Clinical and echocardiographic features of primary infundibular stenosis with intact ventricular septum in dogs.
BACKGROUND
Primary infundibular stenosis is a rare congenital defect in which the right ventricle is divided into a proximal "high-pressure" chamber and a distal "low-pressure" chamber. The condition can be misdiagnosed as ventricular septal defect or valvular pulmonic stenosis and the disease severity underestimated. The purpose of this study was to provide a detailed clinical and echocardiographic description of this anomaly in a series of dogs.


OBJECTIVE
Several anatomic forms of infundibular stenosis exist. High resolution two-dimensional echocardiography could differentiate 3 gross anatomic substrates. Knowledge of the anatomy of the obstructing lesion could influence options for corrective interventions.


METHODS
Thirteen dogs examined at the Ontario Veterinary College teaching hospital from 1994 to 2005 with an ultrasound diagnosis of subpulmonic stenasis.


METHODS
A retrospective review was made of case records from 1994 to 2005.


RESULTS
Thirteen dogs were identified as having primary infundibular stenosis, with apparent increased prevalence in Golden Retrievers (8/13, 62%) and Siberian Huskies (3/13, 23%). Three types of infundibular lesions were identified by ultrasound in 11/13 dogs: a fibrous diaphragm (6), fibromuscular (4), and muscular obstruction (1). Two dogs with a fibrous diaphragm underwent direct surgical dilation without the use of cardiopulmonary bypass or inflow occlusion, resulting in substantial reduction of the severity of stenosis.


CONCLUSIONS
Accurate determination of the severity of the stenosis and the anatomy of the obstructing lesion are important in devising a treatment strategy. Recognition of the fibrous diaphragm by echocardiography identifies a subset of dogs potentially amenable to surgical dilation without the need for cardiopulmonary bypass.
Minors
Sandra L
SL
Department of Cardiology, Veterinary Teaching Hospital, Ontario Veterinary College, University of Guelph, Ontario, Canada. lubshdub@interlynx.net
O'Grady
Michael R
MR
Williams
Regan M
RM
O'Sullivan
M Lynne
ML
D000818:Animals; D001947:Breeding; D006348:Cardiac Surgical Procedures / Q000662:veterinary; D002315:Cardiopulmonary Bypass / Q000379:methods / Q000662:veterinary*; D003937:Diagnosis, Differential; D004283:Dog Diseases / Q000175:diagnosis* / Q000235:genetics / Q000601:surgery; D004285:Dogs; D018618:Echocardiography, Doppler, Color / Q000379:methods / Q000662:veterinary*; D006345:Heart Septal Defects, Ventricular / Q000175:diagnosis / Q000235:genetics / Q000601:surgery / Q000662:veterinary; D011379:Prognosis; D011662:Pulmonary Subvalvular Stenosis / Q000175:diagnosis / Q000235:genetics / Q000601:surgery / Q000662:veterinary*; D012189:Retrospective Studies; D016896:Treatment Outcome; D014694:Ventricular Outflow Obstruction / Q000175:diagnosis / Q000235:genetics / Q000601:surgery / Q000662:veterinary