Pimobendan (INN, or pimobendane; tradenames Vetmedin, Acardi, and Heartmedin) is a veterinary medication. It is a calcium sensitizer and a selective inhibitor of phosphodiesterase 3 (PDE3) with positive inotropic and vasodilator effects. Pimobendan is used in the management of heart failure in dogs, most commonly caused by myxomatous mitral valve disease (also previously known as endocardiosis), or dilated cardiomyopathy. Research has shown that pimobendan increases survival time and improves quality of life in canine patients with congestive heart failure secondary to mitral valve disease when compared with benazepril, an angiotensin-converting-enzyme (ACE) inhibitor. Under the trade name Acardi, it is available for human use in Japan.