Patent Ductus Arteriosus

Relevant physical signs

• Peripheries
  • Differential clubbing – clubbing of the toes but not the fingers
    • PDA usually connects the pulmonary artery to the aorta, distal to left subclavian artery
  • Cyanosis (Eisenmenger’s syndrome)
  • Stigmata of infective endocarditis
  • Pulse
    • Not usually associated with rhythm disturbances
    • Collapsing in character
    • Usually large volume
  • Wide pulse pressure
  • May have central cyanosis (Eisenmenger’s syndrome)
  • Raised jugular venous pressure, giant v waves (tricuspid regurgitation)
• Precordium
  • Palpation
    • Apex beat may be displaced inferolaterally, thrusting quality
    • Right ventricular heave (pulmonary hypertension)
    • Palpable thrill inferior to left clavicle
  • Auscultation
    • Continuous machinery murmur, heard best over left sub-clavicular region
      • Displays systolic accentuation
      • May be heart posteriorly
      • The narrower the shunt, the louder the murmur
    • Normal first heart sound
    • Second heart sound often obscured by murmur
      • May have loud P2 in consequent pulmonary hypertension
    • Other murmurs
      • Mid-diastolic murmur loudest at the apex (increased flow across mitral valve in haemodynamically-significant shunts)
• Complications
  • Pulmonary oedema – left ventricular failure
  • Raised jugular venous pulsation, right ventricular heave, loud P2 – pulmonary hypertension
  • Cyanosis, clubbing – Eisenmenger’s syndrome
  • Janeway lesions, Osler nodes, splinter haemorrhages – infective endocarditis

Differential diagnosis of a continuous murmur

• Coexistent mitral regurgitation and mitral stenosis
• Coexistent ventricular septal defect and aortic regurgitation
• Coexistent tricuspid regurgitation and mitral stenosis
• Coexistent mitral regurgitation and aortic regurgitation
• Arterio-venous fistulae
• Pulmonary arterio-venous shunt (Blalock-Taussig shunts)
• Venous hum (usually right sternal edge, disappears on lying flat, expiration or JVP compression)

Differential diagnosis of a collapsing pulse

• Aortic regurgitation
• Severe mitral regurgitation
• Thyrotoxicosis
• Pregnancy
• Anaemia
• Arterio-venous fistula

Causes of a PDA

• Prematurity
• Low birth weight
• Maternal use of prostaglandins
• Maternal rubella (first trimester)
• High altitude
• Fetal alcohol syndrome
• Maternal phenytoin use
• Maternal amphetamine use
• Maternal hypoxia

Investigation

• Trans-thoracic echocardiogram to confirm diagnosis and assess severity
• Chest radiograph: prominent pulmonary arteries, cardiomegaly, pulmonary oedema
• Electrocardiogram: right ventricular hypertrophy

Management

• Multidisciplinary team approach
• Medical
  • Treat acute episodes of congestive cardiac failure
  • No need for infective endocarditis prophylaxis (unless cyanotic)
  • Prostaglandin inhibitors (preterm infants only)
• Indications for closure (percutaneous catheter occlusion or surgical ligation)
  • Symptomatic left-to-right shunt
  • Left atrial or ventricular enlargement
  • Reversible pulmonary hypertension
• Contraindications for closure: Eisenmenger’s syndrome

Summary

Sir, this patient has a haemodynamically-significant patent ductus arteriosus. On examination of the peripheries, the patient is not clubbed or cyanosed. There are no peripheral stigmata of infective endocarditis. The pulse is regular, large volume and collapsing in nature, and there is a wide pulse pressure. The jugular venous pulsation is not elevated. On examination of the precordium, the apex beat is displaced inferolaterally, and there is a right ventricular heave. On auscultation, there is a grade 5/6 continuous machinery murmur, heard loudest inferior to the left clavicle and also heard at the back. This is associated with a palpable thrill. The first heart sound is normal; the second is obscured by the murmur. I was unable to appreciate a diastolic murmur over the apex which would have signified increased flow across the mitral valve. The patient is currently not in left-sided heart failure.

In conclusion, this patient has a patent ductus arteriosus, which is haemodynamically-significant with a left-to-right shunt.