Heart transplantation in children: risk factors of early and late mortality

Acute right ventricular failure after pediatric cardiac transplant: predictors and long-term outcome in current era of transplantation medicine

OBJECTIVES

To identify pretransplant factors associated with postprocedural right ventricular failure and the relationship between right ventricular failure and long-term survival in children.

METHODS

Records were reviewed for children having heart transplantation from 2000 to 2006.

RESULTS

Right ventricular failure was identified by clinical and echocardiographic parameters in 33/129 (25%) recipients: dilated cardiomyopathy in 14/90 (15%), congenital heart disease in 11/27 (41%), and restrictive cardiomyopathy in 8/12 (66%). In 9 of 12 (75%), known elevated (reactive) pulmonary vascular resistance progressed to right ventricular failure. In a further 23/117 (20%) recipients, pulmonary vascular resistance within predefined acceptable range progressed to right ventricular failure. Multiple logistic regression analyses indicated elevated pulmonary vascular resistance (odds ratio 12.30; 95% confidence interval 2.73, 55.32; P = .001) and primary diagnosis, restrictive cardiomyopathy (odds ratio 9.21; 95% confidence interval 2.07, 41.12; P = .004), and congenital heart disease (odds ratio 4.07; 95% confidence interval 1.36, 12.19; P = .012) were strongly associated with right ventricular failure, but duration of heart failure, pretransplant mechanical support, donor status, and ischemic times were not. Treatment included inhaled nitric oxide in 28 (84%), mechanical support in 10 (31%), hemofiltration in 13 (40%), and retransplantation in 2. A Cox multiple regression model including: primary diagnosis, right ventricular failure, and elevated pulmonary vascular resistance indicated that only the latter was independently linked with eventual mortality (hazards ratio 5.45; 95% confidence interval 1.36, 21.96; P = .017).

CONCLUSIONS

Primary diagnosis and pretransplant elevated reactive pulmonary vascular resistance are both linked to the evolution of right ventricular failure. Pulmonary vascular resistance assessment in end-stage heart failure is challenging; therefore, avoidance of right ventricular failure may not always be possible. Aggressive early treatment may mitigate the effects of right ventricular failure: pretransplant elevated pulmonary vascular resistance was independently associated with long-term survival, but right ventricular failure was not.

Outcomes of Pediatric Patients Bridged to Heart Transplantation from Extracorporeal Membrane Oxygenation Support

Extracorporeal membrane oxygenation (ECMO) is used as a salvage therapy in children with irreversible myocardial failure who may be candidates for heart transplantation (HTx) (at the Hospital for Sick Children). We retrospectively assessed outcomes of children wait-listed for HTx from ECMO, and risk factors for patients (pts) bridged to HTx from January 1990 through December 2005. Of 205 patients supported with cardiac ECMO, 46 were wait-listed for HTx. Sixteen patients died before HTx: eight died while wait-listed on ECMO; eight were delisted (clinical deterioration; all died); five were delisted (improved), and 25 (54%) underwent HTx from ECMO. Of 25 patients who underwent HTx (median age 7.0 years [10 days to 17 years]), 13 had myocarditis or cardiomyopathy, and 12 had congenital heart disease. Median ECMO duration was 6.7 days (3-18 days). Median follow-up was 4.3 years (0.2-10.6 years). Four patients died <1 week post-HTx, and 21 survived until hospital discharge (84%). Post-transplant survival was 67% and 52% at 1 and 5 years, respectively. Risk factors for early death were older age, higher body surface area, higher creatinine before and during ECMO, fungal infections, and exposure to blood products. In summary, few risk factors preclude HTx candidacy from ECMO. The impact of newer assist technology on ECMO, wait-list mortality, and HTx outcomes remains to be elucidated.

Heart transplantation in children: clinical outcome during the early postoperative period

As improved understanding of transplant-related death should improve survival, we report a single center's experience with pediatric heart transplantation including potential risk factors and causes of death during the early postoperative period. This prospective longitudinal study involved 51 pediatric patients ranging in age from 12 days to 15.1 yr (median: 3 yr). The following pretransplant risk factors were evaluated: diagnosis, age at transplantation, recipient sex, weight and blood type, blood type match, donor/recipient sex match, weight ratio, ischemic time, recipient's status, requirement for mechanical ventilation or circulatory support, dialysis, or inotropic support at transplantation. We also determined the actuarial survival, clinical outcomes, and causes of death in this population. Survival was 86% during the early postoperative period (</=30 days), 79.3% at 1 yr, and 76.8% at 3 yr. Seven patients died during the early postoperative period (primary graft failure, rejection, and infection). However, there was no difference in the frequency of any of the risk factors analyzed between these patients and those who did not experience early death. There was a correlation between the duration of intubation after transplantation and pretransplant risk factors (diagnosis, recipient status, requirement for dialysis, inotropic and mechanical ventilation support). Our findings indicate that promising short-term results can be obtained with pediatric transplantation. Although we identified no specific risk factors in this study for death, improved rejection surveillance and treatment strategies remain important goals in pediatric heart transplantation. Retransplantation had high mortality during the perioperative period.

Perioperative management in pediatric heart transplantation from 1988 to 2001: anesthetic experience in a single center

Pediatric cardiac transplantation is currently an accepted option for end-stage heart disease and congenital cardiac malformations. This report focuses on the anesthetic perioperative management in 12 yr. From 1988 to 2001 we performed 90 heart transplantations in 88 children, infants and neonates. The pediatric heart transplant program of the children's heart center at our university hospital started in June 1988 with the transplantation of a 2-yr-old boy who was suffering from congenital heart disease. Since then, 88 transplants have been performed. We divided our patients into two groups. Group 1 ranged from 1988 to 1996 and Group 2 from 1997 to 2001. The patient characteristics have not significantly changed over the years in our institution. At the time of transplantation, mean age of the patients was 2.6 +/- 4.3 yr from the period of 1988-1996 and 2.5 +/- 4.1 yr from 1997 to 2001. Since 1988, 90 transplants (Tx) in 88 patients have been performed. Two patients needed re-Tx within 2 days after the initial operation because of primary graft failure. Indications for Tx were congenital heart disease (n = 67) and cardiomyopathy (n = 21). In the subgroup of the patients suffering from congenital heart disease there were 46 with the diagnosis of HLHS, followed by endocardial fibroelastosis (n = 7); the remaining 14 patients had other complex cardiac malformations and some underwent corrective palliative cardiac surgery before Tx. Sixty-three patients were younger than 1 yr of age and only five children were older than 10 yr. Twenty-three percent of the patients on the waiting list died before Tx was possible. The overall survival rate was 79% at 1 yr and 73% at 5 and 10 yr. Infants with HLHS had a lower probability of survival after 5 yr compared with other diagnosis (69% vs. 84%). Until now 21 patients have died after Tx. The duration of anesthesia, time of CPB and the age at the time of surgery decreased over the years. It is always a challenge for the anesthesiologist to treat these patients with pulmonary hypertension as one of the most critical risks in this group of patients. The preventive therapy with vasodilators as well as the availability of mechanical assist devices before and after heart transplantation reduces the effects of transitional pulmonary hypertension and prevents the development of post-operative right heart failure.

The changing profile of the cardiac donor

BACKGROUND

Expansion of traditional donor criteria has become standard in most centers. To determine how this has affected donor profiles, at our institution, we reviewed all adult (age > or = 16) cardiac donors of the past 15 years.

METHODS

We separated 261 cardiac donors into 2 groups based on time periods: Group I, 1983 to 1991 (n = 131), and Group II, 1991 to 1998 (n = 130).

RESULTS

The groups differed significantly in mean donor age (26.2 years vs 30.9; p < 0.001), percent older than 40 years (6% vs 27%; p < 0.001), percent female (23% vs 35%; p = 0.04), percent distant procurement (54% vs 22%; p < 0.001), and percent minority donors (14% vs 29%; p < 0.001). We found an increase in non-traumatic deaths (24% vs 40%; p = 0.008). Older donors had significantly more non-traumatic deaths than younger donors (79% vs 13%; p < 0.001). Overall 5-year survival of recipients was 64% and was not significantly different between our early and late experiences (60% vs 68%; p = not significant [NS]). Recipients with hearts from older donors had a 5-year survival similar to recipients with younger donor hearts (61% vs 64%; p = NS). Traumatic and non-traumatic donors had similar 5-year survivals (64% vs 63%, p = NS). A stepwise multivariate analysis of the entire cohort identified donor age, donor weight, recipient United Network for Organ Sharing status, and cardiopulmonary bypass time as significant independent risk factors for recipient survival. Recipients of hearts from donors < 90 kg had significantly better 5-year survivals than recipients from donors > or = 90 kg (66% vs 48%; p = 0.01).

CONCLUSIONS

Our evolving cardiac donor pool now has more minorities, women, and older donors whose deaths are often non-traumatic. At our institution, donor pool expansion has had no adverse effect on the long-term survival of recipients.

Pulmonary hypertension in pediatric heart transplantation

Pulmonary hypertension can pose a significant problem in the management of children with congestive heart failure. Assessment of pulmonary artery anatomy, pressures and (when possible) pulmonary vascular resistance is critically important in the evaluation of these children when they are under consideration for heart transplantation. Severe, fixed elevation of the pulmonary vascular resistance is a contraindication to heart transplantation because of concerns of acute post-transplant donor right ventricular failure. However, even modest degrees of pulmonary hypertension can complicate the post-operative management of pediatric heart transplant recipients. This review will provide information regarding the recognition, diagnosis, and pre-operative and post-operative management of pulmonary hypertension in patients under consideration for heart transplantation.

A simple approach to risk stratification in adult heart transplantation

OBJECTIVE

While there are numerous reports in the literature of risk factors for graft failure after heart transplantation, simple models for risk stratification are lacking. This study describes a simple method for risk stratification in adult heart transplantation that can be applied when the size of a dataset is insufficient for formal regression modelling.

METHODS

Multi-centre prospective cohort study. Fourteen risk factors documented in the literature as increasing post transplant graft failure were used to formulate a model. Risk factors included in the model were recipient age >50 years, pre-operative ventilatory support, pre-operative circulatory support, >1 previous sternotomy, pulmonary vascular resistance >2.5 wood units, male with body surface area >2.5 m2, retransplant, ischaemic time >3.5 h, donor age >45 years, donor inotropic support >10 microg/kg per min dopamine, female donor, ratio donor/recipient body surface area <0.7, donor with diabetes and history of donor drug abuse. Four risk groups were defined depending on the number of risk factors present: Low, none; moderate, 1; high, 2 or 3; very high, 4 or more. Graft survival to 30 days was chosen as the primary outcome. The model was tested on 373 adult transplants performed in the UK between April 1995 and December 1996.

RESULTS

Twenty eight transplants were low risk, 82 moderate, 201 high and 62 very high. The 30-day survival (70% CI) for the risk groups was low, 97% (93-100), moderate 95% (92-98), high 87% (84-89) and very high 80% (75-83) (P = 0.02).

CONCLUSIONS

This preliminary model enables some stratification of heart transplant procedures according to donor and recipient risk profile. Further work will be directed at refining and validating the model.

Anomalous left coronary artery from the pulmonary artery: results of isolated aortic reimplantation

Thirty-one consecutive children with anomalous left coronary artery underwent direct aortic reimplantation of the anomalous artery without an associated procedure. There were five deaths (16%; 70% confidence limits, 9% to 26%), three in the hospital and two early (within 3 months). The severity of preoperative left ventricular dysfunction was the only incremental risk factor for mortality: 31% mortality rate among patients with left ventricular shortening fraction of less than 0.20 versus 0% among patients with a left ventricular shortening fraction of 0.20 or more (p = 0.03). There were no late deaths up to 6 years, a survival rate of 84% +/- 7%. Late results were studied in 23 survivors having a follow-up of longer than 12 months. Ninety-six percent were free of symptoms; left ventricular function recovered to normal in all patients; moderate to severe mitral regurgitation decreased to minimal or no regurgitation in most patients (5/7); and the reimplanted anomalous left coronary artery was patent in each patient. Based on this study, we reached five conclusions. (1) Direct aortic reimplantation is technically feasible in most patients with anomalous left coronary artery and yields a high rate of late patency. (2) Left ventricular resection is unnecessary. (3) The mitral valve should not be interfered with at the initial operation, but mitral regurgitation may persist in a few patients and necessitate later operation. (4) In patients with moderate left ventricular dysfunction, the operative risk is low and early operation indicated. (5) In patients with severe left ventricular dysfunction, the operative risk is high; heart transplantation may be suggested, but our current approach favors an immediate corrective procedure.

Heart transplantation in children: mid-term results and quality of life

From 1987 to 1991, heart transplantation was undertaken in 49 infants and children with either end-stage cardiomyopathies (28 patients) or severe congenital heart disease (21 patients including 16 having already been surgically but unsuccessfully treated). Their age ranged from 13 days to 15 years (mean = 4.5 +/- 4.2 years; median = 2.5 years). There were 12 early and 7 late deaths (overall mortality = 38%), mainly due to graft dysfunction, acute or chronic rejection, and infectious complications, mostly viral. Optimal criteria in selecting both donors and recipients are crucial to reduce early mortality and should never be transgressed despite the critical shortage of organs. The actuarial probability of survival was 64% at 1 year and 57% at 5 years. Our 30 mid-term survivors (62%) were submitted to a close follow up programme which includes endomyocardial biopsies, even in the very young, since non invasive criteria failed to mark every rejection episode. Maintenance therapy was always steroid-free to start with (cyclosporin+azathioprine) but in almost one half of our oldest survivors, it failed to avoid rejection and we had to add low-dose oral steroids for at least several months. Epstein-Barr virus related lymphoproliferations occurred in four patients, two of whom died and two recovered with specific therapy. Renal function was closely monitored: tubular and interstitial lesions were found on renal biopsies and were associated with moderate functional changes. The quality of life of the children who survived heart transplantation was considered as near normal in a little more than one half of the cases but many issues (late coronary disease, drug toxicity, long-term compliance to follow up and therapy) remain significant concerns for the future.