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Small tools for small arteries

Critical hand ischemia is an unusual clinical syndrome. Given the robust and redundant circulation to the hand, it usually takes underlying vascular disease combined with an iatrogenic injury, such as an arteriovenous access for renal dialysis, to ultimately reduce distal flow to the hand and cause ischemia. For this unusual syndrome, the introduction of small interventional systems to treat diseased radial and ulnar vessels percutaneously is a welcomed advance. Open procedures are often fraught with limited long-term success due to the small vessel lumens and trauma induced by surgery itself. Percutaneous equipment that permits repair without the addition of unavoidable surgical trauma offers the potential to improve longer-term success. But, before we run out and stock every catheterization with this equipment, one must recognized that critical hand ischemia is a rare disorder. As pointed out by Kawarada et al. in their report in this issue [1], other more common causes for hand ischemia and pain must be excluded before investing effort in angioplasty at the distal radial and ulnar artery level. Proximal arterial disease should not exist and variability in distal vascular, such as the common high radial take-off [2], needs to be excluded and not confused with vascular loss. Finally, one must recognize that while several groups have reported the ability to repair vascular disease at the level of the palmar arch, this has not necessarily resulted in clinical success as thrombotic occlusion of end-vessels in the distal digits is a likely etiology in finger necrosis [3,4] and not cured with palmar revascularization. As transradial cardiac catheterization techniques gain popularity, it might be enticing to consider these microtechniques to open occluded radial arteries. One must temper this type of adventure for several reasons. Patients with true critical limb ischemia are distinct and unusual group who usually have the dual insult of a dialysis fistula and arteriosclerosis resulting in both reduced and shunt forearm flow. These were not simple radial occlusions that are found in the post-transradial catheterization population and are almost universally asymptomatic. In addition, there is a risk to recannulation such as complications at the brachial artery entry site. Under most routine situations of hand pain after transradial cardiac catheterization, hand ischemia is exceedingly rare. Local arteritis, thrombosis, or perivascular nerve crush injuries from hemostasis devices are the dominant etiologies after transradial procedures. These etiologies need to be excluded long before one reaches for the eloquent techniques used by Kawarada et al. to treat the unusual syndrome of critical hand ischemia.