Differential Diagnosis for a One-Day-Old Baby with a Rub or Squeak Type of Cardiac Murmur

• Single Most Likely Diagnosis
  • Functional (innocent) murmur: This is the most common cause of a cardiac murmur in a newborn, often due to the normal transition from fetal to adult circulation. The murmur is usually a soft, systolic ejection murmur, but can sometimes present as a rub or squeak.
• Other Likely Diagnoses
  • Patent ductus arteriosus (PDA): A common congenital heart defect where the ductus arteriosus fails to close after birth, leading to a continuous murmur ("machinery" murmur), but can sometimes be heard as a systolic ejection murmur or a rub.
  • Tricuspid regurgitation: Can occur in newborns, especially those with respiratory distress or other cardiac anomalies, and may present with a systolic murmur.
• Do Not Miss Diagnoses
  • Hypoplastic left heart syndrome (HLHS): A serious congenital heart defect where the left side of the heart is underdeveloped. Although the murmur is often more complex, a single systolic ejection murmur or a rub can be an initial presentation.
  • Critical aortic stenosis: A severe congenital heart defect where the aortic valve is narrowed, leading to significant obstruction of blood flow. The murmur can be a harsh systolic ejection murmur, but in severe cases, may present with a softer murmur or rub due to decreased cardiac output.
• Rare Diagnoses
  • Rhabdomyoma: A rare cardiac tumor that can cause a murmur due to obstruction of blood flow. Although more commonly associated with tuberous sclerosis, it can occur in isolation.
  • Coronary artery fistula: An abnormal connection between a coronary artery and another cardiac chamber or vessel, which can cause a continuous murmur, but may be heard as a systolic ejection murmur or rub in some cases.