Pulmonic Valve Stenosis in Dogs
What is Pulmonic Valve Stenosis?
Pulmonic valve stenosis (PS) is a condition present at birth (congenital cardiac defect). This condition is a narrowing (stenosis) of the pulmonic valve. The pulmonic valve is the valve between the right heart and the pulmonary artery that leads to the lungs. This causes an obstruction to forward blood flow, similar to putting a finger over the end of a garden hose. It causes the velocity of blood entering the pulmonary artery to be much higher than normal, increasing pressure in the right heart. This causes the right ventricle (the chamber of the heart that pumps blood into the pulmonary artery) to become thicker over time (hypertrophied).
What are the symptoms of Pulmonic Valve Stenosis?
If the stenosis is severe it could cause several symptoms:
- The obstruction to forward flow may cause blood back up which can lead to fluid buildup around the lungs (trouble breathing) or in the abdomen (bloating), called congestive heart failure (CHF)
- Poor forward flow may result in periods where the brain does not receive enough oxygen. This causes weakness or fainting episodes (syncope).
- The heart muscle thickens because it has to pump harder and this could damage the electrical system which leads to arrhythmias. This makes the heart very inefficient and leads to weakness, fainting episodes or sudden death.
How is Pulmonic Valve Stenosis diagnosed?
A heart murmur is usually the first abnormality found by your veterinarian during a physical exam. A murmur sounds like a whooshing sound and it can have a varying degree of volume. There are many conditions in which a heart murmur is present, but the location where the murmur is the loudest and the breed of dog may raise concern for PS in particular. A murmur caused by PS is heard best on the left side of the chest, and this condition is common in bulldogs, boxers, terriers and pit bulls.
Diagnosis of PS is confirmed by echocardiogram, which is an ultrasound of the heart. The cardiologist will use this diagnostic tool to see the heart’s structure and functionality in real-time. The severity of PS can also be determined with this test, which helps gauge treatment options and prognosis. An electrocardiogram (ECG) may be done if there is an abnormal heart rhythm heard.
How is Pulmonic Valve Stenosis treated?
Dogs with a mild form may not need treatment and are expected to have a normal lifespan. Dogs with moderate or severe pulmonic stenosis may require medication, such as a beta blocker, which reduces the intensity of the heart's work, allows the heart muscle to relax and helps control arrhythmias. Based on what your cardiologist finds, a surgical procedure called a balloon valvuloplasty may be recommended as well.
What is a balloon valvuloplasty?
This minimally-invasive surgical procedure involves the passage, under general anesthesia, of special catheters into the right heart via the jugular vein (in the neck). When a catheter with an attached balloon is quickly inflated, it opens the restricted valve, allowing for smoother, slower blood flow into the pulmonary artery. This treatment can only be performed by a veterinary cardiologist and requires the use of specifically ordered catheters for each patient. This procedure has been shown to improve prognosis for patients with moderate or severe stenosis.
What is the prognosis? What follow up is recommended?
Prognosis is variable based on the severity of PS and whether medical or surgical treatment is pursued. Some dogs with mild PS remain with a heart murmur but no symptoms. Other dogs with more severe disease may develop symptoms such as activity intolerance, rapid/labored breathing, abdominal distention/bloating, fainting and blue tongue or gums. Medications or surgery may improve or even eliminate these symptoms. Follow up frequency is patient-dependent, but oftentimes an annual recheck is recommended.