Patent Ductus Arteriosus Flashcards

1
Q

What is a Patent Ductus Arteriosus (PDA)?

A

The persistence of the ductus arteriosus after birth

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2
Q

What is the Ductus arteriosus?

A

A vascular connection between the pulmonary artery and the aortic arch

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3
Q

What is the function of the ductus arteriosus?

A

To shunt blood from the right to the left to bypass the foetus’ lungs

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4
Q

Why should blood bypass the lungs?

A

In the foetus they are compressed and filled with fluid

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5
Q

When does the DA usually begin to close?

A

In the first 48 hours of life

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6
Q

What is considered a PDA?

A

When the shunt has failed to close by 1 month after expected delivery date

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7
Q

What causes the DA to usually close?

A
  • Reduced pulmonary vascular resistance

- Bradykinin causing constriction of the smooth muscle of the DA

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8
Q

What causes the reduced pulmonary vascular resistance?

A

When the newborn takes a first breath and the lungs open

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9
Q

Where is the bradykinin released from?

A

The lungs

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10
Q

When is the DA normally significantly narrowed?

A

12-24 hours after birth

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11
Q

When is the DA normally completely sealed?

A

3 weeks

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12
Q

What causes the DA to remain open in PDA?

A

A defect in the constrictor mechanism of the duct

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13
Q

Why is PDA not considered a cyanotic congenital defect?

A

The flow of blood reverses and moves from the aorta to the pulmonary artery

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14
Q

What are the risk factors for PDA?

A
  • Prematurity
  • Maternal rubella
  • Respiratory distress syndrome
  • High altitude
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15
Q

What do most children with PDA present with?

A

A continuous murmur beneath the left clavicle which continues into diastole

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16
Q

Why is the murmur present in PDA?

A

The pressure in the pulmonary artery is lower than in the aorta throughout the cardiac cycle

17
Q

Are symptoms common in PDA?

A

No, they are unusual

18
Q

What happens in PDA if the duct is large?

A

There will be increased pulmonary flow causing heart failure and pulmonary hypertension

19
Q

What are some rarer signs and symptoms of PDA?

A
  • Tachypnoea
  • Failure to thrive
  • Exercise intolerance
  • Widened pulse pressure
20
Q

What investigation can be used to diagnose PDA?

A

Echo

21
Q

What are the signs on CXR and ECG in PDA?

A

Usually normal

22
Q

What are the differentials for PDA?

A
  • Venous hum
  • Coronary artery fistula
  • Left-sided shunts including VSD and ASD
23
Q

What is the recommended treatment for PDA?

A

Closure of the duct

24
Q

Why is PDA closure recommended?

A

To prevent the risk of bacterial endocarditis and pulmonary vascular disease

25
Q

How is PDA closure carried out?

A

With a coil or occlusion device introduced via a cardiac catheter

26
Q

When is PDA closure usually performed?

A

At around 1 year of age

27
Q

What other surgical treatment is sometimes required?

A

Surgical ligation

28
Q

What are the potential complications of PDA?

A
  • Congestive heart failure
  • Eisenmenger’s syndrome
  • Pulmonary hypertension