Distal Revascularization Interval Ligation Procedure




Historical Background


The steal phenomenon was first described in 1969 by Storey and associates after creation of a Brescia-Cimino-Appel autogenous access. Steal can be a potentially limb-threatening event and must be promptly evaluated and treated if clinically significant. The goals for treating steal syndrome are twofold: restoration of antegrade flow sufficient to maintain distal perfusion and maintenance of the access for dialysis. Steal is seen more commonly after graft placement rather than after autogenous access creation, and typically occurs soon after access creation, but has been reported months to years later in up to 25% of cases. The incidence of clinically significant steal may range from 1% for an autogenous arteriovenous (AV) fistula placed in the distal forearm to as high as 9% for prosthetic grafts. The brachial artery is the most frequently involved inflow vessel in cases of steal syndrome. High-flow–induced steal syndrome in the absence of a proximal stenosis and with normal outflow vessels requires a reduction in fistula blood flow to eliminate steal symptoms. Options for intervention include access ligation, banding, relocation of the arterial anastomosis to a more proximal artery, revision using distal inflow (RUDI), and the distal revascularization interval ligation (DRIL) procedure. DRIL has been recommended as the standard of care by a number of surgeons, because it maintains arteriovenous access while maintaining distal limb perfusion.


The DRIL procedure was first described in 1988 by Schanzer and co-workers and subsequently popularized by Berman and colleagues. Since that time, several groups have confirmed its success. Reported long-term results have been excellent. Schanzer described 14 patients, all of whom had an access originating from the brachial artery and 13 of whom had complete recovery of function, including healing of gangrenous lesions after a DRIL procedure. One-year patency was 81.7% and all bypass grafts remained open. Berman described 21 patients with limb salvage and graft patency of 100% and 94%, respectively, and coined the term DRIL. Knox and co-workers published a series of 55 patients. Ninety percent had substantial or complete resolution of ischemia, and 15 of 20 patients had completely healed digital lesions. Access patency was 83% at 1 year, and 80% of DRIL bypass grafts were patent at 4 years.




Indications


If steal syndrome is suspected, urgent vascular evaluation is necessary. A grading system has been developed as a measure of the degree of steal syndrome and to guide intervention. Intervention may be necessary for grade 2 steal (intermittent ischemia during dialysis) but is mandatory for grade 3 steal (ischemic rest pain or tissue loss) ( Fig. 67-1 ). Many patients experience mild transient symptoms, which resolve within a few weeks. These patients should be closely monitored, because worsening symptoms may rapidly progress, leading to a permanent disability. Between one half and two thirds of the patients who develop steal do so within the first 30 days. Rest pain or motor impairment immediately after surgery requires immediate reoperation. Symptoms such as progressive numbness or pain, pallor, diminished sensation, ischemic ulcers, progressive dry gangrene, and muscle atrophy all demand intervention. Early symptoms are accompanied by gradual tissue loss; however, if ignored, rapid progression leads to necrosis and gangrene of the digits. It is important to differentiate hand ischemia from carpal tunnel syndrome and tissue acidosis, and edema from venous hypertension and monomelic ischemic neuropathy. Symptoms of steal syndrome are frequently exacerbated during dialysis. Although simpler options exist for the treatment of steal syndrome, including banding or ligation, the DRIL procedure maintains access and provides a means to revascularize the hand. Avoidance of dissecting at the site of the previous AV anastomosis is an additional benefit of the DRIL procedure.




Figure 67-1


Digital gangrene in a patient with a brachiocephalic AV fistula and steal syndrome.




Preoperative Preparation





  • Physical examination. To determine the optimum method of treatment, it is important to identify the etiology of the problem and the flow state of the fistula. Absence of a palpable pulse distal to the arterial anastomosis in the absence of clinical symptoms is not an indication for intervention. However, in symptomatic patients, absence of a pulse, which is corrected by manual compression of the access, is diagnostic for steal syndrome.



  • Digital pulse oximetry. Tissue oxygen saturation using pulse oximetry is low in the presence of steal and increases with compression of the access to greater than 90%.



  • Duplex ultrasound. Duplex ultrasound can be used to evaluate distal flow, along with photoplethysmography tracings of digital flow with and without access compression. Duplex venous mapping of the great saphenous vein is recommended to ensure an adequate conduit for the DRIL procedure. If the saphenous vein is inadequate, mapping alternate veins should be undertaken.



  • Angiography. Preoperative angiography may be used to identify the presence of a proximal arterial lesion, confirm the adequacy of the distal arterial vasculature, and identify a distal target vessel for revascularization. An arterial stenosis proximal to the anastomosis, such as a subclavian stenosis, may be treated by angioplasty or stenting ( Fig. 67-2 , A-C ).




    Figure 67-2


    A , Angiogram of a brachial artery demonstrating flow through the fistula but without distal arterial flow. B , An angiogram of the brachial artery with passage of a wire into the radial artery. C , Angiography with manual compression of the fistula results in flow into distal vessels.



  • Preprocedural dialysis. Patients should undergo routine dialysis either the day before or the morning of surgery to optimize electrolytes and fluid status.



  • Antibiotics. Prophylactic antibiotics are recommended.





Pitfalls and Danger Points





  • Complexity of the intervention. Compared with banding, ligation, proximalization, or relocation of the anastomosis distally (RUDI), DRIL is a more complex procedure, with limb blood flow dependent on a newly created bypass graft rather than the native arterial system.



  • Inadvertent access of the bypass graft. If the bypass is not clearly identified, it may be inadvertently accessed for dialysis, leading to further ischemia, aneurysmal degeneration, or graft occlusion.



  • Failure to ligate the brachial artery. Failure to ligate the brachial artery proximal to the distal anastomosis may lead to persistent steal syndrome from retrograde flow. However, more recent data suggests that the ligation portion of the procedure only contributes about 10% of the flow, and could possibly be avoided in some patients.



  • Location of the proximal DRIL anastomosis. Placement of the proximal anastomosis too close to the AV anastomosis may lead to failure of the DRIL procedure because of inadequate arterial inflow.





Operative Strategy


Timing of the Dril Procedure


DRIL should be undertaken urgently once ischemic steal syndrome has been confirmed. Delay may lead to tissue loss or amputation of a digit or a limb. The DRIL procedure affords the best augmentation of flow to the hand of all available revascularization procedures.


Type of Conduit


Initial descriptions required use of a venous conduit for the bypass, whereas recent reports have shown good success with prosthetic grafts.




Operative Technique


Choice of Anesthesia


The DRIL procedure is typically performed with general anesthesia, although a regional block may be used.


Incision


Most frequently, the fistula or graft involves the brachial artery. When using a venous conduit, this is typically harvested from the great saphenous vein in the thigh to allow adequate size and length. Alternately, upper extremity veins, cadaveric veins, or prosthetics can be used. The arm is initially prepped and draped on an arm board in an extended, supinated position. The entire arm to the wrist should be prepped to allow evaluation of the radial and ulnar arteries at the completion of the procedure and to allow adequate proximal arterial access. The hand may also be prepped into the field to allow oxygen saturation monitoring of the digits before and after completion of the DRIL procedure. Marking the path of the arteriovenous conduit is recommended so as to avoid injury to the fistula from the incision or tunneling ( Fig. 67-3 ). The proximal incision is made in the upper arm along the sulcus, separating the biceps and the triceps muscles, above the level of the existing arterial anastomosis.


Mar 13, 2019 | Posted by in VASCULAR SURGERY | Comments Off on Distal Revascularization Interval Ligation Procedure
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