The prevalence of ulcerated plaques in the aortic arch in patients with stroke

High risk for vascular events in patients with protruding aortic atheromas: a prospective study

OBJECTIVES

The purpose of this study was to prospectively evaluate the risk of vascular events in patients with protruding aortic atheromas.

BACKGROUND

Protruding atheromas of the thoracic aorta have been shown to be associated with embolic disease in previous retrospective studies.

METHODS

During a 1-year period, 521 patients had transesophageal echocardiography. Of these, 42 patients had protruding atheromas and no other source of emboli. They were followed up for up to 2 years (mean follow-up 14 months) and compared with a control group without atheromas, matched for age, gender and hypertension.

RESULTS

Of 42 patients with atheromas, 14 (33%) had 19 vascular events during follow-up (5 brain, 2 eye, 4 kidney, 1 bowel, 7 lower extremity). Of 42 control patients, 3 (7%) had vascular events (2 brain, 1 eye). Univariate analysis identified only protruding atheromas as significantly correlating with events (p = 0.003). There was no positive correlation of events with age, gender, hypertension, smoking, family history, atrial fibrillation, valve replacement, antithrombotic drug use, diabetes or coronary disease. Multivariate analysis showed that only protruding atheromas independently predicted events (p = 0.005, odds ratio 4.3, 95% confidence interval 1.2 to 15.0). Nine patients died in the atheroma group versus six in the control group, but this was not statistically significant (p = 0.39).

CONCLUSIONS

Protruding atheromas seen on transesophageal echocardiography predict future vascular events.

Superiority of transesophageal echocardiography in detecting aortic arch atheromatous disease: identification of patients at increased risk of stroke during cardiac surgery

It has been shown that transesophageal echocardiography (TEE) is useful in evaluating atheromatous disease of the aortic arch and that such disease is a risk factor for stroke in medical patients. Data obtained by traditional methods of evaluating the aortic arch prior to cardiac surgery, namely, chest x-ray (CXR) and cardiac catheterization (CATH), were compared with that detected by TEE. Images of the descending thoracic aorta and aortic arch seen on intraoperative TEE in 258 cardiac surgical patients were graded as I = normal, II = intimal thickening or plaques < 5 mm thick or with a mobile component (severe disease). The aortic knob seen on CXR in 209 of these patients was graded as normal, < 1/2 or > or = > 1/2 ring of calcification. Calcification in the aortic root (graded as 0, 1+, 2+) and irregularities in the aortic lumen seen at CATH in 33 patients were also examined. Data were analyzed with respect to age, gender, type of surgery, and stroke. Increasing age correlated strongly with increasing severity of aortic arch and descending thoracic aortic disease seen by TEE. Severe disease was not present in patients under age 50 but was present in about 20% of those over age 70. Atheromatous disease was found by TEE in 55% of patients with a normal CXR and 91% of those with heavily calcified aortic knobs. Ischemic strokes occurred in seven patients. Severe arch disease correlated significantly with stroke (P < .01). Other variables did not correlate with stroke.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid and cellular constituents of unstable human aortic plaques

Unstable plaques are undergoing thrombosis which, in most instances, is due to fissuring and rupture of the plaque cap. This process (deep intimal injury) is a complication of plaques with a lipid-rich core. The cap tear allows blood to enter the core from the lumen, leading initially to intraplaque thrombosis and, subsequently, in some cases intraluminal thrombosis. Cap tears reflect the interplay between the force exerted on the tissue and its inherent mechanical strength. Factors which elevate and concentrate circumferential wall stress on the cap during systole include an increasing proportion of the total plaque volume occupied by the lipid core, thinning of the cap and a loss of internal collagen struts within the core. Factors which lead to an inherent reduction in the mechanical strength of cap tissue include a reduction in collagen and glycosaminoglycan concentrations, an increase in the number and density of macrophages, and a concomitant reduction in smooth muscle cells in the cap tissue. It is therefore possible to define a vulnerable plaque as one in which the lipid core is disproportionately large, the cap thin, and in which monocytes preponderate over smooth muscle cells.

The use of expected value as an aid to decisions regarding anticoagulation in patients with atrial fibrillation

BACKGROUND

The method described provides a rational means for determining whether to institute chronic anticoagulation to prevent stroke in patients with chronic atrial fibrillation under a variety of clinical circumstances.

SUMMARY OF COMMENT

The concept of expected value is used in conjunction with data from clinical studies to define the net value of anticoagulation to the patient. A full year of anticoagulation is warranted in patients with recent stroke or transient ischemic attack thought to be due to cardiogenic embolism who feel that stroke is a very serious event with nearly as much disvalue as death. If stroke has a lesser degree of negative value to the patient, or it is uncertain whether the stroke was in a large-vessel distribution, or it is uncertain whether a large-vessel distribution stroke was due to cardiogenic embolism, 6 months or less of anticoagulation may be warranted. Indefinite anticoagulation is justifiable in most patients with chronic atrial fibrillation without a history of stroke or transient ischemic attack but may be contraindicated in certain patients at extremely low risk for embolism and in patients who place a low value on stroke relative to death and who have a modest increase in risk for fatal hemorrhage.

CONCLUSIONS

The method described provides a means readily usable by clinicians to make anticoagulation decisions in patients with chronic atrial fibrillation that will address risk-benefit tradeoffs with somewhat greater precision than current approaches.

Transoesophageal echocardiography in the investigation of stroke: experience in 135 patients with cerebral ischaemic events

BACKGROUND

The importance of cardiogenic embolism as a cause of cerebral ischaemic events may be underestimated if potential cardiac sources of embolism remain undetected. Transoesophageal echocardiography (TOE) is more sensitive in detecting such abnormalities than earlier methods and may result in more frequent recognition of cardiogenic embolism.

AIMS

To establish in an unselected stroke population the prevalence of potential cardiac sources of embolism detectable on TOE and their relationship to atrial fibrillation and carotid stenosis.

METHODS

One hundred and thirty-five consecutive patients with cerebral ischaemic events were studied using transthoracic and monoplane transoesophageal contrast echocardiography and carotid Duplex imaging or cerebral angiography.

RESULTS

Thirty patients (22%) had atrial fibrillation. In 43 patients (32%), no cardiac source of embolism was identified; in eight echocardiography was normal. At least one potential cardiac source of embolism was identified in 92 patients (68%) with multiple findings in 41; these patients were older (70 +/- 9 years vs 61 +/- 14 years; p = 0.0001), more frequently in atrial fibrillation (28/92 vs 2/43; p = 0.0017) and more frequently had cortical or large subcortical stroke (71/92 vs 23/43; p = 0.005). Carotid stenoses were detected in 55% of patients, not significantly different in those with and without cardiac abnormalities.

CONCLUSION

When bias in selection of patients is avoided, TOE detects a potential cardiac source of embolism in most patients with cerebral ischaemia, particularly those older and in atrial fibrillation. Multiple cardiac abnormalities and coexistent carotid disease are common. The implication of these findings for prevention of stroke awaits age-matched controlled studies.

Impact of transesophageal echocardiography on the anticoagulation management of patients admitted with focal cerebral ischemia

Transesophageal echocardiography (TEE) improves the diagnostic accuracy of transthoracic echocardiography in the identification of potential cardiac sources of embolus. However, there are few studies of the impact of TEE on the medical management of patients with focal cerebral ischemia. The records of 52 consecutive, hospitalized patients undergoing both TEE and transthoracic echocardiography for suspected cardiac source of embolus were reviewed to determine the influence of TEE on the decision to anticoagulate patients. Of 52 patients, 39 had focal cerebral ischemia (transient ischemic attack, n = 9; acute cerebral infarction, n = 30). In 4 of these 39 patients (10%), the TEE results changed the management of anticoagulation. In 19 of 39 patients (49%), the TEE results helped confirm anticoagulation decisions, and in 16 (41%), the results had no effect on anticoagulation decisions, because of overriding clinical information. Ten of the latter 16 patients had TEE evidence for a possible source of an embolus, but were not anticoagulated; 5 of these were poor candidates for long-term anticoagulation, and the others had right-to-left shunting across a patent foramen ovale or an interatrial septal aneurysm. Clinical variables (atrial fibrillation, TEE findings and pre-TEE anticoagulation status) were considered as possible predictors of post-TEE anticoagulation status using logistic regression analysis; the strongest predictor of post-TEE anticoagulation status was pre-TEE anticoagulation status (p < 0.0005). Despite the selection of patients presumed to receive maximal benefit from TEE, this study suggests that TEE findings are not predictive of subsequent anticoagulation management. However, TEE is at least confirmatory of anticoagulation decisions in most cases.

Protruding atheromas in the thoracic aorta: a newly recognized source of cerebral and systemic embolization

Up to 40% of stroke patients do not have an obvious etiology for their illness. Because transthoracic echocardiography is often negative in these patients, there has been increasing enthusiasm for transesophageal echocardiography (TEE) as a newer tool for evaluating patients with embolic disease. In a study of patients referred because of unexplained stroke or transient ischemic attacks, the most common finding was protruding atheroma in the aortic arch. In a case control study, protruding aortic atheromas were found in 33 of the 122 patients with emboli (27%). Mobile components to the atheromas were found in 11 case patients, and there were no mobile components found in any control patients. It is also possible that protruding aortic atheromas may play a role in patients with other sources of emboli (e.g., carotid disease). Atheromas may also cause emboli during catheterization, balloon pump placement, and cardiopulmonary bypass. The pathological composition of the lesions seen on TEE has been atheroma with superimposed thrombus. The correct treatment for patients with embolization due to protruding aortic atheromas has not yet been determined, although anticoagulation may play a role, since the mobile components to these lesions appear to be thrombus. We have recommended surgery for several patients. However, the operation is a major one with major potential complications, including aortic dissection. TEE should be done in patients with unexplained emboli, and it may also play a role in patients with other sources of embolization. TEE should be considered in elderly patients or those with extensive vascular disease before cardiac catheterization or heart surgery. In addition, cannulation techniques during bypass can be modified to avoid atheromas. The ideal medical and/or surgical approaches to patients with protruding atheromas remain to be clarified.

Transesophageal echocardiography as a tool in the evaluation of patients with embolic disorders

TEE has become one of the most powerful tools for evaluating patients with unexplained stroke, TIA, and peripheral and pulmonary embolization. This is especially encouraging in view of the previously disappointing results of TTE in these patients. In addition to the dramatic results in terms of clot visualization and the other intracardiac sources of embolization described previously, a new extracardiac source has been identified, namely protruding atheromas in the thoracic aorta. These atheromas have been seen for the first time because of the new diagnostic window that has been opened by the development of TEE. Their recognition and follow-up may lead to information that will change the approach to a significant number of patients with embolic ischemic episodes.

Risk of thrombosis in human atherosclerotic plaques: role of extracellular lipid, macrophage, and smooth muscle cell content

OBJECTIVE

To assess the size of the lipid pool and the number of smooth muscle cells and monocyte/macrophages in human aortic plaques that were intact and to compare the results with those in aortic plaques undergoing ulceration and thrombosis.

DESIGN

The lipid pool was measured as a percentage of the total cross sectional area of the plaque. Immunohistochemistry was used to identify cell types (monocytes/macrophages (M phi) by EBM11 and HAM56, smooth muscle cells by alpha actin). The area of the tissue occupied by each cell type was measured by quantitative microscopy in the peripheral (shoulder) area of the plaque and the plaque cap. Absolute counts of each cell type were expressed as the ratio of SMC:M phi.

MATERIAL

Aortas were obtained at necropsy from men aged less than 69 years who died suddenly (within 6 hours of the onset of symptoms) of ischaemic heart disease. 155 plaques from 13 aortas were studied. Four aortas showed intact plaques only (group A, n = 31). Nine aortas showed both intact plaques (group B, n = 79) and plaques that were undergoing thrombosis (group C, n = 45).

RESULTS

In 41 (91.1%) of the 45 plaques undergoing thrombosis (group C) lipid pools occupied more than 40% of the cross sectional area of the plaque. Only 12 (10.9%) of the 110 intact plaques (groups A + B) had lipid pools of this size. The mean size of the lipid pool in plaques of groups A, B, and C was 12.7%, 27.3% and 56.7% respectively. Compared with intact plaques those undergoing thrombosis contained a smaller volume of smooth muscle cells (2.8% v 11.8%) and a larger volume of monocyte/macrophages (13.7% v 2.9%) in the plaque cap. The ratio of the number of smooth muscle cells to monocytes/macrophages was 7.8 in group A plaques, 4.1 in group B plaques, and 1.0 in group C plaques. This gradient was the result of an absolute increase in monocyte/macrophages and an absolute decrease in smooth muscle cells.

CONCLUSIONS

In the aorta ulceration and thrombosis were characteristic of plaques with a high proportion of their volume occupied by extracellular lipid, and in which there was a shift toward a preponderance of monocyte/macrophages compared with smooth muscle cells in the cap.

Coagulation abnormalities and cerebral infarction

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Abnormalities of hemostasis in ischemic stroke

Despite important new diagnostic laboratory and imaging technologies, the cause of brain infarction remains unexplained in 20% to 40% of subjects. Most stroke patients do not require extensive evaluations of coagulation, but hypercoagulability may account for a significant proportion of unexplained strokes. Hemostatic abnormalities associated with stroke may be broadly classified as familial or acquired. Principal among the familial thrombotic coagulopathies are deficiencies in concentration or function in protein-C, protein-S, and antithrombin III, but other hereditary abnormalities include sickle cell disease, homocystinuria, and dysfibrinogenemia. The acquired disorders of hemostasis associated with stroke probably constitute a larger proportion of the important stroke-related coagulopathies. In particular, the aPL antibody syndrome is now strongly associated with thrombotic events including stroke, although neither the mechanism of thrombosis nor effective therapies for this syndrome have been clearly elucidated. Many of the acquired hemostatic abnormalities exist within a special clinical setting such as with malignancy or with myeloproliferative diseases, nephrotic syndrome, and liver disease. Presumably many of these share common pathways of coagulation activation or dysfunction with the inherited disorders. Most of the hemostatic disorders in stroke are associated with dysfunction of vascular endothelium and abnormalities of or interference with the natural anticoagulant proteins: protein-C, protein-S, and antithrombin III. Improved understanding of these relationships should lead to better diagnosis and treatment for people at risk of stroke.

Combined carotid and coronary revascularization: the preferred approach to the severe vasculopath

The timing of carotid endarterectomy (CEA) and coronary revascularization (CABG) for concomitant disease is controversial. Results of combined CEA/CABG in 127 patients (age range, 46 to 82 years; mean age, 65 years; 61% male) from 1978 to 1991 were reviewed. Ninety-five patients (75%) were in New York Heart Association functional class III or IV, 48 (38%) had left main coronary artery disease, and 32 (28%) had depressed ejection fraction ( < 0.50). Forty (32%) had asymptomatic bruits, 61 (48%) transient ischemic attacks, and 26 (20%) prior strokes. Seventy-five (59%) had bilateral carotid stenosis, including 20 (16%) with contralateral occlusions. Perioperative mortality was 7 of 127 (5.5%), and all deaths were cardiac related. Myocardial infarctions occurred in 6 of 127 patients (4.7%) and were nonfatal in 3 (2.3%). Permanent strokes occurred in 7 of 127 (5.5%) and were ipsilateral in 5 (3.9%). Perioperative stroke did not occur in the asymptomatic group, but the risk was higher in those with prior stroke (19%) or with contralateral carotid occlusion (15%). The stroke risk for our patients with carotid disease having CABG without CEA is not known, but the literature reports rates as high as 14%. For our patients without known concomitant disease, the risk of permanent stroke was 1.0% (31/3012) for isolated CABG and 1.5% (7/482) for isolated CEA. The late results after CEA/CABG revealed a 5-year survival of 70% +/- 5%, which correlated with ejection fraction ( > or = 0.50, 81% +/- 5%; < 0.50, 45% +/- 11%; p < 0.003). Freedom from late permanent ipsilateral stroke was 97% +/- 2% at 8 years. Freedom from stroke at 5 years was lower among patients with a previous stroke (71% +/- 10%) compared with transiently symptomatic (90% +/- 4%) and asymptomatic (96% +/- 4%) patients (p < 0.03). Combined CEA/CABG is a useful option in this high-risk group of patients with extensive atherosclerosis; avoids a subsequent hospitalization, anesthetic, and delay period; and provides long-term protection from ipsilateral stroke.

Diagnostic pitfalls in transesophageal echocardiography

The technology of transesophageal echocardiography is now widely available and has proved extremely useful in evaluating cardiovascular anatomy and pathology. Unfortunately, the enhanced echocardiographic detail and multiple transesophageal imaging planes may sometimes be confusing and cause misinterpretations. The majority of these problems are simply the result of operator inexperience. To help prevent misdiagnoses, we have collected a series of the more common diagnostic and technical "pitfalls" of transesophageal echocardiography.

Transesophageal echocardiographic detection of aortic arch disease in patients with cerebral infarction

BACKGROUND AND PURPOSE

Ulcerated plaques in the aortic arch are frequent autopsy findings in patients with cerebral infarctions, particularly those of unknown cause. It has been suggested that they could be a source of cerebral emboli. Using transesophageal echocardiography, we prospectively studied 12 consecutive patients with cerebral infarction of undetermined cause after noninvasive workup to evaluate the frequency of aortic plaques or mural thrombi that could embolize in cerebral arteries.

SUMMARY OF REVIEW

Six patients (50%) had an intraluminal echogenic mass of the aortic arch, mainly located at the junction of the ascending aorta and arch. This material was pedunculated (in one patient) or broad based (in five patients) with a markedly irregular surface and intraluminal extension from 3 to 15 mm. In addition, we found cholesterol emboli in two of the four patients who underwent quadriceps biopsy.

CONCLUSIONS

These results show that transesophageal echocardiography has capabilities in detecting such lesions and point to the aortic arch as a possible source of cerebral emboli in patients with cerebral infarction of unknown cause.