**5.2.3.3 Echocardiogram**

Echo shows increase in left atrial and left ventricular size, which is again dependent upon the size of the VSD. The location and size of the VSD can be imaged by 2-dimensional echocardiography. Left-to-right shunting across the VSD can be demonstrated by Doppler echocardiography and color mapping (Figure 10).

Fig. 10. Two dimensional echocardiographic views of the ventricular septum in long axis with color flow imaging (left panel) demonstrating a perimembraneous ventricular septal defect (VSD) and of the ventricular septum (arrows) in multiple views (Right panel A, B and C) with left-to-right shunt. Ao, Aorta; LA, left atrium; LV, Left ventricle; RA, right atrium; RV, Right ventricle

Peak Doppler flow velocity magnitude is inversely proportional to the size of defect. Indeed the right ventricular/pulmonary arterial pressures may be estimated by determining to peak Doppler flow velocity across the VSD.

```
RV/PA peak pressure = peak arm blood pressure - 4 VVSD2
```
Where, RV and PA are right ventricle and pulmonary artery and VVSD is the peak Doppler velocity across the VSD.

The right ventricular peak pressure may also be estimated by tricuspid back flow (regurgitant) velocity:

RV peak pressure = 4 VTR2 + RAP

Where, VTR is peak tricuspid regurgitant velocity and RAP is estimated right atrial pressure (5 mmHg).

Both formulas may help to verify internal consistency of the Doppler methodology in estimating the size of the VSD. The higher the estimated RV pressure, larger is the size of the VSD.

Echo shows increase in left atrial and left ventricular size, which is again dependent upon the size of the VSD. The location and size of the VSD can be imaged by 2-dimensional echocardiography. Left-to-right shunting across the VSD can be demonstrated by Doppler

Fig. 10. Two dimensional echocardiographic views of the ventricular septum in long axis with color flow imaging (left panel) demonstrating a perimembraneous ventricular septal defect (VSD) and of the ventricular septum (arrows) in multiple views (Right panel A, B and C) with left-to-right shunt. Ao, Aorta; LA, left atrium; LV, Left ventricle; RA, right atrium;

Peak Doppler flow velocity magnitude is inversely proportional to the size of defect. Indeed the right ventricular/pulmonary arterial pressures may be estimated by determining to

RV/PA peak pressure = peak arm blood pressure - 4 VVSD2 Where, RV and PA are right ventricle and pulmonary artery and VVSD is the peak Doppler

The right ventricular peak pressure may also be estimated by tricuspid back flow

RV peak pressure = 4 VTR2 + RAP Where, VTR is peak tricuspid regurgitant velocity and RAP is estimated right atrial pressure

Both formulas may help to verify internal consistency of the Doppler methodology in estimating the size of the VSD. The higher the estimated RV pressure, larger is the size of the

**5.2.3.3 Echocardiogram** 

RV, Right ventricle

velocity across the VSD.

(regurgitant) velocity:

(5 mmHg).

VSD.

peak Doppler flow velocity across the VSD.

echocardiography and color mapping (Figure 10).
