Transient tricuspid valve regurgitation following surgical treatment of cor triatriatum dexter in a dog.

Echocardiographically documented tricuspid valve regurgitation appeared immediately after surgical treatment of cor triatriatum dexter in a two-month-old rottweiler. Medical treatment was instituted with benazepril, spironolactone and furosemide. Pimobendan was added after five months, and all treatment was discontinued two months later when clinical signs of ascites and hepatomegaly had resolved and tricuspid valve regurgitation was markedly reduced on echocardiography. To the authors' knowledge, this is the first report describing the development and spontaneous improvement of haemodynamically significant tricuspid valve regurgitation following surgical treatment of cor triatriatum dexter in a dog. It is hypothesised that the increase in right atrial volume and pressure following cor triatriatum dexter repair and transient ischaemia of papillary muscles led to dilatation of the right atrioventricular annulus and subsequent severe tricuspid valve regurgitation in the face of an anatomically normal valve. Time and pharmacological preload reduction as well as normalisation of right atrial inflow and subsequent cardiac remodelling substantially reduced tricuspid valve regurgitation and eliminated clinical signs of heart failure. It is also possible that heart recovery has been spontaneous.