LAUSR

To the Editor, there have been documented cases of rare thrombotic events associated with venous thrombosis and thrombocytopenia post vaccination with ChAdOx1 nCov19 (Oxford-AstraZeneca COVID-19 Vaccine). This phenomenon was termed vaccine-induced immune thrombotic thrombocytopenia (VIITT) [1]. Although not as commonly published, there are reports of covid vaccine related arterial thromboses [2], and a suggestion that these events may be more frequent than venous thrombosis [3]. We describe a case of acute arterial lower limb ischemia following vaccination with ChAdOx1 nCov-19. A 49-year-old male, previously fit and well, presented with a 4-day history of cramping left leg pain with progressive pallor and paraesthesia. He denied smoking, alcohol, recreational drug use and had no significant family history. Notably, the patient had received his first dose of the ChAdOx1 nCov-19 vaccination 14 days prior. Examination confirmed left lower acute limb ischemia (Rutherford Class IIa) [4]. Blood laboratory findings demonstrated mild thrombocytopenia (platelet count 135 9 10/L) with elevated D-dimer at 950 ng/mL. CT lower limb angiogram (Fig. 1) demonstrated focal acute thrombus just above the left iliac bifurcation and an acute occlusion of the midpopliteal artery extending into the proximal segments of the crural arteries. Following multidisciplinary meeting discussion, it was decided to proceed with urgent pharmaco-mechanical thrombectomy. Fluoroscopic angiogram confirmed occlusion of the popliteal artery with no distal run-off (Fig. 2). The absence of filling defects in the iliac arteries on angiogram was deemed likely secondary to distal clot embolisation. Treatment was performed using the AngioJet Thrombectomy System and thrombolysis with alteplase. Initial therapy restored in line flow to the ankle with residual filling defects in the infra-popliteal arteries. A multi-sidehole infusion catheter was placed up to the anterior tibial artery (ATA) for overnight thrombolysis with alteplase at 0.5 mg/h, and heparin (250 U/h) was infused via the sheath. Patient remained on thrombolysis for a total of 24 h with two subsequent check angiograms during this time. Further thrombectomy was performed during the first check angiogram in the ATA to reduce the clot burden; however this failed to restore flow. Due to initial concerns from haematology of heparin as a potential cause of further clot formation, it was substituted with 0.9% saline to maintain access sheath patency and thrombolysis with alteplase continued. Final angiogram showed resolution of the popliteal and tibial thrombus with only a short segment residual filling defect in the common plantar artery (Fig. 3). Intravenous Argatroban was commenced as the choice of anticoagulation based on national haematological guidelines to treat suspected VIITT [5] with a target activated partial thromboplastin time (APTT) range of 1.5–3.0 of normal control. Following clinical and symptomatic & Azhar Ali [email protected]