Case Image
Two patients with known bicuspid aortic valve stenosis presented for
surgical aortic valve replacement. During the pre-cardiopulmonary bypass
transesophageal echocardiogram (TEE) examination both patients were
incidentally found to have a fibrous strand that could be intermittently
identified traversing the anterior-posterior axis of the valve(Figure 1A, Video 1A). There was no significant regurgitation
or stenosis appreciated on the Doppler examination of the valve.
3-dimensional (3D) TEE was subsequently used to characterize these
lesions further in both patients. In our first patient 3D-TEE
examination of the valve, showed a fibrous strand connecting the
anterior and posterior leaflets at the leaflet edge level giving this
patient a diagnosis of double orifice mitral valve (DOMV) ‘incomplete
bridge type (Figure 1B&C, Video 1 B&C).’ In our second
patient on 3D-TEE a fibrous bridge could be clearly seen dividing the
atrioventricular orifice completely from the leaflet edge all the way
through the valve annulus (Figure 1D) giving this patient a diagnosis of
DOMV ‘complete bridge type.’
DOMV is a rare congenital cardiac anomaly occurring in 1% of autopsied
cases of congenital heart disease and is typically associated with other
congenital cardiac pathologies.1 DOMV is defined as a
single fibrous annulus with two orifices opening into the left ventricle
and can be classified into three types: the ‘incomplete bridge type’ the
‘complete bridge type’ as described for patients 1 & 2 in our case
image series and the then the ‘hole type’ where a secondary orifice with
subvalvular apparatus occurs in the lateral commissure of the
MV.2 3D-TEE has been shown to be a valuable tool for
characterizing and classifying congenital cardiac lesions such as
DOMV.3 In our first patient, we see how on
2-dimensional TEE the ‘fibrous strand’ could be mistaken for mobile
vegetation or torn chordae tendineae (Figure 1A, Video 1A) , but
when viewed with 3D-TEE and with multiplanar reconstruction we can
clearly see the fibrous strand connecting the anterior and posterior
leaflets at the leaflet edge level (Figure 1B&C, Video 1B&C ).
For our second patient, we see how 3D-TEE clearly demonstrates the
fibrous bridge that divides the atrioventricular orifice completely from
the leaflet edge all the way through the valve annulus (Figure
1D) .
The etiology of DOMV remains unclear with a defect in the endocardial
cushion being one postulated cause. This etiology is supported by the
fact that DOMV is rarely an isolated pathology as it is often associated
with other cardiac congenital anomalies such as coarctation of the
aorta, patent ductus or BAV as seen in both of our cases. Treatment of
DOMV will depend on whether if it is associated with mitral valve
regurgitation or stenosis with surgical repair or replacement being an
option. Many patients remain asymptomatic with DOMV being picked up
incidentally and no intervention is required as in both of our patients
presented in this image series.