Transcatheter closure of symptomatic aortopulmonary window in an infant

An aortopulmonary window is a rare congenital cardiac defect. In the majority of symptomatic neonates and infants, primary surgical repair is the treatment of choice. In selected infants, catheter closure of the defect with a device may be feasible. We report on the successful closure of an AP window in a 12 month old infant, using a 6mm Amplatzer septal occluder. The procedure and follow-up were uneventful.

The diagnostic yield from implantable loop recorders in children and young adults

BACKGROUND

Syncope and palpitations occur frequently in young patients. Noninvasive diagnostic testing may be inconclusive.

AIM

To assess the diagnostic yield of implantable loop recorders in young patients.

PATIENTS AND METHODS

Thirty-three young patients underwent implantation of a loop recorder for long-term monitoring of cardiac rhythm, to establish symptom-rhythm correlation. They belonged to one of three subgroups: those with structurally normal heart, normal electrocardiogram at rest, and negative family history (n = 16); patients with structural heart disease and previous surgical repair (n = 11), and patients with proven or suspected primary electrical disease (n = 6). A combination of automatic and patient-activated recordings was used to monitor cardiac rhythm during symptomatic episodes.

RESULTS

There were no procedural complications. Diagnostic electrograms could be obtained in all patients. A high degree of symptom-rhythm correlation was established. In 8/33 patients, no recurrence of symptoms was observed either until end of battery life of the device (n = 4) or until last follow-up (n = 2). Specific cardiac therapy was required, based on rhythms recorded by the device in 15 patients (until last follow-up). This consisted of catheter ablation of a tachyarrhythmia (n = 7), pacemaker implantation or upgrade (n = 5) or ICD implantation (n = 5). In the remaining patients (n = 10), recurrence of symptoms was associated with a normal electrocardiogram, and in two of these patients a non-cardiac diagnosis was made.

CONCLUSIONS

In selected patients, the implantable loop recorder provides valuable diagnostic information to guide further therapy.

Systemic plasma vascular endothelial growth factor levels as a marker for increased angiogenesis during the single ventricle surgical pathway

Cyanosis and the cavopulmonary anastomosis (CPA) are associated with pulmonary arterio-venous malformations (PAVMs) in single ventricle physiology. Vascular endothelial growth factor (VEGF) may be a marker of abnormal angiogenesis in this setting. Plasma VEGF levels were measured in 14 patients undergoing the surgical pathway leading to total cavopulmonary connection (TCPC). Venous blood samples were taken before and then months after CPA (n=6), and immediately before TCPC and 1 month thereafter (n=9). Corresponding arterial saturations were correlated with VEGF levels at each time frame. In six patients, pre-CPA plasma VEGF levels rose from a mean of 24.4-112.4 pg/ml (p<0.03) just prior to completion of TCPC. In nine patients, VEGF levels diminished from 115.7 to 48.9 pg/ml (p<0.05) after TCPC. VEGF levels were disproportionately elevated to arterial saturations most notably after CPA (r2=0.002), suggesting an additional angiogenic stimulus besides cyanosis. Plasma VEGF levels fluctuate during the single ventricle surgical pathway, with maximal levels after CPA, and regression after completion of TCPC. High VEGF levels are disproportionate to hypoxia after CPA, potentially incriminating the absence of hepatic flow to the lungs as an abnormal angiogenic stimulus. Measuring VEGF in venous blood may serve as a biochemical marker of angiogenesis after CPA.

Intracardiac rhabdomyomas producing symptoms in infancy: the role of radiofrequency catheter ablation

BACKGROUND

Cardiac rhabdomyomas, although benign, may produce symptoms related to arrhythmia or mechanical obstruction. Surgical excision is the therapy of choice for symptomatic rhabdomyomas in infancy.

PATIENTS AND METHODS

Two infants with intracardiac rhabdomyomas producing symptoms underwent radiofrequency catheter ablation of the tumour. In patient 1 the diagnosis of multiple rhabdomyomas associated with recurrent supraventricular tachyarrhythmias and foetal hydrops was made in utero. After birth, several antiarrhythmic agents were administered, without successful suppression of the tachyarrhythmia. At seven months of age, the infant had one large residual tumour on the left atrial aspect of the anterior mitral valve leaflet with associated pre-excitation and re-entrant supraventricular tachyarrhythmia suggestive of a left-sided pathway. Catheter ablation of the accessory pathway was performed via a retrograde femoral arterial approach, targeting the earliest site of ventricular activation. Patient 2 presented as a neonate with multiple rhabdomyomas, one of which, measuring 15 mm × 15 mm, was producing severe mitral valve inflow obstruction resulting in symptoms of heart failure due to a large left-to-right shunt at atrial level and persistent pulmonary hypertension. Via the femoral vein, a 5F ablation catheter was advanced across the atrial septum, and the tumour directly ablated.

RESULTS

Echocardiography performed 24 hours later demonstrated alteration in tumour morphology, with the development of a large central echolucent area, followed by progressive tumour shrinkage in both infants. Patient 1 was discharged at 24 hours, and patient 2 at seven days post-ablation, without symptoms. Follow-up at four weeks confirmed further tumour shrinkage.

CONCLUSION

Transcatheter tumour ablation may be beneficial in selected infants and children.

Transhepatic approach for catheter interventions in infants and children with congenital heart disease

We report on our experience with transhepatic access for catheter interventions in six children (age range 2.5 months-9 years). Three had systemic venous anomalies, and one infant a femoral venous occlusion. In two further patients with bradyarrhythmia after a Fontan operation with an intraatrial Gore-Tex tunnel, transhepatic access was chosen to achieve a perpendicular orientation of the transseptal needle to the atrial baffle, allowing puncture of the Gore-Tex membrane. Two of the patients underwent ablation of an accessory pathway; in one an atrial septal defect was closed. A 2.5 month old baby after Norwood I operation, underwent balloon dilation of the pulmonary arteries. Two patients after prior Fontan surgery underwent DDDR pacemaker implantation. The size of the introducer sheath ranged from 4 F up to two 9 F introducers in the same vein for pacemaker insertion. At the end of the procedure, hemostasis was achieved by external compression.

RESULTS

Transhepatic access could be established in all six patients (using a mirror image approach in children with left atrial isomerism) and the interventional procedures could be performed as planned. In one patient with implantation of a permanent pacemaker, a subcutaneous hematoma occurred, requiring blood transfusion.

CONCLUSION

In selected pediatric patients, transhepatic access for catheter intervention can easily be achieved.

Experience with an ambulatory 12-lead Holter recording system for evaluation of pediatric dysrhythmias

BACKGROUND

The 12-lead electrocardiogram demonstrates noninvasively many details concerning cardiac arrhythmias and their mechanism, but only for a limited period. A Holter system can record heart rhythm for a longer period, but shows 2 or 3 leads only. An ambulatory 12-lead Holter recording system combines the advantages of both. We report on our experience with the 12-lead Holter system in children.

STUDY POPULATION

Twenty-four patients (age range, 3-22 years) underwent one or more 12-lead Holter recordings. Twelve patients had suspected or documented tachyarrhythmia, and 12 patients had suspected or proven long QT syndrome (LQTS).

RESULTS

In the tachyarrhythmia group, 4 patients had supraventricular tachycardia and 7 ventricular tachycardia (VT). In the supraventricular tachycardia, group 1 patient had intra-atrial reentrant tachycardia with a single reentrant circuit, whereas another had multiple P-wave morphologies, suggesting multiple circuits. Two others had evidence for concealed atrioventricular accessory pathways. One patient had isolated supraventricular ectopy. In the VT group, 4 patients had uniform VT, and 3 patients had polymorphic VT. One patient with LQTS had macroscopic T-wave alternans. Two others showed intermittent extreme QT prolongation and T-wave notching during 12-lead Holter recording.

THERAPEUTIC IMPLICATIONS

Patients with uniform VT underwent catheter ablation, guided in 2 instances by intracardiac pace mapping and comparison with the 12-lead Holter QRS morphology. All reentrant supraventricular arrhythmias with single P-wave morphology were ablated. One patient with intra-atrial reentrant tachycardia and multiple circuits received an antitachycardia pacemaker. In the LQTS group, the neonate with T-wave alternans received mexiletine in addition to beta-blocker therapy.

CONCLUSION

In individual patients, the 12-lead Holter system provides important additional information about the arrhythmia and helps to plan appropriate therapy. Intermittent T-wave morphology changes can be diagnosed using 12-lead Holter recordings in patients with LQTS, allowing dynamic T-wave changes to be monitored. In specific cases, this may help identify patients with LQTS and also influence pharmacological therapy.

[Electrical heart diseases--therapy during childhood and adolescence]

With increasing experience, radiofrequency catheter ablation of tachyarrhythmia substrates has become first choice therapy for children >4 years of age with recurrent tachyarrhythmia. In younger patients, the risks associated with the procedure (typically procedure-related AV block or possible coronary artery damage) have to be weighed against the natural history of the tachyarrhythmia substrate, and the degree of control achieved with pharmacologic agents. Ablation for postoperative arrhythmias is more complicated, and associated with lower success rates and a higher rate of recurrence (of the same or a new tachyarrhythmia) despite acute procedural success. In this setting, catheter ablation has to be considered in conjunction with further surgery or the use of a defibrillator as a backup device to prevent arrhythmia-related sudden death. Also in inherited arrhythmias as in long QT syndrome and Brugada syndrome, implantable defibrillators have to be considered as a possible therapeutic option for patients with a higher risk for sudden cardiac death, irrespective of age.

Slow pathway ablation in children with documented reentrant supraventricular tachycardia not inducible during invasive electrophysiologic study

Radiofrequency catheter ablation (RFA) has become the procedure of choice for permanent therapy of atrioventricular nodal reentrant tachycardia (AVNRT). This report presents our experience with atrio-ventricular node (AVN) modification in patients with documented narrow complex reentrant SVT, but no evidence for an accessory pathway, and no inducible tachyarrhythmia during invasive electrophysiology (EP) study.

METHODS

The study population consists of nine children, age range 6-13 years (median 9) with previously documented SVT who had no tachyarrhythmia inducible during EP study (at baseline and following isoprenaline infusion). Eight of the 9 EP studies were performed under general anesthesia, and one under conscious sedation. An accessory pathway was excluded in all patients by appropriate atrial and ventricular extrastimulus pacing techniques. Eight of the nine patients had dual AV nodal physiology, and one had single AV nodal echo beats. The slow AV nodal pathway was empirically ablated, by applying RF lesions in the right inferoseptal AV groove, achieving catheter tip temperature of 50 degrees C. The appearance of an accelerated junctional rhythm during RF application was deemed to denote a successful application site. AV conduction during RF application was confirmed by incremental atrial pacing. The catheter position, and its relation to the compact AV node was constantly monitored using the LocaLisa navigation system. The end-point was absence of dual AVN physiology, and/or AV nodal echo beats.

RESULTS

Successful slow pathway ablation was achieved in all patients. One patient appeared to have two separate slow pathways with different locations and two AH-jumps, which were both successfully ablated. None of the patients had evidence of temporary or permanent AV block at follow-up (median duration 9 months, range 4 to 36 months); none has had recurrence of symptoms or documented tachyarrhythmia.

CONCLUSIONS

In children with structurally normal hearts, a previously documented SVT, absence of an accessory pathway and noninducibility of SVT during EP study, empirical slow pathway ablation appears to be justified.

Radiofrequency catheter septal ablation for hypertrophic obstructive cardiomyopathy in children

BACKGROUND

The definitive therapeutic options for symptomatic obstructive cardiomyopathy in childhood are restricted. At present, extensive surgical myectomy is the only procedure that is of proven benefit.

PATIENTS AND METHODS

Three patients, aged 5, 11 and 17 years, respectively, with progressive hypertrophic obstructive cardiomyopathy and increasing symptoms were considered for radiofrequency catheter septal ablation. The peak Doppler gradient recorded on several occasions ranged between 50 to 90mmHg. Via a femoral arterial approach, the His bundle was initially plotted and marked using the LocaLisa navigation system. Subsequently, using a cooled tip catheter a series of lesions were placed in the hypertrophied septum, taking care to stay away from the His bundle. A total of 17, 50 and 45 lesions were applied in the three patients. In one case, the procedure was complicated by two episodes of ventricular fibrillation requiring DC cardioversion but without any neurological sequelae.

RESULTS

The preablation peak-to-peak gradient between left ventricle and aorta was 50 mmHg, 60 mmHg and 60 mmHg, respectively, and remained unchanged immediately after the procedure. All patients were discharged from hospital 48 hours later. Serial measurement of serum troponin T and CK-MB isoenzyme confirmed significant myocardial necrosis. Follow-up echocardiography both at seven days and at six weeks postablation confirmed a beneficial haemodynamic result, with reduction of left ventricular outflow obstruction and relief of symptoms.

CONCLUSION

In young children, in whom alcohol-induced septal ablation is not an option, radiofrequency catheter ablation offers an alternative to surgery, with the benefits of repeatability and a lower risk of procedure-related permanent AV block.

Radiofrequency catheter septal ablation for hypertrophic obstructive cardiomyopathy in childhood

Two patients, a 5 year old boy with progressive hypertrophic obstructive cardiomyopathy and increasing symptoms despite appropriate pharmacologic therapy and an 11 year old girl with symptoms of tiredness and peak instantaneous LVOT gradient of 80 and 90 mmHg respectively were considered for radiofrequency catheter septal ablation, to relieve the left ventricular outflow tract obstruction. Via a femoral arterial approach, the His bundle was initially plotted and marked using the LocaLisa navigation system. Subsequently, using a cooled tip catheter a series of lesions was placed in the hypertrophied septum, commencing distally in the ventricle and proceeding towards the aortic valve, taking care to stay away from the His bundle. The procedure was deemed to be completed when the entire extent of the hypertrophied septum had been treated. In the boy the procedure was complicated by two episodes of ventricular fibrillation, requiring DC cardioversion, but without any neurologic sequelae. The peak to peak gradient between left ventricle and aorta was 50 mmHg and 60 mmHg respectively pre-ablation, and remained unchanged immediately after. Both patients were discharged from the hospital 48 hours later. Serial measurement of serum Troponin T and CK-MB isoenzyme confirmed significant myocardial necrosis. Follow-up echocardiography at 7 days and at 6 weeks post-ablation respectively confirmed a beneficial hemodynamic result, with reduction of left ventricular outflow obstruction and relief of symptoms. In young children, in whom alcohol induced septal ablation is not an option, radiofrequency catheter ablation offers an alternative to surgery, with the benefits of repeatability and a lower risk of procedure-related permanent AV block.

Catheter ablation of junctional ectopic tachycardia in children, with preservation of atrioventricular conduction

BACKGROUND

Idiopathic junctional ectopic tachycardia is a rare arrhythmia in children. Several studies have demonstrated that drug therapy is often ineffective and sometimes the only achieved effect is rate control. Early presentation and frequent recurrence are associated with adverse outcome.

PATIENTS AND METHODS

Three consecutive children, aged 9, 7 and 12 years respectively, underwent radiofrequency catheter ablation for junctional ectopic tachycardia, after having failed antiarrhythmic drug therapy. The entire His bundle was plotted out and marked, using the Localisa navigation system. The arrhythmia was readily and repeatedly inducible using intravenous isoprenaline infusion and the site of earliest retrograde conduction during tachycardia could be assessed. Ablations were performed in sinus rhythm, empirically targeting the site of earliest retrograde conduction during tachycardia.

RESULTS

This approach was successful in abolishing tachyarrhythmia in the first two patients, in whom the successful ablation site was located superoparaseptally. In the third patient, junctional ectopic tachycardia was inducible, despite abolishing retrograde atrial activation, in a septal location on the tricuspid valve annulus. Further ablations in the superoparaseptal region, closer to the His bundle, were successful in rendering tachyarrhythmia noninducible. Over a median follow-up of 10 months, none of the patients has had recurrence of arrhythmia, despite discontinuing all antiarrhythmic medications.

CONCLUSIONS

Radio frequency catheter ablation of junctional ectopic tachycardia is feasible with preservation of atrioventricular conduction.

Palliative balloon dilation of native coarctation of the aorta in a preterm infant

The role of balloon dilation for native coarctation in neonates is controversial, due to the relatively high recurrence rate. Balloon dilation may however provide adequate palliation in preterm infants, by relieving symptoms and allowing somatic growth until definitive surgical repair can be performed. We report successful balloon angioplasty, on 2 occasions, in a preterm neonate with coarctation of the aorta and associated left ventricular cardiomyopathy.

Pulmonary atresia with ventricular septal defect and an atypical duct

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