Regardless of what type of dialysis access you have, if you’re one of the 700,000 people in the United States needing dialysis, you’re at risk of developing a clot in your dialysis access. If this happens, you need to receive treatment as soon as possible because if your access is clotted you will not be able to receive your next hemodialysis treatment until the access is repaired, or replaced.
There are two main ways a dialysis access can become clotted, or blocked – stenosis and thrombosis. We’ll look at each separately.
Stenosis – Narrowing of a Blood Vessel
Stenosis is when a blood vessel narrows. It’s a common cause of access dysfunction, particularly with arteriovenous (AV) fistulas and arteriovenous grafts. Stenosis in any vein or artery can create changes in blood flow and pressure throughout the dialysis access. ii
A narrowing of an artery that feeds your AV fistula or graft can slow the flow of blood through your access during treatment, and if the blood flow is significantly reduced, it can lead to inadequate dialysis, and quite likely to cause the access to become totally blocked, or clotted
If the stenosis occurs on the venous side of your dialysis access the narrowed vein will result in a backup in pressure and blood flow prior to the stenosis. If the stenosis is significant enough in size it may completely block off the blood flow through your fistula or graft.
In either of the above situations once the blood flow through the fistula or graft has stopped it means that your access has thrombosed (the medical term for ‘clotted’).
If thrombosis occurs in your AV fistula or graft, blood flow will be reduced or even prevented from moving through your access. A blood clot can also occur in a central venous catheter (CVC). Regardless of where a thrombosis occurs, it needs to be treated as soon as it is discovered. ii
The first step in treating a clotted CVC is the administration of a “clot busting” medication called tissue plasminogen activator (tPA) In some cases this can be done in the dialysis center. If this doesn’t work, you might need to be referred to an access center for a vascular specialist to evaluate why the CVC has clotted. There are several methods that the vascular specialist may use to attempt declotting of your CVC. If these methods are unsuccessful you may need to have your catheter replaced. i
Thrombectomy of a fistula or a graft
When blood clots develop in a dialysis access the clotting needs to be treated to restore blood flow through the access. These treatments include:
- Thrombolysis which involves the use of clot-busting medications which are injected directly into the clot to dissolve it.
- Thrombectomy utilizes an angioplasty balloon catheter, and perhaps a specialized mechanical device to break up and remove the blood clot from the fistula or graft
Thrombolysis, also known as thrombolytic therapy, is the use of drugs as treatment for the breakdown (lysis) of blood clots that have blocked your dialysis access. This treatment involves the injection of clot-busting drugs through a catheter to deliver drugs directly to the site of the blockage. The goal of this clot busting procedure is to restore blood flow through your access.
Thrombolysis is a minimally invasive, outpatient procedure performed by a vascular specialist. For the procedure, you will first be given a local anesthetic to numb the area and if needed, a moderate sedative to help you relax.
Then, using X-ray technology to guide a catheter into your clotted access, a clot dissolving medication will be delivered through the catheter directly to the blood clot. Once the medication has been delivered to the affected area it will be left to dwell for a period of time to break up the clot. Removal of the clot from the vessel by thrombolysis is a relatively quick procedure (usually completed in less than one hour). At the end of the procedure, the catheter used to perform the procedure is removed.
A thrombectomy removes the blood clot through a catheter-guided procedure. Our specially trained physicians at Azura Vascular Care perform the outpatient procedure to remove the clot from the fistula or graft using an instrument specifically designed to do so, eliminating the need for a more invasive procedure.
For the thrombectomy procedure, a local anesthetic to numb the area first will be administered and if needed, a moderate sedative may be given to help you relax. An interventional vascular specialist will insert a catheter into your access guided by X-ray technology. The catheter is used to break up and remove the clot. In some cases a specialized instrument will be inserted through the catheter to aid in breaking up and removing the clot. The catheter is removed when the clot has been retrieved and the procedure is complete. This procedure efficiently removes the clot and restores blood flow. The procedure takes about an hour and no overnight stay is required.
If your access clots, it’s important that you seek treatment as soon as possible. Keeping your access free of clots means you’ll be able to rest easy, trusting your access is functioning properly and you’re getting the life-saving dialysis treatments you need.