# The Colt Device for Treating Thoraco-Abdominal Aneurysms - Concept and Clinical Results

## TL;DR

A new stent graft called the Colt was tested for treating thoraco-abdominal aneurysms, showing promising results with few complications.

## Contribution

The Colt device introduces a novel stent graft design with multiple branches and adjustable diameters for treating complex thoraco-abdominal aneurysms.

## Key findings

- The Colt device was successfully implanted in 22 patients with thoraco-abdominal aneurysms with no intraoperative deaths.
- The device showed no migration or dislocation and maintained patency in all cases, with only minor complications like occluded branches and endoleaks.
- The results suggest the Colt device can be applied to a wide range of aneurysm anatomies, potentially guiding future device development.

## Abstract

To report results of application a new stent graft
design for the treatment of patients with thoraco-abdominal aneurysms (TAAAs),
which was co-invented by a vascular surgeon. This is a retrospective
observational study.

The Colt is a self-expanding stent graft,
composed of nitinol metal stents creating a special exoskeleton with asymmetric
springs covered with polyester material. The Colt device offers some advantages
over existing stent graft options. The main body is available in two different
diameters on both ends and in three different lengths. It has four branches
pointing downward and coming from the main stent graft at two levels. It offers
the physician an opportunity to decide which branch to choose for the target
vessel. It may be implanted alone or extended proximally and distally. Balloon
expandable and/or self-expanding stent grafts are used to create the visceral
branches. In complex extensive aneurysms, the procedure is divided into two or
three stages to minimize the risks of spinal cord ischemia.

Between August 2015 and December 2021, twenty-two Colt stent grafts were
implanted in twenty males and two females (aged 56–81) with TAAAs (eight Type
II; twelve Type III; two Type IV). The mean aneurysm diameter was 73.4 mm (range
64–83). All patients were asymptomatic. Eighty-five target vessels were
reconstructed using either self-expanding or balloon-expandable stent grafts.
Fourteen bifurcated, six custom-made tubes and two aortouniiliac (AUI) stent
grafts were used as distal extensions to the Colt device. Completion angiography
revealed no type I endoleaks. Five patients had Type II endoleaks which were
treated conservatively. There were no intraoperative deaths. One patient died on
the 7th postoperative day from multiorgan failure. We did not observe any other
complications within 30 days after implantation. One patient died from Covid-19
two months after discharge. Follow-up ranged from three to 75 months. There was
no migration or dislocation of the docking station or proximal and distal
extensions. All Colt device prostheses remained patent, however, two branches
leading to the coeliac trunk were found occluded at the time of the 12-month CTA,
without any symptoms. In two patients, there were late problems with three renal
bridging stent grafts. One of the Type II endoleaks resolved spontaneously after
one year, while four others remain under observation. No patient had an increase
in sac diameter.

Results from the current series are
promising. The Colt stent graft can be applied to a large variety of TAAA
anatomies, which may facilitate the development of new “off-the-shelf” devices
in the future.