Can Isolated Discordant Atrioventricular Connections Survive Without Interatrial or Interventricular Shunt?

Area of Science:

• Pediatric Cardiology
• Congenital Heart Disease
• Cardiac Anatomy

Background:

• Isolated discordant atrioventricular connections typically present with severe cyanosis at birth.
• Profound cyanosis is expected in neonates lacking significant intracardiac shunts.

Purpose of the Study:

• To describe the clinical presentation and unique cardiac anatomy of an infant with isolated discordant atrioventricular connections.
• To explain the mechanism of mild cyanosis in the presence of an unusual cardiac malformation.

Main Methods:

• Case report of a 5-month-old infant.
• Detailed echocardiographic and anatomical assessment of the cardiac malformation.

Main Results:

• The infant presented with mild cyanosis, atypical for the condition.
• A straddling left-sided tricuspid valve with a closed interventricular communication was identified.
• This anomaly, termed "Double Outlet Left Atrium with three atrioventricular valves," created a necessary left-to-right shunt.
• Severe tricuspid regurgitation and a patent ductus arteriosus ensured effective pulmonary blood flow.

Conclusions:

• A straddling tricuspid valve can create a functional intracardiac shunt, mitigating severe cyanosis in discordant atrioventricular connections.
• This case highlights the diverse clinical presentations of congenital heart defects and the importance of detailed anatomical evaluation.