Nonquasi-Steady Character of Pulsatile Flow in Human Coronary Arteries

1985 ◽  
Vol 107 (1) ◽  
pp. 24-28 ◽  
Author(s):  
F. F. Mark ◽  
C. B. Bargeron ◽  
O. J. Deters ◽  
M. H. Friedman
Keyword(s):  
Coronary Arteries ◽  
Pulsatile Flow ◽  
Laser Doppler Anemometry ◽  
Main Channel ◽  
Left Main ◽  
Vascular Cast ◽  
Pulsatile Flows ◽  
Flow Through ◽  
The Mean ◽  
Flow Experiments

This experiment was conducted to determine if the pulsatile flow through the proximal portion of the left coronary artery system in man exhibits quasi-steady characteristics. Steady and pulsatile flows were passed through an idealized model whose dimensions were based on a vascular cast. The mean Reynolds number was 180 and the unsteadiness number was 2.7. Velocity profiles were measured by laser Doppler anemometry at several locations along diameters in the parent and both daughter channels in the neighborhood of the “left main” bifurcation. Analysis of the results along one diameter in the “left main” channel shows that unsteady flow in the larger coronary arteries may not be simulated by a series of steady flow experiments.

Coronary artery z score values in adolescent elite male soccer players

2020 ◽  
pp. 1-5
Author(s):  
Stephan Gerling ◽  
Tobias Pollinger ◽  
Markus Johann Dechant ◽  
Michael Melter ◽  
Werner Krutsch ◽  
...  
Keyword(s):  
Coronary Artery ◽  
Coronary Arteries ◽  
High Intensity ◽  
Left Main Coronary Artery ◽  
Left Ventricular ◽  
Soccer Players ◽  
Z Score ◽  
Left Main ◽  
Luminal Diameter ◽  
The Mean

Abstract Background: With the increased training loads at very early ages in European elite youth soccer, there is an interest to analyse coronary artery remodelling due to high-intensity exercise. Design and methods: Prospective echocardiographic study in 259 adolescent elite male soccer players and 48 matched controls. Results: The mean age was 12.7 ± 0.63 years in soccer players and 12.6 ± 0.7 years in controls (p > 0.05). Soccer players had significant greater indexed left ventricular mass (93 ± 13 g/m2 versus 79 ± 12 g/m2, p = 0.001). Both coronary arteries origin could be identified in every participant. In soccer players, the mean diameter of the left main coronary artery was 3.67 mm (SD ± 0.59) and 2.61 mm (SD ± 0.48) for right main coronary artery. Controls showed smaller mean luminal diameter (left main coronary artery, p = 0.01; right main coronary artery, p = 0.025). In soccer players, a total of 91% (n = 196) and in controls a total of 94% (n = 45) showed left main coronary artery z scores within the normal range: −2.0 to 2.0. In right main coronary artery, a pattern of z score values distribution was comparable (soccer players 94%, n = 202 vs. controls 84%, n = 40). A subgroup of soccer players had supernormal z score values (>2.0 to 2.5) for left main coronary artery (9%, n = 19, p = 0.01) and right main coronary artery (6%, n = 10, p = 0.025), respectively. Conclusion: Elite soccer training in early adolescence may be a stimulus strong enough to develop increased coronary arteries diameters. In soccer players, a coronary artery z score >2.0–2.5 might reflect a physiologic response induced by multiannual high-intensity training.

Axisymmetric Flow in a Motored Reciprocating Engine

1978 ◽  
Vol 192 (1) ◽  
pp. 213-223 ◽  
Author(s):  
A. D. Gosman ◽  
A. Melling ◽  
J. H. Whitelaw ◽  
P. Watkins
Keyword(s):  
Laser Doppler Anemometry ◽  
Axisymmetric Flow ◽  
Flow Characteristics ◽  
Small Scale ◽  
Mean Velocity ◽  
Inlet Velocity ◽  
Reciprocating Engine ◽  
Laminar And Turbulent Flow ◽  
Flow Through ◽  
The Mean

A study was made of axisymmetric, laminar and turbulent flow in a motored reciprocating engine with flow through a cylinder head port. Measurements were obtained by laser-Doppler anemometry and predictions for the laminar case were generated by finite-difference means. Agreement between calculated and measured results is good for the main features of the flow field, but significant small scale differences exist, due partly to uncertainties in the inlet velocity distribution. The measurements show, for example, that the mean velocity field is influenced more strongly by the engine geometry than by the speed. In general, the results confirm that the calculation method can be used to represent the flow characteristics of motored reciprocating engines without compression and suggest that extensions to include compression and combustion are within reach.

Correlation Among Shear Rate Measures in Vascular Flows

1987 ◽  
Vol 109 (1) ◽  
pp. 25-26 ◽  
Author(s):  
Morton H. Friedman ◽  
Owen J. Deters
Keyword(s):  
Shear Rate ◽  
Vessel Wall ◽  
Maximum Rate ◽  
Laser Doppler Anemometry ◽  
Rate Of Change ◽  
Flow Reversal ◽  
Flow Through ◽  
The Mean ◽  
Highly Correlated

A variety of shear rate measures have been calculated from hemodynamic data obtained by laser Doppler anemometry in flow-through casts of human aortic bifurcations. Included are measures sensitive to the mean and amplitude of the shear rate, its maximum rate of change, the duration of stasis and flow reversal near the wall, and the unidirectionality of the flow. Many of these measures are highly correlated with one another. This suggests that that it will be difficult to identify from in vivo measurements those aspects of the flow field to which the vessel wall is most sensitive. It may be possible to separate the effects of purely temporal factors (e.g., the duration of flow reversal) from those related to wall shear stress.

Mean Flow and Turbulent Stress Estimation Using DPIV in Pulsatile Flow Through Mechanical Heart Valve

2000 ◽  
Author(s):  
Amirthaganesh Subramanian ◽  
Haining Mu ◽  
Jaikrishnan R. Kadambi ◽  
Hiroaki Harasaki ◽  
Mark P. Wernet
Keyword(s):  
Heart Valve ◽  
Pulsatile Flow ◽  
Laser Doppler Anemometry ◽  
Measurement Techniques ◽  
Mechanical Heart Valve ◽  
Accurate Estimation ◽  
Turbulent Stress ◽  
Mean Flow ◽  
Flow Loop ◽  
Pulsatile Flows

Abstract Accurate estimation of turbulent stresses in pulsatile flows is very important in the design of mechanical heart valves to reduce thromboembolism and hemolysis. The flow within the lumen of a fully transparent bileaflet mechanical heart valve model, in the “mitral” position of an in-vitro pulsatile flow loop, is characterized using digital particle image velocimetry (DPIV). A phase-averaging technique is used to obtain the mean velocities and turbulent stresses. The results are compared with those obtained using laser Doppler anemometry which shows good agreement between the two measurement techniques, thereby validating the integrity of the DPIV measurements in the conditionally sampled time dependent flow. Convergence and accuracy issues involving turbulent stress measurements with DPIV in pulsatile flows are addressed in this paper.

Two-equation Turbulence Modeling of Pulsatile Flow in a Stenosed Tube

2004 ◽  
Vol 126 (5) ◽  
pp. 625-635 ◽  
Author(s):  
J. Ryval ◽  
A. G. Straatman ◽  
D. A. Steinman
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Numerical Simulations ◽  
Pulsatile Flow ◽  
Turbulence Modeling ◽  
Area Reduction ◽  
The Standard Model ◽  
Pulsatile Flows ◽  
Flow Through ◽  
Inlet Conditions

The study of pulsatile flow in stenosed vessels is of particular importance because of its significance in relation to blood flow in human pathophysiology. To date, however, there have been few comprehensive publications detailing systematic numerical simulations of turbulent pulsatile flow through stenotic tubes evaluated against comparable experiments. In this paper, two-equation turbulence modeling has been explored for sinusoidally pulsatile flow in 75% and 90% area reduction stenosed vessels, which undergoes a transition from laminar to turbulent flow as well as relaminarization. Wilcox’s standard k-ω model and a transitional variant of the same model are employed for the numerical simulations. Steady flow through the stenosed tubes was considered first to establish the grid resolution and the correct inlet conditions on the basis of comprehensive comparisons of the detailed velocity and turbulence fields to experimental data. Inlet conditions based on Womersley flow were imposed at the inlet for all pulsatile cases and the results were compared to experimental data from the literature. In general, the transitional version of the k-ω model is shown to give a better overall representation of both steady and pulsatile flow. The standard model consistently over predicts turbulence at and downstream of the stenosis, which leads to premature recovery of the flow. While the transitional model often under-predicts the magnitude of the turbulence, the trends are well-described and the velocity field is superior to that predicted using the standard model. On the basis of this study, there appears to be some promise for simulating physiological pulsatile flows using a relatively simple two-equation turbulence model.

In Vitro Fluid Dynamics of the St Jude Valve Prosthesis in Steady and Pulsatile Flow

1988 ◽  
Vol 17 (4) ◽  
pp. 181-187 ◽  
Author(s):  
Daniel D Hanle ◽  
Earl C Harrison ◽  
Ajit P Yoganathan ◽  
William H Corcoran
Keyword(s):  
Pulsatile Flow ◽  
Laser Doppler Anemometry ◽  
Axial Direction ◽  
Valve Prosthesis ◽  
Flow Mapping ◽  
Measurement Methodology ◽  
Instantaneous Point ◽  
Flow Through

The flow downstream from the St Jude valve prosthesis is studied in vitro in both steady and pulsatile flow. Conditions for the pulsatile flow studies approximate the in vivo resting state. Laser-Doppler anemometry (LDA) is used to measure instantaneous point velocities at numerous locations pre-selected to conform to a systematic, flow-mapping measurement methodology. Overall, the results for the St Jude valve indicate a relatively undisturbed forward flow through the prosthesis. The acceleration ratios, defined as the maximum mean axial velocity for the St Jude valve divided by that for no valve obstructing the flow, are small, being 1.2 and 1.4 for steady and pulsatile flow, respectively. Both the secondary flow structure and the flow disturbance produced by this valve are minimal. Maximum mean velocities in the radial and azimuthal directions are only about 5–10 per cent of that in the axial direction. There is, however, notable evidence of flow wakes generated by the valve's opened leaflets. Velocity defects caused by these wakes are found to be as much as 50 per cent. The bulk flow through this valve is in this sense quite unlike that reported by others for the natural aortic valve studied in vitro.

Flow and Compression in Asymmetric Stenosis Models: Influence of Compliance on Flow and Compression

2002 ◽  
Author(s):  
Shunichi Kobayashi ◽  
Daisuke Tsunoda ◽  
Hirohisa Morikawa ◽  
Dalin Tang ◽  
David N. Ku
Keyword(s):  
Pulsatile Flow ◽  
High Speed ◽  
Fluid Pressure ◽  
Arterial Disease ◽  
External Pressure ◽  
Distal Embolization ◽  
Severe Stenosis ◽  
Internal Fluid ◽  
Flow Through ◽  
Flow Experiments

Blood flow through the constricted area of a severe stenosis is similar to that through a venturi or flow nozzle. In the contraction section, the blood can accelerate to high speed. In this situation, the external pressure may be greater than the internal fluid pressure, and the artery could collapse. This collapse may be important in the development of atherosclerotic plaque fracture and subsequent thrombosis or distal embolization [1]. We have developed an asymmetric experimental model that closely approximates the arterial disease situation and performed steady and pulsatile flow experiments. The characteristics of flow and compression concerned with the geometry of the model were discussed [2, 3]. This paper was to examine the influence of compliance on flow and compression under steady and pulsatile flow.

Pulsatile Flow and Deformation in Curved Stenosis Models of Arterial Disease

2004 ◽  
Author(s):  
Shunichi Kobayashi ◽  
Yutaka Fukuzawa ◽  
Yuuki Ayama ◽  
Hirohisa Morikawa ◽  
Dalin Tang ◽  
...  
Keyword(s):  
Experimental Model ◽  
Pulsatile Flow ◽  
Coronary Stenosis ◽  
High Speed ◽  
Fluid Pressure ◽  
Arterial Disease ◽  
External Pressure ◽  
Internal Fluid ◽  
Flow Through ◽  
Flow Experiments

Blood flow through the constricted area of a severe stenosis is similar to that through a venturi or flow nozzle. In the contraction section, the blood can accelerate to high speed. In this situation, the external pressure may be greater than the internal fluid pressure, and the artery could collapse. This collapse may be important in the development of atherosclerotic plaque fracture and subsequent thrombosis or distal embolization. We have developed an experimental model that closely approximates the arterial disease situation and performed steady and pulsatile flow experiments, and the characteristics of flow and compression concerned with the geometry and compliance of the model were discussed [1]. But we had not focused on the coronary stenosis. As the first step to develop the experimental model of coronary stenosis, the curved stenosis model was made. This paper was to examine the influence of curvature and stretch of the stenosis model on flow and collapse under pulsatile flow.

Emergency Management for Critical Left Main Coronary Artery Stenosis

2011 ◽  
Vol 14 (1) ◽  
pp. 12
Author(s):  
Onur Sokullu ◽  
Numan Ali Aydemir ◽  
Erol Kurc ◽  
Batuhan Ozay ◽  
Fuat Bilgen ◽  
...  
Keyword(s):  
Survival Rate ◽  
Left Main Coronary Artery ◽  
Myocardial Revascularization ◽  
Coronary Bypass ◽  
Percutaneous Intervention ◽  
Bypass Grafting ◽  
Left Main ◽  
Bypass Group ◽  
The Mean ◽  
Late Survival

Background: Increased experience and improvements in technology seem to have encouraged the use of percutaneous interventions for left main coronary artery (LMCA) occlusions. There is no consensus, however, and the data are inadequate on whether surgery or percutaneous procedures should be the intervention of choice for critical occlusions.Methods: From January 2002 to December 2006, 108 patients with unprotected LMCA stenosis >80% were treated at our center. Eighty-three patients (77%) underwent bypass grafting and 20 (18%) underwent percutaneous intervention for the purpose of myocardial revascularization. We analyzed parameters demonstrated as risk factors for myocardial revascularization and their predicted effects on outcome.Results: Five patients (5%) died following emergency cardiopulmonary resuscitation before any intervention was performed. The early survival rate was 84.1% in the coronary bypass group and 63% in the percutaneous intervention group. The mean (SD) survival time was 55.7 2.6 months in the bypass group and 7.6 1.3 months in the percutaneous group. The late-survival rate was also significantly higher in the bypass group. The mean late-survival time was 44.5 3.6 months in the bypass group and 2.3 0.8 months in the percutaneous group.Conclusion: Although emergency percutaneous interventions are lifesaving in some cases, these results clearly demonstrate that coronary bypass grafting should be the intervention of choice for myocardial revascularization in patients with critical LMCA occlusion.

Congenital Left Main Coronary Artery to Coronary Sinus Fistula

2011 ◽  
Vol 14 (4) ◽  
pp. 255 ◽  
Author(s):  
Fotios A. Mitropoulos ◽  
Meletios A. Kanakis ◽  
Periklis A. Davlouros ◽  
George Triantis
Keyword(s):  
Coronary Artery ◽  
Coronary Arteries ◽  
Coronary Sinus ◽  
Left Main Coronary Artery ◽  
Coronary Artery Fistula ◽  
Left Main ◽  
Coronary Fistula ◽  
Excellent Outcome ◽  
Surgical Ligation ◽  
Congenital Coronary Artery Fistula

Congenital coronary artery fistula is an extremely rare anomaly that may involve any of the coronary arteries and any of the cardiac chambers. We report the case of a 14-year-old female patient with a symptomatic congenital coronary fistula starting from the left main coronary artery and draining to the coronary sinus. The patient underwent surgical ligation of the fistula and had an excellent outcome.

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