Pulmonic stenosis
Overview
Pulmonic stenosis (or PS) is a general term indicating that there is obstruction to normal blood flow in the pulmonary arterial system, which conducts less oxygenated or "blue" blood to the lungs so it can become oxygenated or "pink". This can be at the level of the pulmonic valve, located between the right ventricle and the main pulmonary artery, or in the pulmonary arterial system itself . For the purposes of this discussion, we will discuss the most common type of PS, which is at the level of the valve. The pulmonic valve is normally quite thin (no more than a few millmeters in an adult), and composed of three portions arranged in a circle like a three-slice pie. Normally, the leaflets open in the direction of blood flow with each contraction of the right ventricle, then close to keep blood from traveling backward from the pulmonary arteries.
Diagnosis
The first indication that your dog has a problem may be when your veterinarian hears a heart murmur on an early physical examination. Alternately, you may see signs in your dog related to heart disease, such as fainting or fatigue with exercise. Your veterinarian will listen carefully to try to determine the location of the murmur and to differentiate it from an "innocent" murmur which disappears by about 6 months of age. If the murmur is significant, your veterinarian will suggest further tests such as a chest x-ray, electrocardiogram, and cardiac ultrasound to help determine the cause, and to see what changes if any have already occurred in the heart as a result of the defect. Once pulmonic stenosis has been diagnosed, Doppler echocardiography or cardiac catheterization can be done to measure the pressure gradient between the right ventricle and the pulmonary artery, to determine the severity of the obstruction. Based on these test results your veterinarian will discuss with you the long term prognosis for your dog and whether surgical correction of the defect should be considered. FOR THE VETERINARIAN: 1. MURMUR: systolic ejection murmur, loudest in pulmonic area near left cranial sternal border, often equally loud along right cranial sternal border. 2. ELECTROCARDIOGRAM: RV hypertrophy and right axis shift, right atrial enlargement, possibly arrhythmia associated with hypertrophy. 3. RADIOGRAPHS: right ventricular hypertrophy , poststenotic dilation of pulmonary artery with distal pulmonary vessels reduced in size. 4. ECHOCARDIOGRAPHY: primary means of diagnosis of pulmonic stenosis, typically see mild to moderate right atrial dilation, concentric RV hypertrophy, deformity and narrowing in the pulmonic valve region, and poststenotic dilation of the pulmonary artery. 5. jugular pulses may be evident. In English bulldogs, pulmonic stenosis is commonly associated with a left coronary artery anomaly which has important implications for surgical correction.
Treatment
Prior to the mid-1980s, the only treatment for PS was an open surgical procedure. The valve commissures could be separated; one or more valve leaflets could be removed; or in certain instances the entire valve could be removed and replaced with a biologic (usually porcine) or mechanical valve. In the early 1980s, the first case reports of non-surgical treatment of valvar PS were first reported. Non-surgical opening of the pulmonic valve (balloon pulmonary valvuloplasty, or BPV) is now the procedure of choice for relief of nearly all cases of valvar PS.