Arterial Thrombosis

Lower limb artery thrombosis was the first recognized complication of HIT (Weismann and Tobin, 1958; Roberts et al., 1964; Rhodes et al., 1973, 1977). Arterial thrombosis most commonly involves the distal aorta (e.g., saddle embolism) or the large arteries of the lower limbs, leading to acute limb ischemia with absent pulses. Sometimes, platelet-rich thromboemboli from the left heart or proximal aorta explain acute lower limb arterial ischemia (Vignon et al., 1996). Other arterial thrombotic complications that are relatively common in HIT include acute thrombotic stroke and myocardial infarction. The relative frequency of arterial thrombosis in HIT by location, namely, lower limb artery occlusion >> stroke syndrome > myocardial infarction (Benhamou et al., 1985; Kappa et al., 1987; Warkentin and Kelton, 1996; Nand et al., 1997), is reversed from that observed in the non-HIT population (myocardial infarction > stroke syndrome >> lower limb artery occlusion).

Uncommon but well-described arterial thrombotic events in HIT include mesenteric artery thrombosis (bowel infarction), brachial artery thrombosis (upper limb gangrene), and renal artery thrombosis (renal infarction). Multiple arterial thrombotic events are quite common, as are recurrences following surgical throm-boembolectomy, especially if further heparin is given during or after surgery. Occasionally, microembolization of thrombus originating from the heart or aorta causes foot or toe necrosis with palpable arterial pulses.

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