1
|
Jain K. The effect of varying degrees of stenosis on transition to turbulence in oscillatory flows. Biomech Model Mechanobiol 2022; 21:1029-1041. [PMID: 35445319 PMCID: PMC9132830 DOI: 10.1007/s10237-022-01579-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 03/25/2022] [Indexed: 11/25/2022]
Abstract
Many complications in physiology are associated with a deviation in flow in arteries due to a stenosis. The presence of stenosis may transition the flow to weak turbulence. The degree of stenosis as well as its configuration whether symmetric or non-symmetric to the parent artery influences whether the flow would stay laminar or transition to turbulence. Plenty of research efforts focus on investigating the role of varying degrees of stenosis in the onset of turbulence under steady and pulsatile flow conditions. None of the studies, however, have focused on investigating this under oscillatory flow conditions as flow reversal is a major occurrence in a number of physiologic flows, and is of particular relevance in cerebrospinal fluid flow research. Following up on the previous work in which a \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$75\%$$\end{document}75% stenosis was studied, this contribution is a detailed investigation of the role of degrees of stenosis on transition in an oscillatory flow. A cylindrical pipe with \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$25\%$$\end{document}25%, \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$50\%$$\end{document}50% and \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$60\%$$\end{document}60% reductions in area in axisymmetric and eccentric configurations is studied for transition with 3 different pulsation frequencies of a purely oscillatory flow. Cycle averaged Reynolds numbers between 1800 and 2100 in steps of 100 are studied for each configuration resulting in 72 simulations each conducted on 76,800 CPU cores of a modern supercomputer. It is found that a higher degree of stenosis and eccentricity causes earlier transition to turbulence in oscillatory flow. The results further demonstrate that a higher frequency of oscillation results in larger hydrodynamic instability in the flow, which is more prominent in smaller degrees of stenosis.
Collapse
Affiliation(s)
- Kartik Jain
- Faculty of Engineering Technology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands.
| |
Collapse
|
2
|
Hemodynamics of cerebral aneurysms: computational analyses of aneurysm progress and treatment. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2012; 2012:782801. [PMID: 22454695 PMCID: PMC3290806 DOI: 10.1155/2012/782801] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 11/10/2011] [Indexed: 12/02/2022]
Abstract
The progression of a cerebral aneurysm involves degenerative arterial wall remodeling. Various hemodynamic parameters are suspected to be major mechanical factors related to the genesis and progression of vascular diseases. Flow alterations caused by the insertion of coils and stents for interventional aneurysm treatment may affect the aneurysm embolization process. Therefore, knowledge of hemodynamic parameters may provide physicians with an advanced understanding of aneurysm progression and rupture, as well as the effectiveness of endovascular treatments. Progress in medical imaging and information technology has enabled the prediction of flow fields in the patient-specific blood vessels using computational analysis. In this paper, recent computational hemodynamic studies on cerebral aneurysm initiation, progress, and rupture are reviewed. State-of-the-art computational aneurysmal flow analyses after coiling and stenting are also summarized. We expect the computational analysis of hemodynamics in cerebral aneurysms to provide valuable information for planning and follow-up decisions for treatment.
Collapse
|
3
|
Richter Y, Groothuis A, Seifert P, Edelman ER. Dynamic flow alterations dictate leukocyte adhesion and response to endovascular interventions. J Clin Invest 2004; 113:1607-14. [PMID: 15173887 PMCID: PMC419491 DOI: 10.1172/jci21007] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2004] [Accepted: 02/17/2004] [Indexed: 01/13/2023] Open
Abstract
Although arterial bifurcations are frequent sites for obstructive atherosclerotic lesions, the optimal approach to these lesions remains unresolved. Benchtop models of arterial bifurcations were analyzed for flow disturbances known to correlate with vascular disease. These models possess an adaptable geometry capable of simulating the course of arterial disease and the effects of arterial interventions. Chronic in vivo studies evaluated the effect of flow disturbances on the pattern of neointimal hyperplasia. Acute in vivo studies helped propose a mechanism that bridges the early mechanical stimulus and the late tissue effect. Side-branch (SB) dilation adversely affected flow patterns in the main branch (MB) and, as a result, the long-term MB patency of stents implanted in pig arteries. Critical to this effect is chronic MB remodeling that seems to compensate for an occluded SB. Acute leukocyte recruitment was directly influenced by the changes in flow patterns, suggesting a link between flow disturbance on the one hand and leukocyte recruitment and intimal hyperplasia on the other. It is often impossible to simultaneously maximize the total cross-sectional area of both branches and to minimize flow disturbance in the MB. The apparent trade-off between these two clinically desirable goals may explain many of the common failure modes of bifurcation stenting.
Collapse
Affiliation(s)
- Yoram Richter
- Harvard-M.I.T. Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
| | | | | | | |
Collapse
|
4
|
Sera T, Satoh S, Horinouchi H, Kobayashi K, Tanishita K. Respiratory flow in a realistic tracheostenosis model. J Biomech Eng 2003; 125:461-71. [PMID: 12968570 DOI: 10.1115/1.1589775] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The possible mechanism of wheeze generation in tracheostenosis was identified by measuring inspiratory and expiratory flow in a "morphological and distensible" realistic tracheostenosis model. The shape of the model was based on CT (Computed Tomography) images of a patient that had tracheostenosis. A trachea consists of tracheal cartilage rings and smooth muscle. Spatial variation of wall distensibility was achieved in the model by varying the wall thickness based on the elastic modulus measured in pig airways. The spatial variation influenced the flow in the airway and the turbulence production rate decreased faster at smooth muscles. Using the model, we investigated the mechanism of wheeze generation by focusing on the turbulence intensity. The turbulence intensity in expiratory flow was about twice that in inspiratory flow, and larger vortices existed in post-stenosis in expiratory flow, and thus might contribute to wheeze generation.
Collapse
Affiliation(s)
- Toshihiro Sera
- Center for Life Science and Technology, School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan.
| | | | | | | | | |
Collapse
|
5
|
Fernandes V, Kałuza GL, Zymek PT, DeFelice CA, Hust R, Raizner AE. Successful balloon valvuloplasty in an adult patient with severe pulmonic stenosis and aneurysmal poststenotic dilatation. Catheter Cardiovasc Interv 2002; 55:376-80. [PMID: 11870946 DOI: 10.1002/ccd.10128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We present a case of pulmonic stenosis with large aneurysmal poststenotic dilatation that was safely and effectively treated with balloon valvuloplasty. Though the poststenotic dilatation persists after the procedure, the risk of dissection and rupture is very low. Hence, balloon valvuloplasty should be considered the treatment of choice in this setting.
Collapse
Affiliation(s)
- Valerian Fernandes
- The Methodist DeBakey Heart Center and Section of Cardiology, Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
| | | | | | | | | | | |
Collapse
|
6
|
Diebold B, Delouche A, Decesare A, Delouche P, Guglielmi JP, Herment A. Fluid mechanics of regurgitant jets and calculation of the effective regurgitant orifice in free or complex configurations. J Biomech 2000; 33:677-84. [PMID: 10807988 DOI: 10.1016/s0021-9290(00)00005-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The velocity fields of turbulent jets can be described using a single formula which includes two empirical constants: k(core) determining the length of the central core and k(turb) the jet widening. Flow models simulating jet adhesion, confinement and noncircular orifices were studied using laser Doppler anemometer and the modifications of the constants were derived from series of velocity profiles. In circular free jets, k(core) was found equal to 4.1 with a variability of 1.4%. In complex configurations, its variability was equal to 15.2%. For k(turb), the value for free circular jets was of 45.2 with a variability of 6.0% and this variability in complex configurations was significantly higher (30. 1%, p=0.025). The correlation between the actual orifice size and the jet extension was poor (r=0.52). However, the almost constant value of k(core) allowed to define a new algorithm calculating the regurgitant orifice diameter with the use of outlines of the jet image (r=0.89). In conclusion, the fluid mechanics of regurgitant jets is modified in complex configurations but, due to the relative independency of the central core, velocity fields could be used to evaluate the dimensions of the effective regurgitant orifice.
Collapse
Affiliation(s)
- B Diebold
- INSERM, U. 494, Hopital Broussais, 96 rue Didot, 75674, Paris Cedex, France.
| | | | | | | | | | | |
Collapse
|
7
|
Sung HW, Hsu TL, Hsu CH, Hsu JC. Pulmonary artery hemodynamics with varying degrees of valvular stenosis: an in vitro study. J Biomech 1998; 31:1153-61. [PMID: 9882048 DOI: 10.1016/s0021-9290(98)00115-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The study was to investigate the effects of varying degrees of valvular stenosis on the hemodynamics of the main (MPA), left (LPA), and right (RPA) pulmonary arteries. Particle flow visualization was used to examine the flow patterns in a series of pulmonary artery models manufactured out of glass. These glass models were made based on the geometry of the porcine pulmonary arteries with dilatation in the MPA and LPA. Also, detailed pressure mappings in the models were conducted using a side-hole catheter. As the valve became stenotic, a jet-like flow was observed in the M PA. A higher degree of valvular stenosis corresponded to a narrower jet. This jet-like flow was noted to deflect away from the centerline and impinge on the roof of the dilated MPA. Additionally, a notable pressure gradient across the deflected jet-like flow in the direction of its radius of curvature was seen. Moreover, secondary flows started to appear in the dilated MPA. This suggested that the change in geometry in the MPA, due to its dilatation, had a marked effect on the pulmonary artery hemodynamics. In the LPA and RPA, the strengths of the secondary flows increased as the valve became more stenotic. The flow patterns observed in the LPA appeared to be more disturbed than in the RPA, due to the poststenotic, dilatation present in the LPA. Pressure recovery along the axial direction in the M PA was observed for all the stenotic valves studied. As the degree of valvular stenosis increased, the transvalvular energy loss increased. Moreover, it was observed that the energy loss decreased progressively as the flow traveled downstream. This tendency was consistent with the phenomenon of pressure recovery observed in the pressure measurement. The study demonstrates the importance of analyzing biological flows from a three-dimensional viewpoint.
Collapse
Affiliation(s)
- H W Sung
- Department of Chemical Engineering, National Central University, Chung-Li, Taiwan, Republic of China.
| | | | | | | |
Collapse
|
8
|
Migliavacca F, Dubini G, Pietrabissa R, de Leval MR. Computational transient simulations with varying degree and shape of pulmonic stenosis in models of the bidirectional cavopulmonary anastomosis. Med Eng Phys 1997; 19:394-403. [PMID: 9302681 DOI: 10.1016/s1350-4533(96)00070-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The bidirectional cavopulmonary anastomosis is a surgical technique utilized to treat severe congenital malformations of the right part of the heart. It is obtained by anastomosing the superior vena cava to the superior aspect of the undivided right pulmonary artery. Transient simulations with a three-dimensional model of the bidirectional cavopulmonary anastomosis were carried out to evaluate the haemodynamics of different types of pulmonic stenosis (shape and severity of the obstruction). Models with a tunnel-like (supravalvar) or discrete (valvar) pulmonic stenosis with different values of reduction of cross-sectional area (60 and 75%) were investigated and compared to a model without stenosis. Calculations were based on a finite element method analysis. The results showed that a tighter stenosis can lead to a blood volume flow to the left lung reaching 70% of the total pulmonary flow. Moreover, the flow fields are highly influenced by the presence and shape of the pulmonic stenosis; the most intense jets in the left pulmonary artery occur for a discrete pulmonic stenosis of 75%. The flow in the right pulmonary artery is nearly steady because it is damped down by the steady caval flow.
Collapse
Affiliation(s)
- F Migliavacca
- Dipartimento di Bioingegneria, Politecnico di Milano, Italy
| | | | | | | |
Collapse
|
9
|
Sømod L, Pedersen EM, Kim WY, Hasenkam JM, Nygaard H, Paulsen PK. Axial development of velocity fields in the porcine main pulmonary artery system. Heart Vessels 1994. [DOI: 10.1007/bf01751940] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
10
|
Sung HW, Philpot EF, Nanda NC, Yoganathan AP. Axial flow velocity patterns in a pulmonary artery model with varying degrees of valvular pulmonic stenosis: pulsatile in vitro studies. J Biomech 1990; 23:563-78. [PMID: 2187876 DOI: 10.1016/0021-9290(90)90049-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
With the advent of noninvasive clinical techniques which can measure blood flow velocities (Doppler ultrasound), it is suggested that a fundamental knowledge of the axial flow velocity patterns in the pulmonary artery, and the changes caused by stenosis, may be used to support accurate diagnosis of valvular pulmonic stenosis. The present study was designed to characterize the axial flow velocity patterns in an in vitro model of a human adult pulmonary artery with varying degrees of valvular pulmonic stenosis. A two-dimensional laser Doppler anemometer (LDA) system was used to map the flow fields in the main (MPA), left (LPA), and right (RPA) branches of the pulmonary artery model. The study was conducted in the Georgia Tech. right heart pulse duplicator system. It was observed that the axial flow velocity patterns in the MPA and the LPA change dramatically with increasing degree of valvular stenosis. This indicates that the axial flow velocity patterns in these two branches are strongly influenced by the degree of valvular stenosis. The axial flow velocity patterns in the RPA, however, do not change much with varying degrees of valvular stenosis, indicating that the axial flow fields in the RPA are mainly influenced by the geometry of the bifurcation. It may be concluded therefore, that the changes in the axial flow velocity patterns in the MPA and LPA (rather than in the RPA) could be sensitive and reliable indicators of the severity of the defect.
Collapse
Affiliation(s)
- H W Sung
- Cardiovascular Fluid Mechanics Laboratory, School of Chemical Engineering, Georgia Institute of Technology, Atlanta 30332-0100
| | | | | | | |
Collapse
|
11
|
Diebold B, Delouche A, Dumée P, Guglielmi JP, Delouche P, Péronneau P. In vitro analysis of a model of intracardiac jet: analysis of the central core of axisymmetric jets. J Biomech 1990; 23:35-44. [PMID: 2307690 DOI: 10.1016/0021-9290(90)90367-c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In order to provide physical information supporting the clinical use of flow mapping, an in vitro model was designed to measure the velocity fields in a pulsatile hydraulic turbulent jet. We used a peak velocity ranging from 2.5 to 5.5 m.s-1, an orifice diameter ranging from 5.8 to 11.3 mm and confined the jet in a receiving tube whose diameter ranged from 16 to 30 mm, thus simulating a large variety of valvular leaks. In steady flow conditions, our results agreed with previously reported descriptions. Under pulsatile conditions, the same structure was found at peak velocity and during the beginning of the deceleration. Below a threshold velocity, the length of the central core was independent of the peak velocity and proportional to about six times the orifice diameter. Above the threshold velocity, this relationship was no longer true, the threshold value being related to the ratio of the orifice diameter to the diameter of the receiving tube.
Collapse
Affiliation(s)
- B Diebold
- Unité INSERM 256, Hopital Broussais, Paris, France
| | | | | | | | | | | |
Collapse
|
12
|
Sung HW, Yoganathan AP. Axial flow velocity patterns in a normal human pulmonary artery model: pulsatile in vitro studies. J Biomech 1990; 23:201-14. [PMID: 2324117 DOI: 10.1016/0021-9290(90)90012-r] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
It has been clinically observed that the flow velocity patterns in the pulmonary artery are directly modified by disease. The present study addresses the hypothesis that altered velocity patterns relate to the severity of various diseases in the pulmonary artery. This paper lays a foundation for that analysis by providing a detailed description of flow velocity patterns in the normal pulmonary artery, using flow visualization and laser Doppler anemometry techniques. The studies were conducted in an in vitro rigid model in a right heart pulse duplicator system. In the main pulmonary artery, a broad central flow field was observed throughout systole. The maximum axial velocity (150 cm s-1) was measured at peak systole. In the left pulmonary artery, the axial velocities were approximately evenly distributed in the perpendicular plane. However, in the bifurcation plane, they were slightly skewed toward the inner wall at peak systole and during the deceleration phase. In the right pulmonary artery, the axial velocity in the perpendicular plane had a very marked M-shaped profile at peak systole and during the deceleration phase, due to a pair of strong secondary flows. In the bifurcation plane, higher axial velocities were observed along the inner wall, while lower axial velocities were observed along the outer wall and in the center. Overall, relatively low levels of turbulence were observed in all the branches during systole. The maximum turbulence intensity measured was at the boundary of the broad central flow field in the main pulmonary artery at peak systole.
Collapse
Affiliation(s)
- H W Sung
- Cardiovascular Fluid Mechanics Laboratory, School of Chemical Engineering, Georgia Institute of Technology, Atlanta 30332-0100
| | | |
Collapse
|
13
|
Krabill KA, Sung HW, Tamura T, Chung KJ, Yoganathan AP, Sahn DJ. Factors influencing the structure and shape of stenotic and regurgitant jets: an in vitro investigation using Doppler color flow mapping and optical flow visualization. J Am Coll Cardiol 1989; 13:1672-81. [PMID: 2723278 DOI: 10.1016/0735-1097(89)90363-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
To evaluate factors influencing the structure and shape of stenotic and regurgitant jets, Doppler color flow mapping and optical flow visualization studies were performed with use of a syringe model with a constant rate of ejection to simulate jets of valvular regurgitation and a pulsatile flow model of the right heart chambers to simulate jets of mild, moderate and severe valvular pulmonary stenosis. Ink-(0 to 40%) glycerol-water jets (viscosity 1 to 3.5 centiPoise) were produced by injecting the fluid at a constant rate into a 10 gallon rectangular reservoir of the same still fluid through 1.4 and 3.4 mm needles. The Doppler color flow scanners imaged the laminar jet length within 3 mm of actual jet length (2 to 6 cm) and the jet width within 2 to 3 mm of the actual jet width. Jet flows with Reynolds numbers ranging from 230 to 1,200 injected into still fluid yielded jet length/width ratios that decreased with increasing Reynolds numbers and leveled off to a length/width ratio of 5-6:1 at a Reynolds number near 600. When the fluid reservoir was swirled to better mimic the effect of flow entering the same cardiac chamber from a second source, the jets showed diminution of the jet length/width ratio and a clearly defined zone of turbulence. Studies of the pulsatile flow model were performed at cardiac outputs of 1 to 6 liters/min for the normal and each stenotic valve. Mild stenosis had an orifice area of 2.8 cm2, moderate stenosis an area of 1.0 cm2 and severe stenosis an area of 0.5 cm2. Laminar jet length represented the length of the total jet, which had a symmetric width and was measured from the valve opening to a region where the jet exhibited a spray effect. Laminar jet lengths (0.2 to 1.1 cm) were imaged by Doppler color flow mapping and optical visualization only in the moderate and severely stenotic valves and only at flows less than or equal to 3 liters/min (mean Reynolds numbers less than or equal to 3,470). Beyond this flow rate the jets exhibited a spray effect. Laminar jet length/width ratio approached unity with an increased amount of valvular stenosis and higher flow volumes (cardiac output). Proximal aliasing was present in each valve studied. the length of aliasing (0 to 3.2 cm) proximal to the valve was longer with increased flow rates and increased amounts of stenosis.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
Affiliation(s)
- K A Krabill
- Department of Pediatrics, University of California, San Diego
| | | | | | | | | | | |
Collapse
|
14
|
Gardin JM, Sung HW, Yoganathan AP, Ball J, McMillan S, Henry WL. Doppler flow velocity mapping in an in vitro model of the normal pulmonary artery. J Am Coll Cardiol 1988; 12:1366-76. [PMID: 2971705 DOI: 10.1016/0735-1097(88)92622-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Pulsed Doppler pulmonary artery velocity measurements are useful in evaluating a number of cardiac conditions including pulmonary hypertension, pulmonary stenosis and insufficiency, intracardiac shunts and other congenital abnormalities. However, variations in sample location relative to the arterial wall and valve have been thought to affect pulmonary artery velocity and acceleration measurements clinically. Therefore, pulsed Doppler and color flow mapping were performed in a pulsatile flow apparatus connected to a glass or Plexiglas model of the main pulmonary artery and its bifurcation, which contained a Hancock 29 mm pericardial tissue valve (5.35 cm2 orifice). Doppler sample volumes were placed at four sites: 1) at the pulmonary valve leaflet tips, centrally; 2) 2 cm distal to the leaflet tips, centrally; 3) 2 cm distal but laterally near the pulmonary artery wall; and 4) at the pulmonary artery bifurcation, centrally. Doppler peak flow velocity and acceleration time were measured. There was no difference between sites 1 and 2 in peak flow velocity or acceleration time. At site 3, peak flow velocity and acceleration time were both less than at site 1 (mean +/- SD, 85 +/- 44 versus 105 +/- 39 cm/s, p less than 0.005, and 162 +/- 65 versus 188 +/- 46 ms, p less than 0.03, respectively). Moreover, the pulmonary artery velocity contour at site 3 exhibited increased spectral dispersion and notching and increased variance on the color spectrum. At site 4, peak flow velocity was less than at site 1 (85 +/- 31 versus 105 +/- 39 cm/s, p less than 0.005), whereas pulmonary artery acceleration time was not significantly different. In this model, Doppler pulmonary artery flow velocity was best recorded within 2 cm of the valve and in the center of the vessel. Similar studies should be performed in the human pulmonary artery to standardize the recording technique and sample sites for Doppler measurements of velocity and acceleration.
Collapse
Affiliation(s)
- J M Gardin
- Cardiovascular Fluid Dynamics Laboratory, School of Chemical Engineering, Georgia Institute of Technology, Atlanta
| | | | | | | | | | | |
Collapse
|
15
|
Lucas CL, Henry GW, Ferreiro JI, Ha B, Keagy BA, Wilcox BR. Pulmonary blood velocity profile variability in open-chest dogs: influence of acutely altered hemodynamic states on profiles, and influence of profiles on the accuracy of techniques for cardiac output determination. Heart Vessels 1988; 4:65-78. [PMID: 3075609 DOI: 10.1007/bf02058992] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Clinical investigations focused on finding characteristics of noninvasively obtained measurements of pulmonary blood velocity that can be used to quantitate pulmonary blood flow and/or pulmonary pressure have often yielded results whose imprecision has been attributed to flow pattern variability. To determine flow pattern variability in an in vivo animal model in varying hemodynamic states, main pulmonary artery blood velocity waveforms were recorded in 17 dogs at 2-mm intervals along an anterior to posterior wall-oriented axis using a 20-MHz pulsed Doppler needle probe. Control data were obtained before the animals were subjected to altered flow (atrial level shunts) and pressure (10% O2 inhalation) states. Instantaneous velocity profiles were computed throughout the cardiac cycle. Estimates of pulmonary blood flow were obtained assuming an elliptical model of the pulmonary artery which allowed computation of velocity at all points in the cross section, based on the measured values along the axis. Model-based estimates were compared to measured values and estimates obtained in the traditional fashion, i.e., the product of centerline velocity and cross-sectional area. Results clearly showed marked interanimal variability, even in control states. Reverse flow in the posterior half of the vessel, which tended to become more pronounced with increased pulmonary artery pressure, was observed during late systole and early diastole. Elevated pulmonary blood flow tended to increase the maximum velocities along the anterior wall relative to midline velocities. Neither estimate of cardiac output yielded consistently accurate results (r = 0.77 for model-based method, r = 0.80 for area times central velocity method). Findings of this study, which highlight the dependency of waveform characteristics on sampling site, the large degree of intersubject variability, and the need for large or multiple sample volumes for pulmonary blood flow determination, help clarify inconsistencies observed by clinicians and suggest that future work with animal models will facilitate a greater understanding of the determinants of human pulmonary velocity waveforms.
Collapse
Affiliation(s)
- C L Lucas
- Department of Surgery, University of North Carolina, Chapel Hill 27599
| | | | | | | | | | | |
Collapse
|
16
|
MURPHY DANIELJ, LUDOMIRSKY ACHI, DANFORD DAVIDA, HUHTA JAMESC. Doppler Echocardiography in Pulmonary Stenosis. Echocardiography 1987. [DOI: 10.1111/j.1540-8175.1987.tb01333.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
|