[Etiology of acute ischemia of the lower limbs].

The most frequent cause of acute ischaemia of the lower limbs is arterial: thrombotic, embolic and spastic. In cases of arterial embolism, the site of origin is the left side of the heart in 9 cases out of 10: ischaemic heart disease in 2/3 of cases, with atrial fibrillation (A.F.) in 50% of cases, rheumatic valvular disease with A.F. in 1/5 of cases and more rarely, idiopathic A.F., auricular disease and cardiomyopathies. Arterial emboli can be fragments from a wall thrombus (aortic or arterial aneurysm), or atheromatous material from an ulcerated plaque. In 11% of cases the origin of the embolus is never found. Arterial thrombosis is due to chronic vascular disease in 1/3 of cases, popliteal aneurysm and thromboangiitis obliterans. The iatrogenic causes are rare: use of the arterial route, and arterial prosthesis, accidental intra-arterial injection during sclerotherapy for varicose veins. Arterial spasm is seen in cases of phlegmatia caerulea dolens. It ben be iatrogenic (ergotamine tartrate, dihydroergotamine, methysergide), toxic (L.S.D.) or spontaneous.