Case Study

15_00064 Oliver S Moderate pulmonary hypertension

A 7-year-old MN Labrador retriever presented for follow up evaluation for pulmonary hypertension. Current therapy is Sildenafil (1mg/kg TID), benazepril, and Lasix. There was an episode of collapse in the previous month.

A 7-year-old MN Labrador retriever presented for follow up evaluation for pulmonary hypertension. Current therapy is Sildenafil (1mg/kg TID), benazepril, and Lasix. There was an episode of collapse in the previous month.

DX

Moderate pulmonary hypertension

Sonographic Differential Diagnosis

Moderate pulmonary hypertension. The etiology remains speculative. The TV pressure gradient is slightly lower than it was previously, but pressure gradients do not necessarily correlate with the clinical symptoms in such cases.

Image Interpretation

The heart is partially volume depleted, and therefore the left ventricle and atrium appear pseudo-hypertrophic. The right ventricle is significantly hypertrophied (including the papillary muscles which gives the IVS an even more thickened appearance). The tricuspid valve is normally shaped but partly prolapses into the right atrium. The main pulmonary artery is severely dilated, while the pulmonic valve looks normal. Flow profiles across the RVOT show normal velocities but are asymmetric, which is a sign of pulmonary hypertension. There is moderate tricuspid insufficiency present. The vmax of the regurgitant jet is 3.87 m/s, which means that systolic pulmonary artery pressure is a least 64 mm Hg (moderate pulmonary hypertension).

Outcome

Furosemide is not recommended in this case, as there is already too little preload on the left side. Pimobendan would be recommended instead of furosemide, as it works as a PDE III inhibitor, and could act synergistically with Sildenafil which is a PDE V – inhibitor. If available, L-Arginine (a pure amino acid) should be added to the diet at a dosage of 2g twice daily. The effect of L-Arginine has not been proven in veterinary medicine but anecdotally it seems to help to alleviate the symptoms (and it has no known side effects). And I would suggest to administer aspirin additionally.