Author + information
- Received January 5, 1995
- Revision received March 30, 1995
- Accepted April 4, 1995
- Published online August 1, 1995.
- Takahiro Shiota, MDa,
- Michael Jones, MD1,b,
- Dag E. Teien, MDa,
- Izumi Yamada, MDb,
- Arnaldo Passafini, MDa,
- Shuping Ge, MDa and
- David J. Sahn, MD, FACCa
- ↵1Address for correspondence: Dr. Michael Jones, National Institutes of Health, National Heart, Lung, and Blood Institute, Building 14E, Room 107A, 9000 Rockville Pike, Bethesda, Maryland 20892.
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.
☆ This study was supported in part by Grant HL 43287 from the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland.
- Received January 5, 1995.
- Revision received March 30, 1995.
- Accepted April 4, 1995.