A 14-year-old boy presented with a 10-day history of left foot pain and swelling of his left anterior dorsal foot. His medical history included thrombocytopenia (platelet count 110 k/microl), found during a school survey one year before admission. There was no history of prior infection or recent vaccination, and the patient's presentation occurred months before the COVID-19 pandemic in our country. Besides the pain, his left second toe had black discoloration and localized tenderness. It was pale and cold on the left dorsal foot, with minimal pulsation over the dorsalis pedis artery (Figure 1). Laboratory results showed a C-reactive protein of 1.81 mg/dl and a D-dimer of 1,750 ng/ml. Vascular Duplex found loss of typical flow pattern of his left dorsalis pedis artery and anterior tibial artery. The flows in the ankle arteries were monophasic, and signals in the veins were still detectable. Moreover, he could still feel pain and move his ankle and toes freely. Acute limb ischemia in Rutherford stage I was diagnosed. Electrocardiography showed no atrial fibrillation, and the heart echo revealed no valvular vegetation or structural abnormalities. He denied photosensitivity, rash, or arthralgia. His mother has systemic lupus erythematosus diagnosed in young adulthood and received treatment accordingly. His autoimmune laboratory profile was abnormal, with a positive antinuclear antibody test, positive anti-double-stranded DNA test, positive lupus anticoagulant, abnormally low complement C3 and C4, and mild proteinuria. Therefore, the boy received a diagnosis of APS associated with SLE. He then received treatment with subcutaneous enoxaparin injection, prostaglandin E1 infusion, aspirin, prednisolone, and hydroxychloroquine. Due to the patient's relatively young age and the limited extent of cyanosis, invasive angiography was not initially considered by his family and primary care team due to the added risks of potential bleeding and vascular access-related complications. After discussing the matter with the patient's family, the team decided to proceed with medical treatment.
However, on day 5 of hospitalization, there was no improvement in the left second toe cyanosis, and the resting pain in the left forefoot persisted. The treatment strategy thus was changed from medical to invasive endovascular approach. During the invasive angiography procedure, the patient's platelet count improved to 257 k/microl after receiving treatment with prednisolone and hydroxychloroquine. Vascular access was established through an ultrasound-guided puncture of the left common femoral artery, and a 6 Fr sheath was placed. The supra-popliteal and posterior tibial arteries were open, with no thrombus detected on the angiography. The flow from the origin of the anterior tibial to dorsalis pedis arteries was prolonged and sluggish (Figure 2). However, the flow stopped at the left dorsalis pedis artery, and the pedal arch to the metatarsal arteries was occluded. After placing a 6 Fr sheath, a soft-tipped 0.014-inch peripheral workhorse wire entered the left posterior tibial artery and the pedal arch (Hi-Torque Command, 300 cm, Abbott, Santa Clara, CA, USA). The smooth wire motion without resistance suggested that the obstructive nature was a soft thrombotic clot, not atherosclerosis. Angioplasty with a peripheral balloon (Amphirion 2.0 mm x 150 mm, Medtronic, Minneapolis, MN, USA) failed to re-establishing the flow. Aspiration thrombectomy then became the salvage endovascular treatment strategy. Because the clot in the distal dorsalis pedis artery and the pedal arch occluded at the plantar branch from the posterior tibial artery, we considered that a dedicated aspiration catheter used during acute ischemic stroke was most suitable in this situation.
We advanced Penumbra 3 Max catheter (150 cm, Penumbra, Alameda, California, USA) into the left dorsalis pedis artery while keeping continuous aspiration by Penumbra pump. After 90 s, the aspiration catheter was slowly retrieved while maintaining negative aspiration pressure (Figure 3). The flow was restored immediately after one pass of Penumbra 3 Max. Small thrombi were removed. The endovascular treatment was then completed with 180 s of balloon angioplasty to the dorsalis pedis artery-plantar arch-plantar branch of the posterior tibial artery (Amphirion 2.0 mm x 150 mm, seven Barr, for 180 s). The flow to distal metatarsal arteries improved significantly (Figure 2). There was no dissection or distal embolization. The radiation dose was 33.6 mGy, the total fluoroscopy time was 18.5 min, and a total contrast medium volume of 50 ml was used during the procedure. One hour after completion of the procedure, the sheath was removed when the activated clotting time was below 150 s. Hemostasis was achieved using manual compression for 15 min followed by sandbag compression for an additional 6 h. The patient was allowed to ambulate 8 h after the procedure. The foot pain, cyanosis, and swelling were relieved, but the gangrene change of his left second distal toe was irreversible.
The patient was prescribed oral dual antiplatelet agents, including aspirin 100 mg daily and cilostazol 50 mg twice daily, and underwent a 2-day course of subcutaneous enoxaparin at 1 mg/kg. The treatment course and timeline can be seen in Figure 4. However, one week after discharge, the patient developed acute respiratory distress due to pulmonary hemorrhage. As a result, urgent plasmapheresis and mini-pulse therapy with methylprednisolone were administered. The patient responded well to the treatment and was able to return to school one month after lower limb revascularization and plasmapheresis. Fortunately, toe amputation was not necessary. As for the anti-inflammatory therapy, his corticosteroid was tapered gradually, and at 9 months after the event, his medications were as follows: aspirin 100 mg/day, azathioprine 50 mg/day, hydroxycholoroquine 200 mg/day, and amlodipine 2.5 mg/day, without use of anticoagulant or steroid. At 6-month and 1-year follow-up, the autoimmune profiles including ANA, anti-dsDNA, C3, C4, and titers of anti-phospholipid antibodies were all normalized. Therefore, the pediatric rheumatologist considered anticoagulation was not necessary.
At 3 months after the index procedure, the gangrene at the patient's left 2nd toe tip spontaneously dislodged. At the one-year follow-up, the patient's five toes were preserved, and vascular Duplex showed normal flow in the left lower limb arteries. The patient was able to resume playing basketball. At the 3-year follow-up, there was no recurrence of thrombotic event.