Outflow obstruction

Question 1

What is aortic stenosis?

Answer 1

Aortic valve leaflets are partly fused together giving a restrictive exit from the LV. May be 1 to 3 aortic leaflets.

Often associated with mitral valve stenosis and coarctation of the aorta - presence should always be excluded.

Question 2

Presentation of aortic stenosis?

Answer 2

Signs:

1) Asymptomatic ejection systolic murmur - UR sternal edge
2) Carotid thrills ALWAYS
3) Small volume, slow rising pulses
4) Apical ejection click
5) Slow, soft 2nd aortic sound

Symptoms:

1) Reduced exercise tolerance + chest pain
2) Syncope

Question 3

Diagnosis of aortic stenosis?

Answer 3

1) CXR - normal/prominant left ventricle, with post-stenotic dilatation of the ascending aorta.
2) ECG - may show LV hypertrophy - deep S wave in V2, and tall R wave in V6

Question 4

Treatment of aortic stenosis?

Answer 4

1) Balloon valvotomy in those with symptoms on exercise or who have a high pressure gradient - safer in older children than neonates
2) Those with significant aortic valve stenosis will eventually require VALVE REPLACEMENT.

Question 5

What is pulmonary stenosis?

Answer 5

Pulmonary valve leaflets are partly fused together giving a restrictive exit from the RV.

Question 6

Symptoms of pulmonary stenosis?

Answer 6

1) Most are asymptomatic
2) Ejection systolic murmur best heard at the UL sternal edge
3) Ejection click heard at the UL sternal edge
4) RV heave when severe

Question 7

Diagnosis of pulmonary stenosis?

Answer 7

1) CXR - Normal or post-stenotic dilatation of the pulmonary artery
2) ECG - Right ventricular hypertrophy (upright T-wave in V1)

Question 8

Treatment of pulmonary stenosis?

Answer 8

1) Transcatheter balloon dilatation

Question 9

What is the ‘coarctation of aorta’?

Answer 9

Defined as a narrowing in the aorta most commonly as the site of insertion of the ductus arteriosus/ligamentum arteriosus just distal to the left subclavian artery (post ductal or preductal).
Associated with berry aneurysms, Turner’s syndrome and PDA.

Question 10

Pathophysiology of coarctation of aorta?

Answer 10

• Narrowing of aorta distal to LSC at ductus arteriosus region, that becomes more severe over many years.
• The net result is the narrowing of the aorta just after the arch, with excessive blood flow being diverted through the carotid and subclavian vessels into systemic vascular shunts to supply the rest of the body.
• This leads to stronger perfusion to upper body compared to lower.
• Resultant decreased renal perfusion leads to systemic hypertension that persists even after surgical correction.
  Neonates:
  Coarctation occurs due to arterial duct tissue encircling the aorta at the point of insertion of the ductus arteriosus, and when the duct closes the aorta also constricts in this region - severe obstruction to LV flow.

Question 11

Clinical presentation of Coarctation of Aorta?

Answer 11

1) Asymptomatic
2) Systemic hypertensions
3) Ejection systolic murmur at upper sternal edge
4) Radio-femoral delay as a result of blood bypassing obstruction via collateral vessels in chest walls - pulse in legs delayed
5) Weak femoral pulses

Neonates:

1) Examination normal on 1st day of life
2) Acute circulatory collapse on day 2 when duct closes
3) Weak femoral pulses
4) Severe metabolic acidosis

Question 12

Diagnosis of coarctation of Aorta?

Answer 12

1) CXR - ‘Rib notching’ due to development of collateral intercostal arteries running under ribs to bypass obstruction.
- 3 sign, with visible notch in descending artery at site of coarctation
2) ECG - Left ventricular hypertrophy
3) 4 limb BP - discrepancy between upper and lower limbs
4) Neonates: CXR - cardiomegaly due to shock and HF
ECG- notmal

Question 13

Treatment of coarctation of aorta?

Answer 13

In the neonate: Prostaglandin E1 can be used to keep ductus arteriosus patent to help support haemodynamic stability in the acute stage: IV Alprostadil

• Stent insertion via cardiac catheter when older
• Surgical repair

Question 14

Hypoplastic left heart syndrome PPx?

Answer 14

1) Underdevelopment of the whole LHS of the heart
2) Mitral valve is small or atretic (absent)
3) Left ventricle in diminutive and small - usually aortic valve atresia
4) Almost always coarctation of the aorta

Question 15

Clinical presentation of hypoplastic left heart syndrome?

Answer 15

1) No flow through the left side of the heart - ductal constriction leads to profound acidosis and rapid CV collapse
2) Weakness or absence of all peripheral pulses (in contrast to weak femoral pulses in coarctation of the aorta)

Question 16

Diagnosis of hypoplastic left heart syndrome?

Answer 16

Often detected antenatally at ultrasound - allowed for effective counselling and prevents child being sick after birth.

Question 17

Treatment of hypoplastic left heart syndrome

Answer 17

Difficult operation called Norwood procedure.