Completely Implantable Total Artificial Heart and Heart Assist Systems: Initial In Vivo Testing

Summary

We have developed and tested systems for long-term heart replacement ventricular assistance without percutaneous leads. A rollerscrew energy converter actuates a single sac-type blood pump for ventricular assistance, or alternately ejects the left and right pumps of a total artificial heart. A simple compliance chamber assures modest variation of pressure within the sealed energy converter housing. An implanted canister contains control electronics and a battery capable of providing 30–50 min of operation. Energy is transmitted inductively from a ring-shaped external coil to a mound-shaped subcutaneous coil. Information is transmitted to the implant by frequency modulation of the power carrier and from the implant by radio frequency transmission. External equipment includes a battery pack with simple indicators, a battery charger, and a physician’s office or laboratory monitoring system. Both systems have undergone initial in vivo testing in calves. Eleven total artificial heart recipients survived from 1 to 118 days. The most common complication of the implant procedure was pulmonary dysfunction. The longest-surviving recipient was euthanized for progressing sepsis originating at a percutaneous monitoring line. The first assist system operated for 84 days before failure of the energy transmission secondary coil. The second assist implant is ongoing at 125 days. These studies thus far have demonstrated the implantability of the systems and have verified the proper function of the implanted controller. Experiments will continue in order to determine long-term interactions with the recipient.