Search

The undulation pump (formerly called the pre-cessional displacement pump) is a continuous flow displacement-type blood pump that is being developed as an implantable total artificial heart. A new undulation pump was developed for chronic use and was examined with animal experiment and flow visualization studies. In the animal experiment using a left ventricular bypass in goats, severe hemolysis occurred. After driving for 12 h, thrombus formation inside the pump was found. In the flow visualization studies, the flow pattern showed that the flow inside the pump was a very complicated turbulent flow. Improvement of hemolysis and thrombus formation is important to realize implantable total artificial hearts using undulation pumps.

The undulation pump is a small size continuous flow displacement type blood pump that has been developed for an artificial heart. Using undulation pumps, 2 types of implantable total artificial hearts (TAHs), the undulation pump TAH (UPTAH) type 1 (UPTAH 1) and UPTAH type 2 (UPTAH 2) were developed. Both UPTAHs were designed to be small enough to implant into the chest of a goat, the experimental animal. UPTAH 1 could be reduced in size to 75 mm in diameter and 78 mm in length. The weight was 520 g. UPTAH 2 could be reduced in size to 75 mm in diameter and 80 mm in length. The weight was 650 g. UPTAH 2 could be tested in an animal experiment using an adult female goat weighing 52.3 kg. The UPTAH 2 could be implanted successfully into the goat's chest with a good fit. The goat stood after the surgery and extubation and survived for 3 h and 40 min; thus, the potential of the UPTAH for a practical implantable TAH was demonstrated.

To realize a totally implantable total artificial heart (TAH), a new pulsatile TAH, the flow-transformed pulsatile TAH (FTPTAH), was developed. The system was composed of a single centrifugal pump (CFP) and two three-way valves. One port of each three-way valve was connected to the inlet and outlet of a CFP. The other two ports of each valve were connected to the right and left atrium, and the pulmonary artery and aorta. The CFP can perfuse the pulmonary and systemic circulation alternately with pulsatile flow by switching the two three-way valves. A prototype and the secondary model in which the solenoid valves and a spool valve were included, respectively, were connected to a mock circulatory unit with the results that a pulsatile TAH with physiological flow wave form could be obtained from a single CFP, about 5 Llmin of pulsatile output could be obtained alternately on the right and left side by switching the solenoid valves or a spool valve, and flow balance between the right and left could be easily controlled by the switching duration. The system is feasible for a totally implantable TAH because it does not need a compliance chamber and can be miniaturized.