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carotid plaque morphology
Plaque morphology, in terms of echogenicity, + plaque surface morphology,
visual evaluation of carotid plaque remains therefore a valuable method in daily clinical practice
assessment of plaque morphology is more important than plaque size as an indicator of prognosis (이성익 교수 논문 첫째)
Intima-Media Thickness
For each subject, the IMTcca was calculated to be the average of the left and right IMTcca. IMTbif was calculated as the average of the thickest point, including plaque, of the left and right carotid bulb origin measurements.
Carotid Plaques
An artery was classified as being affected by plaque if there was a localized thickening .1.2 mm that did not uniformly involve the whole left or right common carotid bifurcation with or without flowdisturbance.1,24 Plaques were identified by the vascular technologistat the time of ultrasound measurement.
IMTcca was positively associated with SBP.
Age is one of the most powerful determinants of IMT, with increases of from 0.01 to 0.02 mm per year,
IMTcca is strongly associated with risk factors for stroke and with prevalent stroke
IMTbif and plaque are more directly associated with ischemic heart disease risk factors and prevalent ischemic heart disease.
Tx: antihypertensives and cholesterol-lowering drugs.
많은 연구들이, Plaque를 IMT 에 포함시켰음. 또는 일정 높이 이상은 Plaque라 정의하고 그 이하는 IMT로.
Many of these studies used an ultrasound scanning protocol that included plaque in the measurement
of the maximum IMT.10,12,30,33 Some investigators dichotomized the IMT measurement above and below a
threshold level of IMT,12,26,30 which has the effect of pooling those subjects with plaques into the higher IMT group since plaques tend to be more common in those with a thicker IMT.2
그래서 따로 측정하는 것이 좋다
Separate characterization of plaque and IMTcca may provide better information to determine disease risk.
* carotid plaques were associated with smokin
It is possible that knowledge of the presence of a presymptomatic plaque may provide added motivation for people to modify lifestyle risk factors and to adhere to any necessary medication.(이성익 교수 논문 2째)
IMT를 치료할 필요는 없다 MOnitor 할 필요도 없다. IMT 이 위험요소라고 의심은 가지만, 아직 risk factor 라고 accepted 되진 않았따. 2004년 논문에서.
IMT측정은, CCA, bulb, the origin of ICA 에서 plaque가 없는 부위를 측정한다. {Manheimm)
Stroke 위험 높은 것
Echolucent
Carotid Plaque Echolucency Increases the Risk of Stroke in Carotid Stenting http://circ.ahajournals.org/content/110/6/756.short
Type 1 uniformly echolucent
Type 2 predominantly echolucent
Type 3 predominantly echogenic
Type 4 uniformly echogenic
Type 5 unclassified owing to heavy calcification
Type 1 plaques were uniformly echolucent, type 2 predominantly echolucent, type 3 predominantly echogenic, type 4 uniformly echogenic and type 5 consisted of plaques that could not be classified owing to heavy calcification and acoustic shadows
http://onlinelibrary.wiley.com/doi/10.1002/bjs.1800801016/abstract
Regression 잘하는 것 : nonencroaching soft plaques. large calcified plaques 은 regression하지 않음.
Plaque classifications
1) flat plaques in the absence of the normal sandwich-like vessel wall structure due to proliferative homogeneous echo-intense material; and
2) soft plaques, such as homogenous or heterogeneous echo-dense tissue compartments encroaching on the vessel lumen without evidence of echo shadows.
The common vascular process consisted of an extended, diffusely distributed, heterogeneous echogenic mass with irregular surfaces distributed in the distal common carotid, proximal internal carotid, and the carotid bifurcation, including the carotid bulb (FigureLA)
As for atherosclerotic plaques in general, we did not observe regression of large calcified plaques. Rather, regression correlated with the initial observation of exclusively nonencroaching soft plaques in our patients.
http://stroke.ahajournals.org/content/22/8/989.full.pdf+html
Plaque size 보다는 plaque composition (morphology) 가 risk factor 와 연관있다.
Atherosclerotic plaque composition appears to be more important than plaque size in determining adverse events [11].
Echo-lucent carotid plaques are lipid-rich and have a greater potential for clinical complications [7,10]. Heterogeneous plaques have a hypoechoic component and are associated with the presence of intra-plaque haemorrhage, ulceration and lipids, more likely to result in adverse events [8,21,22].
heterogeneous: 다른 echogenecity 면적이 20% 이상 차지할 때
Plaques have been characterized as heterogeneous, if the echogenicity of more than 20% of the plaque differed from the echogenicity of the rest of the plaque by two or more echogenicity grades [26].
irregular surface 란 0.4-2mm 높이 차가 날 때
The plaque surface appearance has been defined as irregular when height variations between
0.4 and 2 mm appeared to be present along the contour
of the lesion
심장 동맥 질환이 있는사람이, echo-lucent carotid plaques 이 있으면, 심장 동맥에도 그런 plaque 가 있을 확률이 크고, 따라서 cardiovascular events의 위험이 크다.
Honda et al [10] have demonstrated (using radiofrequency analysis) that echo-lucent carotid plaques predict the presence of complex coronary plaques and the development of future coronary complications in stable coronary artery diseased patients. If carotid and coronary artery plaques share common morphological characteristics within individuals, then the ultrasound of the carotid artery may be a simple, non-invasive test to screen asymptomatic subjects at high risk of cardiovascular events.
2006cardiovascularUltrasoundCarotidplaqueMortality-- 이성익 교수 소장 논문--
A number of investigators have observed that the majority of patients with highly stenotic, atherosclerotic carotid plaques remain asymptomatic. For example, in the Asymptomatic Carotid Atherosclerosis Study (ACAS), unoperated patients with a greater than 60% diameter reducing carotid artery stenosis had only an 11.0% risk for ipsilateral hemispheric stroke at 5 years and a 19.2% 5-year risk for ipsilateral transient ischemic attack or stroke. http://stroke.ahajournals.org/content/28/1/95.short
1. hard plaques (predominantly composed of collagen or calcium)
2. soft plaques (containing atheromatous debris or intraplaque hemorrhage)
Avril et al8 classified carotid plaques as "hard" (predominantly composed of collagen or calcium) or "soft" (containing atheromatous debris or intraplaque hemorrhage). Soft plaques were significantly more common in symptomatic carotid lesions. http://stroke.ahajournals.org/content/28/1/95.short
There was no difference between plaques removed from asymptomatic and symptomatic patients with regard to the presence and volume of fibrous intimal tissue, intraplaque hemorrhage, the lipid core, the necrotic core, or calcification.
http://stroke.ahajournals.org/content/28/1/95.short
Plaque constituents were defined as follows: (1) fibrous intimal tissue: plaque regions rich in collagen bundles (Fig 1a); (2) intraplaque hemorrhage: regions of fibrin deposits and lysed red blood cells with some surrounding inflammatory cell infiltrate (Fig 1b). These areas are in contradistinction to hemorrhage caused by operative manipulation, in which intact red blood cells without surrounding tissue reaction are seen; (3) lipid core: distinct regions containing diffusely distributed clefts from which cholesterol crystals have been extracted (Fig 1c); (4) necrotic core: discrete regions with loosely aggregated necrotic debris, no viable cells, and without admixed collagen (Fig 1d); and (5) calcification: aggregates of prominent calcification, usually of either necrotic cellular debris or collagenous stroma, but devoid of cells (Fig 1e). http://stroke.ahajournals.org/content/28/1/95.short
Characterizing the nature of the fibrous cap that overlies the lipid-rich plaque core may be more productive. For example, a thinned fibrous cap may be more prone to plaque rupture. Defining the surface morphology of the lesion may also be important. In a review of patients enrolled in the North American Carotid Endarterectomy Trial, Eliasziw et al24 found a higher risk for subsequent stroke if angiographic evidence of a plaque ulcer was demonstrated. In unoperated patients with a nonulcerated 85% carotid stenosis, the risk for ipsilateral stroke at 24 months was 21.3% compared with 43.9% in patients with an ulcerated 85% stenosis. In patients with a 95% carotid stenosis, the 2-year risk for ipsilateral stroke was 21.3% in patients without evidence of ulcer and 73.2% in patients with ulcerated lesions.
http://stroke.ahajournals.org/content/28/1/95.full
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혈압을 적극적으로 치료해야 죽상반을 줄일 수 있고...
hypertension may play a more important role with carotid plaque and needs to be reduced confidently to the normal range before carotid plaque is controlled.
Numerous agents have been shown to contribute to reduction of carotid plaque: statin drugs, niacin, fish oil, the anti-diabetic "TZD" drugs (Actos, Avandia), several anti-hypertensive drugs, vitamin E, pomegranate juice, and several others.
http://www.wellsphere.com/heart-health-article/carotid-plaque-can-be-shrunk/393893
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죽상반이 형성되면, 10년 이내에 증상을 일으킨다.
죽상반이 형성된지 이른 시기일 수록 unstable 하다.
we found that the average age of these plaques was less than 10 years.
plaque formation occurs during a relative short and late time span in life (3-5 years). If proven true, the growth of atherosclerotic lesions may be interrupted to prevent clinical manifestation, like TIA and stroke, even in late stages of life, at 60 years of age or possibly later.
plaques with lower age (formed more recently) were found to be more unstable than older plaques and therefore more likely to cause clinical complications.
“The correlation between low plaque age, higher insulin levels and instability is also consistent with our findings of gene activity where younger plaques were characterized with higher activity of genes related to immune responses and oxidative phosphorylation”,
http://www.wellsphere.com/general-medicine-article/carotid-artery-plaques-form-later-in-life-related-to-insulin-levels/1404950
Carotid ultrasound effective alternative to coronary angiography.
physicians might consider using the carotid ultrasound test as an initial screen for CAD in patients with reduced heart pump function and no history of heart attack. If a patient tests positive for plaque buildup in the neck arteries, then it can be followed by angiography of the heart arteries.”
Traditional diagnosis of CAD is through coronary angiography. However, this test is an invasive and expensive catheter imaging procedure that is associated with risks from contrast material and radiation exposure. In the study, patients underwent the noninvasive carotid artery ultrasound to determine the artery’s intima-media thickness (IMT) and presence or absence of plaque. Researchers concluded that carotid artery ultrasound is a valuable screening tool for diagnosing and excluding CAD when a patient has heart muscle weakness without a known cause.
심박출량이 감소한 사람이 CAD가 있는지 screening 하기 위해 angiogram보다 carotid us 가 경제적이고 위험부담이 적다.
http://www.wellsphere.com/general-medicine-article/carotid-ultrasound-effective-alternative-to-coronary-angiography/1151719
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Should Asymptomatic Carotid Artery Stenosis Be Treated?
수술적, 약물치료 에 대한논란은 아직도..
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a person’s total cholesterol level is the most important risk factor for developing the dangerous feature of plaque mentioned above. This indeed supports the claim that by lowering a person’s cholesterol level and hence the risk of the formation of lipid core might reduce his or her risk of the possible clinical events.
http://www.wellsphere.com/heart-health-article/higher-total-cholesterol-may-increase-the-risk-of-plaque-rupture/106158
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MRI identifies high-risk atherosclerosis plaque in blood vessels
MRI를 이용하여 죽상반을 관찰한 동물실험에 의하면, 죽상반이 혈관벽 안에 숨어있거나, 혈관 밖으로 돌출한 것이 더 위험하고, lumen으로 돌출한 죽상반은 상대적으로 덜 위험하다.
plaques that were hidden within the vessel wall and pushing the vessel wall outward instead of occluding the lumen had a very high chance of forming a thrombus; plaques that caused vessel narrowing were almost always stable, which could explain why the most dangerous plaques generally escape detection by x-ray angiography.
http://www.wellsphere.com/general-medicine-article/mri-identifies-high-risk-atherosclerosis-plaque-in-blood-vessels/1126988
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Stenosis
In particular, a non-significant
(<50%) stenosis has been identified by a peak systolic
velocity <125 cm/sec, and a stenosis ≥ 70% by a peak
systolic velocity ≥ 230 cm/sec.
cerebrovascular US 책 p127
Morphologic correltes of plaque integrity
Features implying registance to disruption
* Uniform plaque fibrosis on cross-section
* Circular, regular lumen contour
* Demarcated fibrous cap of uniform thickness:absence of focal erosions or inflamation
Features associated with disruption
*Large plaque with marked stenosis
*Juxtaposed regions of contrasting composition: calcification, lipid pools, fibrosis, cellularity, hematomas
*Lumen irregularities and asymmetiries: thromboses, cavitations
*Focal fibrous cap thinning or defects: erosions and inflammation; neoformation of atherosclerosis within, upon or beneath fibrous caps or at lumen surface.
* Close proximity to fibrous cap or lumen surface of calcification and/or lipid pools
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