Aortic valve morphology influences regurgitant volume in aortic regurgitation

In vivo evaluation

Paul A. Grayburn, Eric J. Eichhorn, Robert C. Eberhart, John B. Bedotto, M. Elizabeth Brickner, Anne L. Taylor

Research output: Contribution to journalArticle

Abstract

Study objective - According to the Gorlin hydraulic orifice equation, aortic regurgitation volume can be determined by the regurgitant orifice cross sectional area, diastolic filling period, mean pressure gradient between the aorta and left ventricle, and a constant relating the coefficients of contraction (Cc) and velocity (Cv). This study was performed to determine whether variation in aortic valve morphology affects regurgitant flow volume, Cc and Cv. Design - Four aortic valve templates, modelled after circular, rheumatic, degenerative, and bicuspid lesions, were constructed with equal orifice cross sectional areas in two sizes, 0.2 and 0.7 cm2. These valves were studied in vitro in a flow model of aortic regurgitation, wherein aortic pressure was regulated by varying the height of a column of fluid. Flow, pressure, and velocity were measured, and the coefficient Cc and Cv were calculated from standard equations. Measurements and main results - Regurgitant volume was assessed at diastolic filling periods of 0.5 and 1.0 s and averaged 15% greater for bicuspid and degenerative as compared to circular or rheumatic valve shapes (p=0.0001). This difference was accentuated at the shorter diastolic filling time and higher pressure gradient, such that bicuspid lesions allowed 29% more regurgitant flow across the 0.2 cm2 orifice at fluid height of 120 cm over 0.5 s. This difference in regurgitant volume between valve shapes was due to an increased Cc for the bicuspid and degenerative valve shapes, suggesting that they are more efficient orifices than rheumatic or circular valve shapes. Conclusions - Aortic valve morphology influences regurgitant volume in aortic regurgitation. Specifically, degenerative and bicuspid orifice shapes have a higher contraction coefficient and allow more regurgitant flow than rheumatic or circular orifices at a given driving pressure and diastolic filling time.

Original languageEnglish (US)
Pages (from-to)73-79
Number of pages7
JournalCardiovascular Research
Volume25
Issue number1
StatePublished - 1991

Fingerprint

Aortic Valve Insufficiency
Bicuspid
Orifices
Aortic Valve
Contraction
Evaluation
Pressure
Pressure Gradient
Coefficient
Pressure gradient
Fluid
Aorta
Mitral Valve
Left Ventricle
Heart Ventricles
Arterial Pressure
Hydraulics
Template
Blood Pressure
Fluids

Keywords

  • Aortic insufficiency
  • Aortic valve morphology
  • Blood flow velocity

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Statistics, Probability and Uncertainty
  • Applied Mathematics
  • Physiology (medical)
  • Physiology

Cite this

Grayburn, P. A., Eichhorn, E. J., Eberhart, R. C., Bedotto, J. B., Brickner, M. E., & Taylor, A. L. (1991). Aortic valve morphology influences regurgitant volume in aortic regurgitation: In vivo evaluation. Cardiovascular Research, 25(1), 73-79.

Aortic valve morphology influences regurgitant volume in aortic regurgitation : In vivo evaluation. / Grayburn, Paul A.; Eichhorn, Eric J.; Eberhart, Robert C.; Bedotto, John B.; Brickner, M. Elizabeth; Taylor, Anne L.

In: Cardiovascular Research, Vol. 25, No. 1, 1991, p. 73-79.

Research output: Contribution to journalArticle

Grayburn, PA, Eichhorn, EJ, Eberhart, RC, Bedotto, JB, Brickner, ME & Taylor, AL 1991, 'Aortic valve morphology influences regurgitant volume in aortic regurgitation: In vivo evaluation', Cardiovascular Research, vol. 25, no. 1, pp. 73-79.
Grayburn, Paul A. ; Eichhorn, Eric J. ; Eberhart, Robert C. ; Bedotto, John B. ; Brickner, M. Elizabeth ; Taylor, Anne L. / Aortic valve morphology influences regurgitant volume in aortic regurgitation : In vivo evaluation. In: Cardiovascular Research. 1991 ; Vol. 25, No. 1. pp. 73-79.
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AB - Study objective - According to the Gorlin hydraulic orifice equation, aortic regurgitation volume can be determined by the regurgitant orifice cross sectional area, diastolic filling period, mean pressure gradient between the aorta and left ventricle, and a constant relating the coefficients of contraction (Cc) and velocity (Cv). This study was performed to determine whether variation in aortic valve morphology affects regurgitant flow volume, Cc and Cv. Design - Four aortic valve templates, modelled after circular, rheumatic, degenerative, and bicuspid lesions, were constructed with equal orifice cross sectional areas in two sizes, 0.2 and 0.7 cm2. These valves were studied in vitro in a flow model of aortic regurgitation, wherein aortic pressure was regulated by varying the height of a column of fluid. Flow, pressure, and velocity were measured, and the coefficient Cc and Cv were calculated from standard equations. Measurements and main results - Regurgitant volume was assessed at diastolic filling periods of 0.5 and 1.0 s and averaged 15% greater for bicuspid and degenerative as compared to circular or rheumatic valve shapes (p=0.0001). This difference was accentuated at the shorter diastolic filling time and higher pressure gradient, such that bicuspid lesions allowed 29% more regurgitant flow across the 0.2 cm2 orifice at fluid height of 120 cm over 0.5 s. This difference in regurgitant volume between valve shapes was due to an increased Cc for the bicuspid and degenerative valve shapes, suggesting that they are more efficient orifices than rheumatic or circular valve shapes. Conclusions - Aortic valve morphology influences regurgitant volume in aortic regurgitation. Specifically, degenerative and bicuspid orifice shapes have a higher contraction coefficient and allow more regurgitant flow than rheumatic or circular orifices at a given driving pressure and diastolic filling time.

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