Current status of paediatric heart, lung, and heart-lung transplantation

Flexible bronchoscopy in pediatric lung transplantation

Pediatric lung transplantation represents a treatment option for children with advanced lung disease or pulmonary vascular disorders who are deemed an appropriate candidate. Pediatric flexible bronchoscopy is an important and evolving field that is highly relevant in the pediatric lung transplant population. It is thus important to advance our knowledge to better understand how care for children after lung transplant can be maximally optimized using pediatric bronchoscopy. Our goals are to continually improve procedural skills when performing bronchoscopy and to decrease the complication rate while acquiring adequate samples for diagnostic evaluation. Attainment of these goals is critical since allograft assessment by bronchoscopic biopsy is required for histological diagnosis of acute cellular rejection and is an important contributor to establishing chronic lung allograft dysfunction, a common complication after lung transplant. Flexible bronchoscopy with bronchoalveolar lavage and transbronchial lung biopsy plays a key role in lung transplant graft assessment. In this article, we discuss the application of bronchoscopy in pediatric lung transplant evaluation including historical approaches, our experience, and future directions not only in bronchoscopy but also in the evolving pediatric lung transplantation field. Pediatric flexible bronchoscopy has become a vital modality for diagnosing lung transplant complications in children as well as assessing therapeutic responses. Herein, we review the value of flexible bronchoscopy in the management of children after lung transplant and discuss the application of novel techniques to improve care for this complex pediatric patient population and we provide a brief update about new diagnostic techniques applied in the growing lung transplantation field.

Pediatric heart-lung transplantation: Technique and special considerations

Heart-lung transplantation has historically been used as a definitive treatment for children with end-stage cardiopulmonary failure, although the number performed has steadily decreased over time. In this review, we discuss current indications, preoperative risk factors, outcomes, and heart-lung transplantation in unique patient subsets, including infants, children with single-ventricle physiology, tetralogy of Fallot/major aortopulmonary collateral arteries, and prior Potts shunt palliation. We also describe the different surgical techniques utilized in pediatric heart-lung transplantation.

Successful venoarterial extracorporeal membrane oxygenation for postoperative septic shock in a child with liver transplantation: A case report

Refractory septic shock after LT is a life-threatening complication. VA ECMO is used to treat refractory cardiorespiratory failure. We present herein the case of a 5-year-old girl with post-Kasai biliary atresia, who underwent a living donor LT and suffered refractory septic shock. VA ECMO was indicated due to progressive cardiac deterioration. After full recovery of her EF, she has been steadily improving and has shown good liver function and no neurological sequelae. This is the first report of successful VA ECMO in a post- LT patient with refractory septic shock.

Experiences of adolescent lung transplant recipients: A qualitative study

Many young transplant recipients experience psychological distress and adjustment difficulties, yet there is little research investigating lung transplantation from the recipients' perspective. This qualitative study aimed to explore experiences of young people who underwent lung transplantation. Semi-structured interviews were conducted with six lung transplant recipients (aged 15-18). Interviews were analysed using IPA, a qualitative research approach examining how people make sense of their major life experiences. The analysis revealed three master themes: "Living with Dodgy Lungs" outlined how participants dealt with their experiences, managing through accepting or discussing their feelings with others, although talking was often difficult. "The Big Deal" reflected participants' experiences of the process, their expectations, and the contrast of their lives pre- and post-transplant. Inherent in their accounts was the profound meaning ascribed to transplantation, the emotional turmoil, and impact on their lives. "A Sense of Self" illustrated participants' developing identities within their social contexts and at times isolating experiences. The results highlight key areas where adolescent lung transplant recipients could be supported by clinicians, enabling the promotion of psychological well-being. Examples include supporting identity integration post-transplant, facilitating social inclusion, considering alternative means of support, and involving adolescents in healthcare decisions.

MMP-14 promotes VSMC migration via up-regulating CD44 expression in cardiac allograft vasculopathy

Cardiac allograft vasculopathy (CAV) was the leading cause of late death in heart transplantation recipients. Matrix metalloproteinase-14 (MMP-14), as a member of the MMPs family, has been reported to play a vital role in coronary vascular lesions of allotransplanted hearts. However, concrete mechanism is still unclear. Herein, we showed that the expression of MMP-14 was different between isografts and allografts. Interestingly, we found MMP-14 could interact with CD44 in allografts. Cluster of differentiation 44 (CD44), as a cell adhesion receptor and is involved in cell migration, caused our interest in MMP-14/CD44 complex in allografts. Then we analyzed the effect of MMP-14/CD44 complex on pro-MMP-9 activation and vascular smooth muscle cell (VSMC) migration in rat VSMC TNF-α treated model. Then, we further found intervention of MMP-14/CD44 complex could inhibit VSMC migration. Our results elucidate the molecular mechanism of VSMC migration after cardiac transplantation and provide theoretical basis for seeking new specific drug targets for CAV prevention and treatment.

Erythroblast transformation-specific 2 correlates with vascular smooth muscle cell apoptosis in rat heterotopic heart transplantation model

BACKGROUND

Cardiac allograft vasculopathy (CAV) decreases the long-term survival of heart transplantation recipients. Vascular smooth muscle cell (VSMC) apoptosis is an important pathological feature of CAV. Erythroblast transformation-specific 2 (Ets-2), as a transcription factor, participates in cell apoptosis and plays an important role in organ transplantation.

METHODS

Hearts from Wistar-Furth (WF:RT1u) rats were heterotopically transplanted into Lewis (Lew:RT1(l)) rats without immunosuppression. Additional syngeneic heterotopic cardiac transplantations were performed in Lewis rats. HE staining was used to identify CAV. Ets-2 expression was examined by western blot. Ets-2 tissue location was examined by immunohistochemical assay and double immunostaining. Cleaved caspase 3 expression was detected by western blot. Co-localization of Ets-2 and cleaved caspase 3 was detected by double immunostaining. Ets-2, p53, cleaved caspase 3 and Bcl-xl expression in rat VSMC line A7R5 was examined after Ets-2 siRNA transfection. TUNEL assay was applied to detect A7R5 apoptosis with or without ETS-2 siRNA transfection. Immunoprecipitation was performed to explore the interaction between Ets-2 and p53.

RESULTS

Ets-2 expression decreased in the allograft group but had no obvious change in the isograft group. Meanwhile, the phenomenon of CAV was observed in the allograft group and there is neointima formation in the isograft group which is not obvious compared with allograft group. Additionally, Ets-2 expression was opposite to VSMC apoptosis in the allograft group. In vitro, Ets-2 siRNA transfection in A7R5cells resulted in enhanced cell apoptosis. Finally, Ets-2 interacted with p53.

CONCLUSIONS

Ets-2 might inhibit VSMC apoptosis via p53 pathway. The results further elucidate the molecular mechanism of VSMC apoptosis after heart transplantation during CAV and provide theoretical basis for seeking new specific drug targets for CAV prevention and treatment.

Induction of substantial myocardial regeneration by an active fraction of the Chinese herb Rosa laevigata Michx

Background

The replacement of lost cardiac tissues by regenerated myocardium would be a therapeutic ideal for myocardial infarction. The objective of this study was therefore to evaluate the ability of an active fraction that was isolated from Rosa laevigata Michx in therapeutic cardiomyogenesis in a myocardial infarction rat model.

Methods

The myocardial infarction animal model was induced by the permanent ligation of the left anterior descending coronary artery in rats. The active fraction, which improves the survival rate and prevents ischemic reperfusion damage, was used to test the therapeutic effect of this fraction on myocardial infarction.

Results

The oral administration of the active fraction for 4 weeks could progressively restore the decreased cardiac function due to myocardial infarction. The significantly improved cardiac function was probably attributed to the active fraction-induced myocardial regeneration, which replaced the lost cardiac tissues in the myocardial infarction animals.

Conclusions

The property of this active fraction appears to be entirely novel and may provide a potential therapeutic alternative for myocardial infarction.

The changes of vaccinia related kinase 1 in grafted heart after rat heart transplantation

OBJECTIVE

To assess the expression and significance of vaccinia-related kinase 1 (VRK1) after rat heart transplantation.

MATERIALS AND METHODS

Lewis and Wistar rats weighing 250 to 300 g were used as donors and recipients. Allografts were from Wistar transplanted into Lewis, and isografts were transplanted from Lewis into Lewis. Grafts were harvested at 1, 3, 5, and 7 days after transplantation. We performed Western Blot of heart tissues after cardiac transplantation. To analyze VRK1 express between the isografts and allografts for immunohistochemical staining. At 5th day after heart transplantation use related cytokines VRK1 for immunohistochemical. We used double immunofluorescent staining on transverse cryosections of graft tissues by co-labeling with different markers, including those for VRK1, activate caspase-3, α-actinin, VCAM-1, CD4.

RESULTS

Compared with rare expression in syngeneic Lewis rat hearts, VRK1 protein level in allogeneic hearts were detected at various survival times after heterotopic heart transplantation, which observably expressed on day 5 postoperative. In addition, we examined the expression of activate caspase-3 in allogeneic hearts, which has a similar expression with VRK1. Immunohistochemical and immunofluorescent method displayed that VRK1 was widely expressed in cytoplasm of cardiac tissue and activate caspase-3 was also expressed in cardiomyocytes. However, the VRK1 wasn't express in inflammation.

CONCLUSIONS

The VRK1 expression has increased after heart transplantation in allograft and isograft, and VRK1 may play a significant role in myocardial apoptosis after heterotopic heart transplantation in rats.

Nanotechnology in the Regeneration of Complex Tissues

Modern medicine faces a growing crisis as demand for organ transplantations continues to far outstrip supply. By stimulating the body’s own repair mechanisms, regenerative medicine aims to reduce demand for organs, while the closely related field of tissue engineering promises to deliver “off-the-self” organs grown from patients’ own stem cells to improve supply. To deliver on these promises, we must have reliable means of generating complex tissues. Thus far, the majority of successful tissue engineering approaches have relied on macroporous scaffolds to provide cells with both mechanical support and differentiative cues. In order to engineer complex tissues, greater attention must be paid to nanoscale cues present in a cell’s microenvironment. As the extracellular matrix is capable of driving complexity during development, it must be understood and reproduced in order to recapitulate complexity in engineered tissues. This review will summarize current progress in engineering complex tissue through the integration of nanocomposites and biomimetic scaffolds.

Myocardial infarction in an adult with cystic fibrosis and heart and lung transplant

We present a case of myocardial infarction in a 19 year old female with cystic fibrosis who had a heart and lung transplant performed at the age of four years old. She presented atypically with a one day history of severe, intermittent, central, sharp chest pain, radiating to her back and down her left arm. A coronary angiogram showed proximal stenosis of the left anterior descending artery and right coronary artery. She was treated with percutaneous coronary intervention, involving drug eluting stents to the left anterior descending artery (LAD) and the right coronary artery (RCA). In this study we discuss the pathophysiology, investigations and treatment of cardiac transplant vasculopathy. Although complete reversal of LAD and RCA stenosis was achieved, routine follow-up with coronary angiography and careful control of cardiac risk factors will be important to identify and reduce future restenosis and adverse cardiac events.

Combined heart-lung transplantation: a perspective on the past and the future

During the last 20 years, there has been a shift away from combined heart-lung transplantation (HLT) in favor of bilateral lung transplantation. This paradigm shift allowed for the donor heart to be transplanted to another patient. However, HLT remains to be the definitive surgical treatment for certain congenital heart disorders and Eisenmenger's syndrome. With a growing population of adult patients with congenital heart disease, there remains a need for HLT. This article provides a perspective on the past and the future of HLT.

Indications for heart transplantation in congenital heart disease

In this review we have looked at indications for cardiac transplantation in congenital heart disease. An outline of the general principles of the use of transplant as a management strategy both as a first line treatment and following other surgical interventions is discussed. We explore the importance of the timing of patient referral and the evaluations undertaken, and how the results of these may vary between patients with congenital heart disease and patients with other causes of end-stage heart failure. The potential complications associated with patients with congenital heart disease need to be both anticipated and managed appropriately by an experienced team. Timing of transplantation in congenital heart disease is difficult to standardize as the group of patients is heterogeneous. We discuss the role and limitations of investigations such as BNP, 6 minute walk, metabolic exercise testing and self estimated physical functioning. We also discuss the suitability for listing. It is clear that congenital heart patients should not be considered to be at uniform high risk of death at transplant. Morbidity varies greatly in the congenital patient population with the failing Fontan circulation having a far higher risk than a failing Mustard circulation. However the underlying issue of imbalance between donor organ supply and demand needs to be addressed as transplant teams are finding themselves in the increasingly difficult situation of supporting growing numbers of patients with a diverse range of pathologies with declining numbers of donor organs.

Developmental pharmacogenetics of immunosuppressants in pediatric organ transplantation

Cyclosporine, tacrolimus, sirolimus, and mycophenolate mofetil are the primary immunosuppressants used on pediatric organ transplantation. Therapeutic drug monitoring is used in daily practice, because their clinical use is hampered by a narrow therapeutic index and large variability. Tailoring immunosuppressive therapy to the individual patient to optimize efficacy and minimize toxicity is therefore essential. Because research in pharmacogenetics already identified polymorphisms impacting their pharmacokinetic parameters in adults, developmental pharmacogenetics of immunosuppressants holds promises for optimizing dosage regimens and improving clinical outcome in children. In this review, we focus on the impact of age and pharmacogenetics on these immunosuppressants in children undergoing organ transplantation.

Chronic kidney disease in children following lung and heart-lung transplantation

CKD is a major co-morbidity in pediatric lung transplant recipients. We report the prevalence of renal impairment post-lung transplant at a single center, using a modified, age-adjusted eGFR for the best approximation of true GFR, and investigated associations and possible predictors of decline in renal function post-transplant. Renal function was assessed by eGFR pre-transplant, three and 12 months post-transplant, and at last follow-up. Decline in renal function was analyzed as percentage fall in eGFR in two phases (0-3 and 3-12). Furthermore, we investigated impact of gender, age, pre-transplant diagnosis and renal function, transplant type, early post-transplant dialysis, and tacrolimus trough levels on decline in eGFR using multivariate analysis. Over a five-yr period, 30 transplants were performed. Mean eGFR pretransplant was 117 mL/min/1.73 m(2) (s.d. 35) with mean decline in eGFR during the first three months post-transplant of 33% (s.d. 31, p < 0.001). Thereafter, mean decline in eGFR was 8% (s.d. 18, p = 0.02). None of the factors assessed were significantly associated with decline in eGFR post-transplant. In conclusion, many children have decline in renal function following lung transplantation, particularly early post-transplant. Unlike in adults, we were unable to detect any predictors of renal impairment in pediatric lung transplant recipients.

Hepatopulmonary syndrome: use of extracorporeal life support for life-threatening hypoxia following liver transplantation

Hepatopulmonary syndrome is an uncommon complication of nonacute liver failure, and in rare cases, hypoxia may be the presenting sign of liver dysfunction. The condition, once thought to be a contraindication, is improved in most cases by transplantation. There is a significant risk of postoperative, hypoxia-related morbidity and mortality in patients with hepatopulmonary syndrome. We present a case of life-threatening hypoxia following liver transplantation for liver failure and associated hepatopulmonary syndrome, with successful management using extracorporeal membrane oxygenation.

Variability in immunization guidelines in children before and after lung transplantation

Lung transplant candidates and recipients are at high risk of infections from vaccine-preventable diseases. However, well-established guidelines neither exist for pre- and post-transplant vaccination nor do monitoring guidelines for pediatric lung transplant recipients. To ascertain the current vaccination and monitoring practices of pediatric lung transplant centers, a self-administered questionnaire was distributed to the 18 pediatric lung transplant centers within the International Pediatric Lung Transplant Collaborative in April 2006. Sixteen of 18 centers (89%) surveyed responded. Pretransplant, national vaccination guidelines are followed. Eleven centers reported following standardized vaccination guidelines post-transplant. Vaccines were more commonly provided by the primary-care physician pretransplant (69%) rather than post-transplant (38%). Post-transplant, 50% of the centers recommend live vaccines for household contacts but not for the transplant recipient. Pretransplant monitoring of response to prior vaccination was performed inconsistently except for varicella (88%). Only 44% of the transplant centers measure for response to vaccination post-transplant, mostly hepatitis B. Current vaccination practices of pediatric lung transplant centers are heterogeneous. The lung transplant community would be well served by studies designed to evaluate the efficacy of vaccinations in this population.

Long-term support with milrinone prior to cardiac transplantation in a neonate with left ventricular noncompaction cardiomyopathy

A 2-week-old female infant presented with acute decompensated left ventricular failure. Echocardiography diagnosed left ventricular noncompaction cardiomyopathy with dilated phenotype and a left ventricular shortening fraction <10%. The infant was mechanically ventilated for 2 weeks and then successfully extubated. She was maintained on intravenous milrinone for 6 months until she underwent successful orthotopic heart transplantation. Young children can be supported with inotropes for prolonged periods while awaiting heart transplantation.

Surveillance bronchoscopy in children during the first year after lung transplantation: Is it worth it?

BACKGROUND

Since January 2002, routine surveillance bronchoscopy with bronchoalveolar lavage (BAL) and transbronchial biopsy has been performed in all paediatric recipients of lung and heart-lung transplants at the Great Ormond Street Hospital for Children, London, UK, using a newly revised treatment protocol.

AIMS

To report the prevalence of rejection and bacterial, viral or fungal pathogens in asymptomatic children and compare this with the prevalence in children with symptoms.

PARTICIPANTS

The study population included all paediatric patients undergoing single lung transplantation (SLTx), double lung transplantation (DLTx) or heart-lung transplantation between January 2002 and December 2005.

METHODS

Surveillance bronchoscopies were performed at 1 week, and 1, 3, 6 and 12 months after transplant. Bronchoscopies were classified according to whether subjects had symptoms, defined as the presence of cough, sputum production, dyspnoea, malaise, decrease in lung function or chest radiograph changes.

RESULTS

Results of biopsies and BAL were collected, and procedural complications recorded. 23 lung-transplant operations were performed, 12 DLTx, 10 heart-lung transplants and 1 SLTx (15 female patients). The median (range) age of patients was 14.0 (4.9-17.3) years. 17 patients had cystic fibrosis. 95 surveillance bronchoscopies were performed. Rejection (> or =A2) was diagnosed in 4% of biopsies of asymptomatic recipients, and in 12% of biopsies of recipients with symptoms. Potential pathogens were detected in 29% of asymptomatic patients and in 69% of patients with symptoms. The overall diagnostic yield was 35% for asymptomatic children, and 85% for children with symptoms (p < 0.001). The complication rate for bronchoscopies was 3.2%.

CONCLUSIONS

Many children have silent rejection or subclinical infection in the first year after lung transplantation. Routine surveillance bronchoscopy allows detection and targeted treatment of these complications.

Transplantation as a treatment for end-stage pulmonary hypertension in childhood

Despite advances in drug therapy, severe sustained pulmonary arterial hypertension can be a fatal disease. When medical therapy is exhausted, transplantation may be an option. The most common approaches are heart-lung transplantation or double-lung transplantation, with repair of the cardiac defect if necessary. Single-lung transplantation optimises the use of scarce donors but leads to particular management problems. Heterotopic cardiac transplantation has occasionally been employed in subjects with pulmonary vascular disease secondary to cardiac disease. Timing of transplantation is a difficult decision and depends largely on the aetiology of pulmonary arterial hypertension and the rate of decline. Outcomes following transplantation are steadily improving but remain poorer than for other solid organ transplants, mainly because of the high incidence of post-transplant bronchiolitis obliterans syndrome.