A cyanotic neonate with tricuspid atresia, normally related great arteries, and a small VSD is being assessed. Which component of the cardiac catheterization data MOST accurately reflects the severity of pulmonary blood flow restriction?
- A Pulmonary artery pressure ✓
- B Right atrial pressure
- C Left ventricular end-diastolic pressure
- D Degree of oxygen saturation step-up at the atrial level
Correct answer: A. Pulmonary artery pressure
Explanation
In tricuspid atresia with normally related great arteries, the entire systemic venous return shunts right-to-left across the ASD into the left atrium. Pulmonary blood flow depends on the size of the VSD and the subpulmonary outflow. Low pulmonary artery pressure with reduced pulmonary blood flow (oligemia on CXR) indicates severe restriction; higher pulmonary artery pressure suggests relatively unrestricted flow. This guides the decision between Blalock-Taussig shunt (for low Qp) versus pulmonary artery banding (for high Qp) as initial palliation.
Reference: Ghai Essential Pediatrics, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.