Embolus

Abstract: The historical development of technologies for catheter-based reperfusion of the acutely ischemic human brain is brief but eventful (Table). The first clinical patients were treated with local microcatheter delivery of intra-arterial fibrinolytics in the mid-1990s. The first mechanical recanalization technique, primary intra-arterial balloon angioplasty, was described a few years later. Over the subsequent decade and a half, successive waves of innovative mechanical thrombectomy devices were introduced. The rapid proliferation of technology reflects the inherent dynamic of biomechanical device development, characterized by rapid engineering innovation focused on a well-circumscribed target, in contrast to the slower, more deliberate arc of drug development, which requires extensive testing of each new molecular entity for unexpected off-target effects on diverse organs. The heterogeneity of target vascular lesions in cerebrovascular disease mandates a diversity of mechanical treatment options for deployment by interventionalists. In many patients, the intracranial occlusion is an embolus that has arisen from the heart or a proximal aortocervical arterial source and landed in a relatively normal recipient artery. Such target thrombi respond well to retrieval and aspiration strategies. In other patients, the occlusive lesion is comprised of an in situ intracranial atherosclerotic plaque with supervening thrombosis. These target lesions will not respond well to retrieval devices, which catch on the plaque, or to aspiration devices, which are effective only for the thrombus component. However, they do respond well to angioplasty and stenting, which accomplish controlled cracking and dissection of the underlying atherosclerotic lesions.1 There is a notable race, ethnic variation in the composition of intracranial occlusions.2 Among whites, emboli from the heart or extracranial arterial sources are common; among Asians and blacks, in situ intracranial atherosclerosis with supervening thrombosis is more frequent. As a result, the most effective and commonly used mechanical treatment strategies vary regionally across the globe. The endovascular …

Abstract: In the 1940s, most strokes were attributed to cerebral vasospasm, a mechanism that is not given a great deal of credence today. It was not until the early 1950s that Harvard neurologist C. Miller Fisher1 stressed the importance of carotid artery atherosclerosis as a major cause of cerebral infarction. Later that decade, the importance of atrial fibrillation as a cause of cerebral embolism began to be stressed,2 and the presence of a left atrial thrombus was first seen on angiocardiography in 1965.3 Despite the established importance of these 2 causes of stroke, carotid disease and atrial fibrillation, nearly half of strokes were listed as “of undetermined cause” in a large stroke registry as recently as 1989.4 In this series, 40% of 1273 cerebral infarctions in the Stroke Databank of the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) were thought to be cryptogenic (from the Latin crypticus , meaning secret or mysterious). The clinical syndrome in those patients, as well as the angiographic and computed tomographic (CT) findings, could be reclassified as embolic; however, because no source of embolus could be identified, the authors kept these strokes in the undetermined cause category. In 1990, a third leading cause of embolic stroke was identified on transesophageal echocardiography (TEE), namely severe atherosclerotic plaques in the aortic arch.5 The 3 patients described in that initial report were a 68-year-old woman with dysarthria and an embolus to the foot, a 77-year-old woman with a cerebellar infarction after cardiac catheterization, and a 70-year-old man with staggering, diplopia, and a visual field cut. All 3 had severe plaque in the aortic arch on TEE. In addition, freely mobile projections were seen superimposed on the plaques, making it seem likely that these findings were the reason for the patients’ embolic …