Simon Haynes

The waiting game: bridging to paediatric heart transplantation

BACKGROUND Although mechanical circulatory support might not increase the number of adults surviving to transplantation, because of the shortage of donor organs, the situation might be different for children. Our aim was to assess the effect of mechanical assist devices to bridge children with end-stage cardiomyopathy to heart transplantation. METHODS A 5-year retrospective review was undertaken with data from the UK paediatric transplant programme and from bridging to transplant done at two paediatric transplant centres in the UK. FINDINGS Between Jan 1, 1998 and Dec 31, 2002, 22 children with end-stage cardiomyopathy, median age 5.7 years (range 1.2-17), were supported by a mechanical assist device as a bridge to first heart transplantation, with a 77% survival rate to hospital discharge. Nine were supported by a paracorporeal ventricular assist device, six received transplantation, five survived to discharge (55%), with one late death. 13 were supported by extra-corporeal membrane oxygenation, and 12 were transplanted and survived to discharge (92%) with one late death. With urgent listing, the median waiting time for a heart was 7.5 days (range 1.5-22 days). The correlation between the proportion of patients bridged to transplantation and the proportion of patients dying while on the transplant waiting list was r=-0.93, p=0.02. INTERPRETATION Our findings lend support to the hypothesis that a national mechanical assist programme to bridge children to transplantation can minimise the number dying while on the heart transplant waiting list. In the context of urgent listing and a short waiting time, extra-corporeal membrane oxygenation seems to provide the safest form of support.

Changing Patterns of Bridging to Heart Transplantation in Children

BACKGROUND Mechanical support as a bridge to cardiac transplantation in children is an accepted treatment. With improved devices and increasing experience, the length of time that children can be supported has increased. Donor organs remain scarce and there is significant associated morbidity. METHODS Retrospective review of all children offered mechanical support as a bridge to heart transplant over 10 years in one of the two UK pediatric heart transplant centers. Outcomes during the years 1998 to 2002 were compared with outcomes during the years 2003 to 2007. RESULTS Forty children in 41 separate patient episodes received mechanical support as a bridge to transplantation or, in 1 case, to recovery. Survival to transplant or recovery was achieved in 29 of 41 (71%); 26 of 40 children (63%) survived to hospital discharge. Devices used were extracorporeal membrane oxygenation (ECMO), the Medos HIAA, the Berlin Heart (from November 2005) and the Levitronix ventricular assist device (VAD) from 2007. All 3 children supported with the Levitronix survived to transplant (median duration of support 10 days). Ten of 13 children (77%) supported by the Berlin Heart survived to transplant or recovery (median duration of support 44 days). Four of 7 (57%) children supported using the Medos device survived to transplant (median duration of support 7 days). Neurologic events were the most common cause of death in both eras (1998 to 2002 and 2003 to 2008). CONCLUSIONS Waiting times to pediatric cardiac transplant in the UK have increased. The Berlin Heart allows children to be bridged to transplant over long periods. Neurologic morbidity remains as a major concern.

Anaesthesia for thoracic surgery in children

Introduction proliferate in number is uncertain, but it is approximately 2 years, when there are normally some During early life anatomical and physiological 300 million present (5). differences, immaturity, size constraints, and difThe diaphragm is a complete membrane by ferent pathology, define the practical limits of 8 weeks gestation. At birth, 10–30% of its striated transposing techniques of anaesthesia for adult muscle fibres are Type 1 (fatigue resistant) compared thoracic surgery into paediatric practice. In children with 50% in adults (6). undergoing thoracic surgery, the lungs are often healthy, the pathological process affecting other organs whereas adult thoracic surgical practise comprises patients with pulmonary pathology Physiological changes at birth compounded by surgical trauma. Anaesthesia for intrathoracic surgery in children involves preserving The first few breaths of extrauterine life overcome physiological stability, minimizing surgical the resistive forces of fluid in the lungs, surface pulmonary trauma, providing postoperative tension of the intra-alveolar air–liquid interface, and analgesia, managing pleural drains and above all, elastic recoil of the chest wall. integration with providers of postoperative care. An intrapleural pressure of−100 cmH2O has been described (7) but in most babies –20 cmH2O appears to suffice (8). Distribution of gas throughout the lungs Anatomy and physiology is achieved because expiratory intrapleural pressures Pulmonary development reach 20–30 cmH2O as a result of grunting respiration (9). The tracheobronchial tree arizes as a bud from the Blood flow through the pulmonary circulation oesophagus during the fourth week of intrauterine establishes as pulmonary vascular resistance (PVR) life. By the sixteenth week, terminal bronchioles are decreases in response to respiration and the larger completely formed (1). At 24 weeks, saccules, capable arterial oxygen and smaller carbon dioxide partial of functioning for gas exchange are formed (2) and pressures of extrauterine life. PVR decreases further alveolar type 2 (surfactant producing) cells are over the next 10 days as collagen and elastin are laid present (3). After 28 weeks, the area available for down in proximal vessels and there is increased gas exchange increases exponentially as alveoli demarcation between intimal and medial cells in proliferate (4) reaching around 50 million in number distal vessels: the net effect is an increased luminal by full term. The age at which alveoli cease to diameter and decreased medial thickness (10,11). Inadvertent hypoxaemia or acidosis at this stage may induce right to left shunting at atrial level because Correspondence to: S.R. Haynes, Department of Cardiothoracic of the immaturity and consequent lability of the Anaesthesia, Freeman Hospital, Newcastle upon Tyne NE7 7DN, UK. pulmonary vasculature (12).

Transfusion-related alloimmune neutropenia: an undescribed complication of blood transfusion

Alloimmune neutropenia in neonates is rare. We describe severe and persistent neutropenia in a 4-week-old neonate, which arose within 2 h of a transfusion of blood that contained about 28 mL of plasma and in which strong antibodies against human neutrophil antigen 1b (HNA-1b) were subsequently identified. The infant was positive for HNA-1b. No other likely cause of neutropenia was discovered. We believe this complication of blood transfusion to be a previously unrecognised one, and have called the condition transfusion-related alloimmune neutropenia (TRAIN).

An evaluation of the laryngeal mask airway during routine paediatric anaesthesia

During a six week period, all anaesthetists at the Royal Hospital for Sick Children, Glasgow were asked to complete a questionnaire whenever a laryngeal mask airway (LMA) was used. Seniority of anaesthetist, age of patient, anaesthetic technique, technique of LMA insertion, ease of LMA insertion, and any problems encountered either during LMA insertion, or during induction, maintenance, and recovery from anaesthesia were documented. Complete data were obtained from 211 patients aged 5 weeks to 15 years. Ninety‐six children were anaesthetized by consultant paediatric anaesthetists, and 115 by trainees. LMA insertion was successful at the first attempt in 86% of all cases, achieved with some difficulty in 11% of cases, and failed or its use was abandoned in 6 cases (3%). Difficulties other than with LMA placement per se occurred in 11% of cases during induction of anaesthesia. Seniority of anaesthetist and choice of anaesthetic agent influenced neither the success rate of insertion nor the frequency of other difficulties encountered during induction of anaesthesia. Significantly fewer problems were encountered at LMA removal if this was done during deep anaesthesia compared with removal when protective reflexes were present (P < 0.05).

The laryngeal mask airway: a review of its use in paediatric anaesthesia

The laryngeal mask airway (LMA) was developed during the 1980s by Dr Brain at the London Hospital, Whitechapel. It became commercially available in 1988 and its use has subsequently become widespread in the United Kingdom. The device is designed to provide a direct connection with the patienfs airway, avoiding some of the problems associated with tracheal intubation, yet affording greater security and convenience than the anaesthetic face mask.

Mechanical cardiac support in children with congenital heart disease with intention to bridge to heart transplantation

OBJECTIVES A significant number of children affected by congenital heart disease (CHD) develop heart failure early or late after surgery, and heart transplantation (OHTx) remains the last treatment option. Due to shortage of donor organs in paediatric group, mechanical circulatory support (MCS) is now routinely applied as bridging strategy to increase survival on the waiting list for OTHx. We sought to assess the impact of MCS as intention to bridge to OHTx in patients with CHD less than 16 years of age. METHODS From 1998 to 2013, 106 patients received 113 episodes of MCS with paracorporeal devices as intention to bridge to OHTx. Twenty-nine had CHD, 15 (52%) with two-ventricle (Group A) and 14 (48%) with single-ventricle physiology (Group B). In Group A, 5 children had venoarterial extracorporeal membrane oxygenation (VA ECMO), 6 left ventricular assist device (LVAD), 2 biventricular assist device (BIVAD), 1 VA ECMO followed by BIVAD and 1 BIVAD followed by VA ECMO. In Group B, VA ECMO was used in 7 children, univentricular assist device (UVAD) changed to VA ECMO in 4, UVAD in 2 and surgical conversion to two-ventricles physiology with BIVAD support changed to VA ECMO in 1. RESULTS Twenty-one of 29 (72%) children survived to recovery/OHTx. Seven of 29 (59%) survived to discharge. In Group A, 11/15 (73%) survived to recovery/OHTx and 9/15 (60%) survived to discharge. Four of 15 (27%) died awaiting OHTx. One child had graft failure requiring VA ECMO and was bridged successfully to retransplantation. One child dying after OHTx had acute rejection, was supported with VA ECMO and then BIVAD but did not recover. One patient had an unsuccessful second run on BIVAD 1 year after recovery from VA ECMO. In Group B, 10/14 (71%) survived to recovery/OHTx and 8/14 (57%) survived to discharge. Four of 14 (29%) died awaiting OHTx. Of deaths after OHTx, 1 occurred intraoperatively and 1 was consequent to graft failure and had an unsuccessful second run with VA ECMO. CONCLUSIONS Children with CHD can be successfully bridged with MCS to heart transplantation. Single-ventricle circulation compared with biventricular physiology does not increase the risk of death before transplant or before hospital discharge.

ABO-incompatible heart transplantation in infants: The Freeman Hospital experience

Background. Incompatibility of the major blood groups A, B, and O has been an absolute contraindication for heart transplantation. However, because of immunologic immaturity, infants may have relative protection from hyperacute rejection and thus could undergo transplantation with ABO-mismatched organs. Methods. Since January 2000, the authors have adopted a policy of considering infants for ABO-incompatible heart transplantation. Serum isohemagglutinin titers were measured before, during, and after transplantation. Two infants (3 and 2 months old) and a 21-month-old child underwent ABO-incompatible heart transplantation. During cardiopulmonary bypass, plasma exchange was performed. No other antibody-removal procedures were performed. A routine immunosuppressive regimen was used, and rejection was monitored by endomyocardial biopsies. An additional two patients (31 and 18 months old) were worked up but were unsuitable for ABO-incompatible transplantation because of high isohemagglutinin titers. They were successfully bridged to transplantation and received heart transplants from ABO-compatible donors. Results. All three infants with ABO-incompatible heart transplants are fit and well, 40 months, 30 months, and 12 months postoperatively. All three had serum antibodies to antigens of the donor’s blood group before transplantation. No hyperacute rejection occurred. No morbidity attributable to the ABO incompatibility has been observed. Conclusions. ABO-mismatched heart transplantation may be undertaken safely and without any short-term adverse consequences in infants and young children in whom isohemagglutinin production is not yet established.

General Anesthesia for Children With Severe Heart Failure

Severe heart failure in children is uncommon. The anesthetic management of children with this condition is challenging. The authors aimed to identify the frequency with which anesthesia for short noncardiac surgical procedures or investigations was complicated by life-threatening hemodynamic instability and to describe the anesthetic techniques used. This study retrospectively reviewed the anesthetic charts and notes of children admitted acutely with a diagnosis of severe heart failure (fractional shortening of 15% or less) who received general anesthesia for noncardiac surgical or diagnostic interventions during the 3-year period from September 2005 to September 2008. In this study, 21 children received a total of 28 general anesthetics. Two patients (10%) experienced a cardiac arrest, and both required unplanned admission to the authors’ pediatric intensive care unit (PICU) postoperatively. A variety of anesthetic techniques was used. In 27 (96%) of the 28 cases, perioperative inotropic support was required. General anesthesia for children with severe heart failure is associated with a significant complication rate and should be administered by anesthetists familiar with managing all aspects of circulatory support for children in an appropriate setting.

Outcome of mechanical cardiac support in children using more than one modality as a bridge to heart transplantation

OBJECTIVES Mechanical cardiac support (MCS) can successfully be applied as a bridging strategy for heart transplantation (OHTx) in children with life-threatening heart failure. Emergent use of MCS is often required before establishing the likelihood of OHTx. This can require bridge-to-bridge strategies to increase survival on the waiting list. We compared the outcome of children with heart failure who underwent single MCS with those who required multiple MCS as a bridge to OHTx. METHODS A retrospective study of patients aged less than 16 years was conducted. From March 1998 to October 2005, we used either a veno-arterial extracorporeal membrane oxygenator (VA-ECMO), or the Medos® para-corporeal ventricular assist device (VAD). From November 2005 onwards, the Berlin Heart EXCOR® (BHE) device was implanted in the majority of cases. Several combinations of bridge-to-bridge strategies have been used: VA-ECMO and then conversion to BHE; BHE and then conversion to VA-ECMO; left VAD and then upgraded to biventricular support (BIVAD); conversion from pulsatile to continuous-flow pumps. RESULTS A total of 92 patients received MCS with the intent to bridge to OHTx, including 21 (23%) supported with more than one modality. The mean age and weight at support was similar in both groups, but multimodality MCS was used more often in infancy (P = 0.008) and in children less than 10 kg in weight (P = 0.02). The mean duration of support was longer in the multiple MCS group: 40 ± 48 vs 84 ± 43 days (P = 0.0003). Usage of multimodality MCS in dilated cardiomyopathy (19%) and in other diagnoses (29%) was comparable. Incidence of major morbidity (haematological sequelae, cerebrovascular events and sepsis) was similar in both groups. Survival to OHTx/explantation of the device (recovery) and survival to discharge did not differ between single MCS and multiple MCS groups (78 vs 81% and 72 vs 76%, respectively). CONCLUSION Bridge to OHTx with multiple MCS does not seem to influence the outcome in our population. Infancy and body weight less than 10 kg do not tend to produce higher mortality in the multiple MCS group. However, children receiving more than one modality are supported for longer durations.