Ventricular septal defect
Where is the hole, how big is the shunt, what does the pulmonary circulation look like — and is the aortic valve in danger?
Numbers to remember
- A high-velocity (≥4 m/s) left-to-right jet means a restrictive defect with low RV pressure [25]
- RV systolic pressure ≈ systolic BP − 4 × (VSD velocity)² [25,33]
- Qp:Qs ≥1.5 with LV volume overload favours closure [25]
Questions echo must answer
- LocationPerimembranous, muscular, outlet (subarterial) or inlet [25].
- Size and restrictionDefect diameter and the jet velocity [25].
- Haemodynamic burdenLV volume overload, Qp:Qs, pulmonary pressure [25,33].
- ComplicationsAortic cusp prolapse and AR (outlet and perimembranous), double-chambered RV, endocarditis [25].
Acquisition protocol
- PLAX and PSAX with colourScan the whole septum; a perimembranous VSD sits beneath the aortic valve at 10–11 o'clock in PSAX.
- CW across the jetPeak velocity; estimate RV pressure.
- LV sizeLV end-diastolic dimension and volume.
- Qp:QsRVOT and LVOT stroke volumes [33].
- Aortic valveCusp prolapse and AR.
Diagnosis & severity
| Type | Echo clue |
|---|---|
| Perimembranous | Below the aortic valve, next to the septal tricuspid leaflet; often an aneurysm of tricuspid tissue |
| Muscular | Anywhere in the trabecular septum; may be multiple |
| Outlet | Below both semilunar valves; aortic cusp prolapse |
| Inlet | Beneath the AV valves; part of an AV septal defect |
Thresholds that change management
- LV volume overload with Qp:Qs ≥1.5 and PVR not prohibitive → closure [25].
- Progressive AR from cusp prolapse → surgery even for a small defect [25].
- Eisenmenger physiology → closure contraindicated [25].
Pitfalls & mimics
- Small muscular defects are missed without colour on every view.
- The tricuspid regurgitation jet can be confused with a VSD jet in the apical view.
- Post-infarction septal rupture is a different disease with a different urgency [138].