Endograft (VORTEC) Reconstruction of Aortic Branches Allowing Endovascular Treatment of Aortic Aneurysms

Viabahn open revascularization technique (VORTEC) is a stent graft–based vascular connection technique that achieves 97% successful end-to-end sutureless anastomoses, which is useful especially when the traditional suture technique is cumbersome. Open graft repair of the aortic arch and thoracoabdominal aorta, with the exception of a few very experienced high-volume centers, generally carries a high mortality as well as a severe long-lasting morbidity. To overcome these limitations, the hybrid repair, which is a combined surgical and endovascular procedure, was introduced in the late 1990s. Unfortunately, hybrid repairs are often time consuming, because multiple vessels have to be bypassed before one or more aortic stent grafts can be implanted. Systemic inflammatory reaction syndrome (SIRS) and eventually multiple organ failure are common after such invasive surgery and might be responsible for significant morbidity and mortality.

The idea to use a stent graft as a vascular connector to facilitate revascularization emerged while dealing with target arteries (such as the right renal artery) that were highly challenging to address with conventional suture techniques. The initial concept was just to telescope a stent graft partially inside the renal artery to make the distal vascular connection easier, and then to anastomose the free end of that stent graft to a standard bypass graft. The Viabahn graft, (W.L. Gore, Flagstaff, AZ) was most appropriate for this, because it covers the range of diameters required, is highly flexible, and has a low profile. The Viabahn is a composite of a nitinol stent and a polytetrafluoroethylene (PTFE) coat, with both components having been shown to be highly biocompatible and stable over time. Moreover, the new generation of Viabahn stent graft is treated on the inner surface with Propaten (stable covalent bonding of heparin to the surface), a well-known antithrombotic coating (Carmeda BioActive Surface [CBAS]), which might be of great importance in vessels less than 6 mm in diameter.

Original Technique

This section briefly describes the procedure for the right renal artery.

The juxtarenal aorta is dissected locally to identify the right renal artery, just enough to puncture the right renal artery and to introduce a guidewire. Then a Viabahn stent graft (5–8 mm in diameter and 5 cm long) is telescoped over the guidewire into the renal artery and deployed partially inside the renal artery (generally about 2 cm) and partially outside the renal artery. Next, the Viabahn is expanded to reach its maximal diameter with a corresponding percutaneous transluminal angioplasty (PTA) balloon catheter. Finally and before suturing the proximal end of the Viabahn to a bypass graft, the Viabahn stent graft is secured with two polypropylene stitches to the renal artery.

Although this technique leads to considerable reduction in the technical difficulties with challenging vascular anastomoses, a sutured Viabahn-to-bypass graft anastomosis is still necessary ( Figures 1 and 2 ). Moreover, suturing the Viabahn, a stent graft with a very thin wall, to a vascular graft proved sometimes to be difficult or resulted in bleeding from the suture lines. Introduction of the stent graft directly through the feeding bypass graft into the renal artery and deploying it as a connector from inside the bypass graft provides a solution to this problem ( Figure 3 ). This technique allows the graft-to-vessel connection to be made in a few seconds. Furthermore, when the proximal end of the bypass graft is already attached to the vascular tree, interruption of blood flow can be kept to less than 1 minute. More recent technical improvements have allowed modifications of this procedure to be applied to almost all vessels, even if they are of small diameter and/or calcified.