Original Articles
Direct quantification of transmitral flow volume with dynamic 3-dimensional digital color Doppler: A validation study in an animal model*

https://doi.org/10.1067/mje.2002.116716Get rights and content

Abstract

Accurately quantifying transmitral flow volume is clinically important not only as a measure of cardiac output, but also as a value from which to subtract aortic flow, for determining the severity of mitral regurgitation. However, controversy exists over the accuracy of pulsed Doppler for mitral flow quantification because of the complexity of mitral flow geometry and dynamic changes in flow profile and flow area. To explore the feasibility of directly quantifying transmitral flow volume with a newly developed dynamic 3-dimensional digital color Doppler technique, this in vivo experimental study was conducted to validate the method. Eight open chest sheep were imaged with a multiplane transesophageal (TEE) probe placed on the heart for digital 3-dimensional gated acquisition of mitral inflow over a 180-degree acquisition. The digital velocity data were contour detected for flow area after computing the velocity vectors and flow profile perpendicular to a spherical 3-dimensional surface across the mitral annulus. Flow areas and actual velocities were then integrated in time and space and the resulting flow volumes were compared with those obtained by a reference electromagnetic flowmeter on the aorta for 26 steady hemodynamic states. The flow volumes correlated closely to the electromagnetic references (y = 0.87x + 2.49, r = 0.92, SEE = 1.9 Ml per beat). Our study shows that transmitral flow volume can be accurately determined in vivo by this dynamic 3-dimensional digital color Doppler flow quantification method. (J Am Soc Echocardiogr 2002;15:55-62.)

Section snippets

Experimental preparation

Eight juvenile sheep weighing 18.1 to 57 kg (mean 43 kg) were studied. Anesthesia was induced with intravenous sodium pentobarbital (25 mg/kg body weight) and maintained with 1% to 2% isoflurane with oxygen. The animals were ventilated by means of an endotracheal tube using a volume-cycle ventilator. Median sternotomy was then performed. All operative and animal management procedures were approved by the Animal Care and Use Committee of the National Heart, Lung and Blood Institute.

Left ventricular flow volumes determined by electromagnetic flow meters

Left ventricular stroke volumes ranged from 9.8 Ml per beat to 29.5 Ml per beat (heart rate 80-140 beats per minute).

Left ventricular flow volumes determined by 3-dimensional echocardiography

Transmitral flow volumes measured by the 3-dimensional method ranged from 9.3 to 29.2 Ml per beat. There was good correlation between these measurements and left ventricular flow volumes with the electromagnetic probe (y = 0.87x + 2.49, r = 0.92, SEE = 1.9 Ml per beat, P <.0001; Figure 4).

. Simple linear regression showed good correlation between 3-dimensional measured transmitral

Discussion

The ability to accurately quantify transmitral flow volume directly, taking into account the dynamic change of mitral flow and without assuming the geometry of the flow area or the flow profile, represents an important technical advance in Doppler echocardiography. It also provides a potential means not only of determining cardiac output but also of quantifying the severity of mitral regurgitation, as the difference between mitral inflow and aortic outflow, in the absence of aortic valve

Conclusion

Our study has demonstrated that the dynamic 3-dimensional digital color Doppler method we developed is an accurate means of directly quantifying transmitral flow volume in an animal model. The technique also allowed temporal characterization of mitral inflow and full spatial characterization of its velocity profile. Our 3-dimensional method could be applied to any of the cardiac valves and should be a promising tool for determining cardiac output and regurgitant volumes in patients.

References (28)

  • K Tamura et al.

    A comparison of failure modes of glutaraldehyde-treated versus antibiotic-preserved mitral valve allografts implanted in sheep

    J Thorac Cardiovasc Surg

    (1995)
  • SC Reimold et al.

    Effective aortic regurgitant orifice area: description of a method based on the conservation of mass

    J Am Coll Cardiol

    (1991)
  • T Shiota et al.

    Evaluation of aortic regurgitation with digitally determined color Doppler-imaged flow convergence acceleration: a quantitative study in sheep

    J Am Coll Cardiol

    (1996)
  • EJ Meijboom et al.

    A simplified mitral valve method for two-dimensional echo Doppler blood flow calculation: validation in an open-chest canine model and initial clinical studies

    Am Heart J

    (1987)

    • Cited by (0)

    *

    Reprint requests: Michael Jones, MD, Room 107A, Building 14E, National Institutes of Health, Bethesda, MD 20892. (E-mail: [email protected]).

    View full text
    Copyright © 2002 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.