Imaging description

A 19-year-old male presented to the emergency department with gangrene of the right great toe. Figure 33.1 depicts an aortogram and bilateral lower extremity runoff that was obtained the next day. In Figure 33.1a, the nephrograms are abnormal, with atrophy of the right lower pole and contour irregularity in the left mid kidney, which were due to old scarring of uncertain etiology but consistent with either chronic atrophic pyelonephritis, reflux nephropathy, or ischemic infarcts. The aorta and renal, inferior mesenteric, and iliac arteries are normal. Figures 33.1b–d demonstrate occlusion of the right deep femoral artery just distal to its origin, with segmental reconstitution in the mid thigh. Figures 33.1d–i demonstrate occlusion of the right popliteal artery at the adductor canal, with reconstitution of the anterior tibial, posterior tibial, and peroneal arteries distal to the trifurcation. The reconstituted right anterior tibial artery occludes after a short patent segment. The peroneal artery is patent to the ankle where it reconstitutes the anterior tibial artery via the anterior perforating artery. The posterior tibial artery is also patent to the foot, with intact plantar arches to the dorsalis pedis artery. The left lower extremity is normal. Two hundred Units/hour heparin (heparin sodium derived from porcine intestinal mucosa; American Pharmaceutical partners, Los Angeles, CA) was also administered intravenously during this period. No improvement occurred during the infusions, and the patient was brought to the operating room where a right popliteal thrombectomy, saphenous vein patch angioplasty, and proximal popliteal to proximal peroneal artery saphenous vein interposition grafting was performed. Unfortunately, the bypass operation occluded several times over the following four months and cyanosis progressed to include the distal half of the right foot despite multiple tPA infusions and operative revisions. Several months into the patient’s course it was recognized that he had a markedly elevated plasma total homocysteine level at 194 μM/L (normal, < 11.4 μM/L), and no cystathionine-β-synthase (CBS) activity in fibroblast tissue (measurement 0.0 nM/h/mg with normal 5.4–18.5). The diagnosis of homocystinuria was made, and vitamins B6, B9, and B12 were added to the aspirin, warfarin, and clopidogrel he was already taking. The plasma homocysteine level fell to 11.1 μM/L within one month of vitamin supplementation. The patient required a forefoot amputation but his bypass graft remained patent for several years.