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L J Levien

Publications and source records attributed to L J Levien.

22 records · Page 2Linked to original sources
PubMedDate not supplied

The value of noninvasive investigation in the diagnosis of total occlusion of the internal carotid artery.

A battery of simple noninvasive tests consisting of directional Doppler ultrasound and carotid phonoangiography has been used to detect carotid stenosis in 700 patients Forty four carotid occlusions in 42 patients were confirmed on angiography, and this study examines the accuracy of this noninvasive battery in predicting the presence of an occluded internal carotid artery. Although the sensitivity of the battery described has been 70% for occlusion, with a specificity of 98% (only five false positives), this relatively low sensitivity and the uniform requirement for surgery in the false positive group have led us to conclude that this battery should not be used as a substitute for angiography when the diagnosis of internal carotid occlusion requires to be confirmed. Nevertheless, these noninvasive tests do have a role in alerting the physician to the presence of carotid occlusion and contralateral carotid artery stenosis, allowing more specific planning of any subsequent arteriography required.

Arterial Occlusive Diseases↗
PubMedDate not supplied

Influence of anatomic origin on intracranial distribution of micro-emboli in the baboon.

The purpose of this study was to investigate whether the anatomic origin of micro-emboli influences their intracranial distribution. In twenty-two baboons, we examined the distribution of 99-Technetium labelled albumin aggregates (5 to 40 microns in size) after injection into the circulation at the left atrium (LA), carotid trifurcation (CA), and anterior and posterior common carotid artery (CCI). In a further subgroup, the emboli were introduced at the carotid trifurcation with the contralateral carotid artery ligated (CA + L). The results of this study demonstrated that aggregates introduced at the carotid artery lodged preferentially in the ophthalmic (p = 0.032) and middle cerebral artery territories (p = 0.016). If the contralateral common carotid artery was ligated, however, more aggregates were found in the ipsi- and contralateral anterior cerebral artery territories (p = 0.01, p = 0.003). Aggregates introduced into the cardiac circulation were equally distributed throughout the brain. This experimental model determined patterns of flow that might be analogous to the human situation where unilateral or bilateral carotid stenosis or stenosis with contralateral occlusion has occurred or embolus from cardiac source has occurred. The results do not imply that the 40 micron microaggregates do cause TIA. These experimental findings support clinical observations that cardiac lesions may cause transient ischemic attacks (TIA) anywhere in the brain. In contrast, those of carotid artery origin cause predominantly middle cerebral or ophthalmic artery territory TIAs unless the contralateral carotid artery is severely stenosed or occluded.

Animals↗