Atrial septal defect & PFO
Type, size and rims, RV volume load, Qp:Qs and PVR — and the saline study done properly.
Numbers to remember
- Closure indicated with RV volume overload (usually Qp:Qs >1.5) and PVR <3 WU [25]
- PVR 3–5 WU → consider closure with significant L→R shunt; ≥5 WU → only after treatment lowers it [25]
- Device closure of secundum ASD usually needs rims ≥5 mm (except the retro-aortic rim) [175]
- Saline bubbles in the LA within 3 cycles = intracardiac shunt; later = intrapulmonary [176]
Questions echo must answer
Echo diagnoses and classifies atrial-level shunts and decides closure [25,175]. Many adult ASDs are found because of an unexplained dilated RV, atrial arrhythmias or PH.
- TypeSecundum (fossa ovalis), primum (partial AVSD, cleft mitral valve), sinus venosus superior or inferior (with anomalous pulmonary veins), or coronary sinus [175].
- Size and rimsFor device suitability (TOE or 3D) [175].
- Haemodynamic significanceRV dilatation, diastolic septal flattening, Qp:Qs [25,175].
- PA pressure and PVREisenmenger physiology forbids closure [8,25].
- PFOOnly relevant with cryptogenic stroke, decompression illness or platypnoea [176,209,210].
Acquisition protocol
- Subcostal 4C and short axisThe septum is perpendicular to the beam, so false dropout is avoided. Colour with a low Nyquist (≈40 cm/s) [175].
- PSAX-AV and A4CLocation, size and colour flow. Look at the anterior mitral leaflet (cleft in primum).
- High right parasternal / subcostal bicavalSVC–RA junction for sinus venosus defects; pulmonary veins [175].
- RVSize, diastolic septal flattening, paradoxical septal motion, TAPSE [3,166].
- Qp:Qs(RVOT VTI × RVOT area) / (LVOT VTI × LVOT area) [175].
- TR velocityPASP; PVR estimate [49].
- Agitated salineAt rest and with Valsalva release. Assess timing of bubble arrival and number [176].
- TOE / 3DMaximal diameter, rims and number of defects when closure is planned [175].
- Type of defect
- Size (2D / 3D)
- Rims (TOE)
- RV size and septal motion
- Qp:Qs
- PASP / PVR estimate
- Pulmonary venous drainage
- Saline study (if PFO question)
Diagnosis & severity
| Type | Where | Associations |
|---|---|---|
| Secundum | Fossa ovalis | Most common; device-closable if rims are adequate [175] |
| Primum | Lower septum next to the AV valves | Cleft mitral valve; part of the AVSD spectrum |
| Sinus venosus (superior) | SVC–RA junction | Anomalous right upper pulmonary vein; often missed on TTE |
| Coronary sinus | Unroofed coronary sinus | Persistent left SVC |
ESC 2020 ACHD: indications for closure [25]
- RV volume overload, PVR <3 WU and no PAH, regardless of symptoms → closure.
- PVR 3–5 WU with significant L→R shunt (Qp:Qs >1.5) → consider.
- PVR ≥5 WU → closure only if PVR falls below 5 WU with PAH therapy and the shunt is still significant.
- Eisenmenger physiology → closure contraindicated.
Thresholds that change management
- Secundum ASD with RV volume overload and suitable rims → device closure; otherwise surgery [25,175].
- Sinus venosus, primum and coronary sinus defects → surgery [25].
- PAH → right-heart catheterisation with PVR before any closure decision [8,25].
- PFO with cryptogenic stroke (age ≤60, high RoPE score, large shunt or atrial septal aneurysm) → closure reduced recurrent stroke in CLOSE [197,209,210].
- Late bubbles (after 3–5 cycles) with hypoxaemia in liver disease → hepatopulmonary syndrome [204].
Pitfalls & mimics
PitfallEcho dropout in the thin fossa ovalis in the apical four-chamber view creates a false ASD. Confirm from the subcostal view with colour [175].
- Flow from the SVC or IVC, or a coronary sinus inflow, can mimic an ASD jet on colour.
- Sinus venosus defects are missed without high parasternal or subcostal bicaval imaging. Unexplained RV dilatation → TOE or CMR.
- A poor Valsalva produces a false-negative saline study. Confirm that the septum bows into the LA on release [176].
- Qp:Qs errors come from the squared diameters of the RVOT and LVOT.