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Ann Thorac Surg 2000;69:186-192
© 2000 The Society of Thoracic Surgeons

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Original Articles

Long-term follow-up of pediatric cardiac patients requiring mechanical circulatory support

^a Departments of Cardiology and Cardiac Surgery, Children’s Hospital, Boston, Massachusetts, USA

Address reprint requests to Dr Jonas, Department of Cardiac Surgery, Children’s Hospital, 300 Longwood Ave, Boston, MA 02115

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
Background. The present study examines the long-term outcome of pediatric patients with cardiac disease who required mechanical circulatory support with extracorporeal membrane oxygenation or ventricular assist devices.

Methods. Telephone interviews and questionnaires were administered to parents and physicians of pediatric cardiac patients who were in-hospital survivors after requiring mechanical circulatory support, with either extracorporeal membrane oxygenation or ventricular assist devices. Data was collected regarding these patients’ general health, cardiac status, and neurologic outcome, and compared between the two modes of support.

Results. Follow-up was available for 26 patients supported with extracorporeal membrane oxygenation (25 survivors, 96%) and 11 patients supported with ventricular assist devices (10 survivors, 91%); median follow-up 42 months, 11 to 92 months). More than 80% of survivors were in New York Heart Association class I or II. Of 31 patients for whom neurologic assessment data was available, moderate to severe neurologic impairment was more common for extracorporeal membrane oxygenation supported patients [13 of 21, 59%) than for ventricular assist device supported patients (2 of 10, 20% p = 0.03). Neurologic impairment was associated with small patient size and the use of circulatory arrest during cardiac surgical repair, but was not associated with in-hospital neurologic complications, carotid cannulation, or presupport cardiac arrest.

Conclusions. The long-term survival and cardiac functional status of pediatric cardiac patients requiring mechanical circulatory support is favorable. Extracorporeal membrane oxygenation supported patients demonstrate higher rates of neurologic impairment than patients supported with ventricular assist devices. Poor neurologic outcomes are associated with institution of support in younger patients with more complex congenital heart disease.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
We recently reviewed the hospital course of children with cardiac disease requiring mechanical circulatory support with either extracorporeal membrane oxygenation (ECMO) or ventricular support devices (VAD) in our institution. The rates of weaning from support and in-hospital mortality (approximately 66% and 40%, respectively) were nearly identical for patients supported with either modality [1]. Several reports exist detailing the long-term follow-up of children supported with ECMO for respiratory failure, but little information is available regarding the long-term follow-up of children managed with ECMO for heart disease. This report describes the long-term outcome of pediatric cardiac patients who survive to hospital discharge after requiring mechanical circulatory support with ECMO or VAD.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
From November 1987 through March 1996, 96 pediatric patients with cardiac disease required mechanical circulatory support at our institution (67 ECMO, 29 VAD). Twenty-seven ECMO supported patients and 12 VAD supported patients survived to hospital discharge [1]. One ECMO supported patient was lost to follow-up. One survivor received both ECMO and left VAD support during the initial hospitalization. The period of left VAD support lasted only a few hours and required conversion to ECMO due to biventricular failure. This patient was included only in the ECMO supported group for the present study, which resulted in 26 ECMO supported patients and 11 VAD supported patients available for long-term follow-up.

Telephone interviews and written questionnaires
Long-term follow-up was obtained for these surviving children after review and approval from the Committee on Clinical Investigation at Children’s Hospital, Boston. A telephone questionnaire was administered by the same investigator, following a standardized format, to the parents or guardians of young children or the patients themselves, if older than 18 years of age. Data collected included a description of these patients’ current health, cardiovascular status, noncardiac medical problems, and growth. Written questionnaires, which covered a wide range of health issues, and were designed to supplement subjective data supplied from the parents’ questionnaires, were administered to the patient’s pediatricians and cardiologists. Cardiac data obtained included the most recent echocardiogram reports, New York Heart Association (NYHA) classification and the need for further cardiac operations. Questions to physicians also covered ongoing medical problems, noncardiac operations and growth, determined as percentile height and weight using standardized National Center for Health Statistics growth charts. The height and weight of the 1 (ECMO supported) child with trisomy 21 was evaluated using percentile growth curves standardized for children with trisomy 21.

Assessment of current neurologic status
The presence of neurologic impairment in these patients was mainly determined by current cognitive functioning, as well as the presence of gross neurologic motor and sensory deficits. Cognitive skills were determined for children placed on support at less than 1 year of age, by determining the age of attaining gross motor and language developmental milestones using established guidelines [2, 3]. Cognitive skills were determined for children that were placed on support at greater than 1 year of age by measuring school performance according to participation at an age-appropriate grade level, requirement for special educational programs, or the inability to attend school altogether because of severe neurologic deficits. Based on present cognitive function, each patient’s neurologic status was placed into one of four groups: normal, mild impairment, moderate impairment, or severe neurologic impairment. In addition to present cognitive function, the presence of significant gross motor abnormalities such as hemiplegia or cerebral palsy, and sensory deficits such as cortical blindness or sensorineural hearing impairment, mandated inclusion into the moderately or severely impaired group. No formal neurologic testing was performed solely for the purposes of this report.

Data management and statistical analysis
Data was collected and analyzed using a statistical program (JMP Software, SAS Institute, Cary, NC). The comparison of neurologic status between ECMO and VAD supported groups was performed with Pearson’s ². Determining the association of factors present at the time of mechanical circulatory support with neurologic status was performed with the Wilcoxon-rank-sum test for continuous variables or Pearson’s ² for discrete variables. Variables attaining a p value of 0.05 were reported as statistically significant.

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
Of the 26 surviving ECMO supported patients and 11 surviving VAD supported patients, 1 patient in each group died after hospital discharge (long-term ECMO survival 25 of 26 (96.2%); long-term VAD survival 10 of 11 [90.9%]) (Fig 1). Median length of follow-up was 43 months (range 11 to 92 months) for the ECMO supported patients and 41 months (range 17 to 81 months) for the VAD supported patients. Median age at follow-up for patients supported with ECMO was 4.6 years of age (range 1.0 to 18 years of age). Median age at follow-up for the patients supported with VAD was 7.1 years of age (range 2.1 to 24 years of age). Nineteen of the 26 ECMO survivors (73%) and 7 of the 11 survivors (64%) in the VAD supported group were less than 1 year of age at the time of support.

View larger version (12K): [in this window] [in a new window]   Fig 1. Survival curves for extracorporeal membrane oxygenation and ventricular support device supported patients.

Our entire experience with VAD used a centrifugal pump system (Bio-Pump; Bio-Medicus, Minneapolis, MN). For infants and children less than 10 kg the 50 cc Bio-Pump was used. For patients above 10 kg the 80 cc Bio-Pump was used. After September of 1994, we employed Carmeda coated cannulas and Carmeda coated polyvinyl chloride tubing (Medtronic Corporation, Minneapolis, MN). Of the VAD supported patients, 10 patients received left ventricular assist device support (LVAD) and 1 patient received right ventricular assist device support (RVAD). The one nonsurviving VAD patient was supported with LVAD. The ACT was maintained at 180 to 200 seconds and lower ACT levels (160 to 180 seconds) were maintained if Carmeda coated tubing was employed.

The original diagnoses (Table 1) and indications for mechanical support (Table 2) are listed for surviving ECMO and VAD patients. Of special interest were those patients who required mechanical circulatory support for cardiac arrest (17 of the ECMO supported patients and 4 of the VAD supported patients) [1]. Eight of these 17 ECMO supported patients (47%) survived to hospital discharge, all of whom are long-term survivors. Two of the 4 VAD supported patients (50%) survived to hospital discharge with 1 long-term survivor. Survivors of cardiac arrest in both groups received cardiopulmonary resuscitation (CPR) for a mean duration of 53.4 ± 28.3 minutes. In an attempt to lessen the impact of cardiac arrest on neurologic function, patients were maintained mildly hypothermic (34°C) for 24 to 48 hours after cardiac arrest, and hyperthermia (above 37°C) was avoided for 4 to 5 days after arrest [4].

View larger version (26K): [in this window] [in a new window]   Fig 2. Description of surviving children’s overall health status as reported by parents.

View larger version (22K): [in this window] [in a new window]   Fig 3. New York Heart Association classification of long-term survivors by patients’ pediatricians and/or cardiologists.

Neurologic outcomes
Information on long-term neurologic outcomes was not available for 3 of the 25 ECMO survivors. In addition, 1 ECMO supported patient was excluded from the analysis because he had Down’s syndrome with severe cognitive and developmental delay prior to support. The remaining patients were considered to be neurologically normal prior to their requirement for mechanical circulatory support. This resulted in follow-up data for neurologic outcomes for 21 long-term survivors of ECMO support and all 10 long-term survivors of VAD support. Based on present cognitive functioning and the presence of gross motor or sensory abnormalities, 13 of these 21 ECMO patients (59%) and 2 of the 10 VAD patients (20%) demonstrated moderate to severe neurologic impairment (p = 0.03) (Fig 4). Of the 9 moderately impaired ECMO supported patients, 8 children demonstrated significant delay in attaining developmental milestones. In addition, 3 of these children demonstrated gross motor abnormalities, hemiplegia in 2 cases due to cerebrovascular accidents suffered during ECMO support and 1 child with cerebral palsy. Another moderately impaired child who required ECMO support at the age of 18 months had severe learning disabilities requiring special schooling for learning disabled children. Of the 4 severely impaired ECMO supported children, 3 patients had severe anoxic encephalopathy, and 2 of these patients required 24-hour nursing care. One of these children was quadriplegic with cortical blindness and the other suffered a cerebral vascular accident with residual left-sided hemiplegia. A fourth child, considered severely impaired, had a left-sided hemiplegia and was severely developmentally delayed. Two VAD supported children demonstrated moderate or severe neurologic impairment. The child demonstrating moderate impairment after VAD support had significant delay in attaining developmental milestones and has significant left-sided hemiplegia due to a cerebrovascular accident, suffered during the initial hospitalization. The severely affected child, after VAD support, suffers from severe anoxic encephalopathy and requires 24-hour nursing care.

View larger version (21K): [in this window] [in a new window]   Fig 4. Neurologic impairment for extracorporeal membrane oxygenation and ventricular support device supported pediatric patients with cardiac disease.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

Survival and general health
The significant in-hospital morbidity and mortality associated with mechanical circulatory support for pediatric cardiac patients requires a continual reevaluation of results to ensure that these heroic measures are justified. These results demonstrate excellent long-term survival with more than 90% of these patients alive after an average follow-up of 4 years. Data on the overall condition of survivors is also encouraging, in that more than 80% of the survivors demonstrate good to excellent general health. These results are reassuring and help to justify an aggressive approach in these children.

An interesting subgroup of survivors are those who had a cardiac arrest as the original indication for support. We have previously demonstrated that the in-hospital survival, for this most critically ill subset of patients, is equivalent to the survival for patients requiring mechanical circulatory support for all other indications [1]. These findings formed the basis for our intensified efforts to quickly resuscitate pediatric cardiac patients that suffer cardiac arrest with a rapid response ECMO circuit [4]. The results of the present study support an aggressive stance in these patients as well, because 9 out of 10 patients that survived to hospital discharge, after requiring ECMO or VAD for cardiac arrest, are long-term survivors. The long-term survival data in these cardiac arrest patients further corroborates the observation that many of these patients have reversible causes for cardiac arrest that can be managed successfully with relatively brief periods of circulatory support. These excellent in-hospital and now long-term results for pediatric cardiac patients, contrast with the dismal results after cardiac arrest in children with other medical diseases [10] or adult patients with cardiac disease [11], but appear to be similar to results in infants with respiratory failure who suffer cardiac arrest prior to the initiation of ECMO [12].

Cardiac status of survivors
The cardiac outcomes of surviving children are favorable, with the majority of children currently in NYHA class I or II. The assessment of ventricular function by echocardiographic data demonstrated normal function in all but 1 of the 28 patients for whom data was available. Many of the significant residual cardiac lesions represent the long-term sequellae of primary corrective or palliative procedures such as conduit deterioration and pulmonic regurgitation secondary to transannular patching of the right ventricle. At present 84% of the ECMO supported patients, and 70% of the VAD supported patients remain free of further cardiac procedures.

Neurologic complications
We previously reported that in-hospital neurologic complications occurred in more than 30% of all ECMO supported patients and in nearly 10% of all VAD supported patients, which was a statistically significant difference between the two modalities [1]. This trend persisted during the period of follow-up for survivors. Based on current cognitive function and the presence of motor or sensory deficits, there was a significantly higher rate of neurologic impairment in the ECMO supported group. However, many patients that demonstrated moderate neurologic impairment in either group are doing quite well overall, with only 16% (5 of 31 patients, 4 ECMO, 1 VAD) demonstrating severe disability.

The causes of adverse neurologic outcomes in the ECMO supported patients is multifactorial, but largely reflects that these are younger patients with more complicated cardiac disease when compared with the VAD supported patients. Sixty percent of the ECMO supported group were neonates, compared with 10% of the VAD supported patients. Small size at the time of support was significantly associated with adverse neurologic outcomes in both ECMO and VAD supported patients. In addition, ECMO supported patients were more likely to have complex cyanotic lesions as opposed to VAD supported patients [1]. The association of neurologic impairment with the use of hypothermic circulatory arrest during cardiac operation in this analysis is consistent with reports that have demonstrated the adverse impact of circulatory arrest on subsequent neurocognitive development [13, 14]. Another important risk factor for poor neurologic outcomes in the ECMO supported patients includes the need for higher levels of anticoagulation that are used, which places these critically ill neonates at risk for intracranial hemorrhage during support. In our previous analysis, intracranial hemorrhage was the most common neurologic complication seen in ECMO supported patients [1]. In addition, the greater complexity of the circuit also predisposes these patients to embolic complications with the oxygenator, and increased tubing lengths required for ECMO, serving as potential sources for thromboemboli. The lack of association with neurologic impairment and carotid cannulation, or reconstruction after ECMO support, is in agreement with the majority of the literature examining the role of carotid reconstruction for children who require ECMO for respiratory failure [15, 16]. In-hospital neurologic complications were not significantly associated with adverse neurologic outcomes in the long-term. The lack of association with in-hospital neurologic complications corroborates the observation that patients suffering neurologic injury may eventually recover without significant sequellae, while poor neurologic outcomes may become apparent in patients without in-hospital neurologic complications as they grow older. Previous reports have demonstrated the inadequacies of imaging studies obtained during ECMO support for respiratory failure in predicting neurologic outcomes [17]. Our results underscore the importance of long-term follow-up in determining the ultimate neurologic status in any survivor of mechanical circulatory support.

The results from the present study are reassuring in that children with heart disease who survive to hospital discharge, after requiring ECMO or VAD support, demonstrate favorable long-term survival, overall general health, and cardiac outcomes. The relatively higher rates of neurologic complications in the ECMO supported group are a cause for concern, and appear to be due to multiple causes in critically ill neonates. Results may be improved by modifications in ECMO that utilize simpler circuits requiring less anticoagulation. These results further underscore the difficulties in predicting the extent of neurologic injury during the acute phases of care in these children, and the necessity of long-term follow-up to assess ultimate neurologic status.

	References

Top Abstract Introduction Patients and methods Results Comment References

 

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Brian W. Duncan Richard A. Jonas Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ibrahim, A. E. Articles by Jonas, R. A. Search for Related Content PubMed PubMed Citation Articles by Ibrahim, A. E. Articles by Jonas, R. A.