Impact of wall constraint on velocity distribution in proximal flow convergence zone. Implications for color Doppler quantification of mitral regurgitation. 1996

M Pu, and P M Vandervoort, and N L Greenberg, and K A Powell, and B P Griffin, and J D Thomas
Cardiovascular Imaging Center, Department of Cardiology, Cleveland Clinic Foundation, Ohio 44195, USA.

OBJECTIVE This study sought to elevate the effect of proximal flow constraint induced by the left ventricular wall on the accuracy of calculated flow rates and to assess a possible correction factor to adjust the proximal convergence angle. We further defined under which hydrodynamic and geometric conditions it is necessary to apply the corrected convergence angle. BACKGROUND The proximal flow convergence method has been proposed as a new approach to quantify valvular regurgitation. However, significant overestimation of the calculated regurgitant flow rate has been reported, particularly in patients with mitral valve prolapse and severe mitral regurgitation. METHODS We used an in vitro flow model and induced various degrees of proximal flow constraint. The accuracy of the proposed convergence angle formula, alpha = tau + 2 tan-1 d/r (d = wall distance; r = isovelocity radius) was tested in vitro and in a three-dimensional numerical simulation. RESULTS With a constraining wall near the orifice, overstimulation of regurgitant flow rates was noted and was most significant with the constraining wall positioned closest to the orifice (calculated flow rate [Qc]/true flow rate [Qo] = 1.85 +/- 0.55 [mean +/- SD]). These findings were similar to the results of the numerical simulation. Applying the correction factor nearly completely eliminated the overestimation of the calculated flow rates (cQc), with cQc/Qo = 1.13 +/- 0.25. CONCLUSIONS In the presence of a constraining wall, significant overestimation of calculated flow rates is observed when hemispheric symmetry of the flow field is assumed. In this situation, it is necessary to apply the corrected convergence angle formula to improve the accuracy of the proximal flow convergence method.

UI MeSH Term Description Entries
D008944 Mitral Valve Insufficiency Backflow of blood from the LEFT VENTRICLE into the LEFT ATRIUM due to imperfect closure of the MITRAL VALVE. This can lead to mitral valve regurgitation. Mitral Incompetence,Mitral Regurgitation,Mitral Valve Incompetence,Mitral Insufficiency,Mitral Valve Regurgitation,Incompetence, Mitral,Incompetence, Mitral Valve,Insufficiency, Mitral,Insufficiency, Mitral Valve,Regurgitation, Mitral,Regurgitation, Mitral Valve,Valve Incompetence, Mitral,Valve Insufficiency, Mitral,Valve Regurgitation, Mitral
D008955 Models, Cardiovascular Theoretical representations that simulate the behavior or activity of the cardiovascular system, processes, or phenomena; includes the use of mathematical equations, computers and other electronic equipment. Cardiovascular Model,Cardiovascular Models,Model, Cardiovascular
D009716 Numerical Analysis, Computer-Assisted Computer-assisted study of methods for obtaining useful quantitative solutions to problems that have been expressed mathematically. Analysis, Computer-Assisted Numerical,Computer-Assisted Numerical Analysis,Analyses, Computer-Assisted Numerical,Analysis, Computer Assisted Numerical,Computer Assisted Numerical Analysis,Computer-Assisted Numerical Analyses,Numerical Analyses, Computer-Assisted,Numerical Analysis, Computer Assisted
D001783 Blood Flow Velocity A value equal to the total volume flow divided by the cross-sectional area of the vascular bed. Blood Flow Velocities,Flow Velocities, Blood,Flow Velocity, Blood,Velocities, Blood Flow,Velocity, Blood Flow
D006334 Heart Function Tests Examinations used to diagnose and treat heart conditions. Cardiac Function Tests,Cardiac Function Test,Function Test, Cardiac,Function Test, Heart,Function Tests, Cardiac,Function Tests, Heart,Heart Function Test,Test, Cardiac Function,Test, Heart Function,Tests, Cardiac Function,Tests, Heart Function
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D015203 Reproducibility of Results The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results. Reliability and Validity,Reliability of Result,Reproducibility Of Result,Reproducibility of Finding,Validity of Result,Validity of Results,Face Validity,Reliability (Epidemiology),Reliability of Results,Reproducibility of Findings,Test-Retest Reliability,Validity (Epidemiology),Finding Reproducibilities,Finding Reproducibility,Of Result, Reproducibility,Of Results, Reproducibility,Reliabilities, Test-Retest,Reliability, Test-Retest,Result Reliabilities,Result Reliability,Result Validities,Result Validity,Result, Reproducibility Of,Results, Reproducibility Of,Test Retest Reliability,Validity and Reliability,Validity, Face
D015982 Bias Any deviation of results or inferences from the truth, or processes leading to such deviation. Bias can result from several sources: one-sided or systematic variations in measurement from the true value (systematic error); flaws in study design; deviation of inferences, interpretations, or analyses based on flawed data or data collection; etc. There is no sense of prejudice or subjectivity implied in the assessment of bias under these conditions. Aggregation Bias,Bias, Aggregation,Bias, Ecological,Bias, Statistical,Bias, Systematic,Ecological Bias,Outcome Measurement Errors,Statistical Bias,Systematic Bias,Bias, Epidemiologic,Biases,Biases, Ecological,Biases, Statistical,Ecological Biases,Ecological Fallacies,Ecological Fallacy,Epidemiologic Biases,Experimental Bias,Fallacies, Ecological,Fallacy, Ecological,Scientific Bias,Statistical Biases,Truncation Bias,Truncation Biases,Bias, Experimental,Bias, Scientific,Bias, Truncation,Biase, Epidemiologic,Biases, Epidemiologic,Biases, Truncation,Epidemiologic Biase,Error, Outcome Measurement,Errors, Outcome Measurement,Outcome Measurement Error
D015986 Confounding Factors, Epidemiologic Factors that can cause or prevent the outcome of interest but are not intermediate variables of the factor(s) under investigation. Confounding Factor, Epidemiologic,Confounding Factors, Epidemiological,Confounding Factors, Epidemiology,Confounding Variables,Confounding Variables, Epidemiologic,Confounding Variables, Epidemiological,Confounding Factor, Epidemiological,Confounding Factor, Epidemiology,Confounding Variable,Confounding Variable, Epidemiologic,Confounding Variable, Epidemiological,Epidemiologic Confounding Factor,Epidemiologic Confounding Factors,Epidemiologic Confounding Variable,Epidemiologic Confounding Variables,Epidemiological Confounding Factor,Epidemiological Confounding Factors,Epidemiological Confounding Variable,Epidemiological Confounding Variables,Epidemiology Confounding Factor,Epidemiology Confounding Factors,Variable, Confounding,Variable, Epidemiologic Confounding,Variable, Epidemiological Confounding,Variables, Confounding,Variables, Epidemiologic Confounding,Variables, Epidemiological Confounding
D018618 Echocardiography, Doppler, Color Echocardiography applying the Doppler effect, with the superposition of flow information as colors on a gray scale in a real-time image. Color Flow Echocardiography,Doppler Echocardiography, Color,Echocardiography, Color Doppler,Echocardiography, Color Flow,Color Doppler Echocardiography,Color Echocardiography, Doppler,Doppler Color Echocardiography,Echocardiography, Doppler Color,Color Flow Echocardiographies,Echocardiographies, Color Flow,Flow Echocardiographies, Color,Flow Echocardiography, Color

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