Transient right-to-left shunt at the atrial level during activities such as coughing is most consistent with which defect?

Transient right-to-left shunt at the atrial level during activities such as coughing is most consistent with which defect?

• A. Patent foramen ovale
• B. Atrial septal defect
• C. Patent ductus arteriosus
• D. Atrioventricular septal defect

Answer: (A)

Transient shunting from right to left at the atrial level during coughing is most characteristic of a patent foramen ovale. The foramen ovale is a flap-like opening between the atria that normally closes after birth as left atrial pressure rises. If the flap remains patent, brief increases in right atrial pressure—such as during coughing or a Valsalva maneuver—can push blood through the flap from right to left, producing a temporary, atrial-level right-to-left shunt. This pattern is not typical of a fixed atrial septal defect, which usually causes left-to-right flow unless pulmonary hypertension develops, nor of a patent ductus arteriosus or a complex AV septal defect, which have different shunting characteristics.

Transient shunting from right to left at the atrial level during coughing is most characteristic of a patent foramen ovale. The foramen ovale is a flap-like opening between the atria that normally closes after birth as left atrial pressure rises. If the flap remains patent, brief increases in right atrial pressure—such as during coughing or a Valsalva maneuver—can push blood through the flap from right to left, producing a temporary, atrial-level right-to-left shunt. This pattern is not typical of a fixed atrial septal defect, which usually causes left-to-right flow unless pulmonary hypertension develops, nor of a patent ductus arteriosus or a complex AV septal defect, which have different shunting characteristics.