Hemodialysis is a method of routing blood through a dialysis machine, which filters it to remove waste. It is a lifeline for the majority of patients with renal failure. It can be performed via a central venous catheter or an access circuit (fistula or graft).
For patients who need dialysis, there are several ways to access the bloodstream so the blood can be cleaned by a dialysis machine.
A dialysis catheter comprises two plastic tubes that are joined together where they enter the body, in the neck or in the groin. When the catheter is hooked up to the dialysis machine, one of the tubes is used to remove "dirty" blood from the body and the other tube is used to return "cleaned" blood back into the body. Dialysis catheters are used only when other methods are not possible because they have a higher rate of infection than dialysis fistulas or grafts.
A dialysis graft is created surgically in the arm or groin by connecting an artery to a vein with a tube made of woven plastic. After a month, the graft can be accessed with two needles at dialysis. While the graft is healing, most patients will need a catheter to receive dialysis. Grafts have lower infection rates than catheters, especially in the last two to three years before clotting off.
A dialysis fistula is created surgically in the arm by connecting an artery directly to a vein without the use of any plastic graft material. The vein near the connection to the artery will enlarge over a month before it becomes big enough to access with needles at dialysis. While the fistula is maturing (enlarging), patients will typically need a dialysis catheter to receive dialysis. In some cases the vein does not enlarge on its own and must be opened using balloon angioplasty. Although fistulas are more difficult to create, they can last up to 10 years. For this reason, a dialysis fistula is preferred over a dialysis graft or tunneled dialysis catheter.
When a dialysis fistula or graft cannot supply the dialysis machine with a high enough flow rate to clean the blood, a fistulogram can be performed. In this procedure, IV contrast is injected through the graft to identify areas where the blood vessel is narrow. Once these narrowings are located, a small balloon is inserted into the fistula or graft and expanded to widen the blood vessel. This process is called balloon angioplasty. If angioplasty does not improve the narrowing, a metallic stent can be placed. Stents are small, metallic tubes that are used to hold the blood vessel open.
When a fistula or graft becomes completely clotted off, a de-clot procedure can be performed. The clotted graft is accessed and contrast is injected to see the extent of the clot formation. Then several technologies can be used to remove the clot from the clotted graft or fistula. Once the clot is removed, there is usually a narrowing identified that caused the access to clot. This narrowing is usually treated with angioplasty or stenting. If a fistula or graft clots off repeatedly in a short time, a dialysis catheter will need to be surgically placed to create a new access point.
Occasionally a graft or fistula can direct too much blood from the artery into the vein. When this happens, patients experience pain, tingling, and numbness in their hand. This condition is called "steal" because the access is stealing blood from the artery. A Doppler ultrasound or a fistulogram can be performed to evaluate for "steal." A small, metal clip can be placed around the access to make it smaller and reduce the blood flow.
After the procedure, you will be observed to make sure the medications have worn off.
In some cases the site where the procedure was performed will require stitches. These will be removed before you leave the hospital.
Most central venous catheters are placed with image guidance. Catheters are not ideal for long-term dialysis because of the risk for infection and blockage of the vein. Our interventional radiologists offer placement of central venous lines for both routine initiation of dialysis and complex situations where other access methods are not possible. Recanalization of occluded veins may be offered as a last resort.
We also play an important role in maintenance of an established dialysis circuit by treating narrowed segments with angioplasty balloons and stents, thereby extending the longevity of the access for dialysis. For clotted access, our interventional radiologists may restore blood flow through the circuit via a de-clot procedure.
Our interventional radiologists are specialists in dialysis maintenance and the areas of the body affected by the treatment. In addition to the training that all radiologists receive, these specialists have additional fellowship training in interventional radiology, plus extensive real-world experience.
Our team of interventional radiologists and physician assistants coordinates your complete care – from imaging evaluation to post-procedure follow-up – maintaining a high level of communication with you throughout the process.
In addition, we coordinate closely with experts from across the UT Southwestern community when necessary.
To meet with an interventional radiologist at UT Southwestern's facilities in Dallas, or for more information about our services, request an appointment or call 214-645-8300.