[Graft or CVC? A prosthetic graft is the better choice].
For more than 30 years, research and industry have attempted to introduce into clinical practice solutions and products that could remedy the impossibility to use native veins. Vascular grafts of various types have been created that would approach the ideal characteristics as closely as possible with low antigenic power, high resistance to infections, low risk of thrombosis, and easy pierceability but high resistance to puncturing. For this purpose various materials, either totally synthetic such as PTFE, biological homologous or heterologous, or biosynthetic with mixed components have been created. In addition, different configurations to improve the hemodynamic outline of synthetic grafts have been studied: grafts of varying caliber, conical or equipped with cuffs, and various systems of wall reinforcement to increase the resistance to punctures. But each of these types favors one aspect over another: biological grafts show better compliance with the native vein but offer less resistance to punctures and ectatic processes; synthetic grafts, instead, tend to be more vulnerable to intimal hyperplasia at the venous anastomosis, which is the Achilles' heel of grafts. In recent years, the use of tunneled central venous catheters (CVCs) has grown exponentially. This has offered a new, important solution to the vascular access problem, but the extensive use of CVCs is not always justified. In comparison with grafts, CVCs have various disadvantages including insertion-related complications, possible malfunctioning, risk of infections and thrombosis, but above all a high risk of steno-occlusion of central veins. Also in this field, research and industry are offering more and more reliable and secure products. More resistant, flexible, tolerable and less thrombogenic materials are being used and various configurations which would offer the best performance with the least insertion-related risks have been introduced: double-lumen CVCs with input and output staggered in oval and circular sections, separate-lumen CVCs, split CVCs, and so on. Also the radiological and ultrasound techniques of insertion have improved, thereby reducing risks and disadvantages. The choice of graft system or CVC is often determined not by clinical factors but by the preference or experience of the operator, the presence of a vascular surgeon, or a radiological staff experienced in vascular accesses. The probability of steno-occlusion of central veins, which may occur as early as 2 weeks after the procedure, could affect any other ''traditional'' vascular access in the corresponding limb owing to the high risk of arm edema. In the surgical timing, the preparation of a graft access should therefore precede the placement of a CVC. The refinement of endovascular procedures has allowed to increase the secondary patency considerably, permitting excellent survival of graft accesses. Statistical studies performed on large samples of patients have reported a marked increase in the mortality connected to CVC access, not only as a result of infection. There are, however, according to my surgical experience, some conditions in which the use of the CVC is a priority, namely in patients with severe cardiopathy and reduced ejection fraction in whom volume overload caused by a graft access increases the risk of cardiac failure; in pediatric patients weighing less than 20 kg, in whom a graft vascular access could cause notable, even insuperable, difficulties of construction and management, as well as negative psychological implications for the small patient; in very elderly patients in poor clinical condition with a short life expectancy or suffering from cancer, in whom a CVC could be used also for the infusion of chemotherapeutic drugs; and in patients with peripheral arteriopathy in whom the alternative is a graft in a lower limb, because of the high risk of ischemia.
Cifarelli
M
M
Unità Operativa di Chirurgia Vascolare, Presidio Ospedaliero A. Perrino, Brindisi. marcifar@gmail.it
D001807:Blood Vessel Prosthesis; D002405:Catheterization, Central Venous; D006801:Humans; D006435:Renal Dialysis / Q000379:methods*