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Keywords

 

Authors

  1. Fitzsimmons, Catherine L. RN, MSN, NP-C, FNP

Abstract

Orthotopic heart transplantation became more successful with the introduction of cyclosporine in the late 1970s. Although congestive heart failure has become a significant public health issue and the proportion of patients with advanced heart failure has increased, the number of heart transplants performed has not increased substantially in the past decade. Transplant waiting times have been related to many different factors. Unfortunately, implantation of ventricular assist devices (VADS) may provoke antibody responses. These result in the sensitization of patients and increased waiting time prior to transplantation. The purpose of this article is to explore etiologies of waiting times for pre heart transplant and left ventricular assist device pre heart transplant candidates, explain new theories of sensitization, define current methods to detect sensitization, and discuss nursing care implications.

 

THE NUMBER of solid-organ transplants has increased dramatically in the past 40 years. When histocompatability theories were demonstrated in the 1960s it became clear that patients needed to wait for the ideal organ and tissue match. Early studies were performed with kidney recipients. In 1969, the number of candidates awaiting a kidney transplant was less than 100. 1 Orthotopic heart transplantation became more successful with the introduction of cyclosporine in the late 1970s. Although congestive heart failure has become a significant public health issue and the proportion of patients with advanced heart failure has increased, the number of heart transplants performed has not increased substantially in the past decade.

 

On the basis of the Organ Procurement Transplantation Network/United Network for Organ Sharing (UNOS) data as of September 2003, the waiting time for heart transplantation has been consistent. Waiting times vary between 40 and almost 400 days. The number of transplanted hearts has remained at a steady plateau since 1988 at about 2000 per year. The number of registered Status I patients has dramatically increased since 1998, which may have resulted from the number of patients receiving mechanical support as well as the rising number of patients requiring inotrope support. 2

 

Transplant wait times have been related to availability of ABO blood type, need for specific heart size, weight, geographical location, length of time on Status I level, and need for HLA tissue matching. 3,4 Unfortunately, implantation of ventricular assist devices (VADs) may provoke antibody responses. These result in the sensitization of patients and increased waiting time prior to transplantation.

 

To date, the only Food and Drug Administration (FDA) approved bridge to transplant mechanical devices are the Thoratec HeartMate pneumatic and electric left ventricular assist devices and the Novacor left ventricular assist device (Baxter Corporation). In July of this year, the FDA approved the DeBakey axial flow ventricular assist device as a bridge to transplant device in clinical trials. Biventricular assist devices, also FDA approved, are the Thoratec and Abiomed BVS 5000. Studies have demonstrated the effectiveness in survival and support to transplantation with implantation of VADs in the failing heart. 2,5

 

The Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) hallmark trial randomized end-stage heart failure patients to either standard medical therapy or left ventricular assist device (LVAD) support. Exclusion criteria included transplant eligibility. The results of the study demonstrated a 48% reduction in the risk of death from any cause in the LVAD group compared to that in the medical management, as well as a greater survival rate of 52% vs 25% at 1 year and 23% vs 8% at 2 years. 6 This study demonstrates that the use of VADs can be used in end-stage heart failure. More effective management of pretransplant heart failure patients has improved chances for more successful outcomes.

 

The Thoratec Corporation reports that there have been more than 3600 LVAD implants. More than 300 patients are on ongoing support. The company reports that their average bridge to transplant time is between 100 and 150 days. Similarly, the Baxter Corporation reports an average waiting time of 115 days with the Novacor left ventricular assist device. 7,8 In the face of increased use of mechanical support and subsequent VAD induced sensitization, shortened waiting times for sensitized patients may be due to pretransplant immunomodulation therapy. None the less, requiring a prospective cross match in sensitized patients often increases the waiting time for finding a suitable donor.