Prognosis

1. Most cases of severe pulmonic stenosis result in:
   • Malignant dysrhythmias and sudden death,
   • Exertional weakness, or
   • Right heart failure with ascites and pleural effusion
2. Mild cases of pulmonic stenosis live a full life (both normal quality and duration).
3. Even cases of moderate pulmonic stenosis can anticipate a life of normal length and quality
4. The severity of the stenosis can be predicted by Doppler echocardiography
   • Mild PS: has a pressure gradient between the LV and Ao of <50 mmHg
   • Moderate PS: has a pressure gradient between the LV and Ao of 50 to 80 mmHg
   • Severe PS: has a pressure gradient between the LV and Ao of >80 mmHg
     • The authors have observed many dogs with pressure gradients of > 100 mmHg experience lives of normal length and quality
     • The authors therefore use a threshold of >100 mmHg as a threshold gradient in the mature dog identifying dogs with a poor prognosis.
     • Dogs appear to handle more severe pulmonic stenosis than comparable subaortic stenosis.

Comment: We have encountered dogs with relatively mild pulmonic stenosis that have developed severe ventricular or supraventricular dysrhythmias which have prematurely shortened their lives. Thus the consequences of the disorder may cause more problems than the stenosis itself. Work with Doppler echocardiography indicates that like subaortic stenosis, pulmonic stenosis is progressive and the rate of progression is greatest in the immature dog and progresses at a very slow rate in the mature dog.