Heart transplantation in perspective

Heart disease remains one of the leading causes of death in the western wor ld. In the 35 years since the first human heart transplants, cardiac transp lantation has become established as the therapeutic option of choice in the management of terminal cardiac failure. Since 1981,the introduction of cyc losporin for immunosuppression has dramatically increased cardiac transplan tation. However, several obstacles limit further utilization, including lim ited availability of donor hearts, limited ischemic time tolerated by donor hearts, and chronic rejection. Research is underway into donor heart prese rvation and new immunosuppressant drugs in an effort to increase donor orga n availability. Due to these constraints, alternative therapies are under d evelopment. More than 2,000 circulatory assist devices have been implanted with >25% used as a bridge to heart transplantation. The University of Otta wa Heart Institute began the,first Canadian implantation of circulatory ass ist devices in 1986 and has implanted 23 total artificial hearts and 23 ven tricular assist devices. The Heart Institute is also developing a totally i mplantable electrohydraulic ventricular assist device (EVAD) for long-term mechanical support outside the hospital. Another alternative being evaluate d for clinical use is xenotransplantation. The major obstacle for widesprea d use of clinical xenotransplantation remains graft rejection, and fundamen tal research is ongoing to address hyperacute and delayed xenograft rejecti on. While cardiac tranplantation is the most effective treatment of termina l heart failure, limited donor hearts compel us to rely on alternatives. In the future, the research underway on xenotransplantation and mechanical ci rculatory assist devices will provide new options for the clinical treatmen t of terminal cardiac failure.