Noonan syndrome associated with anomalous coronary artery and other cardiac defects

Area of Science:

• Pediatric Cardiology
• Congenital Heart Disease
• Genetics

Background:

• Noonan syndrome is a genetic disorder associated with various congenital anomalies, particularly cardiac defects.
• Infants with Noonan syndrome often present with complex structural heart abnormalities requiring surgical intervention.

Observation:

• An 11-month-old infant diagnosed with Noonan syndrome exhibited multiple cardiac anomalies including dysplastic pulmonary valve, biventricular hypertrophy, atrial septal defect, and significant right ventricular outflow tract (RVOT) obstruction (73 mmHg gradient).
• Systolic anterior motion of the mitral valve (SAM) was observed but deemed not clinically significant.
• Anomalous coronary artery was also noted as part of the cardiac presentation.

Findings:

• The infant underwent RVOT transannular repair using a non-cusped xenograft and resection of hypertrophied myocardium.
• The left ventricular outflow tract (LVOT) was intentionally left unrepaired, anticipating that RVOT repair would alleviate dynamic LVOT obstruction.
• Postoperative echocardiography confirmed residual SAM but demonstrated no significant LVOT pressure gradient.

Implications:

• This case highlights the surgical management of complex RVOT obstruction in Noonan syndrome.
• The findings suggest that RVOT repair may influence or resolve dynamic LVOT obstruction, even when SAM is present.
• Further observation is warranted to assess the long-term implications of residual SAM and the effectiveness of the surgical approach in this pediatric population.