In this paper the theory of autocorrelation algorithm for color flow mapping is analyzed and a new way for ultrasound color flow velocity estimation and real-time display is proposed. The method sets up a mapping table which directly relates to the dynamic display range and has only 256 entries using an inverse mapping method instead of calculating the arctangent value directly. This method is ideal for software implementation and offers an interactive way to the user for changing the dynamic range of flow velocity and thus to increasing the display resolution.
Algorithms ; Blood Flow Velocity ; Humans ; Pulsatile Flow ; physiology ; Rheology ; instrumentation ; Ultrasonography, Doppler, Color ; instrumentation ; methods

Pulsatile blood flow plays an important role in maintaining normal vascular endothelial function. Quantitative measurement of pulsatility of artery blood pressure and blood flow in dogs and effects of enhanced external counterpulsation (EECP) on the pulsatility were taken in this study. Common carotid artery blood pressure and blood flow were measured in 6 beagle dogs that had suffered from an acute myocardial infarction 6 weeks before. A 6F tip transducer catheter was inserted into the right common carotid artery to measure blood pressure, and blood flow was measured in the left common carotid artery by an electromagnetic blood flow probe under anesthesia before and during EECP. Blood pulse pressure, pulsatility index (ratio of peak pressure to end diastolic pressure) and standard deviation of blood pressure were calculated to evaluate the pulsatility of arterial blood pressure. Blood pulse flow, pulsatility index (ratio of peak flow to trough flow) and standard deviation of blood flow were calculated to evaluate the pulsatility of blood flow. Mean vascular resistance (MVR) was calculated as MVR = mean blood pressure/mean blood flow. Blood pulse pressure, pulsatility index and standard deviation of blood pressure were elevated from 30 +/- 9 mmHg, 1.26 +/- 0.05 and 8.7 +/- 2.5 mmHg to 43 +/- 8 mmHg (P < 0.05), 1.54 +/- 0.13 and 12.4 +/- 2.0 mmHg (P < 0.05) before and during EECP, respectively. Blood pulse flow, pulsatility index and standard deviation of blood flow were elevated from 317 +/- 48 ml/min, 2.85 +/- 0.21 and 96 +/- 21 ml/min to 447 +/- 88 ml/min, 4.56 +/- 0.90 and 131 +/- 39 ml/min before and during EECP (P < 0.05). MVR was decreased from 578 +/- 72 before EECP to 476 +/- 85 Wood units during EECP(P < 0.05). These data demonstrate that EECP gives an elevation of pulsatility to blood pressure and blood flow, thus it may lead to the decrease of vascular resistance.
Animals ; Blood Pressure ; Carotid Arteries ; physiology ; Counterpulsation ; Dogs ; Hemodynamics ; Pulsatile Flow ; Regional Blood Flow ; Vascular Resistance

To understand the local hemodynamics of modified TF-AHCB carotid bifurcation model, using particle image velocimetry technique to measure the instantaneous velocity distribution of the model attatched to a circuit. The velocity was controlled by regulating the height of the reservoir. The working fluid consists of glycerine and water mixture with viscosity of 3.75 mPa.s similar to human blood. Instantaneous velocity fields were obtained by PIV and the shear stresses were calculated according to the velocity. The results showed that inside the model, there were a large flow separation and an anticlockwise rotating vortex on the lateral wall of ICA, The location and distance of the vortex changed with the flow velocity. The higher the flow velocity, the smaller the vortex distance, and the farther the location. The shear stresses on the lateral wall were significantly lower in all work condition. And there a low shear stress kernel when the velocity was lower than 0.839 m/s. The location of the low shear stress was just the position of atherosclerosis. The flow pattern inside the model consists of large flow separation and vortex zones. And there are low shear stress zones at the lateral wall of ICA, Where are thought to be associated with the genesis of atherosclerosis.
Blood Flow Velocity ; Carotid Arteries ; physiology ; Models, Cardiovascular ; Pulsatile Flow ; Regional Blood Flow ; physiology ; Rheology ; methods ; Stress, Mechanical

Arteriosclerosis is one of the early characteristics of cardiovascular diseases, and pulse wave velocity (PWV) has the ability to reflect on arterial elasticity, so the accurate measurement of PWV can be of benefits for the prevention and treatment of cardiovascular diseases. There are two methods based on volume pulse waveform and based on pressure pulse waveform for taking the measurement of PWV. The precision of detection depends mainly on choosing the recording sites of PWV. There are several methods to choose the recording sites of PWV. We can get it by tangent and by low-water mark or culmination. We also can choose the recording sites of PWV by getting the point where the greatest slope stands. The advantages and limitations of the existing methods are analyzed in this article, and the relative research orientation in the world is addressed. Lastly a scheme for improving the detection method is presented.
Algorithms ; Arteries ; physiopathology ; Arteriosclerosis ; diagnosis ; Blood Circulation ; Blood Flow Velocity ; physiology ; Humans ; Pulsatile Flow ; physiology ; Pulse ; Signal Processing, Computer-Assisted

Pulsatile blood flow plays an important role in maintaining normal vascular endothelial function. Quantitative measurement of pulsatility of human arterial blood pressure and the influence of enhanced external counterpulsation (EECP) on the pulsatility were investigated in this study. Eight healthy young male volunteers aged 22 to 35 were included. A 4F tip transducer catheter was inserted under local anaesthesia into the radial artery up to the aortic arch. Intraarterial blood pressure was recorded before and during EECP. Blood pulse pressure, pulsatility index (ratio of peak pressure to end diastolic pressure) and standard deviation of blood pressure in 5 cardiac cycle was calculated to evaluate the pulsatility of arterial blood pressure. The results showed that blood pulse pressure, pulsatility index and standard deviation of blood pressure were elevated from 47 +/- 5 mmHg, 1.64 +/- 0.11 and 13.6 +/- 1.5 mmHg to 77 +/- 3 mmHg, 2.46 +/- 0.25 and 19.3 +/- 2.2 mmHg before and during EECP respectively (P < 0.05). Decreasing of systolic pressure and increasing of diastolic pressure during counterpulsation were also observed. EECP gives an elevation of pulsatility to human blood pressure.
Adult ; Blood Pressure ; physiology ; Blood Pressure Determination ; Counterpulsation ; Humans ; Male ; Pulsatile 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

OBJECTIVETo evaluate the possibility of radial artery pressure and waveform as a convenient definition of pulsatile flow and the the effect of pulsatile perfusion during cardiopulmonary bypass (CPB) procedures.

METHODSFrom March 2008 to December, Eighty patients underwent open heart surgery were randomly divided into a pulsatile group (P, n=45) and a nonpulsatile group (NP, n=35). Monitored by radial artery pressure and waveform, the pulsatile low was applied from the point of the aortic cross-clamp until its release in P group. A P group of patients whose radial artery pressure and waveform revealed "double peak" or "single peak" (>30 mm Hg, 1 mm Hg=0.133 kPa) were compared with NP group. Parameters examined were lactate, urine volume, high sensitivity C reactive protein, blood urea nitrogen, creatinine, blood uric acid, lactate dehydrogenase, glutamic oxalacetic transaminase, ratio of urine for occult blood test, prothrombin time and tracheal intubation time.

RESULTSThe waveform with "double peak" or "single peak" (>30 mm Hg) presented in 35 (77.78%) in P group. The urine volume during CPB was significantly higher in P group. The lactate (P<0.01) during CPB, high sensitivity C reactive protein (P<0.05), increasing extend of lactic acid dehydrogenase (P<0.05) and the prothrombin time (P<0.01) after CPB were significantly lower in P group. The blood uric acid after CPB was increased in P group and decreased in NP group.

CONCLUSIONSEffective pulsatile flow can be generated by optimization of equipment and adjustment of pulsatile parameter. The radial artery pressure and waveform is a convenient definition of pulsatile flow. The pulsatile flow is predominant monitored by radial artery pressure and waveform.

Adult ; Blood Pressure ; physiology ; Cardiopulmonary Bypass ; Humans ; Middle Aged ; Monitoring, Physiologic ; methods ; Pulsatile Flow ; Radial Artery

The quantitative relationship between blood pressure and blood stream of arteries, which is delineated by hemodynamics, is rather complex to understand and analyze mathematically. An equivalent simulated mathematical model was utilized to numerically describe this sort of relationship. The physiological essence of layered flowage inside the artery was opened out. The numerical simulation was accomplished using several sets of real parameters. Some important conclusions about quantitative relationship of the layered flowage were drawn through the simulation results. The research results presented in this paper have important reference value in respect of quantitative research of circulation physiology and clinical diagnosis and analysis of some illness within circulation system.
Arteries ; physiology ; Blood Flow Velocity ; physiology ; Blood Pressure ; physiology ; Computer Simulation ; Hemodynamics ; physiology ; Humans ; Models, Cardiovascular ; Numerical Analysis, Computer-Assisted ; Pulsatile Flow ; 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

Focus on the defects of the extraction method of velocity pulsated signals in the velocity spectrum image of pulsed Doppler ultrasounds (such as the limited data, great amount of work and low reproducibility), we combine the earlier research results and the basic rules of the velocity spectrum image, and employing the visual basics plateau, to design and develop a software to extract the velocity signals from the spectrum image automatically. Compare the mean velocity and RNS between the PIV and the PDU resulting from the method, the correlations are r = 0.93 and r = 0.78 respectively. The study reveals the software increase the amount of valid data, decrease the amount of work and increase reproducibility of the signals extraction. The method may be an effective way to analyse the velocity spectrum image of PDU in clinic.
Arteries ; diagnostic imaging ; Blood Flow Velocity ; physiology ; Humans ; Pulsatile Flow ; Signal Processing, Computer-Assisted ; Software ; Ultrasonography, Doppler, Pulsed ; methods