Embolic occlusion

Embolic occlusion

An embolus is an object that has become lodged in a vessel and causes obstruction, having been carried in the bloodstream from another site. It is often a thrombus that has become detached from the heart or a more proximal vessel. Sources include the left atrium in atrial fibrillation; a left ventricular mural thrombus following myocardial infarction; vegetations on heart valves in infective endocarditis; and thrombi in aneu rysms and on atherosclerotic plaques. Emboli may lodge in any organ and cause ischaemic symptoms. /uni25CF Arm and leg – pain, pallor, paraesthesia, paralysis and pulselessness (the five Ps of acute limb ischaemia [ALI]) (see Acute limb ischaemia ) ( Figure 61.29 ). Acute arterial occlusion due to an embolus di ff ers from occlusion due to thrombosis on pre-existing atheroma; in the latter ( Figures 61.30 and 61.31 ). It is essential to di ff erentiate between the two as they require di ff erent management. - /uni25CF Brain – the middle cerebral artery (or its branches) is most commonly a ff ected, resulting in TIA or stroke. /uni25CF Retina – amaurosis fugax is fleeting blindness caused by a minute thrombus emanating from an atheromatous plaque in the carotid artery passing into the central retinal artery . Lasting obstruction causes permanent blindness. /uni25CF Mesenteric vessels – possible gangrene and perfora - tion of the corresponding loop of intestine.

Embolus Pain Paralysis Pallor Pulseless Figure 61.29 The symptoms and signs of embolism (four Ps). The /f_i fth feature, anaesthesia, is often stated to be paraesthesia (the /f_i fth P), but, in truth, complete loss of sensation in the toes and feet is characteristic. Figure 61.30 Aortic bifurcation embolus. The source of the embolus is a recent myocardial infarct or atrial /f_i brillation. This causes severe, dramatic symptoms.