J. Navratil The performance of operations on the heart and its replacement by a trans­ planted or artificial heart has been an age old dream of man. Rehn for example in an early attempt, in 1868 performed a closure of a heart wound after a thoracic puncture. At that time noone thought that this attempt was the beginning of cardiac surgery. The dream was partially realized when the replacement of the heart function by the heart-lungmachine became possible. Immediately following the first operations, cardiac surgeons and cardiologists saw with great enthusiasm that this machine could be an important tool for correcting congenital and non­ congenital heart diseases. However, the heart-lungmachine was soon seen to not be an optimal instrument for controlling cardiac failure after cardiopulmonary bypass or myocardial infarction. then arose for the development of mechanical assistance to the heart. Concepts The rollerpump was first designed for assisted circulation and could be applied clinically in 1962. A new concept of mechanical assistance to the heart was pro­ vided by the intra aortic balloon pump and later by the bypass ventricles. Use of the intra aortic balloon pump can reduce cardiac work by counterpulsation in accord with the natural ECG. The bypass ventricle can functionally replace the heart in series or parallel to the natural heart. The intra aortic balloon pump, now an established method, has reduced the number of patients who used to die from cardiac failure.