Case 13 — Text
Text from “Small Animal Cardiovascular Medicine”
Subvalvular Pulmonic Stenosis Associated with a Coronary Artery Anomaly
In the English bulldog and Boxer breeds, subvalvular PS may be associated with an R2A type anomalous left coronary artery. In this malformation, a single large coronary artery originates from the right coronary aortic sinus and quickly divides into right and left branches. The left main coronary artery encircles and apparently compresses the RV outflow tract just below the pulmonary valve, before dividing into the left descending and left circumflex coronary arteries. The course of the right coronary artery is usually normal.
Commonly Associated Lesions
Mild, subclinical deformities of the tricuspid valve apparatus may accompany PS in dogs. More severe tricuspid dysplasia with regurgitation may be a major complicating lesion. Pulmonic stenosis and tricuspid valve dysplasia was diagnosed in 15 dogs between 8/1/86 and 8/1/96 that were in right heart failure (ascites). Four were boxer dogs and three were English bulldogs. The foramen ovale may remain patent in dogs with PS, allowing mild right-to-left shunting due to the hypertrophied and therefore less compliant RV.
Treatment of Dogs with an Anomalous Left Coronary Artery
The proper course of treatment in dogs with subvalvular stenosis associated with an anomalous left coronary artery is currently unresolved. Death associated with transection of the anomalous vessel was originally reported from patch-graft surgery. Subsequently, balloon dilation valvuloplasty was recommended but two English bulldogs with this anomaly died acutely during the procedure due to avulsion of the anomalous vessel. Conduit implantation around the stenosis may be an option but experience has been dismal. Currently, the approach is to not treat these dogs since the prognosis without therapy is considered better than with any type of intervention.