Postoperative flow prediction after creation of a vasculair access for hemodialysis with the aid of a computer simulation model.

Hemodialysis dependent patients, suffering from end-stage renal disease, need a well-functioning vascular access to connect them with the dialyzer. Usually, the vascular access is surgically created by making a connection between an artery and a vein (arteriovenous fistula=AVF). Due to the low resistance leak created and the high arterial-venous pressure difference, vessel adaptation (remodeling) would occur with an enormous increase in blood flow and proximal vessel dilatation. As a results, proper cannulation and the connection with the dialyzer becomes possible. The use of an autogenous wrist AVF (between the radial artery and cephalic vein) is preferred due to its better long-term patency and its smaller complication rate compared to more proximal AVF's and grafts. However, a significant amount of wrist AVF's fail directly after the surgical intervention due to thrombosis and/or insufficient vessel remodeling.

Unless the fact that all those patients are selected based on preoperative diagnostics (duplex, physical examination and CE-MRA), 30% of all newly created wrist AVF's fail within six weeks after surgery and are useless for hemodialysis. For the planning of the type of vascular access for each individual patient, it is very important to preoperatively predict the postoperative flow increase and vessel remodeling. When insufficient vessel remodeling is likely, based on preoperative diagnostics, another type of vascular access can be chosen.
The hypothesis is that the amount of failing AVF's can be reduced, if the blood flow increase through the AVF can be better predicted with the available preoperative diagnostics, since vessel adaptation is related to blood flow increase. A patient-specific computer simulation model, based on preoperative MRA and duplex data, can possibly give insight in the postoperative blood flow increase and failure incidence for different fistula configurations. The big advantage of the computer model is that the combination of the different factors, influencing AVF failure, like vessel diameters, vessel compliances and accessory veins, can be varied and examined.

It is generally accepted that the early-postoperative flow increase is indicative for successful maturation of an autologous arteriovenous fistula. Our hypothesis is that a patient-specific computer simulation model should be able to predict this postoperative flow before surgery. Ultimately, such a model could be used for surgical planning.

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All participants in this study will receive both pre- and postoperatively a CE-MRA examination, a duplex examination (only preoperatively) and pressure measurements (radial artery and finger). The duration of all examinations in total is 4 hours (two hours preoperatively and two hours postoperatively). All measurements are performed when the patient is already in the hospital for hemodialysis, for another examination not related to this study or when they are in the hospital one day before surgery.