Presence Of Complex Plaques Research Articles

Does the degree of coarctation of the aorta influence wall shear stress focal heterogeneity?

The development of atherosclerosis in the aorta is associated with low and oscillatory wall shear stress for normal patients. Moreover, localized differences in wall shear stress heterogeneity have been correlated with the presence of complex plaques in the descending aorta. While it is known that coarctation of the aorta can influence indices of wall shear stress, it is unclear how the degree of narrowing influences resulting patterns. We hypothesized that the degree of coarctation would have a strong influence on focal heterogeneity of wall shear stress. To test this hypothesis, we modeled the fluid dynamics in a patient-specific aorta with varied degrees of coarctation. We first validated a massively parallel computational model against experimental results for the patient geometry and then evaluated local shear stress patterns for a range of degrees of coarctation. Wall shear stress patterns at two cross sectional slices prone to develop atherosclerotic plaques were evaluated. Levels at different focal regions were compared to the conventional measure of average circumferential shear stress to enable localized quantification of coarctation-induced shear stress alteration. We find that the coarctation degree causes highly heterogeneous changes in wall shear stress.

Aortic arch atherosclerosis in patients with severe aortic stenosis can be argued by greater day-by-day blood pressure variability

Background and PurposeAlthough it is well known that the prevalence of aortic arch plaques, one of the risk factors for ischemic stroke, is high in patients with severe aortic stenosis, the underlying mechanisms are not well understood. Increased day-by-day blood pressure (BP) variability is also known to be associated with stroke; however, little is known on the association between day-by-bay BP variability and aortic arch atherosclerosis in patients with aortic stenosis. Our objective was to clarify the association between day-by-day BP variables (average values and variability) and aortic arch atherosclerosis in patients with severe aortic stenosis. MethodsThe study population consisted of 104 consecutive patients (mean age 75 ± 8 years) with severe aortic stenosis who were scheduled for aortic valve replacement. BP was measured in the morning in at least 4 consecutive days (mean 6.8 days) prior to the day of surgery. Large (≥4 mm), ulcerated, or mobile plaques were defined as complex plaques using transesophageal echocardiography. ResultsCigarette smoking and all systolic BP variables were associated with the presence of complex plaques (p < 0.05), whereas diastolic BP variables were not. Multiple regression analysis indicated that day-by-day mean systolic BP and day-by-day systolic BP variability remained independently associated with the presence of complex plaques (p < 0.05) after adjustment for age, male sex, cigarette smoking, hypertension, hypercholesterolemia, and diabetes mellitus. ConclusionsThese findings suggest that higher day-by-day mean systolic BP and day-by-day systolic BP variability are associated with complex plaques in the aortic arch and consequently stroke risk in patients with aortic stenosis.

Complex atheromatous plaques in the descending aorta and the risk of stroke: a systematic review and meta-analysis.

Proximal aortic plaques, especially in the aortic arch, have already been established as an important cause of stroke and peripheral embolism. However, aortic plaques situated in the descending thoracic aorta have recently been postulated as a potential embolic source in patients with cryptogenic cerebral infarction through retrograde aortic flow. The aim of the present study was to evaluate the potential association of descending aorta atheromatosis with cerebral ischemia. We conducted a systematic review and meta-analysis of all available prospective observational studies reporting the prevalence of complex atheromatous plaques in the descending aorta in patients with stroke and in unselected populations undergoing examination with transesophageal echocardiography. We identified 11 eligible studies including a total of 4000 patients (667 patients with stroke and 3333 unselected individuals; mean age, 65 years; 55% men). On baseline transesophageal echocardiograpic examination, the prevalence of complex atheromatous plaques in the descending aorta was higher (P=0.001) in patients with stroke (25.4%; 95% confidence interval, 14.6-40.4%) compared with unselected individuals (6.1%; 95% confidence interval, 3.4-10%). However, no significant difference (P=0.059) in the prevalence of complex atheromatous plaques in the descending aorta was found between patients with cryptogenic (21.8%; 95% confidence interval, 17.5-26.9%) and unclassified (28.3%; 95% confidence interval, 23.9-33.1%) cerebral infarction. Our findings indicate that the presence of complex plaques in the descending aorta is presumably a marker of generalized atherosclerosis and high vascular risk. The present analyses do not provide any further evidence for a direct causal relationship between descending aorta atherosclerosis and cerebral embolism.

Relation of Aortic Arch Complex Plaques to Risk of Cerebral Infarction in Patients With Aortic Stenosis

Aortic stenosis (AS) and systemic atherosclerosis have been shown to be closely related. We evaluated the prevalence of aortic arch plaques and their possible association with the risk of cerebral infarction in patients with severe AS. Transesophageal echocardiography was performed in 116 patients with severe AS (55 men, mean age 71 ± 7 years, mean aortic valve area 0.68 ± 0.15 cm(2)) who were scheduled for aortic valve replacement. The presence, thickness, and morphology of the aortic arch plaques were evaluated using transesophageal echocardiography. Cerebral infarcts (chronic cerebral infarction and cerebral infarction after cardiac catheterization and aortic valve replacement) were assessed in all patients. Compared to age- and gender-matched control subjects, the patients with severe AS had a significantly greater prevalence of aortic arch plaques (74% vs 41%; p <0.0001) and complex arch plaques such as large plaques (≥4 mm), ulcerated plaques, or mobile plaques (30% vs 10%; p = 0.004). Multivariate logistic analyses showed that the presence of complex arch plaques was independently associated with cerebral infarction in patients with AS after adjusting for traditional atherosclerotic risk factors and coronary artery disease (odds ratio 8.46, 95% confidence interval 2.38 to 30.12; p = 0.001). In conclusion, the results from the present study showed that there is a greater prevalence of aortic arch plaques in patients with AS and that the presence of complex plaques is independently associated with cerebral infarction in these patients. Therefore, the identification of complex arch plaques using transesophageal echocardiography is important for risk stratification of cerebrovascular events in patients with severe AS.