Common names or abbreviations:
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Pulmonic stenosis |
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Pulmonic stenosis with anomalous left coronary artery |
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Type A pulmonic stenosis (pulmonary ostium hypoplasia) |
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Valvular pulmonic stenosis |
Description or definition:
| Pulmonic stenosis is a congenital narrowing in the region of the pulmonary valve, which lies between the right ventricular chamber of the heart and the pulmonary artery. As part of the normal circulation of the heart, the right ventricle pumps blood to the lungs to receive oxygen. The oxygenated blood goes back to the left side of the heart from which it is pumped out to the rest of the body. |
With pulmonic stenosis, there is partial obstruction of normal blood flow, most commonly due to a malformation of the pulmonic valve (pulmonic valve dysplasia), but the abnormality may be immediately above or below the valve as well.
The effect of this partial obstruction is to force the heart to work harder to pump blood to the lungs. The extent to which a dog will be affected depends on the degree of narrowing (stenosis) of the valve area. With severe stenosis, the dogs will likely develop congestive heart failure due to the increased workload of the heart. The hemodynamic consequences of pulmonic stenosis are the development of right ventricular concentric hypertrophy (enlargement) and reduced filling of the left ventricle. The right ventricular concentric hypertrophy causes reduced right ventricular compliance with reduced distensibility. The hypertrophied right ventricular wall is prone to initiate dysrhythmias.
Pulmonic stenosis can occur with other defects and it is one of the components of another congenital defect: Tetralogy of Fallot.
| The stenotic lesion may occur in the:
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| Usually, affected animals show no external signs of the
disease and it is frequently diagnosed during routine examination of the heart
with a stethoscope (auscultation). In its milder forms, the slight thickening
of the pulmonary valve will cause minimal or no obstruction and your dog will
not be affected. However, if blood flow is seriously impaired, signs
associated with right –sided heart failure may be seen including poor exercise
tolerance, respiratory difficulties, abdominal swelling due to an enlarged
liver, feinting (syncope), or sudden death. | ||||||
| Pulmonic stenosis appears to be a polygenic threshold
trait – Polygenic traits are controlled by an unknown number of genes. The
gene expression is influenced by a variety of factors including gender,
nutrition, breed, rate of growth, and amount of exercise. These traits are
quantitative traits – that is, there is a wide range within the population.
Such traits include height, weight, character, working abilities, and some
genetic defects. Heritability varies within different breeds, and within
different populations of a particular breed. Because it is virtually
impossible to determine the exact genotype for such traits, it is difficult to
control defects with a polygenic mode of inheritance. | ||||||
| Pulmonic stenosis is reported to be the 2nd
most prevalent congenital cardiac disorder in the dog. Aortic stenosis being
the most common congenital heart disorder. | ||||||
| There is a breed predisposition in the following breeds of dog: |
English Bulldog, Mastiff, Beagle, Wire-Haired Fox Terrier, Chihuahua, Miniature Schnauzer, Samoyed, Boykin Spaniel, West Highland White Terrier, Boxer, Cocker Spaniel, Airedale Terrier and Scottish Terrier.
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Diagnosis can be broken down into two areas:
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| Definitive diagnosis:
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| Diagnostic findings:
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For moderate to severe pulmonic stenosis, the treatment of choice is surgery. However, the efficacy of surgical intervention remains to be substantiated. Surgery is more risky if atrial fibrillation or congestive heart failure has developed. These conditions should be treated medically and the dog stabilized, before surgery is considered.
A relatively new technique is now being used, called Balloon Valvuloplasty. A catheter with a small balloon on the end is guided to the position of the narrowing during heart catheterization. The balloon is then inflated to open the constriction. This procedure will reduce the morbidity and mortality associated with thoracic surgery, it appears to be good in the short-term, but long-term studies are needed.
| The prognosis for individuals with mild cases of pulmonic stenosis is that they can be expected to live a full life with this abnormality. |
For severe cases of pulmonic stenosis the dog may die suddenly if acute dysrhythmias develops (sudden death). Or the dog may develop signs of right sided heart failure and die in 6-12 months.
| Affected individuals and their parents should not be used for breeding. Siblings should only be used after careful screening. If any affected offspring are born, breeding of the parents should be discontinued. |
Links to sites about this disease:
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http://www.upei.ca/~cidd/Diseases/cardiovascular%20diseases/pulmonicstenosis.htm |
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http://www.provet.co.uk/health/diseases/cardiac-pulmsten.htm |
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Resources:
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Clinical Cardiology Concepts for the Dog and Cat: Michael R. O’Grady DVM, MSc, Diplomate, ACVIM (Cardiology) & Lynne O’Sullivan DVM, DVSc, Diplomate ACVIM (Cardiology) – VetGo Cardiology. |
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Pulmonic Stenosis: Provet Healthcare Information. |
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Pulmonic Stenosis: Alice Crook, BSc, DVM & Brian Hill DVM, MS, DACVIM. University of Prince Edward Island. Canine Inherited Disorders Database. |
This summary provided by:
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Olga I. Twombly |
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WhiteFang Shilohs |