Pulmonary Embolism
This station covers the echocardiographic signs that may be seen in pulmonary embolism. Remeber that echo cannot be used to rule out pulmonary embolism. Echo signs are however invariably present in hemodynamically unstable patients with pulmonary embolism.
A. 2D Imaging
1. RV Size, Interventricular Septal Flattening, McConnell's Sign, IVC Resp Variability, CIT
- RV Size
- RV Size can be compared to the LV visually. A normal RV is less than 2/3 the size of the LV
- RV:LV ratio can be measured in the apical 4 chamber view by using the basal dimensions close to the AV valves. It should normally be < 0.6. A value > 0.9 indicates severe RV dilatation.
2. McConnell’s Sign
- Low sensitivity but high specificity for pulmonary embolism
- RV dilatation, hypokinesis of RV free wall with preserved RV apical contraction
3. Interventricular Septum Flattening
- RV pressure and volume overload will cause the IVS to be displaced towards the LV in both diastole and systole.
- This causes the LV to have a D shape
- LV systolic function and filling is impaired
4. Subcostal Views
- The subcostal views can be used to determine IVC caliber and respiratory variability.
- The Subcostal 4C view is useful to determine RV wall thickness. RV hypertrophy will not be present in acute RV strain.
5. Clot in Transit
- Visualising clot in transit is virtually diagnostic of PE.
- The PSAX Aortic level is seen here. There is a saddle thrombus present at the bifurcation of the pulmonary artery.