Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The calcium antagonists provide a unique tool to reduce myocardial oxygen demand and prevent increases in coronary vasomotor tone. For patients with Prinzmetal's variant angina, diltiazem, nifedipine and verapamil are extremely effective in preventing episodes of coronary vasospasm and symptoms of ischemia. Unstable angina pectoris is a more complex pathophysiologic syndrome with episodes of ischemia due to increases in coronary vasomotor tone, intermittent platelet aggregation or alterations in the underlying atherosclerotic plaque. Each of the calcium antagonists is effective as monotherapy in decreasing the frequency of angina at rest. Nifedipine is the only calcium antagonist that has been studied in a combination regimen with beta blockers and nitrates for patients with unstable angina, and control of angina is better with the combination regimen than with either form of therapy alone. Although symptoms of myocardial ischemia in unstable angina are reduced by calcium antagonists, these agents do not seem to decrease the incidence of adverse outcomes. Antiplatelet therapy appears to improve morbidity and mortality in patients with unstable angina, suggesting that thrombus formation may play a central role in that disorder. Episodes of silent or asymptomatic myocardial ischemia, identified by ST-segment monitoring, occur in a variety of disorders of coronary disease. Among patients with Prinzmetal's variant angina and unstable angina, episodes of silent ischemia appear to be as frequent as episodes of angina and the calcium antagonists are effective in decreasing episodes of ischemia regardless of the presence or absence of symptoms. Persisting episodes of silent ischemia among patients with unstable angina despite maximal medical therapy identify patients at high risk for an early unfavorable outcome. Among patients with stable exertional angina, episodes of silent ischemia may be up to 5 times as frequent as episodes of angina, and may be due to increases in coronary vasomotor tone, transient platelet aggregation or increases in myocardial oxygen demand. Preliminary experience suggests that calcium antagonists and beta blockers are effective in decreasing episodes of silent ischemia in patients with stable exertional angina and that a combination regimen may be more effective than either form of therapy alone.
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PMID:Calcium antagonists for Prinzmetal's variant angina, unstable angina and silent myocardial ischemia: therapeutic tool and probe for identification of pathophysiologic mechanisms. 354 88

We present preliminary findings on the effectiveness of panretinal photocoagulation in preventing neovascular glaucoma in eyes with radiation-induced ocular ischemia. Our study group consisted of 20 patients who developed radiation-induced ocular ischemia following cobalt-60 plaque radiotherapy for a choroidal or ciliary body melanoma. Eleven of the 20 patients were treated by panretinal photocoagulation shortly after the diagnosis of ocular ischemia, but nine patients were left untreated. In this non-randomized study, the rate of development of neovascular glaucoma was significantly lower (p = 0.024) for the 11 photocoagulated patients than for the nine who were left untreated.
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PMID:Panretinal photocoagulation for radiation-induced ocular ischemia. 365 14

Dynamic, rapid sequence, axial computed tomography (CT) was employed to evaluate the extracranial common and internal carotid arteries in 17 patients with clinical histories suggesting recent or remote ischemia in the territory supplied by the internal carotid artery. The CT findings were correlated with arteriographic observations and with gross and histologic evaluations of endarterectomy specimens. Areas of arterial wall thickening were evaluated on CT scans with regard to both degree of thickening and radiographic density (attenuation). The degree of vessel wall thickening secondary to atheromatous plaque demonstrated on CT scans corresponded closely to the severity of luminal compromise seen on arteriograms. Isodense or mildly hypodense focal mural thickening noted on CT scans of seven endarterectomy specimens proved to be primarily fibrotic (simple) atheromatous plaque on gross and histologic examination. Areas of markedly lucent focal mural thickening on CT scans of 11 specimens all demonstrated varying amounts of subintimal hemorrhage within loosely arranged and rather acellular (complex) atheromatous plaques on pathologic examination. While arteriography provides information regarding the status of the arterial lumen, CT offers the potential of accurate characterization of pathologic changes in the wall of the extracranial carotid arteries in patients with symptoms of cerebral ischemia.
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PMID:Atheromatous extracranial carotid arteries: CT evaluation correlated with arteriography and pathologic examination. 389 77

Atherosclerotic plaques and high grade stenosis in the carotid circulation are responsible for symptoms of cerebral and retinal ischemia. Identification of these lesions by angiography has been the "gold standard" for which the decision of endarterectomy depended. The recent introduction of high resolution carotid ultrasonography has allowed us to compare thirty-seven surgical specimens with the results of preoperative screening with angiography. UCI had a 97% correlation whereas angiography was accurate only 70%. More importantly there were ten negative angiograms in patients with clinically active ulcerative plaque disease. If surgery were based solely on the angiographic appearance of ulcerative plaques or high grade stenosis, then less than half of the patients have received the correct treatment. UCI deserves to be considered the new reference standard.
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PMID:Carotid ultrasonography--the new "gold standard". Surgical and angiographic correlation. 389 35

Atherosclerosis is a progressive and degenerative disease of the artery wall which begins relatively early in life, years if not decades prior to the onset of clinical signs and symptoms. One of the major challenges which face investigators in this field of research is to establish the validity and reliability of noninvasive methods which can detect atherosclerotic plaques before they become severe enough to result in tissue ischemia, and to determine whether or not atherosclerotic lesions can be monitored both in terms of rate and direction over time. Although several methods of direct arterial visualization are available currently, high-resolution B-mode ultrasound imaging appears to have the most advantages. This technique is noninvasive, relatively inexpensive, and can visualize not only lumen contour and configuration, but also the atherosclerotic plaque in the underlying wall. Preliminary experiments in animal models suggest that lesions as small as 0.5 mm in the carotid arteries can be detected using this method. Whether or not atherosclerotic plaques can be monitored over time, however, has not been demonstrated.
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PMID:Noninvasive assessment of atherosclerosis in nonhuman primates. 389 44

It is not unusual to find ischemia of limbs in drug addicts and two new cases are reported, together with a literature review, allowing analysis of physiopathologic mechanisms and therapeutic modalities. The first case was a 20 year old man who presented with sensory-motor ischemia of the right hand after injection of heroin into the radial artery. Arteriography showed partial occlusion of the deep palmar arch and all collateral arteries of fingers. Regression of ischemia followed administration of thrombolytics, heparin and vasodilators, arteriography showing restoration of palmar arch and digital arteries flow apart from that of the 4th finger. The latter developed distal necrosis which required, in spite of thoracic sympathectomy, amputation of the 3rd phalanx. Histology of amputation piece showed presence of intra-arterial foreign bodies. The second case was a 30 year old man who presented with an acute sensory-motor ischemia of left calf and foot after injection of heroin into the retromalleolar groove. Arteriography showed absence of opacification of vascular axes in the middle third of leg and an atheromatous plaque in left main iliac artery. Heparin therapy plus lumbar sympathectomy resulted in reheating of the foot, but ischemia recurred one month later. A repeat arteriography with oblique images demonstrated that the plaque in the main iliac artery was larger than it appeared in frontal images and that an embolus had developed in the deep femoral artery. Final treatment in this patient involved an inter-femoral saphenous vein bypass and amputation of 4th toe. Histology of amputation piece showed only a banal arterial thrombosis without foreign body.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Acute ischemia of the extremities and drug addiction]. 394 20

In patients who present with TIA, RIND, or CVA, the cranial CT scan can rule out other etiologies for neurologic symptoms. In addition to the clinical presentation, the CT scan allows further stratification of patients being considered for carotid endarterectomy. We propose that patients be classified as TIA (+), TIA (-), RIND (+), or CVA (-). The CT scan has defined a new subgroup of patients, TIA (+) and RIND (+)--the Silent Cerebral Infarction. Patients who are categorized as TIA (+), RIND (+), and CVA (+) (cerebral infarction on CT or by history) are at increased risk for intraoperative ischemia and postoperative neurologic deficit. As such, they should be selectively shunted based on intraoperative EEG monitoring or routinely shunted. There is a strong association between ulcerative plaque at the carotid bifurcation and cerebral infarction on CT. The CT scan is a critical diagnostic procedure in evaluating the patient with an acute neurologic event. Patients with negative CT scans are candidates for early operation. Carotid endarterectomy should generally be delayed for 4 to 6 weeks in patients with positive CT scans.
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PMID:The role of cranial computed tomography in carotid surgery. 395

Recent clinical and experimental evidence indicates that coronary artery stenoses may rapidly change their size and shape in response to alterations in vasomotor tone and intraluminal pressure. This theoretical study models a partially compliant arterial stenosis to examine the hemodynamic impact of these alterations. In rigid vessels, a 98% reduction in luminal area would predictably produce subendocardial ischemia in the resting state. In contrast, stenoses, with part of the arterial wall normal by the underlying plaque, responded to vasoconstriction and to changes in intraluminal pressure. With part of the arterial wall normal by the plaque, both vasoconstriction and decreases in intraluminal pressure could increase the hemodynamic severity of the stenosis. Further, the more eccentrically positioned the underlying plaque was, the greater the effects of vasoconstriction and intraluminal pressure on stenotic severity. Thus the morphological configuration of the plaque and the normal wall segment in the stenosis appear to be important determinants of the hemodynamic response of the stenosis to vasoconstriction and blood pressure changes. In turn, these changes in stenotic severity can greatly influence flow through the vessel.
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PMID:A theoretical model of a compliant arterial stenosis. 397 Feb 28

The human abdominal aorta is particularly susceptible to the formation of aneurysms with atrophic walls. This aortic segment normally has fewer medial lamellar units than would be expected for a mammalian aorta of comparable diameter as well as far fewer medial vasa vasorum than would be expected for an aortic wall of comparable thickness. To test the hypothesis that ischemia and/or loss of normal lamellar architecture are predisposing factors for aneurysm formation, we used the pig thoracic aorta, which is furnished with 75 medial layers and vasa supplying the outer two thirds. Vasal blood flow was surgically ablated, and crushing injury was used to reduce the number of intact lamellar units. Mural ischemia alone resulted in necrosis of cells in the medial zone furnished by vasa but did not lead to aneurysmal dilatation, and all the fibrous tissue layers persisted during the 2-month observation period. Mechanical injury resulted in aneurysms in both ischemic and nonischemic aortic segments, but only if fewer than 40 intact lamellae remained and the average tension per lamellar unit exceeded three times the normal value of 1316 +/- 202 dynes/cm (4543 +/- 1624 for ischemic and 4087 +/- 871 for nonischemic segments; p less than 0.01 for each). We conclude that a critical reduction in the number of intact lamellar units results in aneurysmal dilatation. Protracted medial ischemia due to intimal plaque formation in the avascular abdominal aorta may eventually reduce the number of intact lamellae and favor the development of aneurysms.
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PMID:Role of medial lamellar architecture in the pathogenesis of aortic aneurysms. 648 94

Four hundred eighty-eight consecutive carotid endarterectomies were performed on 417 patients. Stroke, as a procedure-related complication, occurred in 12 patients, or 2.4 per cent of cases. Five causes of operative or postoperative stroke were identified: 1) operative embolization, 2) postoperative hypertensive episodes with cerebral hemorrhage, 3) technical error, 4) conversion of ischemic infarct to hemorrhagic infarct, and 5) clamp-time ischemia. The use of several modalities evolved as routine in an effort to reduce mortality and morbidity: 1) minimal manipulation of the artery until after cross clamping to prevent microembolization; 2) routine direct arterial blood pressure monitoring and control during and after surgery; 3) routine operative arteriography to detect and correct technical errors at the time of surgery; 4) liberal use of CAT scans preoperatively to avoid surgery on patients with small, unrecognized infarcts; and 5) stump pressure measurement and selective shunting to prevent ischemia during the endarterectomy. The anatomical-pathological combination of a high bifurcation and high plaque is identified as a high-risk situation.
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PMID:The causes and prevention of stroke associated with carotid artery surgery. 707 27


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