In Vivo Long-Term Evaluation of the Utah Electrohydraulic Total Artificial Heart

In Vivo Evaluation of the National Cardiovascular Center Electrohydraulic Total Artificial Heart

“…The IAS was simply made by punching an orifice at the site of the fossa ovalis in the native atrial septum. The optimal diameter of the IAS had been determined to be 4.0–5.0 mm from our group's and other groups' previous studies ( 2, 9, 10). The atrial cuffs and outflow grafts were then sutured to the respective natural tissues, and the pumping unit was installed in the thoracic cavity.…”

“…To utilize the pumping performance of the EHTAH fully, we are now developing a physiologic control method responsive to output demand. Planned to be involved in the control algorithm is fill‐to‐empty variable heart rate control logic which has been well authenticated in in vitro and in vivo evaluations ( 2, 10). To this fundamental logic providing a Starling‐like response, we contemplate adding an algorithm which transiently augments output increase in response to exercise.…”

“…Accommodation of the left‐right imbalance, which is caused by a left‐to‐right shunt through the bronchial arteries and a lesser stroke volume of the left heart as a consequence of greater valvular and compliance losses, is one of the major issues in a volumetrically coupled TAH system. The IAS has been documented to redistribute unequal left‐right atrial pressures and volumes both in acute and chronic settings ( 2, 10, 11). The advantage of the IAS in comparison to other balancing methods is its simplicity of fabrication and implantation.…”

“…Therefore, the IAS constructed by our method has a certain risk of early occlusion. The University of Utah group employed a composite atrial cuff with an IAS located between the left and right free cuff walls and have demonstrated in a series of in vivo experiments that the IAS was consistently patent for as long as 5 months ( 2). We are now preparing a different type of composite cuff in which the IAS is made in the artificial atrial septum for the next series of animal experiments.…”

“…Recent efforts in TAH development, therefore, have been directed toward a totally implantable system which can reduce the chance of infection and provide patients with an acceptable quality of life by eliminating an external tether. Considerable progress has been made in developing such a system during the last decade, especially in the United States where it is being accelerated by NIH sponsored contracts, with chronic animal survivors for over 5 months ( 1, 2). Nevertheless, all the systems under development in the United States seem too bulky to be implanted into the pericardial space of oriental patients of standard physique.…”