Pediatric Heart Transplantation Periprocedural Care

Many pediatric patients awaiting heart transplantation can be managed out of the hospital. Evaluate patients on a frequent basis (at least monthly). Pay particular attention to any febrile illness because transplantation in the face of acute infection can be dangerous. Aggressive infection surveillance and treatment is warranted.

The issue of vaccination may arise in this setting. Generally, vaccinations (especially live virus vaccines) are not given during the pretransplant waiting period; stimulation of the immune system should be avoided, given that a donor may become available at any time. However, if the child is believed capable of safely waiting at least 6 weeks for the transplant, administration of live virus vaccines (if age-appropriate) before the procedure is probably better because live virus vaccines are commonly avoided entirely after transplantation.

Laboratory studies

The blood type is determined so that the patient can be listed for an appropriate organ. Knowing the infant recipient’s blood type is important, but successful transplantation across ABO-incompatible blood types has been successfully performed in infants.

Infection screening is carried out, including a complete blood count (CBC) with differential, urine and blood cultures, cytomegalovirus (CMV) titer or CMV polymerase chain reaction (PCR), hepatitis B surface antigen (HBsAg) test, HIV test, rapid plasma reagin (RPR) test, Toxoplasma titer, Epstein-Barr virus (EBV) PCR, and endotracheal tube (ETT) aspirate (if applicable)

Renal function and liver function are assessed by measuring electrolyte, blood urea nitrogen (BUN), and creatinine levels and obtaining a liver profile. Pretransplant sensitization is evaluated by measuring panel-reactive antibody (PRA) levels.

Imaging studies

Head ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI) or magnetic resonance spectroscopy (MRS), and electroencephalography (EEG) are performed as appropriate to assess neurologic status. Chest radiography and renal ultrasonography are also helpful. Echocardiography is performed to assess cardiac anatomy and function.

Cardiac catheterization

Cardiac catheterization may be needed to assess anatomy, to rule out pulmonary venous drainage abnormalities, to assess pulmonary artery adequacy, and to assess pulmonary vascular resistance (PVR). Pulmonary artery pressure may be estimated by means of echocardiography, but a more formal analysis usually requires cardiac catheterization.

Recipients with elevated PVR are at increased risk for acute right-heart failure in the early posttransplant period. In the first few months of life, if the main and branch pulmonary arteries are of normal caliber and distribution, the elevated PVR of the newborn period usually normalizes rapidly soon after transplantation. If pulmonary venous obstruction is present, pulmonary artery pressures may not normalize as quickly.

Elevated PVR that is reactive (ie, responsive to vasodilator therapy) can usually be managed with oxygen or intravenous (IV) vasodilator therapy in the pretransplant period. This can lead to a decrease in the PVR, which simplifies posttransplant management. Elevated PVR that is fixed is an indicator of significant risk for acute graft failure.

Close outpatient follow-up is essential to ensure long-term success. The highest risk of complications occurs in the first few months after transplantation; for this reason, the child should remain near the transplantation center for the initial follow-up. The following is an outline of the outpatient testing schedule at the author’s institution (Loma Linda University Children’s Hospital).

Physician visits take place twice weekly for 6 weeks, then less frequently as the rejection-free interval increases. The minimum visit frequency is monthly for the first year and every 3 months thereafter.

Echocardiography is performed twice weekly for 4 weeks, then less often as the rejection-free interval increases; after the initial period, it should be performed at the same time as the routine physician visits. In patients who have undergone arch reconstruction, full-study echocardiography is performed at 1 month, 3 months, and 12 months to evaluate the aortic arch.

Electrocardiography (ECG) is performed monthly for the first 3 months, then quarterly until 1 year after transplantation, and then every 6 months thereafter.

Chest radiography is performed monthly for 3 months, at 12 months, and then annually.

The cyclosporine or tacrolimus trough level is assessed twice weekly for 2 weeks after discharge, weekly for 4 weeks, monthly for the first year, and then every 3 months thereafter. Target cyclosporine levels (with a favorable rejection history) are 250-300 ng/mL for 6 months, 200-250 ng/mL for 6-12 months, and 125-150 ng/mL thereafter. Tacrolimus trough levels are maintained at 10-13 ng/mL for 6 months, 8-10 ng/mL from 6-12 months, and 5-8 ng/mL thereafter if rejection history is favorable.

Mycophenolate mofetil (MMF) levels are checked concurrently with calcineurin inhibitor levels. Mycophenolic acid levels are maintained at 2.5-5 µg/mL. Note that immunosuppression blood level targets are only starting points. Adjustments are needed in the individual child because of rejection history and side effect profile.

The use of genomics to evaluate the response to immunosuppressive medication and to assess the risk of rejection and graft vasculopathy is being studied; this is interesting and potentially treatment-shifting work. Gene array techniques that measure up-regulation and down-regulation of peripheral blood gene markers are also being studied as a means of individually assessing the degree of immunosuppression and, thus, the risk of rejection and infection.

A CBC with platelets is obtained every 2 weeks for 2 months, then monthly for the first year, and every 3 months thereafter. levels of basic electrolytes are obtained at the same time as the CBC count for the first year, with a complete metabolic profile (including magnesium levels) obtained every 3 months.

The CMV immunoglobulin G (IgG) titer is assessed at 6 months, 12 months, and then annually until conversion. EBV PCR is assessed every 3 months. HIV and HBsAg tests are obtained at 6 months.

Isotopic glomerular filtration rate (GFR) is assessed at 3 months, 12 months, and every year thereafter for patients who undergo transplantation during infancy. Isotopic GFR is assessed every 2 years for patients who undergo transplantation after the first year and for children who are older than 2 years and whose most recent GFR is higher than 100 mL/min/1.73 m².

Renal ultrasonography is performed at 3 months, 12 months, and every other year thereafter.

Endomyocardial biopsy is obtained annually for newborns and children aged 2 years or less at transplantation; at 1 month, 3 months, 12 months, and annually thereafter for children aged 2-8 years at transplantation; and before discharge, at 1 month, 2 months, 3 months, 6 months, 12 months, and annually thereafter for patients aged 9 years or older at transplantation.

Coronary angiography is performed annually, starting at the first anniversary of transplantation. Intravascular ultrasonography is performed at age 6 years and every other year thereafter unless previous intravascular ultrasonography demonstrated Stanford class 4 findings.

All routine vaccinations, except for live virus vaccines (eg, oral polio, varicella, and measles-mumps-rubella [MMR] vaccines), should be administered, starting as early as 6 weeks after transplantation.