Supramitral congenital mitral stenosis: a rare case

Congenital mitral stenosis (CMS) is a rare congenital heart disease and is anatomically divided into typical mitral stenosis, hypoplastic congenital mitral stenosis, supravalvalar mitral stenosis, parachute mitral valve and subvalvar stenosis. A 40 days old male prematurely delivered, very low birth weight was symptomatic since neonatal period was admitted with respiratory distress and not gaining weight. On examination, he had respiratory distress and tachycardia without dysmorphism. He had pansystolic murmur and pulmonary hypertension. Echo cardiography revealed supramitral membrane with mitral stenosis and ventricular septal defect. Clinically congenital mitral stenosis is difficult to diagnose as coexisting intracardiac lesions may mask or unmask the disease.Despite great advances in surgical technique, surgical treatment of CMS is still challenge able particularly in neonates and small infants.


Introduction
Mitral valve formation begins during the fourth week of gestation of life. Anatomically, mitral valve apparatus is composed of annulus, leaflets, chordae, and papillary muscle. Isolated congenital mitral stenosis (CMS) is rare and the reported incidence in autopsy series with congenital heart disease is about 0.6% and in clinical series about 0.4% [1,2]. Clinically, anatomic types of congenital mitral valve stenosis divides into typical mitral stenosis, hypoplastic congenital mitral stenosis, supravalvalar mitral stenosis, parachute mitral valve and subvalvar stenosis which is also known as mitral arcade [3]. In neonates, congenital mitral stenosis is unlikely to present as an isolated lesion; rather it is frequently part of a complex or syndrome involving the left heart. CMS most commonly exist in association with left heart under development, coarctation of aorta, subvalvar aortic stenosis, atrial septal defect, ventricular septal defect with or without pulmonary stenosis, shone's complex and variable degrees of hypoplastic left heart syndrome [4,5,6]. Here, we describe an infant with supramitral congenital mitral stenosis with ventricular septal defect.

Case Report
A 40 days old male infant was admitted with fever, cough/cold and difficulty in respiration. He also had history of feeding difficulty and not gaining weight adequately. He was born prematurely (32 weeks of gestation), first of birth order through vaginal delivery with birth weight 1500 grams without any history of maternal teratogenic drug intake, radiation exposure, maternal infection, medical or surgical illness during pregnancy.
He was NICU graduate for prematurity, respiratory distress and feeding difficulty and was advised feeding with nutritional supplementation on discharge. None of his family members had congenital heart diseases or genetic diseases. He was immunized for BCG vaccine and developmentally normal as per age. On physical examination, he had signs of failure to thrive, tachycardia (HR172/min) with normal rhythm and pulses were palpable in all four limbs with systemic The examination of cardio vascular system revealed a grade III/VI pansystolic murmur in mitral area and conducted widely to other areas of precordium. The second heart sound had a loud pulmonary component.
The liver was palpable 2cm below the right costal margin.
Respiratory system examination revealed crepitations on the right mammary and inframammary area.
The Chest X ray showed a cardiomegaly and pulmonary plethora ( Figure 1).
The electro cardiogram revealed sinus rhythm and was suggestive of left atrium and right ventricular hypertrophy.
Echocardiography was diagnostic and showed dilatation of left atrium and right ventricle.
There was a supramitral membrane with reduced mitral valve area (0.7cm/sq m) and 3mm ventricular septal defect.
Severe tricuspid regurgitation and severe pulmonary hypertension were noted (Figure 2A &2B).
Diagnosis of severe congenital mitral stenosis due to supramitral membrane with severe pulmonary hypertension was confirmed and patient was referred to cardiothoracic surgeon for further management. Congenital mitral stenosis is a rare entity; reported incidence on clinical series with congenital heart disease is 0.21 to 0.4% [1,2] and takes several types. A recent opinion to surgical management is balloon dilatation, which is appropriate even for infants, with unsuccessful medical management but chances of restenosis reported from various studies [2]. Operative results and long-term outcome are extremely variable and highly dependent on coexisting anomalies [2,7,8,9].