Differential Diagnosis for a 28-month-old Boy with Cyanosis and Syncope
- Single most likely diagnosis
- Tetralogy of Fallot: This condition is characterized by cyanosis since birth, episodes of syncope (due to decreased blood flow to the brain), and specific heart sounds such as a systolic click and a single S2. The presence of a right ventricular heave and a grade 3/6 systolic murmur also supports this diagnosis, as Tetralogy of Fallot involves right ventricular outflow tract obstruction, which can cause these clinical findings.
- Other Likely diagnoses
- None: Given the combination of symptoms and signs, especially the presence of cyanosis since birth and the specific cardiac findings, Tetralogy of Fallot stands out as the most fitting diagnosis. However, other congenital heart diseases could potentially present with some similar features, though they would not as neatly align with all the provided details.
- Do Not Miss diagnoses
- Patent ductus arteriosus with pulmonary hypertension and reversal of shunt (Eisenmenger syndrome): Although less likely given the specific murmur and click described, any condition leading to significant pulmonary hypertension could result in cyanosis and needs to be considered due to its implications for management and prognosis.
- Coarctation of the aorta: While coarctation primarily presents with hypertension in the arms, decreased or delayed pulses in the lower extremities, and might not directly cause cyanosis unless associated with other cardiac anomalies, it's a critical diagnosis not to miss due to its potential for severe complications if untreated.
- Rare diagnoses
- Bicuspid aortic valve: This condition might lead to a systolic murmur but is less likely to cause cyanosis and the specific constellation of findings described.
- Mitral stenosis: Rare in children and not typically associated with cyanosis at birth or the specific cardiac examination findings mentioned.
- Other complex congenital heart diseases: There are numerous other congenital heart defects that could potentially present with cyanosis and murmurs, but they would be less common and might not fit as well with the specific details provided in the scenario.