Risk factors for DASS include female gender, age > 60years, diabetes, atherosclerosis, previous access surgeries in the affected limb, and use of proximal versus distal artery for anastomosis [1]. The incidence of symptomatic steal is higher with a proximal creation site. Reported incidence is 1-2% with rcAVF versus 5-10% with brachial artery fistula.
Hand ischemia may occur during hemodialysis because dialysis tends to lower venous return, reducing cardiac output and lowering the perfusion pressure in the fistula outflow artery and collaterals that supply the hand. Acute presentation, i.e. occurring within hours of dialysis access creation, is more common with arteriovenous graft (AVG) and associated with poor vessel quality. Subacute and chronic presentations are usually associated with AVF. Symptoms can be mild including nail changes, occasional tingling and numbness during dialysis, or moderate to severe with muscle weakness, pale or cyanotic fingernail beds, rest pain, fingertip ulcerations and tissue loss [3]. Digital blood pressure, ultrasound and angiography can help with the diagnosis [3].
Four vascular beds that contribute to the pathophysiology of DASS are [1, 3]:
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(i)
Artery proximal to anastomosis: If diseased, cannot adapt to supply adequate flow to the arteriovenous access and distal extremity.
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(ii)
Artery distal to anastomosis: If diseased, can increase differences in resistance between vascular beds and result in DASS.
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(iii)
Draining veins: The larger the diameter of the draining vein the lower the resistance in the AVF, predisposing to DASS. Similarly, the diameter of the arteriovenous anastomosis can increase the risk.
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(iv)
Collateral arteries: Inadequate hypertrophy and dilation of the proximal and distal arterial system to supply adequate flow to the AVF and distal extremity can increase the risk of DASS.
DASS is also a factor in AVG, and is related to the larger diameter of the anastomosis relative to the artery. A smaller anastomotic diameter of 5 mm created by WavelinQ technology can also result in symptomatic steal [4].
Treatment is based on the severity of symptoms, and is often not required with mild DASS. Surgical management is indicated for moderate to severe symptoms. Distal Revascularization and Interval Ligation (DRIL), and Revision Using Distal Inflow (RUDI) are two surgical techniques that preserve the AVF and improve blood flow into the distal arm. Surgical ligation of the fistula is usually considered in patients with severe symptoms [3]. While the DRIL or RUDI surgical interventions may have improved our patient’s steal symptoms, these symptoms were mild, only occurring during dialysis, hence surgical intervention was not undertaken.
Our patient had an occluded distal radial artery and a focal area of severe stenosis in the distal ulnar artery, not seen at pre-AVF creation angiography, causing an increase in the resistance between the vascular beds, promoting DASS. Additionally, the angiogram demonstrated lack of sufficient collateral formation around the region of radial artery occlusion. The angiogram also showed a large diameter draining vein contributed by prior rcAVF creation, resulting in decreased vascular resistance and increased flow through the fistula. Thus our patient demonstrated 3 out of the 4 pathophysiological factors contributing to DASS.
DASS, though rare, can be seen with pAVF creation. Identification of the risk factors prior to creation, especially in ESRD patients who are at higher risk of peripheral vascular disease, can help avoid this complication. Management is largely guided by clinical presentation. As long as there is adequate collateral supply to the extremity, single vessel occlusion is not a contraindication to pAVF creation with the use of WavelinQ technology. Careful patient selection with pre-creation angiogram for pAVF may reduce the risk of symptomatic steal.
