Cleft Anterior Mitral Leaflet with Supravalvular Aortic Stenosis a Rare Association.

A 20 year old female was referred to us for evaluation of effort dyspnoea of NYHA class II with feeble left common carotid, left brachial and left radial artery as compared to other sides. Detail evaluation with two dimensional (2D) transthoracic echocardiographic, 2D transesophageal echocardiography and multidetector computed tomography (MDCT) delineated Cleft AML and diffuse type of supravalvular aortic stenosis. To the best of our knowledge, no such case have been described in the literature where these anomalies co-existed in the same patient.

INTRODUCTION

The anterior mitral leaflet (AML) cleft is an unusual congenital lesion first described in 1954.[1] It results from the failure of the endocardial cushions to seal together the two components of the anterior leaflet of the mitral valve.[2] Echocardiography is the investigative modality of choice in the evaluation of suspected or known mitral valve congenital abnormalities as it provides useful information about the anatomical and morphological details, mechanism of mitral regurgitation (MR) and its quantitative evaluation. We describe a clinical case of cleft AML associated with supravalvular aortic stenosis (SAS).

CASE REPORT

A 20-year-old female was referred to us for evaluation of effort dyspnoea of New York Heart Association class II. On general examination, the pulse rate was 88/min., upper limb pulse was asymmetric with feeble pulse involving the left common carotid, left brachial and left radial arteries. The lower limb pulses were bilaterally symmetrical. The blood pressure was 140/88 mmHg in right arm and the jugular venous pressure was normal. Cardiovascular examination revealed a pansystolic murmur at apex radiating to the axilla and an ejection systolic murmur at right second intercostal space radiating to carotids.

Chest, abdomen and central nervous system examination were normal. Chest X-ray showed cardiomegaly and electrocardiography showed left atrial enlargement and left ventricular hypertrophy. Evaluation with two-dimensional TTE showed dilated left atrium (LA) and left ventricle (LV) with hypoplastic ascending aorta [Figure 1a] and a trileaflet aortic valve [Figure 1b]. Continuous wave Doppler showed a peak velocity of 6 m/s with a peak gradient of 144 mmHg across the supra valvular narrowing [Figure 1c]. Parasternal short axis view clearly demonstrated the cleft in the AML [Figure 2a and b], with severe eccentric MR [Figure 2c]. Further evaluation with two-dimensional TEE clearly delineated the hypoplastic ascending aorta [Figure 1d] and the severe eccentric jet of the MR [Figure 2d] [Videos 1–5]. To know the extent of hypoplasia of the aorta, MDCT with volume rendering was done, which showed hypoplasia involving the ascending aorta, left common carotid, left subclavian artery with normal arch and the descending thoracic and abdominal aorta. The LA was dilated secondary to severe MR [Figure 3]. The patient is awaiting corrective surgery.

Figure 1

Two-dimensional transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) - parasternal long axis view (a) dilated left atria, left ventricle with hypoplastic ascending aorta and basal short axis view, (b) tricuspid aortic valve. Continuous wave Doppler, (c) a peak velocity of 6 m/s with a peak gradient of 144 mmHg across the supra valvular narrowing. Two-dimensional TEE, (d) clearly delineated the hypoplastic ascending aorta. Asc. Ao = Ascending aorta; LA = Left atria; LV = Left ventricle; AS = Aortic stenosis; AR = Aortic regurgitation

Figure 2

Two-dimensional transthoracic echocardiography and transesophageal echocardiography (TEE) - parasternal short axis view (a) the cleft in the anterior mitral leaflet, which was leading to severe eccentric mitral regurgitation, (b) apical four chamber view, (c) and two-dimensional TEE, (d) clearly delineating above mentioned finding. AML = Anterior mitral leaflet; MR = Mitral regurgitation

Figure 3

Multidetector computed tomography - showing hypoplasia involving the ascending aorta, left common carotid, left subclavian artery with normal arch and the descending thoracic and abdominal aorta (a and b). Asc. Ao = Ascending aorta

DISCUSSION

Clefts, defined as slit-like holes or defects, are hypothesized as being a result of an incomplete expression of an endocardial cushion defect (ECD), which most commonly involves the anterior mitral valve leaflet. The pediatric incidence is 1:1340.[3] The lesion is responsible for 33% of congenital MR and is an uncommon entity in adults.[4] Cleft AML occurs as part of a congenital syndrome associated with ECD, atrial septal defect, ventricular septal defect, or transposition of the great arteries.[5] If atrio-ventricular junction is normal and MR is mild, patients may be asymptomatic for many years and the mitral cleft may be found by chance. Cleft is the main determinant of MR, but often annular dilatation and restricted motion of the anterior leaflet coexist. Furthermore, the interactions between leaflets, an accessory chordal attachment, papillary muscles, LA and LV free wall contributes to MR.

Supravalvular aortic stenosis was first described by Mencarelli in 1930[6] and is estimated to occur in approximately 1 of 25,000 live births.[7] It accounts for approximately 0.5% of congenital heart diseases cases. Out of the total cases of SAS, 30–50% have associated Williams–Beuren syndrome,[8] about 20% of cases are familial without other feature of Williams–Beuren syndrome, and the remaining cases are sporadic. It exists in two forms, (1) discrete form in which the narrowing is localized to the supravalvar area of the ascending aorta, or (2) as a diffuse form in where the narrowing affects the whole length of the ascending aorta and a variable amount of the arch and brachiocephalic vessels.[9] Our case had the diffuse variety of SAS. SAS can also be a part of Shones complex.

Cleft AML and diffuse type of SAS are rare entities individually. To the best of our knowledge, no such case have been described in the literature where these anomalies co-existed in the same patient. Also, the combination of anomalies seen in our case is dangerous as the severity of MR is increased in the presence of any obstruction in the LV outflow region. Hence, the patient is advised to undergo corrective surgery as early as possible.