Value of Three-Dimensional Echocardiography in Assessing Double-Orifice Mitral Valve in an Asymptomatic Patient

Abstract

Double-orifice mitral valve (DOMV) is a rare congenital anomaly consisting of an accessory bridge of fibrous tissue, which divides the mitral valve (MV) into two orifices. The mitral leaflets are essentially normal in most cases, but they can be regurgitant or stenotic. It is most commonly associated with a variety of other cardiac anomalies. Isolated DOMV with normal MV function is very rare. We present here a rare case of congenital DOMV in a 25-year-old female diagnosed by real-time three-dimensional echocardiography (RT3DE). RT3DE enabled complete anatomical and functional assessment of MV apparatus. It added much valuable information over conventional 2DE that helped in establishment of the diagnosis, identification of the anatomical type, and selection of the proper management.

INTRODUCTION

Double-orifice mitral valve (DOMV) is a rare congenital anomaly that was first described by Greenfield in 1876.[1] It can be seen in young and middle-aged patients, with an estimated incidence of 0.06%.[2] This anomaly is consisting of an accessory bridge of fibrous tissue, which partially or completely divides the mitral valve (MV) into two orifices. The size of the orifices is balanced in only 15%.[2] Anatomically and functionally, the mitral leaflets are essentially normal in most cases, but they can be regurgitant or stenotic. It is most commonly associated with a variety of other cardiac anomalies such as coarctation of the aorta, a bicuspid aortic valve, Ebstein's anomaly, and most commonly, atrioventricular septal defects.[1,3] The concomitant cardiac anomalies and malfunction of the valve usually lead to an early diagnosis in childhood. Isolated DOMV is extremely rare, but the exact incidence, prevalence, and prognostic relevance have not been established.[4] DOMV with normal MV function was seen in 37% of the patients.[5]

We present here a rare case of congenital DOMV in a 25-year-old female diagnosed by real-time three-dimensional (3D) echocardiography.

CASE REPORT

A 25-year-old female was referred to our hospital for cardiac evaluation. She had no previous medical history. She was asymptomatic. The clinical examination was normal. Accordingly, a complete transthoracic 2D echocardiography with color Doppler examination using Philips ultrasound machine (EPIQ-7) was performed. In parasternal short-axis view, the MV orifice showed an accessory tissue between both leaflets, but it was not clearly identified as two orifices [Figure 1a]. Two papillary muscles were clearly visualized [Figure 1b]. Apical two-chamber view showed the division of MV opening into 2 by an accessory tissue. The MV was functioning well (no regurgitation or stenosis). The other valves were normal in function and morphology. To obtain a detailed description of MV apparatus, transesophageal echocardiography (TEE) was performed using the same machine and X7 matrix probe that enabled to do 2D and 3D images at the same time. At mid-esophageal level, the MV orifice was divided into two unequal orifices with normal function [Figure 1c and Video 1]. The 3D en face view of MV from both atrial and ventricular aspects clearly showed that the MV orifice was divided by a complete anteroposterior bridge into two asymmetrical orifices. The orientation of leaflets from both atrial and ventricular aspects showed that each orifice had its own annulus, leaflets, and commissures [Figure 1d]. 3D planimetry measurement of orifice area of the anterolateral one is 0.9 cm² and the posteromedial one is 2.1 cm² [Figure 2]. There were no other associated cardiac anomalies. Despite normal blood pressure and absence of radiofemoral pulse delay, it was important to exclude associated mild degree of coarctation. 2D echocardiography showed turbulent color flow across the descending aorta, but the maximum pressure gradient recorded by continuous Doppler was 12 mmHg. That is why computed tomography scan was performed to rule out associated coarctation. The diagnosis was established as an isolated congenital DOMV with normal valve function, and no further step is needed.

Figure 1.

(a) Two-dimensional transthoracic echo of mitral valve orifice in parasternal short-axis view, (b) Two papillary muscles (white arrows) in short axis, (c) X-plane two-dimensional transesophageal echo at mid-esophageal level showed mitral valve opening divided into two orifices, (d) En face view from both atrial (right image) and ventricular (left image) aspects of mitral valve by three-dimensional transesophageal echocardiography showed two asymmetrical orifices (yellow arrows) separated by complete bridge

Figure 2.

Quad screen of three-dimensional multiplanar reconstruction of the double-orifice mitral valve with measurement of both orifices (arrows)

DISCUSSION

DOMV is a rare congenital cardiac anomaly characterized by a MV with a single fibrous annulus and two orifices. The clinical presentation and management depend on the type and severity of valve dysfunction and the associated congenital defects.

Various classifications for DOMV have been proposed.[3,4] Based on the size and location of the two orifices, four types were identified: (1) complete bridge type (about 15% of DOMVs), in which both orifices are visible from the leaflet edge, all the way through the valve ring. Both openings are circular (equal or unequal in size), (2) incomplete bridge type: A connection is seen between the anterior and posterior leaflets only at the leaflet edges, resulting in a double circle only at the leaflet level. At the mid-basal level, the MV appears normal, (3) hole type – the most common variety, characterized by a small accessory orifice situated at either the anterolateral or posteromedial commissure, and (4) duplicate MV with two annuli and valves, each with its own set of leaflets, commissures, chordae, and papillary muscles.[5]

DOMV is usually detected by 2D echocardiographic examination in short-axis parasternal views. However, information obtained by 2D may be incomplete in recognition of the different types of DOMV. Some authors recommended to use magnetic resonance imaging once DOMV is nearly assured or suspected by 2D echocardiography to confirm the clinical suspicion and to exclude any concurrent cardiac and vascular abnormalities.[6,7] Performing 3D echocardiography is extremely useful in identifying the morphology type and providing further anatomical and functional information, such as orifice size, number of leaflets, and its spatial relationship.[8,9]. In our patient, 2D transthoracic echocardiography was not helpful for assuring the diagnosis due to poor window and low image quality. Transesophageal 2D and 3D echo was used to reach the final diagnosis of DOMV, the duplicate MV type.

DOMV can be rarely diagnosed in asymptomatic middle-aged and elderly patients, as in our case. In any case, the presence of other coexistent cardiovascular abnormalities should be excluded. The management of DOMV is related to the type and severity of MV dysfunction. Asymptomatic DOMV usually requires no active intervention; in case of severe mitral regurgitation, stenosis, or associated cardiac anomalies, surgical repair is needed.[10] In our case, due to the absence of any abnormalities, only long-term follow-up was advised for the early detection of complications.

CONCLUSION

In cases of DOMV, RT3D-TEE is the most reliable method to establish the diagnosis. It also provides a comprehensive assessment of the morphology to determine the type of DOMV.

Human rights statements and informed consent

Echo procedures were performed in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1964 and later revisions. Informed consent was obtained from the patient for being included in that report.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.