Tetralogy of Fallot

1. Right ventricular outflow obstruction. Typically multi-level: small, malformed pulmonic valve, hypoplastic proximal pulmonary artery, and muscular narrowing below the valve.

2. Ventricular septal defect. With significant obstruction in the right ventricular outflow tract, blood will shunt from right to left, bypassing the lungs and leading to cyanosis.

3. Right ventricular hypertrophy (thickened muscle wall) secondary to higher pressure load on this chamber.  

4. The aorta "overrides" the VSD. 

Tetralogy Repair: Intracardiac View

5. Muscular right ventricular outflow obstruction has been cut away as part of the repair.

6. Patch closure of the VSD.

Tetralogy Repair: Surface View

7. Right ventricular outflow patch to address all levels of obstruction.