Rejection Surveillance And Treatment

Acute cardiac rejection is the most common cause of death in pediatric heart transplant recipients after 31 days and prior to 3 years posttransplant. After 3 years, chronic rejection (graft arteriopathy) is the most common cause of death. Clearly, rejection surveillance is extraordinarily important. In children, surveillance is done by clinical assessment, echocardiography, and endomyocardial biopsy. Still investigational are certain EKG parameters as assessed by an implanted pacemaker, new radionuclide imaging studies, and blood levels such as serum vascular endothelial growth factor (VEGF). Clinical parameters observed include change in activity or appetite, atrial or ventricular ectopy, and resting tachycardia (15-20 bpm over baseline). Because endomyocardial biopsy is invasive and not readily available to neonates with relatively small central veins and a thin right ventricle (risk of perforation), echocardiography is the key component of rejection surveillance in neonates and infants. The smallest child in our series to have a biopsy weighed 4 kg. By ECHO, a decrease in the peak rate of posterior wall diastolic thinning may be the most sensitive indicator of acute mild rejection in the infant.12 Some patients develop a new pericardial effusion with rejection. Severe rejection is evidenced by an increase in LV posterior wall thickness and decrease in LV shortening fraction. Our patients undergo ECHO twice weekly in the first month, weekly in the second month, and monthly throughout the first year. In children over 6 months of age we have used endomyocardial biopsy—more frequently the older the child. It is our belief that any time there is a question regarding the ECHO findings, endomyocardial biopsy remains the "gold standard" for diagnosis of rejection.13 Allograft rejection is graded according to ISHLT criterion (see Table 13A.5).14

We have a protocol that calls for yearly biopsies in older children. In these patients, coronary angiography is also performed on a yearly basis to look for transplant coronary artery disease. Our center has recently shown that intravascular ultrasound (IVUS) is more sensitive than angiography for the detection of TCAD.15 We have also successfully used dobutamine stress echocardiogram to screen for TCAD.16 Endomyocardial biopsy also provides tissue for the diagnosis of humoral/ vascular rejection.17 We have treated grade 2 or higher rejection with a 3 day pulse

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