Dialysis Access Diagnosis and Intervention
Technical and device options for achieving arteriovenous access.
By Scott S. Berman, MD, FACS
Diagnostic Fistulograms
Sheath Sizes
Flush Diagnostic Catheters
Selective Diagnostic Catheters
Diagnostic Guidewires
- .018-inch micropuncture
- Angled .035-inch hydrophilic wire
Diagnostic Notes
- Determine the best site for access based upon preprocedure physical examination of the access combined with duplex imaging.
- Anticipated venous anastomotic or outflow lesion: Enter at arterial end of access.
- Anticipated arterial anastomotic lesion: Enter venous limb of access, aiming toward arterial anastomosis.
- Unclear explanation for access dysfunction: Enter brachial artery at the antecubital fossa for diagnostic arteriogram and fistulogram.
INTERVENTIONAL TREATMENT
Sheaths
Wires
- Use a floppy hydrophilic .035- or .018-inch wire to cross straight, forward lesions.
- Use a stiff .035-, .018-, or .014-inch wire to cross difficult lesions or occlusions.
PTA Balloons
- Monorail/rapid exchange is ideal for small-diameter interventions.
- 4 to 16 mm in diameter, with various lengths (2–6 cm).
- For small-diameter interventions (2–8 mm), use small sheaths (4 or 5 F) and low-profile over-the-wire or monorail balloons.
- For large-diameter and/or resistant lesions, ultra-high-pressure balloons may be necessary.
Stents
- Bare-metal stents have poor patency.
- Covered stents may be more efficacious.
- Best results are seen in the axillary and iliac veins for recurrent lesions or severe recoil in complicated de novo lesions; usually limited to or adjacent to the venous anastomosis.
- No efficacy using stents in the forearm or at arterial anastomoses.
Thrombectomy Devices
- Over-the-wire Fogarty balloons (Edwards Lifesciences, Irvine, CA)
- Mechanical thrombectomy devices
- Rheolytic devices
Thrombolytic Agents
- Tissue plasminogen activator
- Ultrasound-activated microbubble
Flow Measurement
- Catheter-based intragraft bloodflow-measurement system
Interventional Notes
- For patent arteriovenous access sites, careful preprocedure physical examination combined with duplex scanning can direct treatment and limit the number of products used to a single sheath, wire, and balloon in many cases.
- Full imaging of the access should include the artery/vein (graft) anastomosis, the access body, and the venous outflow inclusive of the central veins. Extreme angulation of the image intensifier may be necessary to obtain a truly sagittal view of an anastomotic lesion.
- Detailed imaging of the arterial inflow or the extremity arterial runoff are not usually necessary and should only be performed based upon clinical findings before or during the procedure, rather than on a routine basis.
- For thrombosed access sites, systemic anticoagulation with heparin should be considered during the procedure.
- For thrombosed access sites, completion imaging of the entire access circuit should be done after the access is cleared of thrombus and any lesions are treated.
- For thrombosed access sites, the crossed-catheter technique is usually necessary to clear the entire access of thrombus.
- Because venous lesions are most common, begin clearing thrombus from the venous limb and treating the inciting stenosis before dislodging the arterial plug and restoring flow.
- Caution should be exercised when treating central venous lesions, particularly at or proximal to the thoracic outlet. Stents are usually of limited durability in this location.
- In elderly patients, compression of the left subclavian vein by a calcified aortic arch may by a source of venous obstruction that will not respond well to percutaneous intervention.
- Although little data exist, maintenance angioplasty every 6 to 12 weeks may be the only way to keep a central venous lesion patent.
- Catheter-derived postprocedure bloodflow rate of <600 mL/min for an arteriovenous graft or <500 mL/min for an arteriovenous fistula suggest residual dysfunction.
Tips & Tricks: Buttressed Purse-String Suture to Expedite Hemostasis After Dialysis Access Interventions
A time-saving alternative to manual hemostasis.
The use of closure devices has become ubiquitous after cardiac catheterizations and peripheral arterial interventions. A number of devices exist to facilitate arterial access closure and subsequent patient mobilization. No such product exists to expedite hemostasis in dialysis access fistulas and grafts after percutaneous interventions. Most diagnostic fistulograms can be accomplished using a 4-F system and without the need for therapeutic anticoagulation. Upon completion, simple manual hemostasis with or without an alginate-impregnated pad can be achieved in 5 minutes. With more complicated interventions either to restore or maintain access patency, larger-size sheaths are necessary up to 9 F in diameter. Moreover, these procedures often use heparin and/or thrombolytic agents as adjuncts during the procedure. As a result, hemostasis may take up to 30 minutes per site, and often two sheaths are used to complete the procedure.
A simple suture technique can be used to accomplish instantaneous hemostasis upon sheath removal. This not only reduces the risk of sheath site bleeding after the procedure, but also expedites the completion of the procedure, therefore allowing increased throughput of patients in a busy department. The technique employs the principle of a purse-string suture to close the skin and soft tissue over the puncture in the access. However, a bare suture can erode through the skin and create an access-site ulcer, particularly if it is not removed in a timely fashion. The technique I employ uses pieces of the sheath sideport tubing as a suture buttress that absorbs the cutting force of the suture and protects the skin.
A small, 4-mm segment of sheath sideport tubing is threaded on a 4–0 polypropylene double-armed vascular suture. Each needle is then passed subcutaneously on either side of the sheath insertion site (Figure 1). A second 4-mm piece of tubing is threaded over one of the two suture strands. The suture is then tied down securely as the assistant removes the sheath (Figure 2). The end result is a completely hemostatic site. The force of the tied suture is on the tubing pieces and not directly applied to the skin, which is often compromised in the dialysis patient population. There is no need or urgency to reverse any anticoagulation to achieve hemostasis. The suture can be simply removed before discharge from the recovery area or the next day at the dialysis unit.
The technique is not without potential complications. Care must be exercised in placing the suture so that the needle does not penetrate the graft or fistula. Needle penetration should be limited to the skin and subcutaneous tissue and requires the development of "tissue sense" for those operators not accustomed to the differential feel of these layers. Also, although the technique minimizes stress on the tissue, the suture should not be left in place indefinitely because skin erosion and ulceration are likely to result. Careful application of this technique will be appreciated by all involved in the interventional management of dialysis access—particularly the patients and staff who will no longer need to endure the time-consuming process of manual hemostasis.
Scott S. Berman, MD, FACS, is Medical Director of The Southern Arizona Vascular Institute, in Tucson, Arizona. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Berman may be reached at sberman@azvasc.com.
|
