Thoracic Transplantation
Steven A. Webber
Laura A. Loftis
Aarti Bavare
Renee M. Potera
Nikoleta S. Kolovos
KEY POINTS
Cardiac Transplantation
There have been significant improvements in survival over the last two decades, almost entirely related to improvements in early outcome.
There is increasing use of ventricular assist device support for bridge-to-transplant indications with excellent shortterm outcomes.
A wide array of immunosuppressive regimens is used in children, but no large, randomized, controlled trials have been performed.
Primary graft failure, infection, and acute rejection are the principal causes of death in the first year after transplantation.
Rejection with severe hemodynamic compromise is associated with high mortality and requires early diagnosis and aggressive intervention, including mechanical circulatory support when necessary.
Graft coronary artery disease is the principal cause of late graft loss.
Retransplantation is associated with poor results if performed early after primary transplantation, or during acute rejection events, but is associated with better results when performed for late indications.
The ultimate goal of transplantation is the development of donor-specific graft tolerance.Lung Transplantation
End-stage lung disease secondary to cystic fibrosis remains the primary indication for pediatric lung transplantation, although many complex disease states may benefit from transplantation.
Advances in extracorporeal technology may provide benefit to patients awaiting transplantation, although further study in children is warranted.
High levels of immunosuppression are required for the lung transplant recipient; the risk of opportunistic infection as well as colonization is a major challenge in the posttransplant period.
Lung transplant recipients face some of the worst survival statistics among the solid-organ transplants; the development of bronchiolitis obliterans significantly impacts survival.CARDIAC TRANSPLANTATION
Transplantation offers the only hope for survival and improved quality of life for selected children with end-stage heart disease that is due to either acquired or congenital cardiac defects. Kantrowitz and associates performed the first pediatric transplant in December 1967, only a few days after Dr. Christian Barnard’s pioneering operation in an adult. Interest in transplantation of the heart declined throughout the 1970s due to the high mortality that resulted primarily from lack of effective immunosuppressive medications. A resurgence of clinical activity developed in the early 1980s with the introduction of cyclosporine, the first oral immunosuppressive agent with relative specificity for inhibition of 
T lymphocytes, the primary mediators of allograft rejection. This therapy resulted in dramatic improvements in survival of all transplanted organs. With improvements in candidate and donor selection, preoperative management, surgical technique, and early postoperative care, ˜95% of heart transplant recipients are able to leave the hospital alive and in good health after transplantation (1). Furthermore, pretransplant mortality has fallen. This section provides an overview of the current state of the art of pediatric heart transplantation, focusing on issues of key interest to those who work in the pediatric intensive care unit (PICU).
T lymphocytes, the primary mediators of allograft rejection. This therapy resulted in dramatic improvements in survival of all transplanted organs. With improvements in candidate and donor selection, preoperative management, surgical technique, and early postoperative care, ˜95% of heart transplant recipients are able to leave the hospital alive and in good health after transplantation (1). Furthermore, pretransplant mortality has fallen. This section provides an overview of the current state of the art of pediatric heart transplantation, focusing on issues of key interest to those who work in the pediatric intensive care unit (PICU).Indications for Cardiac Transplantation
Transplantation of the heart is generally considered to be indicated when expected survival is under 2 years and/or when the patient has an unacceptable quality of life. Cardiomyopathy (predominantly dilated forms) and complex congenital heart defects remain the primary indications and together account for ˜90% of transplantations undertaken in children (2). Worldwide, transplant activity remains relatively constant and reflects a finite donor pool. Diagnoses that lead to transplantation are age-dependent, with congenital heart disease accounting for two-thirds of transplants in the infant age group and cardiomyopathy accounting for a similar proportion among adolescents (2).
The indications for heart transplantation in children were summarized in a 1999 report from the Pediatric Committee of the American Society of Transplantation and in a more recent report from 2007 (3,4). Perhaps the most controversial indication for heart transplantation is hypoplastic left heart syndrome and related pathologies in the newborn. Survival rates in excess of 80% at 1 year may be achieved at experienced centers, with either Norwood reconstruction or primary transplantation for this condition. Median waiting times for newborn heart transplant candidates are ˜2 months in the United States (and longer in many US regions and in some other countries), resulting in very high costs of care prior to transplantation, significant pretransplant morbidities, and wait-list mortality as high as 25%. In light of these observations, most centers have moved away from transplantation and toward staged reconstruction for neonates with hypoplastic left heart syndrome. This strategy increases availability of organs for other infants with cardiac disease unsuitable for surgical palliation.
Relative and/or absolute contraindications include chronic infection with either hepatitis B or C, or HIV; prior nonadherence with medical therapy; recent or current treatment of malignancy with inadequate follow-up to ensure likely cure; active acute viral, fungal, or bacterial infections; elevated and fixed pulmonary vascular resistance (PVR), inadequate intraparenchymal pulmonary vascular bed; diffuse pulmonary vein stenosis; and major extracardiac disease felt to be nonreversible with heart transplantation (e.g., severe systemic myopathy). Inevitably, some centers consider specific contraindications absolute, whereas others may feel that they are relative. Decision-making is based on consensus discussion among all team members, including intensive care staff.
Evaluation of the Cardiac Transplant Candidate
A vast number of children who undergo heart transplantation evaluation are hospitalized in the PICU. For many, the transplant will occur during the first hospital admission. Thus, the intensivist will be deeply involved in the transplant evaluation, which should include an assessment of expected survival without transplantation, the patient’s current quality of life, the potential for alternate surgical or medical therapies, and the inherent risks of the transplant surgery itself. A typical evaluation protocol is shown in Table 76.1.
Anatomic and Hemodynamic Considerations
Children with the most complex cardiac anatomy may receive a cardiac transplant, provided the lung vasculature is adequately developed and PVR is acceptable. The anatomic points of most interest to the surgeon include abnormalities of cardiac and visceral situs (especially anomalies of the systemic and pulmonary venous return) and the size and anatomy of the main and branch pulmonary arteries (including the presence of stenoses, distortions, and nonconfluence). Intracardiac anatomy is less important, as the bulk of the cardiac mass will be explanted. Abnormalities in the relation of the great arteries usually pose few problems. Extreme care on entry to the sternum must be taken when a right ventricular-pulmonary artery conduit or enlarged right atria (after Fontan procedure) is present. Cardiac catheterization is usually indicated pretransplant to assess PVR. Excessive fixed resistance will result in acute donor right ventricular failure. This situation would necessitate the need for a right ventricular assist device in the immediate postoperative period.
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TABLE 76.1 EVALUATION OF CANDIDATES FOR HEART TRANSPLANTATION | ||
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In general, children with indexed PVR (PVRI) ≤6 indexed units (IU) are considered low risk for acute donor right heart failure. If resistance is between 6 and 10 IU, the risks are higher, but transplantation is still generally not contraindicated (5). A PVRI
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