The first cardiovascular operation in Duesseldorf, a ligation of an open ductus arteriosus (Botallo), was performed in 1938 by E. K. Frey. During the Second World War and the subsequent years many difficulties hindered cardiovascular surgery in Duesseldorf. However, it was resumed on 3 May 1949 by Prof. Ernst Derra, again by ligating an open ductus arteriosus. This was the starting pOint of the successful cooperation between the cardiological and surgical working groups - the birthday of the Duesseldorf Heart Centre. Further highlights in cardiac surgery were the introduction of open heart surgery by means of surface-cool- ing hypothermia (9 February 1955) and extracorporeal circulation (21 February 1959) . In addition to cardiac catheterization and surgery in patients with acquired and congenital heart disease, the diagnosis and treatment of arrhythmias was one of the focal points of the centre. On 3 October 1961 the first pacemaker was implanted in a patient with a third-degree AV-block after he had been treated using an external device for about 1 year. In recent years interest has increasingly turned to the tachy- arrhythmias. Close cooperation between the medical and surgical teams made possible the application of new pacing techniques for the treat- ment of tachycardia. In patients with intractable arrhythmias, surgical interventions were made to eliminate the focus of the arrhythmia. In the past 2 years intraoperative electrophysiologic studies (endo-cardi- al and epicardial mapping) were applied to enhance the success of the surgical procedures.