2DE views, including ME MC and TG basal SAX, demonstrated the rare congenital anomaly of DOMV. The appearance of the pivot point on the MV leaflets (Fig. 1A) in the ME MC suggests that the tissue bridge is at the annular level. Unfortunately, we did not acquire a TG 2-chamber view or a TG long-axis view. These views could have been instrumental in demonstrating separate subvalvular apparatuses for each orifice as well as showing 2 separate jets on CFD coming into the LV.
Even though this patient had no hemodynamically significant valvular abnormalities associated with his complete bridge type, approximately 50% do have significant regurgitation or stenosis that needs to be surgically repaired. It is much more common to have regurgitant lesions rather than stenotic ones with double-orifice MVs. When examining these patients for mitral stenosis, it is crucial that the pulsed-wave Doppler sampling gate be placed at the tips of the MV leaflets of both orifices. If there is only 1 orifice with stenosis, the echocardiographer should calculate the total MV area (MVA) by combining the area of both orifices. If this total MVA is <1.0 to 1.5 cm2, it necessitates surgical repair. The MVA of both orifices can be calculated by the pressure half-time method or deceleration time and added together. Likewise, it can be calculated by the continuity equation but the 2 combined velocity time integrals (VTIs) of the MV orifices should be in the denominator.
where D = diameter, LVOT = left ventricular outflow tract.
Mitral regurgitation should be evaluated as if it is a single orifice valve. Severe mitral regurgitation through only 1 orifice would constitute need for surgical repair. This could be evaluated by measurement of the vena contracta width, regurgitant volume, or effective regurgitant orifice area.
Due to the en face atrial view of the MV, RT3DE allows the echocardiographer to visualize the tissue bridge more clearly. The RT3DE atrial and ventricular views demonstrated that the orifices were of equal size and were positioned anterolateral to inferomedial. Regrettably, we did not acquire a full volume 3D image that could be cropped across the valve from lateral to medial, necessary to determine the depth of the bridge. Both 2DE and RT3DE established that the tissue bridge was across the middle scallop of the posterior leaflet (P2) and middle segment of the anterior leaflet (A2). Transesophageal echocardiography can be useful in the evaluation of this anomaly regarding the specific type of DOMV, as well as whether or not there is hemodynamically significant mitral regurgitation or stenosis.
Clinician’s Key Teaching Points
By Kent H. Rehfeldt, MD, Nikolaos J. Skubas, MD, and Martin J. London, MD
* Double-orifice mitral valve (DOMV) is a rare congenital anomaly where a fibrous bridge divides the MV into 2 orifices. Many patients with DOMV are asymptomatic though approximately 50% have either mitral regurgitation or stenosis that warrants surgical intervention; regurgitation is more common than stenosis.
* DOMV is suspected by the finding of a pivot point at the level of the bridging tissue in the midesophageal mitral commissural view. Transgastric basal short-axis or en face views of the MV, obtained with 2D and 3D imaging, respectively, may be used to identify the separate orifices. In approximately 85% of cases, DOMV is characterized by a smaller, eccentric accessory orifice adjacent to one of the commissures.
* In this case, the tissue bridge at the annular level created 2 nearly equal-sized orifices. Color Doppler showed only trivial mitral regurgitation with no evidence of diastolic inflow turbulence and pulsed-wave Doppler performed separately for each orifice confirmed the lack of stenosis.
* When assessing MV area in patients with DOMV, the areas of each orifice should be combined; continuity or pressure half-time methods can be used and valve replacement should be considered if the MV area is <1.5 cm2. Regurgitation can be assessed as though the valve has a single orifice using vena contracta, regurgitant volume, or effective regurgitant orifice calculations.
Name: Nadia Hensley, MD.
Contribution: This author helped write the manuscript.
Attestation: Nadia Hensley approved the final manuscript.
Name: Rosanne Sheinberg, MD.
Contribution: This author helped write the manuscript.
Attestation: Rosanne Sheinberg approved the final manuscript.
This manuscript was handled by: Martin J. London, MD.
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