Case Studies In Small Animal

Cardiovascular Medicine

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Case 13

Pulmonic Stenosis Chapter from "Small Animal Cardiovascular Medicine" On-Line

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. We diagnosed pulmonary stenosis and tricuspid valve dysplasia in 15 dogs between 8/1/86 and 8/1/96 that were in right heart failure (ascites). Four of these dogs were boxer dogs and three were English bulldogs. The foramen ovale may remain patent in dogs with PS, and may allow mild right-to-left shunting of blood 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. Originally, death associated with transection of the anomalous vessel was reported resulting from patch-graft surgery. Consequently, balloon dilation valvuloplasty was recommended in these patients. Two English bulldogs with this anomaly that died acutely during balloon dilation valvulotomy due to avulsion of the anomalous vessel from its origin at the right coronary have been reported. Conduit implantation around the stenosis may be an option for these dogs. However, our experience with this procedure in this situation has been dismal. We currently opt not to treat these dogs since we feel that the prognosis without therapy is better than with any type of intervention.

 

Mark D. Kittleson, D.V.M., Ph.D. All rights reserved.