C. Burch

Use of assist devices and ECMO to bridge pediatric patients with cardiomyopathy to transplantation

BACKGROUND Pulsatile ventricular assist devices (VADs) are used to bridge adults with end-stage heart disease to transplantation. A combination of external implantable pulsatile and continuous-flow external mechanical support now can be used to bridge pediatric patients with end-stage cardiomyopathy to orthotopic heart transplantation (OHT). METHODS We reviewed consecutive pediatric patients with cardiomyopathy (n = 28) who required mechanical cardiac support from July 1995 to February 2001. All were OHT candidates with severe hemodynamic compromise despite maximal medical support. We excluded from this series patients who had undergone cardiotomy. RESULTS Nineteen patients received support from external continuous-flow devices, either with extracorporeal membrane oxygenation or with centrifugal VADs, and 9 patients received pulsatile support. Nineteen of 28 (68%) patients were successfully bridged to transplant (17) or weaned (2) from their devices after recovery. Of the patients successfully bridged to transplant or recovery, 89% are alive to date. Univariate analysis revealed that a lower bilirubin concentration after 2 days of support was associated with a favorable outcome (p = 0.006). As expected, the patients with pulsatile VADs had significantly higher rates of extubation and oral feeding. CONCLUSION Pulsatile and continuous-flow devices can complement each other to significantly extend the lives of a wide range of pediatric patients with severe cardiomyopathies.

B-type natriuretic peptide in children after cardiac transplantation

BACKGROUND The normal B-type natriuretic peptide (BNP) concentration and the significance of increased BNP concentration in children after orthotopic heart transplant (OHT) remain unknown. We sought to determine plasma BNP concentrations in relation to post-transplant time and to explore factors associated with increased BNP in pediatric OHT recipients. METHODS We obtained plasma BNP concentrations in 44 pediatric patients at 1 to 171 months after OHT. All patients underwent endomyocardial biopsies and echocardiography. We analyzed the association between BNP and post-transplant time, as well as the association between BNP concentration and left ventricular end-diastolic dimension (LVEDD) after transplantation. RESULTS The age of study patients ranged from 0.9 to 21.2 years (mean, 11.4 +/- 6.2 years; median, 10.5 years). We evaluated BNP concentrations immediately after transplantation. The mean BNP concentration decreased exponentially to 100 pg/ml by 14 weeks after OHT. Although BNP concentration relative to time after OHT varied among individuals, all patients with multiple measurements showed predictable rates of decrease. This decrease in BNP concentration was not associated with changes in LVEDD. CONCLUSIONS Plasma BNP concentration was elevated in children after OHT and decreased exponentially in time to 100 pg/ml by 14 weeks after OHT. The decrease in BNP concentration was unrelated to left ventricular dimension.

The yield of surveillance endomyocardial biopsies as a screen for cellular rejection in pediatric heart transplant patients

Abstract:  Endomyocardial biopsy is commonly used to screen for cellular rejection in pediatric heart transplant patients. The yield of EMBs when combined with newly developed immunohistochemical techniques and modern immunosuppression in pediatric heart transplant patients is unknown. After OHT, surveillance biopsies were performed on a routine basis on all pediatric patients. EMBs were also performed on symptomatic OHT patients suspected to have rejection. All positive results (greater than ISHLT grade 1B) were confirmed with immunohistochemical staining. A retrospective review of consecutive EMBs performed in this institution from January 1995 to January 2003 was performed. The echocardiographic results, clinical history and treatment changes at the time of every biopsy were also catalogued. Of the 1093 EMB results from 136 pediatric heart transplant grafts (127 patients, 64 male) reviewed, 825 biopsies were performed on patients managed with tacrolimus and 268 were performed on patients managed with cyclosporine. The patients managed with tacrolimus had an incidence of 0.85% (7/825) for significant rejection (greater than ISHLT grade 1B rejection) vs. an incidence of 4.1% (11/268) for the patients on cyclosporine (p < 0.0005). In the asymptomatic tacrolimus patients, only two screening biopsies (0.26%) manifest significant rejection, and both of these were performed within the first month after transplantation. Of the symptomatic tacrolimus patients, 9.1% (n = 5) had findings on biopsy consistent with significant cellular rejection. There were 25 patients with grade 1B rejection. Twenty‐two of these patients were not treated, and all cases of grade 1B rejection resolved without clinical sequelae. For pediatric patients more than 30 days after OHT, EMB has failed to reveal significant episodes of cellular rejection in asymptomatic patients managed with tacrolimus.

Use of OKT3 for acute myocarditis in infants and children

Acute viral myocarditis triggers an autoimmune phenomenon that aggressive immunosuppressive therapy with monoclonal OKT3 may suppress. We treated 5 patients, aged 15 months to 16.5 years, who had acute viral myocarditis and left ventricular ejection fraction (LVEF) of 5% to 20%, with a combination immunosuppressive regimen that included OKT3, intravenous immunoglobulin, methylprednisone, cyclosporine, and azathioprine. Within 2 weeks of therapy, all patients demonstrated normalization of LVEF to 50% to 74%, and on mid-term follow-up, we have found no recurrence of heart failure or progression to dilated cardiomyopathy. In patients with severe acute myocarditis, aggressive immunosuppressive regimen based on OKT3 is safe and may inhibit or reverse the immune response, resulting in dramatic improvement in myocardial function.

Cardiac allografts with ischemic time over 300 minutes.

ing a cardiopulmonary bypass (CPB). Hemodynamics of the transplanted graft was assessed by comparing recovery rates (%) from donor hearts 2hr after weaning from CPB. Endothelin-1 (ET-1) levels were measured in the blood obtained from the coronary sinus 30 min after reperfusion. Transplanted grafts were then harvested for histological study. Results: CO, LVP and LVdP/dt were significantly (p , 0.05) better in the high group than in the low group (table). There were no significant differences in the ET-1 levels between the groups. Transmission electron microscopic findings revealed that degeneration of mitochondria was less extensive in the high group than in the low group. There was no obvious ultrastructural damage of the endothelial cells in either group. Conclusion: When using UW solution in heart procurement, a higher pressure is optimal for complete washout of blood components and distribution of the solution.