medtronic received CE mark approval for the Valiant Navion thoracic stent graft system. The Navion device had acceptable safe profiles with a low 30-day perioperative mortality of 2.3% and secondary procedures at 2.3%. Type Ia endoleaks at 1.2% at 1-month imaging follow-up. The Valiant thoracic stent graft is essentially a tube graft composed of polyester graft fabric that is scaffolded by nitinol wires sewn on the outside of the graft, together with nonabsorbable sutures. There is no longitudinal backbone metal support, allowing the advantage of the graft to conform to tortuous patient anatomy. There are several configurations of the graft available, giving a physician the ability to choose between proximal and distal bare-spring extension fixation as well as tapered grafts to accommodate size discrepancies. In the case of large flow lumen, large aneurysms in the descending thoracic distal fixation should be considered. The Valiant offers distal strut configuration for fixation and can be augmented with APTUS fixation systems to prevent device migration in the dynamic thoracic aorta.

Radiopaque markers are embedded into the graft to allow precision deployment at the proximal and distal fabric lines. There are four markers shaped as a figure 8, which delineate the proximal fabric edge. In the midgraft there is a single figure 8 marker showing the minimum amount of overlap needed to treat the longer aortic segments.

The Captiva delivery system is designed for the proximal bare-metal stent thoracic pieces. It allows recapturing and repositioning the stent graft in the event of malpositioned deployment. The deployment system for the closed web stent graft components does not allow recapturing because of the lack of front end bare-metal stent pieces. This ability to recapture the proximal seal zone can be advantageous for precise deployment in zone 0–1 settings.

The indications for use for the Valiant thoracic stent graft with the Captiva delivery system is to repair fusiform aneurysms, saccular aneurysms, and penetrating ulcers of the descending thoracic aorta in patients with appropriate anatomy, including: iliac–femoral vessels compatible with vascular access techniques, devices and accessories, nonaneurysmal aortic diameter ranging from 18 to 42 mm (44 mm for traumatic dissections), and nonaneurysmal aortic proximal and distal neck lengths >20 mm.

Unique to this graft, it does not require a separate sheath and can be barebacked into the patient for lower profile access arteries. The outer diameter of the device (24 French) is on a par with being the lowest available on the market up to 2017. When barebacked, the device has its own hydrophilic lining, allowing ease of delivery and less tissue trauma.

In terms of the safety profile of the device, Conrad et al. demonstrated the 5-year safety data showing a 94.8% freedom from aneurysm-related death, 89% sac showing no growth or shrinking aneurysm, no loss of stent graft integrity, no migration and loss of patency. In terms of endoleaks, Type I endoleaks as an aggregate of the data showed a rate of 7.2% and Type II endoleaks with a rate of 10.7%.