Sneezing or coughing at times may cause a mild shunt from the right atrium to the left atrium through which defect?

Sneezing or coughing at times may cause a mild shunt from the right atrium to the left atrium through which defect?

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

Answer: (A)

When intrathoracic pressure rises, as during sneezing or coughing, the right atrial pressure can transiently increase. If the foramen ovale remains open (a patent foramen ovale), this pressure rise can push blood from the right atrium into the left atrium through the flap-like opening, causing a mild right-to-left shunt. This shunt is dynamic and occurs with momentary pressure changes, which is why sneezing or coughing can reveal it. Other atrial septal defects involve a persistent opening between the atria, but the normal situation is left atrial pressure being higher, so the typical shunt is left-to-right rather than right-to-left and is not usually triggered by brief pressure spikes. The patent ductus arteriosus and atrioventricular septal defects create different pathways and shunt patterns that aren’t characteristically opened by a simple Valsalva-like maneuver.

When intrathoracic pressure rises, as during sneezing or coughing, the right atrial pressure can transiently increase. If the foramen ovale remains open (a patent foramen ovale), this pressure rise can push blood from the right atrium into the left atrium through the flap-like opening, causing a mild right-to-left shunt. This shunt is dynamic and occurs with momentary pressure changes, which is why sneezing or coughing can reveal it.

Other atrial septal defects involve a persistent opening between the atria, but the normal situation is left atrial pressure being higher, so the typical shunt is left-to-right rather than right-to-left and is not usually triggered by brief pressure spikes. The patent ductus arteriosus and atrioventricular septal defects create different pathways and shunt patterns that aren’t characteristically opened by a simple Valsalva-like maneuver.