DIAGNOSIS AND SURGICAL REPAIR OF PARTIAL ATRIOVENTRICULAR SEPTAL-DEFECTS IN 2 DOGS

Four types of atrial septal defects (ASD) are recognized: ostium secun dum ASD, sinus venosus defect, coronary sinus ASD, and atrioventricula r (AV) septal defect.(1-4) Atrioventricular septal defects represent a spectrum of malformations that involve the ventral portion of the atr ial septum (ie, septum primum), inlet portion of the ventricular septu m, and AV valves.(1,3-8) Atrioventricular septal defects can be comple te or partial.(1,4,7,9) A complete AV septal defect is a combination o f an ostium primum defect and a ventricular septal defect, such that a single AV valve is common to the right and left ventricles. Complete AV septal defects have also been called endocardial cushion defects.(4 -7,10,11) A partial AV septal defect is a combination of an ostium pri mum defect and malformation of the mitral valve.(1,3,4,7) The septal d efect is usually large enough that it does not restrict blood flow. Mi tral valve malformation consists of a cleft in the septal cusp that ch anges the valve into a tricuspid structure and causes substantial mitr al insufficiency in most human patients with this defect.(8,9) In this report, we describe clinical findings associated with partial AV sept al defects in 2 dogs, a method for surgical repair of this defect, and outcome of surgical repair in these 2 dogs.