Evaluation of a new 3-dimensional color Doppler flow method to quantify flow across the mitral valve and in the left ventricular outflow tract: an in vitro study.
OBJECTIVE
The aim of this study was to assess the accuracy, feasibility, and reproducibility of determining stroke volume from a novel 3-dimensional (3D) color Doppler flow quantification method for mitral valve (MV) inflow and left ventricular outflow tract (LVOT) outflow at different stroke volumes when compared with the actual flow rate in a pumped porcine cardiac model.


METHODS
Thirteen freshly harvested pig hearts were studied in a water tank. We inserted a latex balloon into each left ventricle from the MV annulus to the LVOT, which were passively pumped at different stroke volumes (30-80 mL) using a calibrated piston pump at increments of 10 mL. Four-dimensional flow volumes were obtained without electrocardiographic gating. The digital imaging data were analyzed offline using prototype software. Two hemispheric flow-sampling planes for color Doppler velocity measurements were placed at the MV annulus and LVOT. The software computed the flow volumes at the MV annulus and LVOT within the user-defined volume and cardiac cycle.


RESULTS
This novel 3D Doppler flow quantification method detected incremental increases in MV inflow and LVOT outflow in close agreement with pumped stroke volumes (MV inflow, r = 0.96; LVOT outflow, r = 0.96; P < .01). Bland-Altman analysis demonstrated overestimation of both (MV inflow, 5.42 mL; LVOT outflow, 4.46 mL) with 95% of points within 95% limits of agreement. Interobserver variability values showed good agreement for all stroke volumes at both the MV annulus and LVOT.


CONCLUSIONS
This study has shown that the 3D color Doppler flow quantification method we used is able to compute stroke volumes accurately at the MV annulus and LVOT in the same cardiac cycle without electrocardiographic gating. This method may be valuable for assessment of cardiac output in clinical studies.
Department of Pediatric Cardiology, Oregon Health and Science University, 3181 SW Sam Jackson Park Dr, L608, Portland, OR 97239-3098 USA. sahnd@ohsu.edu.
Sumito
S
Kimura
Cole
C
Streiff
Meihua
M
Zhu
Eriko
E
Shimada
Saurabh
S
Datta
Muhammad
M
Ashraf
David J
DJ
Sahn
D000818:Animals; D001783:Blood Flow Velocity; D018618:Echocardiography, Doppler, Color / Q000379:methods*; D019560:Echocardiography, Three-Dimensional / Q000379:methods*; D005240:Feasibility Studies; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D066298:In Vitro Techniques; D008943:Mitral Valve / Q000000981:diagnostic imaging* / Q000502:physiology*; D015203:Reproducibility of Results; D012212:Rheology / Q000379:methods; D012680:Sensitivity and Specificity; D013318:Stroke Volume / Q000502:physiology*; D013552:Swine; D016277:Ventricular Function, Left / Q000502:physiology*
3-dimensional; color Doppler; echocardiography; flow quantification; in vitro model