Original Article
Australian Experience with VAD as a Bridge to Paediatric Cardiac Transplantation

https://doi.org/10.1016/j.hlc.2009.07.002Get rights and content

Abstract

The Royal Children's Hospital, Melbourne is the National Paediatric Heart Transplant Centre of Australia. A variety of ventricular assist devices (VADs) have been used effectively as a bridge to heart transplantation in adult patients, however, the experience in the paediatric population is limited. We present our initial experience using the Thoratec and Medos VAD systems as a bridge to heart transplantation in the designated centre for paediatric cardiac transplantation in Australia.

The medical records of all patients supported with a Thoratec or Medos VAD at the RCH from July 2005 to July 2007 were retrospectively reviewed.

Seven patients between 5 and 16 years of age were supported with the Thoratec or Medos VAD during the period of study. All of the patients were supported with a left sided ventricular assist device (LVAD). The length of time supported ranged from 6 to 230 days, with a median of 22 days. Co-morbidities included surgical re-exploration for bleeding, cannula site wound infections and thromboembolic events. Two patients died before a donor heart became available.

From our limited experience, the use of a VAD as a bridge to heart transplantation is a feasible option for children with end stage cardiac failure.

Introduction

The Royal Children's Hospital (RCH) is the National Paediatric Heart Transplant Centre of Australia. Prior to 2005, the RCH offered no bridge to transplant program for its paediatric patients using long-term mechanical devices. All patients needing long-term VAD (ventricular assist device) support were referred to the Alfred Hospital, Melbourne. The waiting list mortality of the RCH during the period 1988–2005, for children of all ages and diagnoses, was 29% (Nationally Funded Centre review data).

In July 2005, because of the small size of the patient, we decided to proceed with our first implantation of a Thoratec (Thoratec Corp., Pleasanton, CA) LVAD with the help of the team of the Alfred Hospital. In July 2007, we supported our first five-year-old child with the Medos VAD (Medos Medizintechnik AG, Stolberg, Germany).

A variety of VAD's have been used effectively as a bridge to transplantation in adult patients, however, the experience in the paediatric population is limited [1], [2]. It is anticipated that the use of a VAD in children pending heart transplantation would keep them alive for an additional three to six months, and consequently allow the majority to undergo successful heart transplantation. VAD support prior to heart transplantation also allows for stabilisation of the patient's general condition and reduces the risk of wasting an invaluable donor heart on a failed transplant [3].

The Thoratec and Medos VAD are both pulsatile, pneumatically driven devices providing left, right or bi-ventricular support. Long-term VAD support has been shown to allow recovery of organ dysfunction and to improve rehabilitation of patients with heart failure. It allows increased physical activity, hospital discharge, and a reasonable quality of life [4]. Although extracorporeal membrane oxygenation (ECMO) has been used successfully in many paediatric cardiac transplant programs overseas, it's use was deemed unsuitable in Australia because of the extended waiting times in our country [5].

We hereby present our initial experience using the Thoratec and Medos VAD systems as a bridge to heart transplantation in the paediatric population in Australia.

Section snippets

Methods

The medical records of all seven consecutive patients supported with a Thoratec or Medos VAD at the RCH from July 2005 to July 2007 were retrospectively reviewed. Details of the patients are listed in Table 1. The clinical indications for VAD support were end-stage heart failure and escalating intensive therapy with respiratory support and/or inotropic therapy. Four of the seven patients also had progressive malnutrition and continuous weight loss despite nasogastric tube supplementation.

Surgical techniques

All patients were implanted under cardio-pulmonary bypass, with mild hypothermia (32–34 °C). The presence of PFO was excluded with TOE in all patients. Patient 7 who had an atrial septostomy after the initiation of ECMO support had this opening closed during the procedure. The left-sided cavities were vented through the superior pulmonary veins in all patients. All patients had a cannula inserted in the apex of the left ventricle and the outflow graft of the device implanted as an end-to-side

Post-operative management

Post-operatively patients were managed in the intensive care unit (ICU) where they received ventilation, inotropic support and close monitoring.

With the Thoratec VAD, they were initially connected to the dual drive console (Thoratec Corp., Pleasanton, CA) and later transferred to the TLC-II portable driver (Thoratec Corp., Pleasanton, CA) once ambulating.

Our patient implanted with the Medos VAD remained connected to the same console. Every patient supported with a VAD had a back-up driver in

Anticoagulation management

Our initial anticoagulation regimen was inspired by the recommended anticoagulation regime provided by the Thoratec Company.

Prior to bypass and throughout the procedure, aprotinin was administered. Patients received an initial intravenous bolus of 10,000 kIU/kg, followed by a continuous infusion of 10,000 kIU/kg until 6 h post operatively.

At the end of the procedure, heparin was fully neutralised with the administration of protamine. The patient remained without anticoagulation until bleeding was

Results

Seven patients between 5 and 16 years of age were supported with the Thoratec or Medos VAD during the period of study. Their details are listed in Table 1. All of the patients were supported with a left sided ventricular assist device (LVAD) only. All of the patients were on inotropic support at the time of implantation. The length of time supported ranged from 6 to 230 days, with a median of 22 days. Four patients (57%) required chest re-exploration for bleeding. The number of surgical

Discussion

Despite decades of technological advances and progress in patient management, the mortality of patients on mechanical circulatory support remains high [7]. Our experience of 66% of the patients surviving to transplantation is consistent with the 69% reported survival of adolescents implanted with a Thoratec VAD [1].

Over the years, it has become clear that ECMO is not a suitable mechanical support for bridge to transplantation if the support is expected to last for more than a few weeks. After

Acknowledgement

There has been no financial assistance for this project.

References (13)

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    The results of this study sought to provide knowledge specific to the timing of bleeding and TE events in the context of their anticoagulation therapy. The major bleeding incidence in our study of 39% is within the previously reported incidences in pediatric VAD patients of 26–57% [2,3,7–10]. The incidence of chest re-exploration for bleeding (14%) is on the lower end of the reported range of 21–47% [9–13] and has significantly reduced compared to the 57% incidence we reported early in our experience [7].

  • Antithrombotic therapies in children on durable Ventricular Assist Devices: A literature review

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    TE events included TE neurological events, arterial non-central nervous system thrombosis, device exchange due to thrombosis and Venous Thromboembolism (VTE). The cause of death was reported in 20 studies [3,8,9,11,14–18,22–25,27,29–34]. The most frequent causes of death were: multi-system organ failure in 17% of patients (24/143), TE neurological complications in 16% (23/143), ICH in 14% (20/143), circulatory failure in 10% (15/143), sepsis in 7% (10/143), systemic TE in 2% (3/143), and pump thrombosis in 0.7% (1/143).

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