Thanks for putting up your query at HealthCareMagic. I am sorry to hear than your daughter has a heart condition since birth. Aortic stenosis refers to a condition that causes obstruction to blood flow between the left ventricle and the aorta. There are a variety of causes, including muscular obstruction below the aortic valve, obstruction at the valve itself, or aortic narrowing immediately above the valve. The most common form of aortic stenosis is obstruction at the valve itself, referred to as aortic valvar stenosis. Aortic stenosis occurs when abnormalities of the aortic valve lead to narrowing and obstruction between the left ventricle and the aorta. The most common abnormality occurs when the aortic valve has only two (instead of three) leaflets. Balloon aortic valvuloplasty is considered the initial treatment of choice in pediatric patients with congenital aortic valve stenosis. Surgical repair or replacement of an aortic valve is primarily reserved for patients in whom balloon valvuloplasty has failed with severe stenosis or have significant valve insufficiency in association with progressive left ventricular dilation or deterioration of left ventricular systolic function. In the neonate, transthoracic echocardiography provides complete diagnostic and hemodynamic information. This would help in evaluating the course of action. Hope that helps. Feel free to revert back in case of further queries if any.