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Ann Thorac Surg 1998;65:775-778
© 1998 The Society of Thoracic Surgeons
Division of Pediatric Cardiac Surgery, Medical College of Ohio, Toledo, Ohio, USA,
Division of Cardiology, Medical College of Ohio, Toledo, Ohio, USA
Accepted for publication September 30, 1997.
Dr Wilson, The Children’s Hospital–University Hospital and Clinics, MA 312, One Hospital Dr, Columbia, MO 65212 (e-mail: william_wilson@surgery.missouri.edu).
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Abstract |
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Methods. The medical records of 5 children with implantable cardioverter-defibrillators were retrospectively reviewed. All patients had experienced syncope and 3 (60%) an out-of-hospital cardiac arrest. Underlying pathology included hypertrophic cardiomyopathy in 2, long QT syndrome in 2, and ventricular arrhythmia after remote repair of congenital heart disease in 1. Open thoracotomy with epicardial lead placement and transvenous endocardial approaches were used.
Results. There was no early or late mortality in the 5 pediatric patients undergoing implantable cardioverter-defibrillator placement. Postoperative complications occurred more frequently when open thoracotomy was used for placement. At mean follow-up of 34 months, 4 of the 5 (80%) have received shocks.
Conclusions. Implantable cardioverter-defibrillator is a safe and reliable therapy for children with resuscitated sudden death and syncope due to ventricular tachycardia unresponsive to antiarrhythmics. Transvenous lead placement lowers morbidity and hospital length of stay.
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Introduction |
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The implantable cardioverter-defibrillator (ICD) has had widespread use in adults and limited use in children. This therapy allows prompt recognition and termination of life-threatening arrhythmias and should improve outcomes in children prone to sudden death. We report our institutional experience in 5 pediatric patients with ICDs.
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Material and Methods |
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There were 4 boys and 1 girl. Age at the time of implantation ranged from 7 to 18 years (mean, 12 ± 4 years) and weight from 23 to 70 kg (mean, 52 ± 20 kg).
All patients (100%) had experienced syncope, usually multiple episodes. Three patients (60%) had an out-of-hospital arrest with cardiopulmonary resuscitation and defibrillation or cardioversion in the field. One patient with previously corrected congenital heart disease presented with malaise and ventricular tachycardia, which degenerated to ventricular fibrillation during evaluation in the emergency department. In the last patient sustained ventricular tachycardia developed during a stress test and then again during an electrophysiologic study for the evaluation of multiple syncopal episodes. All 5 patients had been treated with antiarrhythmics including ß-blockers, calcium-channel blockers, and amiodarone before placement of an ICD. Two patients had a previous cardiac operation: 1 underwent placement of a DDD permanent pacemaker for long QT syndrome and the other correction of tetralogy of Fallot.
Pathologic diagnoses included hypertrophic cardiomyopathy in 2 (40%), long QT syndrome in 2 (40%), and congenital heart disease in 1 (20%). The last child had ventricular tachycardia and fibrillation 5 years after total repair of tetralogy of Fallot. No residual hemodynamic lesion could be found during evaluation before placement of the ICD.
Device and Technique of Implantation
CPI Ventak pulse generators, models 1550, 1600, 1705, or 1745 (Cardiac Pacemakers, Inc, St. Paul, MN) were implanted, with newer generators being used as updated devices became available. The basic device has programmable and recording functions. It is capable of delivering biphasic shocks of set energy upon recognition of fibrillation or tachycardia of a predetermined rate. Electrograms and events are stored for interrogation and retrieval. Maximum output averages 30 J.
All implantations were performed with the patients under general anesthesia. Two distinct approaches and lead configurations were used (Fig 1). Three patients, the first in the series and the 2 smallest children, had epicardial sensing and shocking leads placed by open thoracotomy. With a roll under the left shoulder and the left arm held flexed and elevated on an ether screen, a small left anterior lateral thoracotomy was made through the fifth intercostal interspace. The pericardium was opened and two unipolar screw-in myocardial leads were placed in the epicardium of the left ventricle for rate sensing. For defibrillation in the open cases, two small patches were positioned over the right ventricle anteriorly and posterolaterally over the left ventricle and sewn in place. Two larger children, most recently, have had totally transvenous lead placement using the Endotak lead (Cardiac Pacemakers, Inc). Through a 14F introducer and the left subclavian vein, the single lead containing two shocking coils was placed transvenously with the distal coil optimally positioned at the apex of the right ventricle and the proximal coil in the superior vena cava. One patient required addition of a subcutaneous patch to achieve adequate defibrillation threshold.
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Follow-up
After recovery from the operation and before discharge, all patients had an electrophysiologic study performed. Ventricular fibrillation was induced and appropriate recognition and termination determined. Patients were routinely seen every 3 months, the history of shocks or syncope was recorded, and the device was interrogated for number of shocks administered and end-of-life indicators.
At the end of the study period, all patients and their families were contacted regarding resumption of normal activities, functional status, and neurologic outcomes.
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Results |
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Initial defibrillation thresholds were acceptable in all 5 patients and ranged from 8 to 25 J. The patient with the highest defibrillation threshold was a child with severe hypertrophic cardiomyopathy who had transvenous lead system placement. He required placement of additional subcutaneous patch to achieve an acceptable value.
Mean follow-up has been 34 ± 25 months (range, 6 to 73 months). The first 2 patients in the series have now had replacement of their generators for end-of-life with adequate pacing thresholds and defibrillation thresholds at that time. Four of the 5 (80%) of the patients subsequently received shocks from the device at an average interval of 2 months from the time of placement until the first discharge (range, 1 to 3 months). Interrogation revealed that shocks were appropriately administered for ventricular tachycardia or fibrillation in 62 of 63 discharges, with only one shock occurring after an episode of sinus tachycardia. This occurred in the child with tetralogy who received a shock for a sinus tachycardia of 190 beats/min while running on the playground. His ventricular tachycardia typically occurs at a rate of 240 beats/min. After adjustment of his rate criterion to 210 beats/min he has received no further inappropriate shocks, although he received one shock for ventricular tachycardia. All 5 patients are receiving ß-blockers to decrease maximum heart rate and avoid inappropriate shocks for sinus tachycardia.
Of the 3 patients presenting with out-of-hospital arrest, cardiopulmonary resuscitation, and defibrillation in the field, 2 had significant transient neurologic sequelae. Patient 3 arrested at school and was intubated and defibrillated by the rescue squad. While at the hospital before ICD placement, he appeared agitated and confused at times. Computed tomographic scan was normal and electroencephalography was negative. Since placement and hospital discharge, he has had occasional bouts of depression with suicidal ideation. Patient 4 had been followed up for 6 years with syncope, a known diagnosis of long QT syndrome for 3 years, and one previous out-of-hospital arrest before her ICD placement. Immediately before ICD placement, she experienced a second arrest, this time while sledding. Cardiopulmonary resuscitation was started by her brother, and she was defibrillated in the field as well as multiple times in the emergency department before stabilization. This patient suffered significant anoxic brain damage with posturing, confusion, and memory loss. Electroencephalography showed diffuse encephalopathy. At 1 year after ICD placement, she is just going back to school. The other 3 patients are neurologically normal and without limitation of activity.
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Comment |
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Recent studies of outcomes of children with out-of-hospital arrests have documented extremely poor outcomes, with survivals to hospital discharge of 8% to 9% of pediatric patients resuscitated from sudden death [2][3]. Survivors often have profound neurologic impairment, with moderate deficits or persistent vegetative states in a high percentage. Schindler and associates [2] reported 6 hospital survivors out of 80 pediatric patients arriving at the emergency room with cardiac arrest, and all had neurologic impairment.
Identification of children at risk with potentially treatable underlying pathology should improve outcomes. Children with cardiac pathology at particular risk include those with long QT syndrome and hypertrophic cardiomyopathy. In an international multiinstitutional study of 287 pediatric patients with the long QT syndrome, overall incidence of sudden death was 8% [5]. A subset of patients with a QTc interval of greater than 0.6 and failure of ß-blocker therapy appeared to be at particular risk. This subgroup may be appropriate for prophylactic ICD placement. Four patients in this series had ICD placement with no further sudden deaths.
Children with hypertrophic cardiomyopathy may have a risk of sudden death as high as 4% per year [1]. In these children particularly strong risk factors include syncope, young age at presentation, severe hypertrophy, family history, and unsustained ventricular tachycardia.
An additional group of children prone to the development of arrhythmias are those with corrected congenital heart disease. Long-term follow-up of repaired tetralogy of Fallot carries a risk for the development of sudden death due to ventricular arrhythmias of up to 5% at 15 years [6]. Preoperative mapping followed by surgical resection or cryoablation of the responsible focus has been successfully used, particularly if there is a concomitant need for correction of a residual hemodynamic lesion. An ICD can be placed at the time of surgical ablation to avoid sudden death due to a failed resection. In our patient, no residual hemodynamic lesion was found and the focus could not be mapped because of the hemodynamic instability associated with his rapid ventricular tachycardia. An ICD alone was used as definitive therapy due to its low risk and maximum safety.
As has been described by other authors [7][8][9][10], our present practice is to insert an ICD in pediatric patients with aborted sudden death due to ventricular tachycardia or fibrillation or syncope in patients with sustained ventricular tachycardia or inducible tachycardia unresponsive to antiarrhythmic medication. The high-risk groups, long QT and hypertrophic cardiomyopathies, may be considered for prophylactic ICD. Patients with dilated cardiomyopathy and significant tachyarrhythmias may have ICD used as a bridge to transplantation.
The choice of device for implantation and the technique used have undergone significant evolution since the 1980s, as the technology has improved. Earlier approaches relied on epicardial lead placement for sensing and defibrillation, necessitating open thoracotomy. Newer lead systems allow totally transvenous lead placement in the larger children [11][12][13][14]. The two coiled springs, one in the apex of the right ventricle and a second positioned in the superior vena cava, allow an appropriate vector through the myocardium to achieve defibrillation. A subcutaneous patch electrode or array, or the generator itself, can be added as additional defibrillation poles to the system to lower the defibrillation threshold.
Morbidity was higher in our series in the patients undergoing open placement of ICDs. Significant pleural space problems developed in 2 of the 3: a pleural effusion requiring late tube thoracostomy drainage in 1 and significant left lower lobe atelectasis in 1. Postoperative hospital stays were longer in the open group (5 to 7 days as opposed to 3 and 4 days in the transvenous group).
As suggested by other authors [10], we continue to use an open approach in our smallest children, particularly those weighing 40 kg or less, because of the worry that axial growth will change the relationship between two endocardial spring electrodes and myocardial mass, affecting ability to successfully defibrillate. As the device becomes smaller, it will become possible to place the generator in a pectoral location for children as we have seen in our adult population.
Poor neurologic outcomes have been observed in other series of children receiving ICD therapy. Kaminer and colleagues [8] reported 2 of their 4 patients had severe neurologic dysfunction from the presenting arrest. In 2 of our 5 patients, there were neurologic sequelae, although both patients are now functional and back in school. Both have suffered depression and suicidal ideation.
The majority of children in this series received shocks within several months of ICD placement. Knowledge of the child’s typical rate for ventricular tachycardia through electrophysiologic testing and ß-blocker therapy to decrease sinus response allows the rate criterion to be set high enough to avoid shocking of sinus tachycardia and still recognize the ventricular tachycardia. At an average follow-up of 34 weeks, the children had received a total of 63 shocks. Interrogation of the devices’ stored electrograms revealed that all shocks but one were for ventricular tachycardia.
In summary, ICD is a safe and reliable therapy for resuscitated sudden death and syncope due to ventricular tachycardia unresponsive to antiarrhythmics. All children in our series are alive and functional with ICDs in place.
Earlier recognition of children at risk for sudden death and prophylactic ICD placement in selected groups of high-risk children may lower the neurologic sequelae of an out-of-hospital arrest. Transvenous lead placement, when possible, lowers morbidity and postoperative length of stay.
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References |
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TopAbstractIntroductionMaterial and MethodsResultsCommentReferences |
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This article has been cited by other articles:
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  A. Pedrote, F. J. Morales, L. Garcia-Riesco, and F. Errazquin Documented exercise-induced cardiac arrest in a paediatric patient with hypertrophic cardiomyopathy Europace, June 1, 2006; 8(6): 430 - 433. [Abstract] [Full Text] [PDF]
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 R. Chatrath, C.-b. J. Porter, and M. J. Ackerman Role of Transvenous Implantable Cardioverter-Defibrillators in Preventing Sudden Cardiac Death in Children, Adolescents, and Young Adults Mayo Clin. Proc., March 1, 2002; 77(3): 226 - 231. [Abstract] [PDF]
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 H. Watanabe, J.-i. Hayashi, M. Haga, M. Saito, H. Suzuki, and S. Sato Successful implantation of a cardioverter defibrillator in an infant Ann. Thorac. Surg., December 1, 2001; 72(6): 2125 - 2127. [Abstract] [Full Text] [PDF]
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