The cardiac insufficiency can be referred to as cardiac muscle insufficiency. In this case, the heart is no longer able to pump enough blood through the body circulation system. The most frequent cause of it is coronary heart disease with a decreased blood supply of the heart or a high blood pressure. There are also such causes as heart muscle inflammations, genetic changes or heart valve diseases. The complaints depend on the extent and the stage of cardiac insufficiency, and also on the fact whether a big or a small cardiac circulation circle is affected. All forms of cardiac insufficiency require an early recognition and treatment, in order to delay the progression of insuffiency and to sustain vitality. A special performance examination, such as spiroergometry, can define the individual perfomance and the diffentiation between causes and complaints associated with either lung or heart diseases can be made.