Transcatheter coil embolization of patent ductus arteriosus was successfully performed for 10-year-old female Pembroke Welsh Corgi. Sustained ventricular tachycardia was complicated after 30 hours of surgery. Repetitive intravenous lidocaine was ineffective on the arrhythmia. Subsequently, intravenous dipyridamole suppressed the ventricular tachycardia immediately. No clinical case report of dogs has shown the effect on ventricular arrhythmia. On the other hand, the preventive effect of dipyridamole on Adenosine- or ATP-sensitive ventricular tachycardia and reperfusion arrhythmia is well known in human. It is considered that electrophysiological mechanism of postoperative ventricular tachycardia in this case is similar to that of reperfusion arrhythmia in human because of response to dipyridamole administration, and that dipyridamole also has antiarrhythmic effect clinically on ventricular arrhythmias caused by similar operative mechanisms in dogs.