A 6/6 murmur was detected in this Cockerpoo puppy at routine examination, and he was referred for further examination with suspicion of a patent ductus arteriosus (PDA). Often with referrals for a suspected PDA, nothing is found on echo, and the animal has to be referred for further examinations (such as fluoroscopy).
From the right parasternal view, it was immediately apparent that we were not faced with a normal echo. The right ventricle was hypertrophied and of similar size to the left.
From the short-axis, the thickened walls of the right ventricle are again very obvious. The interventricualr septum is compressed by the high pressures in the right ventricle, with the classic ‘D’ shaped left ventricle.
The eccentricity index came out at 1.8 (D2/D1, with D2 being the larger and more horizontally orientated diameter). In a normal heart this should of course be 1, because the left ventricle should be circular in shape from the short-axis.
The classic sign of a PDA is a volume-loaded left ventricle. This was clearly not the situation we were being faced with in this instance. We next checked the pulmonary artery, both to check again for the presence of a PDA but also to find the cause of the high pressures in the right ventricle.
In the below view, we adjusted the probe position to visualise the bifurcation of the pulmonary artery. There is no obvious sign of a PDA, but the very turbulent flow through the pulmonary valve is evident, as well as the presence of pulmonary regurgitation.
Using continuous wave Doppler, we obtained a peak gradient through the valve of 134mmHg, with over 80mmHg being the threshold for severe pulmonary stenosis in dogs (Locatelli et al., 2013).
Although we had the main diagnosis, it is important in more complex cases to perform as thorough an examination as the patient will allow. We managed to obtain some apical views. The below clip shows mild aortic regurgitation demonstrated from apical and parasternal views.
With careful angulation from the subcostal view, it was possible to follow the path of the pulmonary artery from another perspective and again observe the point of turbulence. Note the gall bladder visible at the top! This is because the puppy had been starved in case he was going to need any sedation.