Here is an image my father drew of interatrial defects
- There are 4 types of interatrial defects – their name depends on their location: at the top is a sinus venosus defect, middle is secundum ASD (and PFO) and at the bottom is primum ASD
- A persistent sinus venosus defect should result in RA / RV enlargement due to the left to right shunting
- A sinus venosus defect involves either the SVC (superior) or IVC (inferior)
- Superior sinus venosus defects (which are located the junction of the SVC and RA) make up 2-3% of all ASDs and are often associated with anomalous drainage of the right sided pulmonary veins into the RA instead of the LA
- When people refer to an “ASD” – they’re usually referring to a secundum ASD
- Primum ASDs are difficult to treat percutaneously especially if there is no “ridge” (which is apparently best visualised on TOE) and therefore are often treated surgically
- In general, when it comes to interatrial shunting seen on TTE / TOE, if there are no right heart changes, the shunt is probably significant (and certainly not enough to be causing symptoms or oxygen desat)
Teach me Cardiology 