Right parasternal short axis view with colour Doppler focused over the tricuspid valve showing regurgitation. The right atrium is not particularly dilated (ie. normal). However the velocity of the regurgitation is elevated (see still image below).

This spectral Doppler tracing indicates the peak tricuspid regurgitation to be near 4m/s. This equates to a pressure gradient between the right ventricle (RV) and right atrium (RA) of ~60mmHg. Assuming the RA pressure to be normal at ~5mmHg then the systolic pressure in the RV must be ~65mmHg. If there is no pulmonic stenosis, then the pulmonary artery systolic pressure must also be ~65mmHg (normal 25-30mmHg). Therefore this dog has pulmonary hypertension secondary to it's MVD and treatment for this would be indicated.