PURPOSE: Lacunar stroke, in the context of small vessel disease, is a type of cerebral infarction caused by occlusion of a penetrating artery. Pulsatility index (PI) is an easily measurable parameter in Transcranial Doppler ultrasound (TCD) study. PI reflects distal cerebral vascular resistance and has been interpreted as a surrogate marker of small vessel disease. We hypothesized that an increased PI, a marker of small vessel disease, might be associated with a larger infarct volume in acute lacunar stroke. MATERIALS AND METHODS: This study included 64 patients with acute lacunar stroke who underwent TCD and brain MRI. We evaluated the association between the mean PI value of bilateral middle cerebral arteries and infarct volume on diffusion-weighted MRI using univariate and multivariate linear regression. RESULTS: The mean infarct volume and PI were 482.18±406.40 mm3 and 0.86±0.18, respectively. On univariate linear regression, there was a significant positive association between PI and infarct volume (p=0.001). In the multivariate model, a single standard deviation increase of PI (per 0.18) was associated with an increase of 139.05 mm3 in infarct volume (95% confidence interval, 21.25 to 256.85; p=0.022). CONCLUSION: We demonstrated that PI was an independent determinant of infarct volume in acute lacunar stroke. The PI value measured in acute stroke may be a surrogate marker of the extent of ischemic injury.
Aged ; Cerebral Infarction/*diagnostic imaging/*physiopathology ; *Diffusion Magnetic Resonance Imaging ; Female ; Humans ; Linear Models ; Male ; Middle Aged ; Middle Cerebral Artery ; Pulsatile Flow/physiology ; Retrospective Studies ; Stroke, Lacunar/*diagnostic imaging/*physiopathology ; *Ultrasonography, Doppler, Transcranial ; Vascular Resistance/physiology

Aged ; Atherosclerosis ; Case-Control Studies ; Coronary Artery Bypass ; methods ; Coronary Artery Disease ; surgery ; Female ; Hemodynamics ; physiology ; Humans ; Male ; Mammary Arteries ; physiology ; transplantation ; Middle Aged ; Pulsatile Flow ; Radial Artery ; physiology ; transplantation ; Rheology ; Saphenous Vein ; physiology ; transplantation ; Shear Strength ; Stress, Mechanical ; Vascular Patency ; physiology

Computational fluid dynamics (CFD) technology has the potential to simulate normal or pathologic aortic blood flow changes of mechanical properties and flow field, thereby helping researchers understand and reveal the occurrence, development and prognosis of aortic disease. In aortic diseases research, the initial conditions of CFD numerical simulation has experienced a developed process from idealization (forward engineering), rigid vessel wall, uniform cross-sections, laminar flow and stable blood flow towards personalization (reverse engineering), elastic vessel wall (fluid-solid coupling technique), cone-shaped diminishing cross-sections, turbulent flow, pulsatile blood flow. In this review, the research status, the technical superiority and application prospect of CFD technology were discussed with examples in following three major application areas: (1) dynamics characteristic and mechanical properties in normal thoracic aorta; (2) occurrence, advance and disruptive risk predicting in thoracic aortic aneurysm; (3) therapeutic effect and aneurysmal dilatation simulation in thoracic aortic dissection. For the future, the CFD technology may profoundly put an influence on the awareness to aortic diseases and treatment strategies.
Aorta ; pathology ; physiology ; Aortic Aneurysm, Thoracic ; physiopathology ; Computer Simulation ; Dilatation ; Hemodynamics ; Humans ; Pulsatile Flow ; Regional Blood Flow

Quantitative measurement of strain distribution of arterial vessel walls due to pulsatile blood flow within the vascular lumen is valuable for evaluating the elasticity of arterial wall and predicting the evolution of plaques. The present paper shows that the three-dimensional (3D) strain distribution are estimated through uni-directional coupling for 3D vessel and blood models reconstructed from intravascular ultrasound (IVUS) images with the computational. fluid dynamics (CFD) numerical simulation technique. The morphology of vessel wall and plaques as well as strain distribution can be visually displayed with pseudo-color coding.
Arteries ; diagnostic imaging ; physiology ; Elasticity ; Hemodynamics ; Humans ; Imaging, Three-Dimensional ; Pulsatile Flow ; Ultrasonography

The aim of this study was to determine the normal value of brachial-ankle pulse wave velocity (baPWV) and carotid-femoral pulse wave velocity (cfPWV) according to age group, gender, and the presence of cardiovascular risk factors in healthy Koreans, and to investigate the association between PWV and risk factors such as prehypertension, dyslipidemia, smoking, and obesity. We measured an arterial stiffness in 110 normal subjects who were 20 to 69 yr-old with no evidence of cardiovascular disease, cerebrovascular accident or diabetes mellitus. The mean values of baPWV and cfPWV were 12.6 (+/-2.27) m/sec (13.1+/-1.85 in men, 12.1+/-2.51 in women; P=0.019) and 8.70 (+/-1.99) m/sec (9.34+/-2.13 in men, 8.15+/-1.69 in women; P=0.001), respectively. The distribution of baPWV (P<0.001) and cfPWV (P=0.006) by age group and gender showed an increase in the mean value with age. Men had higher baPWV and cfPWV than women (P<0.001). There was a difference in baPWV and cfPWV by age group on prehypertension, dyslipidemia, current smoking, or obesity (P<0.001). In multiple linear regression, age and prehypertension were highly associated with baPWV and cfPWV after adjustment for confounding factors (P<0.001). The present study showed that baPWV and cfPWV are associated with age, gender, and prehypertension in healthy Koreans.
Adult ; Age Factors ; Aged ; *Ankle Brachial Index ; Blood Pressure ; Brachial Artery/*physiology ; Cardiovascular Diseases/diagnosis/etiology/physiopathology ; Carotid Arteries/*physiology ; Female ; Femoral Artery/*physiology ; Humans ; Male ; Middle Aged ; Obesity/physiopathology ; Prehypertension/physiopathology ; Pulsatile Flow ; *Pulse Wave Analysis ; Republic of Korea ; Risk Factors ; Sex Factors ; Smoking ; Vascular Stiffness/physiology

PURPOSE: To evaluate orbital blood flow velocities and optic nerve diameter with Doppler and gray-scale sonography in patients with acute unilateral optic neuritis (ON). METHODS: Orbital Doppler and gray-scale sonography was performed in 46 eyes of 23 patients aged 19- to 47-years with acute unilateral ON. ON was diagnosed by an ophthalmologist on the basis of clinical presentation, presence of decreased visual acuity and assessment of visual evoked potentials. The peak systolic velocity (PSV) and end-diastolic velocity (EDV), as well as the resistance index (RI) and pulsatile index (PI) of the ophthalmic artery (OA), central retinal artery (CRA), posterior ciliary arteries (PCAs) and optic nerve diameter were measured in both eyes. We compared results from affected and unaffected eyes using the paired t-test. The area under the receiver operating characteristic (ROC) curves was used to assess the diagnosis of ON based on measured blood flow parameters of the OA, CRA and PCAs and optic nerve diameter. RESULTS: The mean (standard deviation) optic nerve diameter in eyes with ON was 4.1 (0.8) mm, which was significantly larger than the 3.0 (0.4) mm diameter measured in unaffected control eyes (p < 0.001). There were no differences in average PSV, EDV, RI, or PI of the OA and CRA between affected and unaffected eyes (p > 0.05). The mean RI in the PCAs was slightly lower in the eyes with ON than in the contralateral eyes (0.60 vs. 0.64, p < 0.05). The area under the ROC curves indicated that optic nerve diameter was the best parameter for the diagnosis of ON. CONCLUSIONS: Optic nerve diameter was related to ON, but orbital blood flow parameters were not.
Adult ; Humans ; Middle Aged ; Ophthalmic Artery/*physiology/*ultrasonography ; Optic Nerve/*blood supply/*ultrasonography ; Optic Neuritis/*physiopathology/*ultrasonography ; Orbit/blood supply/ultrasonography ; Pulsatile Flow/physiology ; Regional Blood Flow/physiology ; Ultrasonography, Doppler, Color ; Vascular Resistance/physiology ; Young Adult

OBJECTIVETo evaluate wave intensity (WI) on left ventricular (LV) performance in the different hypertensive remolding hearts.

METHODS105 hypertensive and 98 control subjects were underwent noninvasive evaluation of carotid arterial wave intensity, LV structure and function.

RESULTS(1) There were increasing trends in the levels of blood pressure, LV end-diastolic diameter and LV mass index in the control, normal geometry group, concentric remodeling group, concentric and eccentric hypertrophy group. LV ejection fraction increased in the concentric hypertrophy group and decreased in the eccentric hypertrophy group in which mid-wall fractional shortening showed a decreasing trend. LV diastolic filling pressure presented increased progression accompanied by LV remodeling (P < 0.05). (2) Transient acceleration wave intensity (W1) in hypertensive subjects were higher than that in the control (P < 0.05). Transient deceleration wave intensity (W2) was lower than that in the control (P < 0.05). (3) W1 in the concentric hypertrophy group was higher and lower in the eccentric hypertrophy, compared with that in the control group, normal geometry group and concentric remodeling group (P < 0.05). W2 was lower in concentric hypertrophy group and eccentric hypertrophy group than that in the control, normal geometry group and concentric remodeling group (P < 0.05).

CONCLUSIONWI is a noninvasively obtained, clinically useful parameter for evaluation of LV performance.

Aged ; Blood Flow Velocity ; physiology ; Carotid Artery, Common ; physiopathology ; Case-Control Studies ; Female ; Humans ; Hypertension ; physiopathology ; Male ; Middle Aged ; Pulsatile Flow ; physiology ; Ventricular Function, Left ; physiology ; Ventricular Remodeling

The distribution of shear stress on the bottom of the parallel plate flow chamber under different inlet velocities was analyzed by numerical simulation. In the present experimental study, the projection planes of the relative errors at 0.7% level were obtained, and then the efficient region and the actual entrance length were further corrected by introducing the concept of relative error. The results showed that the efficient region of the chamber increased with the direction of length while the inlet velocity was increased, and the actual entrance length was much greater than that of the theoretical entrance length. Therefore, in accordance to the needed range of shear stress in experiment and to the needed efficient region area, the optimum design of the flow chamber is necessary.
Algorithms ; Blood Flow Velocity ; Blood Pressure ; physiology ; Computer Simulation ; Humans ; Models, Cardiovascular ; Numerical Analysis, Computer-Assisted ; Pulsatile Flow ; Rheology ; Shear Strength ; Stress, Mechanical

As there are a number of ankle arteries and some of them can not be blocked completely under higher pressure from the external inflate cuff, we can not accurately identify the starting point of the pulse wave, so the errors of lower limb systolic blood pressure measurement take place and affect the accuracy of ankle-brachial index in diagnosing vascular disease. In this paper, we constructed delay vectors from the data we already collected from lower limb pulse wave and formed an embedding matrix; thus solving the problem of inadequate sensor dimensions. We extracted a single arterial pulse wave through the blind signal separation on the basis of embedding matrix, and we identified the lower limb systolic blood pressure corresponding to the starting point. Simulation and clinical experiments show the method can be used to separate the wave signals of ankle artery which contains information of systolic blood pressure. It improves the accuracy of lower limb systolic blood pressure measurement and hence provides accurate data for the clinical diagnosis of arterial disease.
Algorithms ; Ankle ; blood supply ; Blood Pressure ; Blood Pressure Determination ; methods ; Brachial Artery ; physiology ; Humans ; Leg ; blood supply ; Pulsatile Flow ; physiology ; Signal Processing, Computer-Assisted

By virtue of computational fluid dynamics and the fundamental principles of hemodynamics, this paper gives numerical simulations and analyses of blood flow in the human thoracic aorta. The distributive features of velocity and pressure of the blood flow are obtained with the use of initial parabolic pulsatile blood flow. The numerical results show that, due to the angularity of thoracic aorta and due to the branch arteries, the distributions of velocity and pressure display marked difference, especially for the horizontal velocity, in the thoracic aorta connecting with the second and third branch artery, which indicate the place where thoracic aortic dissection often happens.
Aneurysm, Dissecting ; physiopathology ; Aorta, Thoracic ; physiology ; Aortic Aneurysm, Thoracic ; physiopathology ; Blood Flow Velocity ; physiology ; Blood Viscosity ; Computer Simulation ; Hemodynamics ; Humans ; Models, Cardiovascular ; Pulsatile Flow