Carotid Endarterectomy - Essay Example

Carotid Endarterectomy Introduction The treatment for patients with significant narrowing of the internal carotid artery, those at a risk of having a stroke or for those who had a stroke previously is carotid endarterectomy (CEA). The gold standard of diagnosis is angiography but it is a invasive procedure, and has an associated 0.1% risk of death and 1% risk of permanent neurological sequelae. Comparatively, Duplex scanning is a non-invasive, accurate and cost effective means of screening for carotid artery stenosis. Nevertheless, concerns have been raised about the accuracy of duplex, as well as interobserver and machine variability. In addition, in the presence of subtotal occlusions, heavily calcified vessels and tandem lesions, it can only play a limited role. This study aimed to validate duplex ultrasound against angiography and to find out whether the combination of angiography and duplex scanning has any change in the clinical management of patients. Methods The patients considered for the study included those with significant internal carotid artery stenosis, and those who were suitable and wished to have CEA. Fully accredited vascular technicians performed all the duplex scans by using the Bluthe criteria. A consultant radiologist reported the angiograms by using the North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria. The sample size included 64 patients with a median patient age range of 70 years with a male to female ratio of 1.5 to 1. These patients were recruited over a two-year period. Of the 64 patients, 2 were asymptomatic, 25 patients had a previous cerebrovascular accident, 28 had a transient ischaemic attack (TIA), and 9 had amaurosis fugax. Results On the basis of angiography findings, 9 (14%) patients did not require surgery, in 11 (17%) patients, insufficient views of the distal vessel were seen on duplex scanning. Extensive disease in three of these patients excluded surgery. One patient had a transient ischaemic attack (TIA) during angiography. Conclusion The benefit of surgery of carotid artery stenosis depends on the rapid and accurate classification of the degree of stenosis. This study pointed out the limitations in performing duplex scanning alone, and the cost factor due to an unnecessary procedure or development of a further stroke because of not doing the right surgery. The study also does not recommended Duplex scanning as the only investigation prior to CEA, and non-invasive carotid imaging techniques like magnetic resonance angiography or CT angiography needs to be also considered. The Utility of Duplex Ultrasound Scanning of the Renal Arteries for Diagnosing Significant Renal Artery Stenosis Olin JW, Marion R. et al., 1995. Annals Of Internal Medicine. June 1995. Volume 122, Issue 11. Pages 833-838. Introduction About 1% to 5% of all cases of hypertension are attributed to renovascular hypertension. The gold standard for detecting renal artery stenosis is arteriography, but the drawbacks are that it is invasive, expensive, improperly assesses the functional significance of the renal artery lesion, and has a chance of inducing contrast-induced acute renal failure or atheromatous embolization to the kidneys. Other tests like intravenous urography, renal scintigraphy, determination of plasma renin activity, and the captopril test have low sensitivity and specificity. Magnetic resonance angiography is expensive and may overestimate the degree of stenosis. Duplex ultrasound scanning of the renal arteries is a non-invasive screening test for renal artery stenosis, and has advantages of providing both anatomical and a functional assessment. The procedure is also unaffected by patient medication, and level of renal function. Methods A total of 102 patients who had both duplex ultrasound scanning of the renal arteries and renal arteriography were included for the study. Of these, 44 were men and 58 were women with a mean age of 63.3 ±13.4 years. 187 arteries were studied. Ninety-eight (96%) patients had atherosclerosis, and 4 (4%) patients had medial fibroplasia of the renal artery. Hypertension that was difficult to control or unexplained azotemia (or both), was present in most of the patients who were studied, thus giving them a 70% pretest likelihood of renovascular disease. A smaller number of patients were evaluated because of associated peripheral vascular disease or abdominal aortic aneurysm (pretest likelihood, approximately 40%). At least two views of the renal artery were included in all renal arteriograms, with a visual examination of the degree of stenosis. Results Duplex ultrasound scanning correctly identified 62 of the 63 arteries with stenosis of less than 60%, and 31 of 32 arteries with 60% to 79% stenosis using arteriography were correctly identified as having 60% to 99% stenosis on duplex ultrasound, whereas 67 of 69 arteries with 80% to 99% stenosis on arteriography were correctly identified as having 60% to 99% stenosis on ultrasound. Duplex ultrasound also correctly identified 22 of 23 arteries with total occlusion on arteriography. When compared with arteriography, duplex ultrasound had an overall sensitivity of 0.98, 0.98 specificity, 0.99 positive predictive value, and 0.97 negative predictive value. Conclusion The noninvasive nature of duplex ultrasound scanning of the renal arteries makes it an ideal screening test. It can also predict the presence or absence of renal artery stenosis with a high degree of accuracy. Read More