Pediatric heart transplantation in refractory cardiogenic shock: a critical analysis of feasibility, applicability and results

Rational Use of Mechanical Circulatory Support as a Bridge to Pediatric and Congenital Heart Transplantation

Introduction

Donor shortage and organ allocation is the main problem in pediatric heart transplant. Mechanical circulatory support is known to increase waiting list survival, but it is not routinely used in pediatric programs in Latin America.

Methods

All patients listed for heart transplant and supported by a mechanical circulatory support between January 2012 and March 2016 were included in this retrospective single-center study. The endpoints were mechanical circulatory support time, complications, heart transplant survival and discharge from the hospital.

Results

Twenty-nine patients from our waiting list were assessed. Twelve (45%) patients were initially supported by extracorporeal membrane oxygenation (ECMO) and a centrifugal pump was implanted in 17 (55%) patients. Five patients initially supported by ECMO were bridged to another device. One was bridged to a centrifugal pump and four were bridged to Berlin Heart Excor®. Among the 29 supported patients, 18 (62%) managed to have a heart transplant. Thirty-day survival period after heart transplant was 56% (10 patients). Median support duration was 12 days (interquartile range [IQR] 4 - 26 days) per run and the waiting time for heart transplant was 9.5 days (IQR 2.5-25 days). Acute kidney injury was identified as a mortality predictor (OR=22.6 [CI=1.04-494.6]; P=0.04).

Conclusion

Mechanical circulatory support was able to bridge most INTERMACS 1 and 2 pediatric patients to transplant with an acceptable complication rate. Acute renal failure increased mortality after mechanical circulatory support in our experience.

Percutaneous Mechanical Circulatory Support Using Impella Devices for Decompensated Cardiogenic Shock: A Pediatric Heart Center Experience

Cardiogenic shock remains a significant cause of mortality and morbidity in children with heart failure. Percutaneous mechanical circulatory support may be an additional tool to augment left heart support and decompression in addition to conventional therapies. This report aims to review the clinical and hemodynamic outcomes of the Impella device at a pediatric center. A retrospective review of all implants between October 2014 and November 2016 was conducted. Clinical outcomes, device implant techniques, complications, and hemodynamic data were collected. Statistical analysis was performed on hemodynamic and echocardiographic data. There were 10 Impella device placements in 8 patients with a median age of 17 years (6.5-25) and support duration of 8 days (1-21). Implant diagnosis included 5 patients with either posttransplant rejection or allograft vasculopathy, 2 patients with myocarditis, and 1 patient with refractory ventricular tachycardia. Extracorporeal membrane oxygenation support was required in 4 patients. Significant reduction in pulmonary capillary wedge pressures/left atrial pressures (p = 0.031) and increase in near infrared spectroscopy (p = 0.039) was seen pre- and post-Impella implant. All patients survived to discharge from the intensive care unit with one late death. Percutaneous mechanical circulatory support is a viable option in experienced pediatric centers as a mode to augment cardiac output or to decompress the left heart in patients on extracorporeal membrane oxygenation or with cardiogenic shock.

Use of short-term circulatory support as a bridge in pediatric heart transplantation

BACKGROUND

Heart transplantation is considered the gold standard therapy for the advanced heart failure, but donor shortage, especially in pediatric patients, is the main limitation for this procedure, so most sick patients die while waiting for the procedure.

OBJECTIVE

To evaluate the use of short-term circulatory support as a bridge to transplantation in end-stage cardiomyopathy.

METHODS

Retrospective clinical study. Between January 2011 and December 2013, 40 patients with cardiomyopathy were admitted in our Pediatric Intensive Care Unit, with a mean age of 4.5 years. Twenty patients evolved during hospitalization with clinical deterioration and were classified as Intermacs 1 and 2. One patient died within 24 hours and 19 could be stabilized and were listed. They were divided into 2 groups: A, clinical support alone and B, implantation of short-term circulatory support as bridge to transplantation additionally to clinical therapy.

RESULTS

We used short-term mechanical circulatory support as a bridge to transplantation in 9. In group A (n=10), eight died waiting and 2 patients (20%) were transplanted, but none was discharged. In group B (n=9), 6 patients (66.7%) were transplanted and three were discharged.The mean support time was 21,8 days (6 to 984 h). The mean transplant waiting list time was 33,8 days. Renal failure and sepsis were the main complication and cause of death in group A while neurologic complications were more prevalent en group B.

CONCLUSION

Mechanical circulatory support increases survival on the pediatric heart transplantation waiting list in patients classified as Intermacs 1 and 2.

Twisting immune responses for allogeneic stem cell therapy

Stem cell-derived tissues and organs have the potential to change modern clinical science. However, rejection of allogeneic grafts by the host's immune system is an issue which needs to be addressed before embryonic stem cell-derived cells or tissues can be used as medicines. Mismatches in human leukocyte class I antigens and minor histocompatibility antigens are the central factors that are responsible for various graft-versus-host diseases. Traditional strategies usually involve suppressing the whole immune systems with drugs. There are many side effects associated with these methods. Here, we discuss an emerging strategy for manipulating the central immune tolerance by naturally "introducing" donor antigens to a host so a recipient can acquire tolerance specifically to the donor cells or tissues. This strategy has two distinct stages. The first stage restores the thymic function of adult patients with sex steroid inhibitory drugs (LHRH-A), keratinocyte growth factor (KGF), interleukin 7 (IL-7) and FMS-like tyrosine kinase 3 (FLT3). The second stage introduces hematopoietic stem cells and their downstream progenitors to the restored thymus by direct injection. Hematopoietic stem cells are used to introduce donor antigens because they have priority access to the thymus. We also review several clinical cases to explain this new strategy.