Summary This chapter discusses the symptoms, complications and procedures of the septal defects. Hemodynamically significant atrial and ventricular septal defects (ASD, VSD) occur relatively infrequently as solitary congenital defects in the dog and cat. Depending on the size and position of the defect, both ASD and VSD may be amendable to catheter based occlusion either via a percutaneous or a hybrid procedure that utilizes a thoracotomy. Hemodynamically significant ASD and VSD can lead to congestive heart failure (CHF) that can manifest as pulmonary edema, with or without ascites and the commensurate clinical signs. Percutaneous and transcatheter hybrid ASD occlusion with Amplatzer ASO appears to be a reasonably safe and efficacious option in many dogs. As for other catheterization procedures in patients with structural heart disease, animals with ASD or VSD are at risk for the development of pulmonary edema and significant ventricular and supraventricular arrhythmias.
