Pulmonic Stenosis: Balloon Valvulolasties

Congenital pulmonic stenosis can occur in some dogs. It is a genetic disease characterized by incomplete separation of the 3 leaflets that are forming the pulmonic valve (the valve that is at the base of the pulmonary artery). The valve cannot open properly, and this hinders the ejection of blood from the right ventricle into the pulmonary artery. If the obstruction is severe enough, this could lead to syncopes (fainting), exercise intolerance, and right heart failure.

Typically, affected dogs have a loud systolic heart murmur present at birth.

Final diagnosis is established via echocardiography. This allows measuring the severity of the obstruction (evaluation of the "pressure gradient"). Normally, the pressure gradient should not exceed a few mm of mercury (mm Hg). If the pressure gradient exceeds 60-80 mm Hg, then the stenosis is called severe, and this could lead to heart failure or syncopes as mentioned above. The risk is heightened if the valve located upstream of the obstruction (the tricuspid valve) is leaking.

If the obstruction is strictly at the level of the pulmonic valve, then a balloon valvuloplasty can be performed to open the valve and decrease the amount of obstruction. This technique is based on the insertion of a catheter with a balloon through the narrowed valve. To get there, the catheter is introduced via the vein in the neck (the jugular vein) and pushed into the heart. We use fluoroscopy to follow the progress of the catheter. Once the balloon is straddling the valve, we inflate it in order to stretch the valve and open it. The intervention is considered successful if the pressure gradient drops by at least 50%. The choice of the balloon size is critical to success, and needs to be determined by the echocardiographic measurements.

This "non-surgical" technique can improve the prognosis of these patients, and is routinely done at our hospital.