TY - JOUR
T1 - Dynamic change in mitral regurgitant orifice area
T2 - comparison of color doppler echocardiographic and electromagnetic flowmeter-based methods in a chronic animal model
AU - Shiota, Takahiro
AU - Jones, Michael
AU - Teien, Dag E.
AU - Yamada, Izumi
AU - Passafini, Arnaldo
AU - Ge, Shuping
AU - Sahn, David J.
N1 - Funding Information:
Doppler echocardiographie quantitative evaluation of valvular regurgitant lesions has been attempted using a number of methods, none of which has achieved general clinical utilization (1-5). Imaging of the proximo! flow convergence region in the left ventricle for flow accelerating retrograde across the mitral valve has been reported (6-8) to 4-useful for identifying the site of regurgitation and for grading its severity. The flow convergence phenomenon has been used experimentally and clinically for quantifying the regurgitant flow volume and flow rate using a variety of assumptions, most commonly that of a hemispheric isovelocity flow convergence sllrface (9-22). Recently, methods for computing mitral regurgitant orifice SciencesU niversity,P ortland,O regon;a nd *Laboratoryo f Animal Medicinea nd Surgery, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland. This study was supported in part by Grant HL 43287 from the National Heart, Lung, and Blood Institute, National Insftutes of Health, Bethesda,M aryland. Manuscriptr eceivedJ anuary5 , 1995;r evised':oanuscriptr eceivedM arch3 0, 1995, acceptedA pril 4, 1995. ~ddress for corresoondence:D r. Michael Jones, National Institutes of Health, National Heart, Lung, and BloodI nstitute, Building 14E, Room 107A, 9000 RockvilleP ike, Bethesda, Maryland2 0892.
PY - 1995/8
Y1 - 1995/8
N2 - Objectives. The aim of the present study was to investigate dynamic changes in the mitral regurgitant orifice using electromagnetic flow probes and flowmeters and the color Doppler flow convergence method. Background. Methods for determining mitral regurgitant orifice areas have been described using flow convergence imaging with a hemispheric isovelocity surface assumption. However, the shape of flow convergence isovelocity surfaces depends on many factors that change during regurgitation. Methods. In seven sheep with surgically created mitral regurgitation, 18 hemodynamic states were studied. The aliasing distances of flow convergence were measured at 10 sequential points using two ranges of aliasing velocities (0.20 to 0.32 and 0.56 to 0.72 m/s), and instantaneous flow rates were calculated using the hemispheric assumption. Instantaneous regurgitant areas were determined from the regurgitant flow rates obtained from both electromagnetic flowmeters and flow convergence divided by the corresponding continuous wave velocities. Results. The regurgitant orifice sizes obtained using the electromagnetic flow method usually increased to maximal size in early to midsystole and then decreased in late systole. Patterns of dynamic charges in orifice area obtained by flow convergence were not the same as those delineated by the electromagnetic flow method. Time-averaged regurgitant orifice areas obtained by flow convergence using lower aliasing velocities overestimated the areas obtained by the electromagnetic flow method ([mean ± SD] 0.27 ± 0.14 vs. 0.12 ± 0.06 cm2, p < 0.001), whereas flow convergence, using higher aliasing velocities, estimated the reference areas more reliably (0.15 ± 0.06 cm2). Conclusions. The electromagnetic flow method studies uniformly demonstrated dynamic change in mitral regurgitant orifice area and suggested limitations of the flow convergence method.
AB - Objectives. The aim of the present study was to investigate dynamic changes in the mitral regurgitant orifice using electromagnetic flow probes and flowmeters and the color Doppler flow convergence method. Background. Methods for determining mitral regurgitant orifice areas have been described using flow convergence imaging with a hemispheric isovelocity surface assumption. However, the shape of flow convergence isovelocity surfaces depends on many factors that change during regurgitation. Methods. In seven sheep with surgically created mitral regurgitation, 18 hemodynamic states were studied. The aliasing distances of flow convergence were measured at 10 sequential points using two ranges of aliasing velocities (0.20 to 0.32 and 0.56 to 0.72 m/s), and instantaneous flow rates were calculated using the hemispheric assumption. Instantaneous regurgitant areas were determined from the regurgitant flow rates obtained from both electromagnetic flowmeters and flow convergence divided by the corresponding continuous wave velocities. Results. The regurgitant orifice sizes obtained using the electromagnetic flow method usually increased to maximal size in early to midsystole and then decreased in late systole. Patterns of dynamic charges in orifice area obtained by flow convergence were not the same as those delineated by the electromagnetic flow method. Time-averaged regurgitant orifice areas obtained by flow convergence using lower aliasing velocities overestimated the areas obtained by the electromagnetic flow method ([mean ± SD] 0.27 ± 0.14 vs. 0.12 ± 0.06 cm2, p < 0.001), whereas flow convergence, using higher aliasing velocities, estimated the reference areas more reliably (0.15 ± 0.06 cm2). Conclusions. The electromagnetic flow method studies uniformly demonstrated dynamic change in mitral regurgitant orifice area and suggested limitations of the flow convergence method.
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U2 - 10.1016/0735-1097(95)80033-D
DO - 10.1016/0735-1097(95)80033-D
M3 - Article
C2 - 7608460
AN - SCOPUS:0029102702
SN - 0735-1097
VL - 26
SP - 528
EP - 536
JO - Journal of the American College of Cardiology
JF - Journal of the American College of Cardiology
IS - 2
ER -