aortic stenosis

 Aortic stenosis

Aortic stenosis is also called aortic valve stenosis.

Aortic stenosis narrowing of aortic valve, which controls blood flow between left ventricular and aorta.

Types of aortic valve stenosis

1. Valvular 

Stricture of aortic valve.

2. Subvalvular stenosis

Narrowing below valve resulting from thin membrane or thick fibrous ring in subvalvular region of aortic valve.

3. Supravalvular aortic stenosis

Stenosis above aortic valve.

Pathophysiology

Presence of aortic stenosis

Obstruction to outflow of blood from left ventricle

Result thickening or hypertrophy of left ventricle, in response to increased work load require to eject blood.

Degree of obstruction varies from mild to severe

Pressure in left ventricle increases with degree of obstruction.

Incase of moderate to severe aortic stenosis

Left ventricle hypertrophied and left ventricular pressure is quite high.

Heart failure develop due to excessive workload placed on left ventricles which pumps blood against obstruction.

In severe cases, 

Pulmonary edema occur result of increased left atrial pressure.

May cause a backflow of blood into lungs.

Clinical features

Depend upon type and degree of stenosis.

Most children asymptomatic and defect is diagnosed during routine Physical examination.

With severe obstruction to outflow of blood from left ventricle, children present following symptoms-

1. Fatigue and excercise intolerance

2. Exertional dyspnea; shortness of breath during excercise

3. Chest pain

4. Syncope- fainting and sudden loss of consciousness

5. Infant with severe aortic stenosis, present with cardiac failure in neonatal period.

Symptoms are - irritable, pale, hypotensive, tachypenic, tachycardia

Decrease perfusion

and cause pulmonary congestion

Diagnostic Evaluation

1. Cardiac Examination

Systolic murmur

Ejection click heared

Suprasternal notch, palpable 

2. Electrocardiogram

ECG may normal or show left ventricular hypertrophy.

May ST - segment depression- indicates myocardial ischemia.

3. Chest radiograph

Heart size, dilatation of ascending aorta seen incase of valvular stenosis.

4. Echocardiogram

2D echocardiogram

Type of aortic stenosis

Left ventricular wall thickness

Left ventricular function evaluated

5. Cardiac catheterization

Determine site and size of stenosis.

Incase of severe stenosis, aortic pressure is abnormal and left atrial pressure is increased.

Therapeutic Management

Infants and children 

1. Mild to moderate aortic stenosis, require no surgery.

2. For infant with severe valvular aortic stenosis; surgery or balloon dilatation done.

a. Median sternotomy; valvular aortic stenosis is repaired.

b. Balloon dilatation, catheter placed across aortic valve, inflated to separate leaflets and then deflated and removed.

Procedure known Aortic balloon valvuloplasty.

In significant aortic insufficiency; aortic valve replacement required.

3. Konno procedure

1. In subvalvular aortic stenosis; surgery done to remove obstructing membrane or fibrous ring below aortic valve.

Which involves removing obstructing muscles, widening outflow area of left ventricle and replacing aotiv valve with artificial valve.

Three common types of valve available when replacing aortic valve - 

1. Heterograft valve ; (porcine valve and bovine pericardium valve).

2. Prosthetic valve

3. Homograft valve (human donor valves)

If obstruction to outflow cannot relieved,

Value conduit be placed from left ventricle to descending aorta.

2. Supravalvular aortic stenosis repaired by in using narrow segment of aorta and widening area with patch graft.