Differential Diagnosis of Isolated Right Ventricular Dysfunction in a Previously Well Infant

Single Most Likely Diagnosis

• Viral myocarditis: This is often the most common cause of isolated right ventricular dysfunction in infants, as viral infections can directly affect the myocardium, leading to inflammation and dysfunction. The right ventricle may be more susceptible due to its thinner walls and higher compliance.

Other Likely Diagnoses

• Congenital heart defects: Although the infant was previously well, some congenital heart defects may not be immediately apparent and can lead to right ventricular dysfunction over time, such as tetralogy of Fallot or pulmonary stenosis.
• Pulmonary embolism: Though less common in infants, pulmonary embolism can cause acute right ventricular dysfunction due to the sudden increase in pulmonary vascular resistance.
• Anomalous left coronary artery from the pulmonary artery (ALCAPA): This rare congenital coronary anomaly can lead to myocardial ischemia and dysfunction, particularly affecting the right ventricle.

Do Not Miss Diagnoses

• Pulmonary hypertension: This condition can rapidly progress and is critical to identify early, as it can lead to severe right ventricular dysfunction and failure. Causes can include persistent pulmonary hypertension of the newborn (PPHN), congenital heart disease, or other pulmonary vascular diseases.
• Arrhythmogenic right ventricular cardiomyopathy (ARVC): Although rare in infants, ARVC is a condition where the muscle in the right ventricle is replaced by fat and scar tissue, which can disrupt the heart's normal function and lead to life-threatening arrhythmias.
• Toxic ingestions: Certain substances can directly affect the heart, leading to dysfunction. In infants, accidental ingestions can occur, and it's crucial to consider this in the differential diagnosis.

Rare Diagnoses

• Right ventricular non-compaction: A rare cardiomyopathy characterized by the presence of excessive trabeculations in the right ventricle, which can lead to dysfunction.
• Neonatal lupus: A rare condition caused by the transplacental passage of autoantibodies from mother to fetus, which can affect the heart and lead to congenital heart block or cardiomyopathy, including right ventricular dysfunction.
• Storage diseases: Certain metabolic storage diseases, such as Pompe disease or Hurler syndrome, can affect the heart and lead to ventricular dysfunction, though they are rare and often present with other systemic symptoms.