Subaortic membrane with patent ductus arteriosus

A 10 years old boy diagnosed as subaortic membrane with patent ductus arteriosus presented with history of occasional fever, repeated respiratory tract infection since childhood and poor gain weight.


Introduction
Sub aortic membrane is an infrequent disease that produces variable degree of obstruction to the degrees of blood across left ventricular outflow tract. 1 Its prevalence is 1-2% of all congenital cardiac defects and causes 15-20% of all fixed left ventricular outflow tract obstructtions. 2 Disease has overall male preponderance with gender ratio of 2:1 to 3:1.2The prevalence of discrete subaortic stenosis is increasing in adults due to greater number of repaired congenital heart diseases. 3Ventricular septal defect, atrial septal defect, patent ductus arteriosus, coarctation of aorta, bicuspid aortic valve, parachute mitral valve, and persistent left superior venacava are among the associated congenital cardiac defects in 25-50% of the cases.Disease etiology is not completely understood. Patent ductus arteriosus is usually found as an isolated lesion in the patients with noncyanotic congenital heart disease.Association of patent ductus arteriosus with sub aortic membrane is found in about 14% of the patients. 6Children usually become symptomatic at the age of 10-20 years.Exertional dyspnea, effort angina and syncope are most common symptoms.On cardiovascular examination, a low pitched ejection systolic murmur in second and third left intercostal space with radiation to suprasternal notch and absent ejection click is the most important clue for the diagnosis of subaortic membrane.ECG may show left ventricular hypertrophy (50-85%) and strain pattern in 25% of the patients.
Echocardiography is the main imaging study.2D echo allows definition of exact type, location, extent of left ventricular outflow tract and aortic valve involvement.CW Doppler records peak and mean pressure gradient across left ventricular outflow tract.Transesophageal echocardiography allows per operative evaluation of lesion, guides surgical resection and provides immediate surgical results. 7

Case Report
A 10 year old boy was admitted in the Department of Cardiac Surgery, Bangabandhu Sheikh Mujib Medical University with the history of occasional fever, repeated respiratory tract infection since childhood and poor weight gain.On clinical evaluation there was systolic murmur best heard in the aortic area.Chest X-ray was normal.ECG revealed sinus tachycar-dia.Echocardiography revealed: Subaortic membrane causing severe aortic valve stenosis (peak pressure gradient was 107 mm Hg).Mitral regurgitation was in Grade II.There was mild tricuspid regurgitation with mild pulmonary hypertension (pulmonary artery systolic pressure: 38 mm Hg).There was a large patent ductus arteriosus (size: 5.

Discussion
In a study of 35 patients, the prevalence of associated other congenital cardiac defects was 65% [patent ductus arteriosus (34%), VSD (20%), coarctation (23%), PS (9%) and miscellaneous defects (9%). 8n our case, it was found to be associated with patent ductus arteriosus.Association of subaortic stenosis with tetrology of fallot, especially in women, is extremely rare.The etiology of discrete subaortic stenosis in general and in association with patent ductus arteriosus is unclear. 9This endocardial abnormality involves the subaortic ridge and the leaflets of the adjacent valves. 10Those patients who have left ventricle-aorta gradients beyond 30 mm Hg 11 or has a co-existing cardiac defect requires surgical correction while some authors advocate surgical resection for subaortic membrane for any degree of obstruction because aortic insufficiency, left ventricular hypertrophy and infective endocarditis may develop due to subaortic stenosis Surgical. 12, 13As in our case the patient had patent ductus arteriosus with peak pressure gradient 107 mm Hg.It is also said that recurrence and reoperation can be prevented by surgical resection of fixed subaortic stenosis before the development of a significant outflow tract gradient i.e., >40 mm Hg. 14 The most favorable surgical method for patients with subaortic membrane is questionable.Enucleation of the discrete membrane with its fibromuscular ridge is the most preferable method for some surgeons, while other surgeons do the resection of the hypertrophied muscle with routine myomectomy.The occurrence of late aortic regurgitation can be reduced by radical excision of all diseased tissue. 15But this aggressive process may increase the risk of iatrogenic damage to the conduction tissue (injury to the conduction tissue between the right and noncoronary cusps), mitral valve and ventricular septal defect.In this case, ligation of the patent ductus arteriosus was done then radical excision of the diseased tissue was done and adequate opening of the aortic valve was secured.
There is significant rate of recurrence of subaortic stenosis but cause of recurrence for left ventricular outflow tract obstruction is still unknown even after adequate excision.Routine removal of underlying septal muscle may prevent recurrence which may be an important cause as it is the initial site of fibromuscular obstruction. 16 8 mm) with left to right shunt with peak pressure gradient of 120 mm Hg.He was scheduled for patent ductus arteriosus ligation and subaortic membrane resection on 18/3/2017.The standard median sternotomy | Case | Report | Abstract A 10 years old boy diagnosed as subaortic membrane with patent ductus arteriosus presented with history of occasional fever, repeated respiratory tract infection since childhood and poor gain weight.