Ultrasound Diagnosis of Carotid Artery Stiffness in Patients with Ischemic Leukoaraiosis

Turk, Monika; Oblak, Janja Pretnar; Zupan, Matija; Žvan, Bojana; Zaletel, Marjan

doi:10.1016/j.ultrasmedbio.2014.08.002

Cited by 10 publications

(14 citation statements)

References 35 publications

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“…What is particularly unique about the current study is that it involves pre-carotid endarterectomy surgical patients, including those patients with unstable plaques. Given that arterial stiffness has previously been associated with an increased amount of white matter changes, we extended this examination to include patients with unstable plaques and significant degrees of stenosis ( Turk, 2015 ). Turk et al propose that stiffness of the carotid may be a better, more sensitive indicator of vascular mediated white matter disease than aortic stiffness, which at present, is considered the gold standard for large arterial stiffness measurements.…”

Section: Discussionmentioning

confidence: 99%

“…Arterial stiffness measurements have recently been shown to correlate with increased white matter changes in the brain. In a comparative study of patients (average age 53.2) with and without ischemic leukoaraiosis, patients with increased white matter disease had higher strain and pulse wave velocity measurements in the carotid artery ( Turk, 2015 ). In that study, however, patients with unstable carotid plaques or greater than 50% stenosis were excluded ( Turk, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

“…In a comparative study of patients (average age 53.2) with and without ischemic leukoaraiosis, patients with increased white matter disease had higher strain and pulse wave velocity measurements in the carotid artery ( Turk, 2015 ). In that study, however, patients with unstable carotid plaques or greater than 50% stenosis were excluded ( Turk, 2015 ). Since unstable plaques are believed to embolize at a higher rate than more stable plaques, we sought to determine how plaque stability is associated with WMH lesion volume in a sample of patients scheduled to undergo carotid endarterectomy for treatment of their carotid vascular disease.…”

Section: Introductionmentioning

confidence: 99%

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The relationship between carotid artery plaque stability and white matter ischemic injury

Berman

Wang

Mitchell

et al. 2015

NeuroImage: Clinical

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Higher local carotid artery strain has previously been shown to be a characteristic of unstable carotid plaques. These plaques may be characterized by microvascular changes that predispose to intraplaque hemorrhage, increasing the likelihood of embolization. Little is known however, about how these strain indices correspond with imaging markers of brain health and metrics of brain structure. White matter hyperintensities (WMHs), which are bright regions seen on T2-weighted brain MRI imaging, are postulated to result from cumulative ischemic vascular injury. Consequently, we hypothesized that plaques that are more prone to microvascular changes and embolization, represented by higher strain indices on ultrasound, would be associated with an increased amount of WMH lesion volume. This relationship would suggest not only emboli as a cause for the brain degenerative changes, but more importantly, a common microvascular etiology for large and small vessel contributions to this process. Subjects scheduled to undergo a carotid endarterectomy were recruited from a neurosurgery clinic. Prior to surgery, participating subjects underwent both ultrasound strain imaging and brain MRI scans as part of a larger clinical study on vascular health and cognition. A linear regression found that maximum absolute strain and peak to peak strain in the surgical side carotid artery were predictive of WMH burden. Furthermore, the occurrence of microembolic signals monitored using transcranial Doppler (TCD) ultrasound examinations also correlated with increasing lesion burden. It is becoming increasingly recognized that cognitive decline is often multifactorial in nature. One contributing extra-brain factor may be changes in the microvasculature that produce unstable carotid artery plaques. In this study, we have shown that higher strain indices in carotid artery plaques are significantly associated with an increased WMH burden, a marker of vascular mediated brain damage.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The relationship between carotid artery plaque stability and white matter ischemic injury

Berman

Wang

Mitchell

et al. 2015

NeuroImage: Clinical

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“…No such in vivo test has been specifically developed to provide insight into cerebrovascular function, physiology, and risk, but it is conceivable that ICA shear-mediated dilation may provide a window on the health of the cerebrovascular endothelium. Indeed, there is a positive association between greater arterial stiffness and microvascular brain disease and cognitive impairment, [40][41][42] and a lower ICA dilation in response to a standardized, shear-mediated stimulus may therefore provide a useful marker of cerebrovascular function and future risk. Future studies will be necessary to test this proposal.…”

Section: Sex Differencesmentioning

confidence: 99%

Evidence for Shear Stress–Mediated Dilation of the Internal Carotid Artery in Humans

et al. 2016

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S mall cerebral arteries and arterioles (eg, pial vessels) respond rapidly to changes in their metabolic milieu and are highly sensitive to the partial pressure of arterial carbon dioxide (PaCO 2 ).1 Vasomotor responsiveness to PaCO 2 , termed CO 2 reactivity, is integral to stabilizing blood pH levels, and previous studies have associated lower CO 2 reactivity to increased cardiovascular and all-cause mortality.2 Recent magnetic resonance imaging studies in humans have revealed that vasomotor changes also occur in the middle cerebral artery (MCA) 3-5 and basilar artery 6 across the hypo-and hypercapnic range. These studies demonstrate the involvement of larger cerebral arteries in the PaCO 2 reactivity response, 7 findings consistent with well-controlled, animal studies. 8 Other recent studies using Duplex ultrasound have investigated extracranial artery responses during hypo-and hypercapnia.9,10 These studies provide direct evidence that changes in end-tidal CO 2 (PETCO 2 ) are associated with directionally similar, and dosedependent, changes in internal carotid artery (ICA) diameter. The mechanism(s), however, mediating these changes in extracranial ICA diameter remain unclear.Significant and rapid changes in extracranial artery blood flow occur across the hypo-and hypercapnic range. [9][10][11] In peripheral conduits such as the radial and brachial arteries, such changes in flow and attendant arterial shear stress represent potent vasoactive stimuli.12,13 Although Pohl et al 14 and Rubanyi et al 15 were the first to identify that flow-mediated dilation (FMD) is endothelium dependent, it is now well established that this phenomenon occurs in humans and that NO plays a significant role. [16][17][18][19] The widely used FMD test 13 relies on dilation of small arteries and arterioles in the limbs, as a consequence of cuff-induced ischemia, to induce an increase in upstream conduit artery shear stress and dilation. In the context of these studies, it is conceivable that rapid and profound dilation of intracranial vessels in response to hypercapnia induces extracranial (ICA) dilation as a consequence of increased shear stress. The aim of this study was to identify whether hypercapnia induces shear-mediated dilation in the carotid arteries. Using high-resolution Duplex ultrasound combined with novel, edge-detection software, we assessed simultaneous common Abstract-Increases in arterial carbon dioxide tension (hypercapnia) elicit potent vasodilation of cerebral arterioles. Recent studies have also reported vasodilation of the internal carotid artery during hypercapnia, but the mechanism(s) mediating this extracranial vasoreactivity are unknown. Hypercapnia increases carotid shear stress, a known stimulus to vasodilation in other conduit arteries. To explore the hypothesis that shear stress contributes to hypercapnic internal carotid dilation in humans, temporal changes in internal and common carotid shear rate and diameter, along with changes in middle cerebral artery velocity, were simultaneously assessed in 18 su...

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“…In our previously published studies, we found increased carotid stiffness and diminished flow through the ICAs in patients with ILA compared to CVD risk factor-matched controls. 22 , 23 The combination of stiff large arteries with loss of the Windkessel effect and lower cerebral blood flow (CBF) could synergically cause insufficient diastolic perfusion in the deep white matter region and cause ILA. In this case, the ratio between local carotid stiffness parameters and CBF could be used as a diagnostic index of ILA.…”

Section: Introductionmentioning

confidence: 99%

Ratio between carotid artery stiffness and blood flow – a new ultrasound index of ischemic leukoaraiosis

Turk¹,

Zaletel²,

Oblak³

2016

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BackgroundIschemic leukoaraiosis (ILA) is associated with cognitive decline and aging. Its pathophysiology is believed to be ischemic in origin due to its association with cerebrovascular risk factors and similarity in location to lacunar infarctions. ILA diagnosis is still based on magnetic resonance imaging (MRI) as well as exclusion of other causes of white matter hyperintensities. So far, there are no known confirming diagnostic tests of ILA. Ultrasound studies have recently shown increased large artery stiffness, increased cerebrovascular resistance, and lower cerebral blood flow in patients with ILA. Increased arterial stiffness and decreased blood flow could have a synergistic effect, and their ratio could be a useful diagnostic index of ILA.MethodsIn this post hoc analysis, we introduced new ILA indices (ILAi) that are ratios of the carotid stiffness parameters (pulse wave velocity beta [PWVβ], pressure–strain elasticity modulus [Ep], β index), and diastolic and mean blood flows in the internal carotid artery: Q-ICAd and Q-ICAm. We compared the ILAi of 52 patients with ILA and 44 sex- and risk factor-matched controls with normal MRI of the head. ILA diagnosis was based on MRI and exclusion of other causes of white matter hyperintensities. The diagnostic significance of ILAi for the prediction of ILA was analyzed.ResultsAll ILAi significantly differed between the groups; the most significant were PWVβ/Q-ICAd (ILA group: 1.96±0.64 vs control group: 1.56±0.40, P=0.001) and PWVβ/Q-ICAm (ILA group: 1.13±0.32 vs control group: 0.94±0.25, P=0.003). All ILAi were significantly associated with ILA (P<0.01) and were significant independent predictors of ILA. All ILAi were also sensitive and specific for predicting ILA (area under the curve: 0.632–0.683, P<0.05).ConclusionThe new ultrasound indices significantly differed between patients with ILA and the control group and were significant predictors of ILA. A combination of lower carotid blood flow and increased carotid stiffness represented as ILAi probably has a diagnostic value in patients with ILA.

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Ultrasound Diagnosis of Carotid Artery Stiffness in Patients with Ischemic Leukoaraiosis

Cited by 10 publications

References 35 publications

The relationship between carotid artery plaque stability and white matter ischemic injury

The relationship between carotid artery plaque stability and white matter ischemic injury

Evidence for Shear Stress–Mediated Dilation of the Internal Carotid Artery in Humans

Ratio between carotid artery stiffness and blood flow – a new ultrasound index of ischemic leukoaraiosis

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Ultrasound Diagnosis of Carotid Artery Stiffness in Patients with Ischemic Leukoaraiosis

Cited by 10 publications

References 35 publications

The relationship between carotid artery plaque stability and white matter ischemic injury

The relationship between carotid artery plaque stability and white matter ischemic injury

Evidence for Shear Stress–Mediated Dilation of the Internal Carotid Artery in Humans

Ratio between carotid artery stiffness and blood flow &ndash; a new ultrasound index of ischemic leukoaraiosis

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Ratio between carotid artery stiffness and blood flow – a new ultrasound index of ischemic leukoaraiosis