For patients requiring regular dialysis, the shunt (also known as a fistula or graft) is the "lifeline" that enables the treatment. The shunt is an artificial connection between an artery and a vein, usually in the forearm or upper arm, created surgically to allow the high blood flow necessary for the dialysis machine. However, over time, these blood vessels tend to develop various problems that can jeopardize the continuation of treatment. The most common issues are narrowing of the blood vessel (stenosis) due to internal scarring, or complete blockage caused by blood clots (thrombosis). When the shunt does not function properly, effective dialysis cannot be performed, and the patient is in immediate danger.

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The treatment for these problems is currently performed using a minimally invasive approach by an interventional radiologist, without the need for repeat open surgery. The procedure takes place in a catheterization room, under local anesthesia and mild sedation. The physician inserts a catheter (a thin tube) directly into the shunt through a small puncture in the skin, guided by ultrasound and X-ray fluoroscopy. If the problem is narrowing, the doctor uses a special balloon at the tip of the catheter, which they inflate inside the narrowed area to widen it and restore flow (a procedure called angioplasty). In some cases, a stent (a metal mesh support) will also be inserted to keep the blood vessel open over time. If blood clots are present, the doctor will use special devices to aspirate or dissolve the clots, a procedure called thrombectomy. The ultimate goal is to return the shunt to full function as quickly as possible.