Figure 4d.

Fourth-degree frostbite of the left hand in a 45-year-old woman. (a) Dorsal photograph shows gangrene throughout the distal aspects of the second through fifth digits. Note the sparing of the thumb. (b–d) DSA images obtained at presentation (b) and after 12 (c) and 36 (d) hours of continuous intra-arterial tPA infusion via the ulnar artery show persistent occlusion of the second through fifth proper digital arteries distal to the metacarpophalangeal joints. Note the vasospasm of the ulnar artery at 12 hours (arrowhead in c), which complicates interpretation of the distal perfusion defects. The patient ultimately underwent amputation of the second through fifth digits through the mid proximal phalanges.