The invention refers to a method of fast, reliable as well as high sensitive and specific determination of a type of an atrial and ventricular arrhythmia in a patients heart, the method comprising:● monitoring the atrial and ventricular rate of the heart● detecting a pathological initial ventricular and/or atrial rate during a first time period● administering, preferably intravenous administering, of at least one antiarrhythmic cardioactive drug only over a second time period, preferably over a short time period of 1 to 10 seconds, in case that a pathological initial ventricular and/or atrial rate is detected● detecting the response of the ventricular and atrial rate of the heart to the administerring of the at least one drug, comparing the ventricular and atrial rate response with the initial ventricular and atrial rate, respectively, within a third time period and determining whether there are changes within the ventricular and/or atrial rate response and determining the type of changes and● determining the type of atrial or ventricular arrhythmia from the presence or absence of changes of the atrial and/or ventricular rate response compared with the initial atrial and ventricular rate and from the type of these changes.The invention further refers to an appropriate device comprising an implantable cardiac device (10) and a drug delivery device (20).
