postoperative arrhythmia is a recognized complication after pediatric cardiac surgery , reported to occur in 15 - 48% of cases.1)2 ) patients with congenital heart disease ( chd ) are especially vulnerable to rhythm disturbances . transient low cardiac output syndrome is frequently observed in the early postoperative period , which can result in significant morbidity and mortality . the present report describes our experiences using mechanical circulatory support ( mcs ) for pediatric patients with postoperative medically intractable arrhythmias ( table 1 ) . a 10-month - old boy with tetralogy of fallot ( tof ) and juxtaductal left pulmonary artery ( lpa ) stenosis was admitted for a total corrective operation . during the induction of anesthesia , supraventricular tachycardia ( svt ) developed with a heart rate of > 200 beats / min , and then spontaneously resolved . the major procedures performed were ventricle septal defect ( vsd ) patch closure , right ventricular outflow tract obstruction relief and lpa angioplasty . all were completed without any remarkable events . during cardiopulmonary bypass ( cpb ) weaning , however , svt recurred . initially the svt was controlled by a single adenosine dose , but it again recurred immediately and repeatedly and was accompanied by hemodynamic compromise . these latter events could not be controlled using adenosine , electric cardioversion or body cooling . a transesophageal pacing trial revealed an ectopic atrial tachycardia which was not terminated by overdrive pacing ( fig . after loading 5 mg / kg / hr of amiodarone , 5 mg / kg / day of amiodarone was continuously infused for rate control . two days after the operation , the heart increased to a consistent rate > 220 beats / min , and was accompanied by hypotension . mcs was provided using extracorporeal membrane oxygenation ( ecmo , centrifugal pump , bio - console560 , medtronic inc . , minneapolis , mn , usa . all patients in this report were supported with this ) . after approximately 48 hours of ecmo support and without any antiarrhythmic agent , the heart rhythm converted to sinus rhythm . , brain magnetic resonance imaging ( mri ) showed a small chronic subdural hemorrhage , however , no definite clinical neurological deficit was observed . the patient has been followed - up for 6 years , during which time there have been no arrhythmic events , and he is now a 7-year - old - boy in a good general condition . a male baby was born at 41 weeks gestation , weighing 3,200 g. the patient had chd comprising of a functional single ventricle , an unbalanced complete atrioventricular septal defect , a double outlet right ventricle , pulmonary atresia and a bilateral superior vena cava . the patient also had multiple extracardiac anomalies such as a cleft palate and lip , an ear anomaly ( low set right ear with microtia , left anotia and peripheral conduction defect ) , hemifacial microsomia and torticollis . during neonatal intensive care , a right modified blalock - taussig ( rmbt ) shunt operation ( 3.5 mm graft via sternotomy ) was performed at 13 days postnatal , and he was discharged on postoperative day 42 . at 8 months old , a bilateral cavopulmonary shunt ( bcs ) was planned , but a preoperative ct revealed a severe long segment lpa stenosis . therefore , we performed an left modified blalock - taussig ( lmbt ) shunt rather than a bcs . the patient was extubated on postoperative day 6 , but showed respiratory difficulty with chest wall retraction . intermittent self - limiting tachycardia and pericardial effusion developed , starting from postoperative day 11 . after the operation of sternal fixation combined with laryngo microsurgery at postoperative day 18 , sustained tachycardia developed which could not be controlled with body cooling or amiodarone continuous infusinon . the estimated duration of cardiopulmonary resuscitation ( cpr ) was about 120 minutes . during cpr , a ventricular assist device ( vad ) was deployed and both shunts were kept in the open state to maintain pulmonary blood flow for gas exchange . the child subsequently underwent 2 further open - heart surgery procedures : a bcs at 2 years old and an extracardiac conduit fontan operation at 5 years old . a 3-month - old boy with a vsd and pulmonary stenosis ( ps ) was admitted for surgery . we performed a vsd patch closure , right ventricular outflow tract relief ( rvotr ) and main pulmonary artery ( mpa ) angioplasty . during cpb weaning , a narrow qrs tachycardia developed with a heart rate > 200 beats / min . the tachycardia could not be controlled using adenosine , digoxin , verapamil or epicardial defibrillations , though it appeared to be converted to sinus rhythm after left atrial auricle stimulation . the patient was transferred to the intensive care unit ( icu ) with an atrial pacing wire . immediately upon arrival in the icu the tachycardia again occurred , and was found to be junctional ectopic tachycardia ( jet ) , with a heart rate of 220 - 260 beats / min ( fig . with body cooling , an amiodarone continuous infusion ( 5 mg / kg / day ) was commenced after 5 mg / kg / hr of loading , but it did not control the tachycardia , and the hemodynamic collapse progressed . on postoperative day 15 , jet again developed and was controlled using a continuous amiodarone infusion . from postoperative day 16 brain mri showed hypoxic ischemic encephalopathy , mild diffuse brain atrophy and multiple staged subdural hemorrhages ( sdh ) . a subduroperitoneal shunt operation for sdh was performed when the patient was 8 months old , and the shunt was removed 6 months later . the patient is now 4 years old , and shows mild developmental delay with good cardiac function . a 10-month - old boy with tetralogy of fallot ( tof ) and juxtaductal left pulmonary artery ( lpa ) stenosis was admitted for a total corrective operation . during the induction of anesthesia , supraventricular tachycardia ( svt ) developed with a heart rate of > 200 beats / min , and then spontaneously resolved . the major procedures performed were ventricle septal defect ( vsd ) patch closure , right ventricular outflow tract obstruction relief and lpa angioplasty . all were completed without any remarkable events . during cardiopulmonary bypass ( cpb ) weaning , however , svt recurred . initially the svt was controlled by a single adenosine dose , but it again recurred immediately and repeatedly and was accompanied by hemodynamic compromise . these latter events could not be controlled using adenosine , electric cardioversion or body cooling . a transesophageal pacing trial revealed an ectopic atrial tachycardia which was not terminated by overdrive pacing ( fig . after loading 5 mg / kg / hr of amiodarone , 5 mg / kg / day of amiodarone was continuously infused for rate control . two days after the operation , the heart increased to a consistent rate > 220 beats / min , and was accompanied by hypotension . mcs was provided using extracorporeal membrane oxygenation ( ecmo , centrifugal pump , bio - console560 , medtronic inc . , minneapolis , mn , usa . all patients in this report were supported with this ) . after approximately 48 hours of ecmo support and without any antiarrhythmic agent , the heart rhythm converted to sinus rhythm . , brain magnetic resonance imaging ( mri ) showed a small chronic subdural hemorrhage , however , no definite clinical neurological deficit was observed . the patient has been followed - up for 6 years , during which time there have been no arrhythmic events , and he is now a 7-year - old - boy in a good general condition . a male baby was born at 41 weeks gestation , weighing 3,200 g. the patient had chd comprising of a functional single ventricle , an unbalanced complete atrioventricular septal defect , a double outlet right ventricle , pulmonary atresia and a bilateral superior vena cava . the patient also had multiple extracardiac anomalies such as a cleft palate and lip , an ear anomaly ( low set right ear with microtia , left anotia and peripheral conduction defect ) , hemifacial microsomia and torticollis . during neonatal intensive care , a right modified blalock - taussig ( rmbt ) shunt operation ( 3.5 mm graft via sternotomy ) was performed at 13 days postnatal , and he was discharged on postoperative day 42 . at 8 months old , a bilateral cavopulmonary shunt ( bcs ) was planned , but a preoperative ct revealed a severe long segment lpa stenosis . therefore , we performed an left modified blalock - taussig ( lmbt ) shunt rather than a bcs . the patient was extubated on postoperative day 6 , but showed respiratory difficulty with chest wall retraction . intermittent self - limiting tachycardia and pericardial effusion developed , starting from postoperative day 11 . after the operation of sternal fixation combined with laryngo microsurgery at postoperative day 18 , sustained tachycardia developed which could not be controlled with body cooling or amiodarone continuous infusinon . the estimated duration of cardiopulmonary resuscitation ( cpr ) was about 120 minutes . during cpr , a ventricular assist device ( vad ) was deployed and both shunts were kept in the open state to maintain pulmonary blood flow for gas exchange . the child subsequently underwent 2 further open - heart surgery procedures : a bcs at 2 years old and an extracardiac conduit fontan operation at 5 years old . a 3-month - old boy with a vsd and pulmonary stenosis ( ps ) was admitted for surgery . we performed a vsd patch closure , right ventricular outflow tract relief ( rvotr ) and main pulmonary artery ( mpa ) angioplasty . during cpb weaning , a narrow qrs tachycardia developed with a heart rate > 200 beats / min . the tachycardia could not be controlled using adenosine , digoxin , verapamil or epicardial defibrillations , though it appeared to be converted to sinus rhythm after left atrial auricle stimulation . the patient was transferred to the intensive care unit ( icu ) with an atrial pacing wire . immediately upon arrival in the icu the tachycardia again occurred , and was found to be junctional ectopic tachycardia ( jet ) , with a heart rate of 220 - 260 beats / min ( fig . 1c ) . with body cooling , an amiodarone continuous infusion ( 5 mg / kg / day ) was commenced after 5 mg / kg / hr of loading , but it did not control the tachycardia , and the hemodynamic collapse progressed . on postoperative day 15 , jet again developed and was controlled using a continuous amiodarone infusion . from postoperative day 16 , a normal sinus rhythm was maintained without any medication . brain mri showed hypoxic ischemic encephalopathy , mild diffuse brain atrophy and multiple staged subdural hemorrhages ( sdh ) . a subduroperitoneal shunt operation for sdh was performed when the patient was 8 months old , and the shunt was removed 6 months later . the patient is now 4 years old , and shows mild developmental delay with good cardiac function . a variety of arrhythmias can develop in pediatric patients after congenital heart surgery.3)4 ) the etiology of arrhythmias is , in many cases , multi - factorial . cpb , the type of surgery , younger age , aorta cross clamp time , some medical treatments such as high - dose inotropics , and electrolyte imbalances have been identified as important provoking factors.5 - 7 ) in our study there was no specific intraoperative events or perioperative electrolyte imbalances . postopetaively only a low dose inotropic ( dopamine 5 ug / kg / min ) agent was needed in all three patients . jet is the most common tachyarrhythmia in the postoperative course of congenital heart surgery in children . although it may be transient , despite vigorous treatments it can sometimes be associated with a high rate of morbidity and mortality . the cause of cat is still unclear,8)9 ) and can not be controlled easily ; it can induce congestive heart failure . pediatric patients are vulnerable to tachyarrhythmias , especially during the early postoperative period , often resulting in hemodynamic instability.6 ) acute cardiovascular collapse in pediatric patients with chd carries a poor prognosis , having an estimated survival rate of 14 - 41%.10 ) therefore , in order to maintain a proper postoperative cardiac output and better surgical outcomes , it is necessary to aggressively manage tachyarrhythmia associated with unstable vital signs . medical management of tachyarrhythmia includes discontinuation of high - dose of inotropics , hypothermia , correction of electrolyte imbalances , and use of anti - arrhythmic agents . among pharmacologic managements , several studies reported the efficacy and safety of amiodarone in use for postoperative arrhythmias.11)12 ) in our experiences , these medications served no purpose in any of these three patients . if medical treatments fail to control the tachyarrhythmia , immediate mcs such as ecmo or vad should be considered as therapeutic options.5)13 ) ecmo has traditionally been utilized for preoperative , intraoperative or postoperative cardiac failure , and cardiomyopathies.14)15 ) more recently , the indications for ecmo have expanded to patients with acute cardiovascular decompression including intractable arrhythmias.16)17 ) in these cases , mcs was used to give the heart a period of rest and decompression , until the arrhythmia could be controlled . mcs may also provide sufficient time to achieve efficacy and rate control of the arrhythmia by medical management . in this study , neurologic complications arose in two patients , because prolonged cpr was performed before mcs was initialized . although the upper limit of duration of cpr before mcs to predict survival or acceptable neurologic recovery is unknown,18 ) < 60 minutes of cpr followed by mcs could be a reasonable , acceptable survival rate.19 ) for a more favorable survival and neurologic outcome , a specialized mcs team and a prepared ecmo circuit would be useful , to decrease the time of cpr to mcs . recent technical advances have reduced the frequency of device - related problems associated with mcs . for example , the need for aggressive anticoagulation carries a substantial risk of hemorrhage and stroke . postoperative arrhythmias in pediatric cardiac surgery patients are one of the major causes of morbidity and mortality . early intervention and prompt termination of hemodynamically unstable tachyarrhythmia is important for both better survival and a favorable neurologic outcome . postoperative arrhythmias in pediatric cardiac surgery patients are one of the major causes of morbidity and mortality . early intervention and prompt termination of hemodynamically unstable tachyarrhythmia is important for both better survival and a favorable neurologic outcome .
postoperative intractable arrhythmia can result in high morbidity and mortality . 
 this report describes our experiences using mechanical circulatory support ( mcs ) to control medically intractable arrhythmias in three pediatric patients with congenital heart disease ( chd ) , after palliative or total corrective open - heart surgery .