Temporary left heart bypass and total artificial replacement.

Research into left heart assistance was initiated in Berlin in the 1960s with a small implantable pump between the left atrium and the aorta with an extracorporeal driving unit. From thereon, different blood pumps were developed from different materials, the latest types being made out of polyurethanes. Similar designs are used for the total artificial heart. Longest function times exceed 200 days, partly with problems similar to those of the artificial heart. Total artificial heart research began in 1962. The present system consists of 2 polyurethane blood pumps divided by 3 membranes into blood and energy transmission chambers. The longest testing function time is now more than 2 years. The outside driving units of different sizes and designs are connected with tubes and special quick connectors to the right and left atrium, aorta and pulmonary artery. Air capsulae for pressure measurements are incorporated. In addition to all the interesting hemodynamic parameters a great deal of analysis on hematology, biochemistry and metabolic function has been done. The longest survival time in animals is over 200 days. Complications and problems are mostly due to the material, in which small lesions, cracks or slight flaws in fabrication or biodegradation are the starting point for thrombosis and later on calcification. The number of patients who should be given temporary cardiac assistance or total replacement is discussed.