Cardiac disorders - Outflow obstruction in the well child

Question 1

Outflow obstruction in the well child

Aortic stenosis

Answer 1

• Small volume, slow rising pulses
• Carotid thrill (always)
• Ejection systolic murmur maximal at the upper right sternal edge radiating to the neck
• Delayed and soft aortic second sound
• Apical ejection click.

Management:

• Children with symptoms on exercise or who have a high resting pressure gradient (>64 mmHg) across the aortic valve will undergo balloon valvotomy
• Most neonates and children with significant aortic valve stenosis requiring treatment in the first few years of life will eventually require aortic valve replacement

Question 2

Outflow obstruction in the well child

Pulmonary stenosis

Answer 2

• An ejection systolic murmur best heard at the upper left sternal edge; thrill may be present
• An ejection click best heard at the upper left sternal edge
• When severe, there is a prominent right ventricular impulse (heave).

Management:

• Most children are asymptomatic and when the pressure gradient across the pulmonary valve becomes markedly increased (> about 64 mmHg), intervention will be required.
• Trans-catheter balloon dilatation is the treatment of choice in most children.

Question 3

Outflow obstruction in the well child

Adult-type coarctation of the aorta

Answer 3

Uncommon lesion is not duct dependent. It gradually becomes more severe over many years.

Clinical features:

• Asymptomatic
• Systemic hypertension in the right arm
• Ejection systolic murmur at upper sternal edge
• Collaterals heard with continuous murmur at the back
• Radio-femoral delay. This is due to blood bypassing the obstruction via collateral vessels in the chest wall and hence the pulse in the legs is delayed

Management:

When the condition becomes severe, as assessed by echocardiography, a stent may be inserted at cardiac catheter. Sometimes surgical repair is required

Question 4

Outflow obstruction in the sick infant

Coarctation of the aorta

This is due to arterial duct tissue encircling the aorta just at the point of insertion of the duct. When the duct closes, the aorta also constricts, causing severe obstruction to the left ventricular outflow. This is the commonest cause of collapse due to left outflow obstruction.

Answer 4

Clinical features:

• Examination on the first day of life is usually normal. The neonates usually present with acute circulatory collapse at 2 days of age when the duct closes.
• A sick baby, with severe heart failure
• Absent femoral pulses
• Severe metabolic acidosis

Managment:

• As for all the children in this section with an obstructed left outflow tract. Surgical repair is performed soon after diagnosis

Question 5

Outflow obstruction in the sick infant

Interruption of the aortic arch

Answer 5

• Uncommon, with no connection between the proximal aorta and distal to the arterial duct, so that the cardiac output is dependent on right-to-left shunt via the duct
• A VSD is usually present
• Presentation is with shock in the neonatal period as above
• Complete correction with closure of the VSD and repair of the aortic arch is usually performed within the first few days of life.
• Association with other conditions (DiGeorge syndrome – absence of thymus, palatal defects, immunodeficiency and hypocalcaemia and 22q11.2 gene micro-deletion).

Question 6

Outflow obstruction in the sick infant

Hypoplastic left heart syndrome

Answer 6

• In this condition there is underdevelopment of the entire left side of the heart.
• The mitral valve is small or atretic, the left ventricle is diminutive and there is usually aortic valve atresia.
• The ascending aorta is very small, and there is almost invariably coarctation of the aorta.

Management:

The management of this condition consists of a difficult neonatal operation called the Norwood procedure. This is followed by a further operation (Glenn or hemi-Fontan) at about 6 months and again (Fontan) at about 3 years.