The type of arrhythmia in a patients heart can be determined by monitoring the atrial and ventricular rate of the heart detecting a pathological initial ventricular and/or atrial rate during a first time period if a pathological initial rate is detected, then administering at least one antiarrhythmic cardioactive drug over a short second time period detecting the hearts response to the administered drug(s), as by comparing the responsive ventricular and atrial rates with the initial ventricular and atrial rates, respectively, within a third time period and determining the type of atrial or ventricular arrhythmia from the presence or absence of differences, and the type of differences, between the responsive atrial and ventricular rates compared with the initial atrial and ventricular rates. The invention further involves a related device which includes an implantable cardiac device (10) and a drug delivery device (20).
