Atrial Septic Defect in the Cat
Atrial septal defect (ASD) is a birth defect similar to VSD, just between the atria. Many times,
ASDs are not clinically significant, especially when the defect is small. As the only defect, ASDs cause left-to-right shunting of blood. This leads to increased blood volume that the right atrium and ventricle have to move into the lungs. Click here to learn more about the normal functioning of cat hearts. In severe cases, right sided congestive heart failure develops. Treatment for this disease is only warranted in patients with direct clinical signs to their disease. A mesh occlusion disc is placed into the defect via catheters. This is available at most veterinary schools.
Interestingly, this defect is fairly common in humans; however, it is rare in dogs and cats. 
Congenital heart disease has a reported prevalence of between 0.2-4% in the general cat population. ASDs make up only 4% of the congenital heart disease in the cat population.
V. Chetboul, et al. Retrospective Study of 156 Atrial Septal Defects in Dogs and Cats (2001–2005) J. Vet. Med. A 53, 179–184 2006
Buchanan JW. Causes and prevalence of cardiovascular disease. In: Kirk RW, Bonagura JD, editors. Kirk’s current veterinary therapy XI. Philadelphia: Saunders; 1992. p. 647-55.
