More than 100,000 heart and heart–lung transplants have been reported to the Scientific Registry of the International Society for Heart and Lung Transplantation (ISHLT) since the first heart transplant in 1967 [5]. From 1987 through 2006, 35,334 adults were reported to the United Network for Organ Sharing (UNOS ) and the Organ Procurement and Transplantation Network for cardiac transplantation. Of these adult patients, 689 (1.9 %) underwent transplantation for CHD.

The total number of heart transplants performed worldwide has remained relatively stable over the past several decades, but the prevalence of heart transplantation for CHD has increased by 41 %, from 1.8 to 2.5 % of the total transplant population. This increase in the CHD transplant population contrasts with the 28 % decrease in transplants performed in adult recipients for all other indications. The adult cardiac transplant population will probably increase further as more patients with CHD reach adulthood. A similar trend has occurred with combined heart–lung transplantation, which has a prevalence among adult CHD patients ranging from 1.8 to 2.4 %.

As reported by ISHLT [6], this increase in CHD patients across the transplant population is likely a combination of both effective medical therapy and the use of mechanical support for the more “conventional” forms of heart failure. Little data exist to guide effective medical therapy for most congenital heart lesions. Furthermore, mechanical support options are limited in CHD patients because of anatomical and hemodynamic factors. Thus, heart failure may progress in adult CHD patients, with transplantation being the only suitable advanced treatment option.

The number of adults with CHD needing transplantation will likely increase and present new challenges [7]. Elevated pulmonary vascular resistance (PVR ), challenges in measuring PVR accurately, elevated antibody levels, complications following a Fontan procedure , technical surgical challenges, and more complicated postoperative care are issues that complicate transplantation in these patients.

Not surprisingly, the outcome for transplantation differs for patients with CHD or other conditions. Comparing 41,849 adults listed for cardiac transplantation between 1995 and 2009, the 1035 with CHD had a higher early, 1-year, and 5-year mortality following the operation [8]. The higher early mortality may be partly related to the complexity of the transplant surgery itself.

CHD patients often had prior complex cardiac operations. In a study of 24 adults with CHD, 22 had a mean of two previous operations and, at transplantation, 18 of the 24 patients had an additional procedure performed on an extracardiac lesion [9]. Complications from a prior sternotomy and additional reconstructive procedures result in significantly longer mean ischemic and bypass times compared to adults without CHD [10]. This is a well-recognized risk factor for both poor short- and long-term outcomes. The unique surgical challenges pose increased reoperative risk for CHD patients, with a mortality of 18.9 % compared to 9.6 % for non-CHD patients. The early mortality in CHD patients was still higher (16.6 %), even in those without a previous cardiac operation, compared to 6.3 % for those without CHD.

Additional factors affecting survival include cytomegalovirus (CMV ) mismatch, previous right heart bypass procedures, high levels of human leukocyte antigens (HLA), and elevated PVR or transpulmonary pressure gradient. In over half of CHD patients, PVR exceeds 4 Wood units, an established risk factor for operative mortality. Finally, heart failure before transplantation contributes to a higher early mortality. Conventional “bridging” therapies, such as mechanical support devices or inotropes, may be unavailable or less effective, resulting in CHD patients being more ill at transplantation. Thus, a CHD patient is often sicker at the time of transplantation than a non-CHD patient.

Knowledge and experience gained over the past decades likely contribute to the decreasing posttransplant mortality among the CHD population. A recent study [11] compared survival in 19 adults with CHD aged 39 ± 13 years with 428 adults aged 54.7 ± 12 years who received transplants for other conditions. No difference in posttransplant survival was found for any period through 5-year posttransplant, with survival being 70 % and 72 %, respectively. No correlation was found for a number of factors including failed Fontan procedure, end-stage liver disease, or percent of reactive antibodies. The authors were encouraged that, with proper donor and recipient selection, the results for adults with CHD resembled those for other patients undergoing transplantation. Greutmann and associates [12] compared 13 adults and adolescents with CHD to 322 patients without CHD. The survival of the 13 was 85 % at 30 days, 1 year, 5 years, and 10 years and 77 % at 20 years. This survival was no different from that of either the entire group or the age-matched patients with dilated cardiomyopathy.

Finally, recent data from ISHLT confirms that adult CHD patients at the time of transplant tend to be younger and have fewer comorbidities. These statistics, combined with improved patient selection, surgical techniques, and postoperative management, have resulted in an overall median survival for CHD patients of 13 years compared to 10 years for the remaining populations. In fact, the conditional median survival (survival of patients who live the first year following transplant) is even more favorable for the CHD population: 18 years versus 13 for non-CHD patients [13]. These data further support transplantation as a viable option in carefully selected CHD patients.

With a relatively small number of adults with CHD, experience and information about adults with acquired cardiac disease are used to direct transplantation care. Because CHD patients are younger at time of transplant and posttransplant survival is limited, the operation should not be performed prematurely nor prolonged by palliative or other operations, which may decrease the success of transplantation. One group [14] suggested that transplantation be delayed, if possible, until a child with CHD has reached at least late adolescence. None of the author’s 14 patients had an early or late death, suggesting that a larger body size makes it easier to perform the transplant and provide postoperative care. Determining optimal transplant timing for a CHD patient is complicated by the lack of data about outcomes of medical therapy and the risk of developing irreversible complications in other organ systems.

In adults with acquired heart disease, the VO2 max has been used to define severe congestive heart failure (CHF) and is associated with 1-year posttransplant mortality. A <14 ml O₂kg⁻¹/min⁻¹ (or <12 ml O₂kg⁻¹/min⁻¹ if treated with beta-blockade) or <50 % predicted VO2 max has been considered an indication for heart transplantation [15, 16]. These guidelines have been extrapolated to CHD patients despite the lack of supporting data. Given the known reduction in exercise capacity in a large percentage of CHD patients [17, 18], the results of such cardiopulmonary stress testing should be complemented by other factors including functional classification, hospitalization requirements, ventricular function, abnormal laboratory results (low serum sodium, renal dysfunction, elevated brain natriuretic peptide, etc.), and underlying etiology.

Elevated pulmonary artery pressure and/or vascular resistance are contraindications for transplantation. Specifically, a pulmonary vascular resistance >5 Wood units and a transpulmonary pressure gradient >15 mmHg are considered contraindications. If initial testing reveals elevated pulmonary vascular resistance, pulmonary vasodilators are administered to assess patients. If pulmonary vascular resistance falls to normal levels, transplantation can be considered, but with an increased risk. If levels are unresponsive to vasodilators, transplantation should not be performed.

Data about patients needing transplantation are submitted to UNOS and classified according to body size, blood group, and clinical status (see below). An encouraging fact is that the survival of patients listed with UNOS has improved from 49.5 to 69.0 % between 1990–1994 and 2000–2005 [19].

While adults with CHD have a higher initial mortality following transplantation, their 10-year survival is favorable [23]. The relative risk for death during the first year compared to those with a cardiomyopathy was 2.46 for those aged 18–30 years and 2.18 for those aged 31–60 years [23]. In part, this relates to unique issues faced by adults with CHD following transplantation:

Because of these unique challenges facing CHD patients, it is important for a team of physicians and nurses, including those with advanced knowledge and experience with CHD, to participate in posttransplant care.

Common transplant comorbidities are also present in CHD patients, but their incidence is unknown. These include the well-identified factors of hypertension, hypercholesterolemia, renal dysfunction, and diabetes, all of which can result from immunosuppression protocols. Allograft rejection is most common during the first year posttransplant. A higher rejection risk exists because of underlying anti-HLA antibodies. Patients with rejection during the first postoperative year have a lower survival (88 % compared to 94 % at 3 years) [25]. Additionally, rejection increases the risk of developing cardiac allograft vasculopathy. Vasculopathy, which may be a form of chronic rejection, is an important contributor to long-term mortality. Other contributing factors are hypertension, hypercholesterolemia, diabetes in the heart donor, male gender, large body size, and HLA mismatch. Although malignancies are usually a late complication of immunosuppression, lymphoma, specifically posttransplant lymphoproliferative disease (PTLD ), occurs more commonly during the first years after transplantation. PTLD is closely associated with Epstein–Barr infection. Because of the younger average age at time of transplant, CHD recipients are more frequently EBV naïve. This increases the risk of developing primary EBV infection and subsequent PTLD. Therefore, heightened EBV monitoring is indicated in all posttransplant recipients who are EBV naïve.

The fact that a younger age is usually associated with fewer comorbidities suggests that long-term transplant survival would be greater. Younger adults (aged 18–35 years), however, may have a higher death rate than older patients following heart transplantation. Data from the Cardiac Transplant Research Database showed 5-year survival rates at 67 % (aged 18–35 years), 78 % (35–59 years), and 76 % (>60 years) [25]. Furthermore, compared to those over age 35, the younger age group had a higher risk of death from rejection, but a low risk of death from infection. Younger patients’ tendency to not comply with treatment regimens was of significant magnitude; however, this did not solely account for the difference. George et al. [25] considered current immunosuppression regimens suboptimal for young adults and believed they should be changed, but did not suggest specific modifications.

Congenital heart disease encompasses a variety of anatomic and hemodynamic anomalies. Ideally, survival could be determined for each individual condition, but that data are unavailable. The next three sections address issues related to and results of heart transplantation for different hemodynamic lesions.