Neonatal heart transplantation

Abstract

I 'NITIALLY, pediatric heart transplantation was reserved for relatively older recipients who suffered from one of the several types of cardiomyopathy. Although the most common cause of heart disease in childhood ts congenital anomaly, such children were not considered appropriate candidates for heart transplantation because of their complicated surgical anatomy, history of frequent previous operations, and the presence of concomitant pulmonary hypertension. 1'2 These contraindications denied the transplantation option to a sizeable number of patients, since congenital heart disease occurs in approximately 0.8% to 1.0% of all live births. More than 1,000 neonates each year are diagnosed to have lesions such as hypoplastic left heart syndrome (HLHS), 3 pulmonary atresia with intact ventricular septum, or severely unbalanced atrioventricular septal defects. Collectively, these lethal forms of congenital heart disease are among the leading causes of death in the first month of life. 3 Although conventional surgical therapies are available, the perioperative mortality for this group is between 20% and 50%. 4 5 Considering these bleak statistics, several centers, most notably Loma Linda University led by Dr Leonard Bailey, chose to concentrate on heart transplantation as an alternative therapy for such children. In the mid-1980s, these centers published their successful experiences treating congenital heart disease by heart transplantation 6-8 and as a result, attitudes towards transplanting in these children radically changed worldwide. This is reflected in the dramatic shift in the primary pathology of pediatric recipients from 19801989, when congenital heart disease became the most common indication for heart transplantation in children.l Close examination of these statistics (Fig 1) shows a particularly rapid growth in the proportion of pediatric cardiac recipients under the age of 1 year, virtually all of whom have congenital heart disease. In 1993, children comprised more than 10% of the total heart transplants performed, 60% of whom were under 5 years of age, and 46% had congenital heart disease. 9 The specific indications stratified by age group (Fig 2) clearly show that congenital heart disease is the most common cause of end-stage heart disease in the younger patients, such that 80% of children less than 1 year old, and 45% of those 1 to 5 years old, have congenital heart disease. In contrast, the proportion drops to 26% in the 6 to 18 year old age group. By far the most common pathology is HLHS. However, children with one of several variants of complex ventricle anomalies (eg, single ventricle with aortic obstruction), and those with complex varieties oftruncus arteriosus, are also candidates for heart transplantation.~~ Although the early (30-day) mortality was still higher for children (1 to 18 years old; 16.6%) than adults (8.5%) 12 there were also improvements in survival during the period of rapid growth in pediatric heart transplantation. Recent data (Fig 3) show that mortality is highest in the youngest recipients, who have an approximately 25% early mortality. This progressively decreases with maturity, until mortality equals adult levels by the teenage years. As can be seen in Fig 4, the majority of the difference in pediatric versus adult mortality can be accounted for by early, eg, perioperative, death. The reasons for this are related to the technical difficulties involved in correcting congenital heart lesions, infection, and pulmonary hypertension-related allograft dysfunction.13 Centers with special expertise and experience have achieved even better results; 14'15 thus it is likely that continued improvements in survival will be forthcoming. However, at the present time, the most optimistic statistics would predict a 12% to 15% in-hospital mortality, plus an av-