29 Heart Transplantation
Heart transplantation has become an established treatment for children with terminal heart failure. In some centers, heart transplants are performed even on neonates with complex congenital heart defects. In childhood, heart transplants are most often performed on patients with a dilated cardiomyopathy. In children under 1 year old, the indication for heart transplantation is a hypoplastic left heart syndrome.
Lifelong immunosuppressive therapy is required after a heart transplant. Transplants are also considerably limited due to the global lack of donor organs.
In Germany, donor organs are assigned via Eurotransplant in Leiden (Netherlands). Besides Germany, Austria, the Benelux countries, Croatia, and Slovenia are linked with this central registry for organ donors and recipients. There are also links with other European centers.
More than 75,000 heart transplants have now been performed across the world. Children are involved in around 10% of all heart transplants. Every year, around 400 children receive heart transplants.
A heart transplant is considered the last treatment option for terminal heart failure when other measures are not likely to succeed. For complex congenital heart defects, it may be an alternative to surgical palliation. According to clinical aspects, a heart transplant is generally indicated if the estimated survival time is less than 6 to 12 months.
Possible indications for heart transplantation in childhood include the following:
Dilatated cardiomyopathy (most frequent indication for heart transplantation in childhood)
Arrhythmogenic right ventricular cardiomyopathy
Congenital heart defects:
Hypoplastic left heart syndrome
Shone complex (extreme form)
Complete AVSD with hypoplastic left ventricle
Single ventricle with subaortic obstruction
Severe forms of Ebstein anomaly
Pulmonary atresia with intact ventricular septum and pronounced coronary fistulas/sinusoids
Bland–White–Garland syndrome with extensive infarction
Irreversible failure of the systemic ventricle following an atrial baffle procedure or Fontan procedure
Cardiac tumors (obstructive, nonresectable tumors)
Malignant arrhythmias (untreatable by pharmacological means or intervention, e.g., associated with arrhythmogenic right ventricular dysplasia)
Coronary anomalies (severe changes, e.g., after Kawasaki syndrome)
The list of contraindications for a heart transplant is continuously evolving. Some of the contraindications listed below are relative contraindications. From the surgical perspective, for a heart transplant due to a congenital heart defect, it is important that the pulmonary veins are sufficiently large. In addition, for a total anomalous pulmonary vein connection, pulmonary venous confluence must be present that can be anastomosed with the left atrium of the donor heart.
Absolute or relative contraindications are:
Severe fixed increase in pulmonary resistance
Diffuse hypoplasia of the pulmonary arteries
Total anomalous pulmonary vein connection without a pulmonary venous confluence
Active systemic Infection
HIV infection or chronic active hepatitis B or C
Irreversible liver or kidney dysfunction
Multiple organ failure
Untreatable malignant disease
Systemic diseases that impair the recovery or survival after the transplantation (e.g., neuromuscular diseases)
Severe malformation syndromes
Severe diseases of the CNS
Lack of compliance by the patient or family
Weight less than 1,800 g
Preterm infants born before the 36th week of gestation
29.1.4 Diagnostics of the Organ Recipient
The diagnostic measures for the recipient before the heart transplant include the following examinations:
Routine blood tests: blood count, blood sugar, electrolytes including magnesium, phosphate, urea, creatinine, uric acid, protein, INR, PTT, AT III, AST, ALT, γGT, LDH, AP, CK, CRP, iron, ferritin, transferrin, cholesterol, triglycerides, carnitine, T3, fT4, TSH, BGA
Auto-antibodies: ANA, smooth muscles, heart muscle, cardiolipin antibodies
Infection serology: CMV, EBV, HSV, hepatitis A, hepatitis B, hepatitis C, Coxsackie, adenovirus, influenza/para-influenza virus, HIV, measles, mumps, rubella, varicella, Candida, Aspergillus, toxoplasmosis.
HLA typing and HLA antibody screening
Stool test for pathogens
Cardiac catheterization including coronary angiography and biopsy
Abdominal ultrasonography, also cranial ultrasound for infants
ENT examination and dental status (to rule out a source of infection)
29.1.5 Diagnostics of the Organ Donor
The organ donor must fulfill the German Medical Association’s criteria for brain death. The current criteria can be seen at www.baek.de.
The transplantation is generally between compatible blood types. However, even ABO-incompatible hearts have now been successfully transplanted—especially in children under age 1 year, in whom antibodies against the blood type characteristics have not yet formed. The significance of the human leukocyte antigens (HLAs) is not fully understood. Prospective HLA matching is not yet carried out, although a total HLA mismatch is considered to be a risk factor. Donor and recipient hearts should be of approximately the same size. A weight difference of up to 20% between donor and recipient is tolerable. Larger donor hearts are better tolerated than smaller. To prevent long ischemia times, the time between explantation and implantation should not exceed 4 (–8) hours. After explantation, the organ is stored in a cardioplegic solution at 4°C. The donor should be stabilized in intensive care until explantation (e.g., maintain adequate blood pressure, balance fluids and electrolytes, avoid hypoxia and anemia).
Exclusion criteria for organ donors (from Overbeck 2007):
Malignant disease (except primary brain tumors)
Active bacterial, viral, or mycotic infections
Positive HIV serology
Diffuse coronary sclerosis
Documented heart attack
Treatment-resistant ventricular arrhythmias
Relative exclusion criteria:
Positive HBsAg or HBc test
Severe chest trauma
High catecholamine use
Known cardiac diseases (except patent foramen ovale, ASD II, PDA)
29.1.6 Surgical Procedure
Orthotopic heart transplantation is the usual procedure. A surgical technique is used that was described in 1960 by Lower and Shumway. In this procedure, the diseased heart is excised, leaving the posterior walls of the right and left atria, which are anastomosed with the donor heart. The stump of the aorta and pulmonary artery of the donor heart are anastomosed end-to-end with the respective vessels of the recipient (Fig. 29.1).
A modification of this surgical technique is required in a hypoplastic left heart syndrome because the aorta of the recipient must be augmented with a long segment of the donor aorta (Fig. 29.2).