Abstract
An atrial septal defect was diagnosed in an 11-year-old small male dog which was treated for mitral valve insufficiency over a period of five months. Continuous wave Doppler echocardiography revealed a left-to-right interatrial shunting flow with a maximal velocity of 3.5m/sec. With a worsening of the mitral valve insufficiency, the maximal velocity of interatrial shunting flow was elevated to 5.2m/sec. In spite of conservative therapy, the dog died after 86 days from left-sided heart failure. In the postmortem examination, a secundumatrial septal defect that measured 2 mm in diameter was detected. It was suggested that the hemodynamics of severe mitral valve insufficiency were unaffected by the small atrial septal defect
