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Shear rate specific blood viscosity and shear stress of carotid artery duplex ultrasonography in patients with lacunar infarction.

Jeong SK, Rosenson RS - BMC Neurol (2013)

Bottom Line: All cardiovascular disease (CVD) risk factors including BV values were similar between the two groups.In both common carotid arteries, PS and ED shear stresses were significantly lower in the patients with lacunar infarction than in controls in multivariate models that included age, sex, and other major CVD risk factors.Lacunar infarction was associated with reduced carotid arterial shear stress.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: This study describes a new method for determining site-specific vascular shear stress using dynamic measures of shear rate and blood viscosity (BV) in the carotid arteries, and examines characteristics of carotid arterial shear stress among patients with lacunar infarction.

Methods: Vascular shear stress measurements were conducted in 37 patients (17 lacunar infarction patients and 20 control subjects) using duplex ultrasonography. Vessel wall diameters and velocities were measured in each arterial segment at peak-systolic (PS) and end-diastolic (ED) phases, for calculation of PS/ED shear rates. PS/ED shear stresses [dyne/cm²] were determined with PS/ED shear rates and shear-rate dependent BV values. For comparison, both values of hematocrit-derived BV and BV measurements at 300 s⁻¹ were used for calculation of shear stress.

Results: All cardiovascular disease (CVD) risk factors including BV values were similar between the two groups. In both common carotid arteries, PS and ED shear stresses were significantly lower in the patients with lacunar infarction than in controls in multivariate models that included age, sex, and other major CVD risk factors. PS and ED shear stresses using the shear rate specific BV were 4.5% lower and 7.3% higher than those using the two other BVs, respectively.

Conclusion: Lacunar infarction was associated with reduced carotid arterial shear stress. The use of estimated BV for calculating carotid arterial shear stress provides more accurate assessment of the hemodynamic contribution of shear stress than previous models that have arbitrarily assigned a constant value to this dynamic flow property.

No MeSH data available.


Related in: MedlinePlus

Representative ultrasonographic measurements of right common carotid internal diameters, intima-media thicknesses (IMTs), and blood flow velocities in a control subject (A) and a patient with lacunar infarction (B). Peak-systolic and end-diastolic internal diameters were measured at the segment 1 cm proximal to the beginning portion of carotid bulb, while IMT was measured at the peak of the R wave (end-diastole).
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Figure 1: Representative ultrasonographic measurements of right common carotid internal diameters, intima-media thicknesses (IMTs), and blood flow velocities in a control subject (A) and a patient with lacunar infarction (B). Peak-systolic and end-diastolic internal diameters were measured at the segment 1 cm proximal to the beginning portion of carotid bulb, while IMT was measured at the peak of the R wave (end-diastole).

Mentions: In the present study, internal diameter, maximum centerline velocity, and intima-media thickness (IMT) were measured bilaterally along the common carotid artery (CCA), carotid bulb, and internal carotid artery (ICA), as shown in Figure 1. To calculate site-specific shear rates, diameters and velocities of both CCAs were used [14]. In the patients with lacunar infarction, carotid ultrasonography was performed at least one week after the vascular attack. A higher-frequency 5-to-12 MHz (12 L5) linear transducer (Terason t3000, Teratech, Inc, Burlington, MA) was used with ECG triggering, and all the examinations were performed by a certified neurosonologist (SKJ) who has performed more than 5,000 cases (10,000 carotid arteries) during the past 8 years. Intra-luminal diameters were measured separately at peak-systole (PS) and end-diastole (ED) using two-dimensionally guided continuous M-mode tracings of the intimal-luminal interface of the near and far walls of carotid arterial segments, as reported previously [14]. In all segments, video images of the interfaces between lumen and intima over 5 cardiac cycles were captured, stored, and the diameters were measured from fixed images. The axial resolution of the M-mode system was 0.1 mm.


Shear rate specific blood viscosity and shear stress of carotid artery duplex ultrasonography in patients with lacunar infarction.

Jeong SK, Rosenson RS - BMC Neurol (2013)

Representative ultrasonographic measurements of right common carotid internal diameters, intima-media thicknesses (IMTs), and blood flow velocities in a control subject (A) and a patient with lacunar infarction (B). Peak-systolic and end-diastolic internal diameters were measured at the segment 1 cm proximal to the beginning portion of carotid bulb, while IMT was measured at the peak of the R wave (end-diastole).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3643866&req=5

Figure 1: Representative ultrasonographic measurements of right common carotid internal diameters, intima-media thicknesses (IMTs), and blood flow velocities in a control subject (A) and a patient with lacunar infarction (B). Peak-systolic and end-diastolic internal diameters were measured at the segment 1 cm proximal to the beginning portion of carotid bulb, while IMT was measured at the peak of the R wave (end-diastole).
Mentions: In the present study, internal diameter, maximum centerline velocity, and intima-media thickness (IMT) were measured bilaterally along the common carotid artery (CCA), carotid bulb, and internal carotid artery (ICA), as shown in Figure 1. To calculate site-specific shear rates, diameters and velocities of both CCAs were used [14]. In the patients with lacunar infarction, carotid ultrasonography was performed at least one week after the vascular attack. A higher-frequency 5-to-12 MHz (12 L5) linear transducer (Terason t3000, Teratech, Inc, Burlington, MA) was used with ECG triggering, and all the examinations were performed by a certified neurosonologist (SKJ) who has performed more than 5,000 cases (10,000 carotid arteries) during the past 8 years. Intra-luminal diameters were measured separately at peak-systole (PS) and end-diastole (ED) using two-dimensionally guided continuous M-mode tracings of the intimal-luminal interface of the near and far walls of carotid arterial segments, as reported previously [14]. In all segments, video images of the interfaces between lumen and intima over 5 cardiac cycles were captured, stored, and the diameters were measured from fixed images. The axial resolution of the M-mode system was 0.1 mm.

Bottom Line: All cardiovascular disease (CVD) risk factors including BV values were similar between the two groups.In both common carotid arteries, PS and ED shear stresses were significantly lower in the patients with lacunar infarction than in controls in multivariate models that included age, sex, and other major CVD risk factors.Lacunar infarction was associated with reduced carotid arterial shear stress.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: This study describes a new method for determining site-specific vascular shear stress using dynamic measures of shear rate and blood viscosity (BV) in the carotid arteries, and examines characteristics of carotid arterial shear stress among patients with lacunar infarction.

Methods: Vascular shear stress measurements were conducted in 37 patients (17 lacunar infarction patients and 20 control subjects) using duplex ultrasonography. Vessel wall diameters and velocities were measured in each arterial segment at peak-systolic (PS) and end-diastolic (ED) phases, for calculation of PS/ED shear rates. PS/ED shear stresses [dyne/cm²] were determined with PS/ED shear rates and shear-rate dependent BV values. For comparison, both values of hematocrit-derived BV and BV measurements at 300 s⁻¹ were used for calculation of shear stress.

Results: All cardiovascular disease (CVD) risk factors including BV values were similar between the two groups. In both common carotid arteries, PS and ED shear stresses were significantly lower in the patients with lacunar infarction than in controls in multivariate models that included age, sex, and other major CVD risk factors. PS and ED shear stresses using the shear rate specific BV were 4.5% lower and 7.3% higher than those using the two other BVs, respectively.

Conclusion: Lacunar infarction was associated with reduced carotid arterial shear stress. The use of estimated BV for calculating carotid arterial shear stress provides more accurate assessment of the hemodynamic contribution of shear stress than previous models that have arbitrarily assigned a constant value to this dynamic flow property.

No MeSH data available.


Related in: MedlinePlus