Clinical Relevance

Percutaneous procedures for hemodialysis shunts are becoming increasingly important for interventional radiologists. A growing number of patients with renal insufficiency are enrolled in dialysis programs, the majority of them undergoing hemodialysis. In the West, this affects some 150 to 200 persons per million inhabitants. Given the increase in patients’ life expectancy, maintaining access to the vascular system continues to be a problem.¹ For example, the number of long-term functioning shunts is estimated to be 15%.¹ Primary patency of hemodialysis shunts is low: approximately 65% of Brescia-Cimino shunts and 50% of polytetrafluoroethylene (PTFE)-covered shunts exhibit primary patency after 1 year, and the numbers sink after 2 and 4 years to 60% and 45% for Brescia-Cimino shunts and to 43% and 10% for PTFE-covered shunts.¹

In Europe, arteriovenous Brescia-Cimino shunts are the preferred primary shunts, used in conjunction with the radial artery and veins of the lower arm. Autologous veins in the proximal lower arm and elbow region are generally preferred even for renewed shunt application. For percutaneous revascularization, the choice of access site, indications, and interventional technique employed depend on the nature and location of the shunt, site of the lesion, and nature of the obstruction.

Shunt thrombosis of native fistulas is a complication not as frequent as in grafts.¹ Besides an underlying stenosis that is present in almost all cases, cofactors are manifold: clotting abnormalities, thrombocytosis, disturbed fluid balance, hypotension, and aneurysmatic degeneration of the native vein causing low flow may lead to shunt thrombosis. There are, however, different types of shunt thrombosis that require different strategies of percutaneous intervention.

Indications

Indications for interventional treatment are acute or subacute occlusions in native fistulas that prevent use of the arteriovenous connection for dialysis. Relative indications are occluded fistulae in patients with a functioning renal allograft. Percutaneous intervention is contraindicated in acute infections of the vein or perivenous space. It is, however, worth trying to recanalize even thrombosed immature fistulas because there is a good chance of restoring flow and allowing development of a mature fistula after percutaneous recanalization.2,3 Natario et al. achieved clinical success in immature fistulas in 97%, with a 1-year primary patency of 51%.³ Miller et al. achieved 85% technical success in thrombosed immature fistulas, 79% clinical success, and a secondary patency of 90% at 12 months.²

Contraindications

There are few contraindications to percutaneous thrombectomy from native fistulas. One is definitely a suspected superinfection of the thrombus or vein. This is rare; although thrombosed venosus segments are frequently painful, this does not necessarily indicate infection.

Large amounts of thrombus, especially in large venous aneurysms, are poorer candidates for mechanical thrombectomy, because there is increased risk of pulmonary embolization.

Equipment

A high-quality angiographic unit with a C-arm, digital pulsed fluoroscopy, and preferably a table that allows lateral rotation to position the patient’s arm are prerequisites for shunt interventions. For thrombectomy in particular, no special requirements are needed.

The anatomy of native hemodialysis fistulas is very individual and may alter due to current arterialized blood stream, pressure, and traumatization. There are some principal forms of fistula that determine which access to the thrombosis is appropriate.

Native Upper Arm Shunts

In lesions near the anastomosis, retrograde puncture of the upper cephalic vein is performed at a position near the trunk. If the lesion is located more centrally, a puncture site is chosen close to the anastomosis (Figs. 117-1 and 117-2). A double access is often advisable in thromboses of upper arm shunts, whereby the puncture can be made in the thrombosed venous portion and thrombectomy first performed on one segment via retrograde access and then the second segment via antegrade access.

Ipsilateral puncture of the internal jugular vein with retrograde probing has been described as an alternative access to the brachiocephalic vein.⁴

Technical Aspects

Percutaneous Treatment

Published literature describes a number of approaches to treating clotted native fistulas:

• Thrombolysis and spray-lysis

• Mechanical thrombectomy:

• Balloon angioplasty

• Aspiration thrombectomy

• Hydrodynamic thrombectomy

• Mechanical clot dissolution

• Stent placement

Frequently a combination of methods becomes necessary to finalize a case. All methods have been used with success, and interventional radiologists should be familiar with several of them to achieve best possible results.

Thrombolysis

Thrombolysis is (relatively) infrequently described to treat native fistulas. Rajan et al.⁵ described their experience in 25 fistulas with 30 episodes of occlusion, including 19 forearm radiocephalic fistulas in 18 patients and 6 upper arm brachiocephalic fistulas in 6 patients. Lytic therapy with urokinase or recombinant tissue plasminogen activator (rtPA) was administered as a bolus into the fistula in 24 cases, with the exception of one case in which a 16-hour infusion of rtPA was initiated. Clinical success was achieved in 73% of cases (22 of 30). All patients were followed for a maximum of 66 months (mean 12 months). Primary patency rates were 36% at 3 months and 24% at 1 year. The assisted primary patency rate was 40% at 3 months and 32% at 6 months. The secondary patency rate stabilized at 3 months was 44%. Patency rates after clot removal were not significantly different between upper and lower arm fistulas.

Schon and Mishler⁶

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related posts:

Aortic Stent-Grafts Use of Skull Views in Visualization of Cerebral Vascular Anatomy Carotid Revascularization Balloon Catheters Image-Guided Percutaneous Biopsy of Musculoskeletal Lesions Percutaneous Nephrostomy, Cystostomy, and Nephroureteral Stenting

Stay updated, free articles. Join our Telegram channel

Join