Mechanical Lock of the Lumen: Researching towards new Approaches for Permanent Vascular Access

Abstract

Theoretical proposals for two new vascular access devices (a central venous catheter (CVC) and a peripheral vascular access system, PVAS) are presented in this article. The new CVC concept is based on a mechanical obturator used for CVC locking. Compared to conventional locks, it should, theoretically, allow the reduction of bacterial contamination, biofilm and thrombotic formation. A new tunneling technique, based on a "rigid tunnel sheath" providing a more stable connection, as compared to a traditional CVC cuff, and an increasingly protected exit site, allows CVC changing changeover to take place through the sheath; therefore, avoiding surgical intervention. PVAS, based on the same mechanical lock concept, is structured from four components: obturator, soft graft, rigid tunnel sheath and foldable sheath. The total graft length is about 80 mm, its inner extremity being uncovered to allow a gentle curve reaching the native vessel. The outer extremity and bifurcation are reinforced by a titanium rigid sheath together with a Dacron cuff. The obturator is protected, and several technical solutions have been considered to guarantee sterility: the "accordion sheath", the "foldable sheath", and the "balloon obturator system". The major advantage of PVAS on CVC is the implant on the peripheral vessel which allows the saving of central veins and possibly avoiding life-threatening complications. As compared with an arterial-venous fistula or an arterial-venous graft, PVAS's main advantage should be the possibility of implanting even in "desperate" cases, so avoiding fistula needle positioning. It could be indicated for pediatric or psychiatric patients, for home-based or frequent dialysis schedules. Lower hemodynamic stress should therefore reduce vessel damage, such as aneurism, pseudo-aneurism, intimal hyperplasia and cardiac overload. The development of prototypes is in progress to verify both device usefulness and safety in clinical practice.