Although major advances in the treatment and prevention of heart disease have been achieved in the last two decades, diseases of the cardiovascular system contribute to about 20% of the fatalities in people between the ages of 36 and 74. Atherosclerosis, a process affecting the large and medium-sized diameter muscular arteries, especially the aorta, coronary arteries and cerebral arteries, is a major cause of death. In addition, valvular leakage results in insufficient cardiac output thereby making even moderate exercise difficult. Atherosclerotic vessels as well as leaky heart valves are routinely replaced by materials that are synthetic or of natural origin.