Heart and Lung Transplantation in Adult Congenital Heart Disease

Indications

Little is known about the long-term needs for thoracic transplantation in ACHD. The 2015 report of the Registry of the International Society for Heart and Lung Transplantation (ISHLT) shows that only 3.3% of adult heart transplants were performed for a diagnosis of CHD in the current era (2009–2014) ¹ ; a significant increase compared with 2% of adult heart transplants performed for this diagnosis in the era 1992–2003. Similarly, only a small proportion of adult lung transplantations (0.9%) are performed for this diagnosis. By contrast, CHD accounted for more than one-third of adult heart-lung transplants reported to the registry between 1982 and 2014. Indeed, CHD remains the most common diagnosis leading to heart-lung transplantation in children and adults. However, the total number of heart-lung transplants performed annually has fallen dramatically since its peak in the early 1990s ( Fig. 14.1 ), reflecting a better understanding of which patients can be managed with single and bilateral lung transplants and a desire to optimize use of scarce thoracic organs. This trend may disenfranchise patients with complex CHD that can only be managed by heart-lung transplantation. Listing criteria for adult patients with CHD warrants careful refinement.

The number of thoracic transplants performed for the indication of CHD almost certainly underestimates the true need. Many patients are not referred for consideration for transplantation because it is assumed that their disease may be too complex or the risk is too high. Others die while on the waiting list. With almost all forms of CHD now deemed suitable for palliation or repair in infancy and childhood, an ever-increasing population of patients with severe forms of CHD is now reaching adult life. Thus increasing demand for transplantation in adults with CHD is inevitable.

Types of Heart Disease Requiring Transplantation

A few patients who have never undergone palliation for their congenital defects survive into adult life. These include patients with simple anatomic defects such as atrial or ventricular septal defect or patent arterial duct who have developed pulmonary vascular disease. Few such patients without prior surgery will be suitable for isolated heart transplantation. Another population is composed of patients who were palliated for complex cyanotic heart disease (with reduced pulmonary blood flow) before the modern era of congenital heart surgery. Many of these underwent systemic-to-pulmonary shunts such as Waterston or Potts procedures or a classic Blalock-Taussig shunt. These (relatively) unrestricted shunts provided excellent long-term palliation for many patients but caused chronic ventricular volume overload as well as excessive pulmonary blood flow, resulting in ventricular dysfunction and pulmonary hypertension that is generally irreversible. Some of these patients are potential heart-lung transplant candidates.

An increasing population of patients referred for transplant consideration are those palliated with partial (Glenn) or complete (Fontan) atriopulmonary or cavopulmonary anastomoses. It is now recognized that the Fontan procedure is palliative, although complete, or near complete, separation of the circulations is achieved. Most patients with Fontan circulation will likely need consideration for heart transplantation at some point in their adult life. Of note, those receiving Fontan palliation for a diagnosis of hypoplastic left heart syndrome are much more likely to develop “Fontan failure” with potential need for transplantation.

Two final groups of patients form a significant proportion of adults with CHD who are referred for consideration for thoracic transplantation. These are patients with tetralogy of Fallot with complex pulmonary atresia and patients with simple transposition of the great vessels who underwent childhood repair with atrial baffling (Mustard or Senning procedure). The former group poses enormous challenges. Most are referred for consideration of heart-lung transplantation with progressive cyanosis. Some have never been palliated, but many have received one or multiple systemic-to-pulmonary shunts, often with multiple unifocalization procedures. Patients with right ventricular failure after a Senning or Mustard procedure are also being seen with greater frequency as it becomes apparent that the systemic right ventricle is unlikely to perform well into late adult life. Several years ago it was believed that many of these adults with right ventricular failure could be helped by left ventricular training and subsequent atrial baffle takedown and arterial switch procedure. It is now recognized that the mortality of this approach is very high in the older patient, and most of these patients are probably best considered for heart transplantation.

Timing of Transplantation

For patients with ischemic or dilated cardiomyopathy, a number of risk factors for survival have been recognized. Peak oxygen consumption has proved a useful guide for timing of transplantation. In the setting of CHD, no such guidelines exist and each patient’s pathophysiology is unique. Life expectancy of less than 2 years can be considered a good indication for listing, given the long waiting times for donor organs in this population. This is not always easy to predict and emphasizes the need for involvement of physicians highly experienced in the management of adults with CHD in the transplant evaluation. Evaluation of quality of life is as important as estimation of survival in determining the timing of transplantation. It must also be remembered that many adults with end-stage CHD may not be suitable for ventricular assist device support as a bridge to transplantation and, overall, mechanical circulatory support may not improve waitlist mortality in this population. Therefore late referral should be avoided.

Pretransplantation Evaluation

The principles of evaluation of the thoracic organ candidate are covered in detail in standard texts. Specific considerations in the evaluation of the patient with ACHD are summarized in Box 14.1 .