Before kidney dialysis treatments can begin, doctors need to create a site where blood can flow both in an out of the patient’s body. By inserting a small tube (shunt) into a blood vessel, called an arterial venous shunt, they create an artificial connection between a vein and an artery.

Sometimes the shunt becomes narrowed or blocked, making it difficult for blood flow. When that happens, interventional radiologists can correct this problem using an ultrasound machine and a small needle. They first inject dye into the shunt and then watch an X-ray image on a screen to see if there is a narrowing in either the shunt or the veins.

If narrowing is found, then venoplasty is performed. This procedure is similar to an angioplasty in which a small balloon is inflated and deflated several times to clear the vein of the obstruction.