Differential Diagnosis
- Single most likely diagnosis
- Ventricular septal defect (F): The presence of a grade 4/6 holosystolic murmur with a thrill along the lower left sternal border is highly suggestive of a ventricular septal defect. The symptoms of progressive fatigue, increasing dyspnea, and excessive perspiration during feeding are also consistent with a large left-to-right shunt, which is typical of a ventricular septal defect. The accentuated P₂ and diastolic murmur at the apex further support this diagnosis, indicating increased flow across the pulmonary valve and potential pulmonary hypertension or increased flow across the mitral valve.
- Other Likely diagnoses
- Atrial septal defect (A): Although less likely than a ventricular septal defect given the murmur characteristics, an atrial septal defect could still present with increased flow across the pulmonary valve (accentuated P₂) and signs of heart failure in infancy, such as failure to thrive and respiratory distress. However, the holosystolic nature of the murmur and the presence of a thrill are more characteristic of a ventricular septal defect.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Hypoplastic left heart syndrome (C): This condition is less likely given the acyanotic status and the specific murmur characteristics, but it is crucial to consider because it requires urgent surgical intervention. Infants with hypoplastic left heart syndrome often present with severe heart failure and may have a single S2 due to the underdeveloped left side of the heart.
- Transposition of the great arteries (E): Typically presents with cyanosis, which is not mentioned in this case. However, it's a critical diagnosis to consider in any infant with signs of heart failure or respiratory distress, as it requires prompt recognition and treatment.
- Rare diagnoses
- Ebstein anomaly (B): Characterized by an abnormal tricuspid valve and right ventricular hypoplasia. It might present with cyanosis and signs of heart failure, but the murmur pattern described does not typically match Ebstein anomaly.
- Pulmonary stenosis (D): Could present with a systolic ejection murmur and signs of right ventricular hypertrophy, but the combination of findings, especially the holosystolic murmur and the diastolic murmur at the apex, makes this less likely.