A decade of insertable cardiac monitors with remote monitoring in pediatric patients.

BACKGROUND: Remote monitoring-enabled insertable cardiac monitors (ICMs) are useful tools for arrhythmias and symptom management. This study sought to evaluate the outcome of ICM implantation in a large, heterogeneous cohort of pediatric and young adult patients. METHODS: Single centre, retrospective analysis of patients who underwent ICM implantation in 2010-2019. Patients were analysed according to age, symptoms, arrhythmias and underlying heart disease. RESULTS: A total of 200 consecutive patients (58% male), aged 11.5 ± 5.8 years at ICM implantation, were included. Follow-up was 31 ± 18 months. Electrophysiologic study (EPS) was initially performed in 123 patients and was negative in 85%. Patients had no heart disease (57.5%), congenital heart defects (21%), channelopathies (14.5%), cardiomyopathies/heart tumors (8%). The commonest symptoms were syncope/presyncope (45.5%) and palpitations (12.5%). A definite diagnosis was made in 63% of patients (positive diagnosis in 25%, negative in 38%) after 8 (2-19) months of monitoring. EPS results and the presence/absence of an arrhythmia before ICM implantation had no impact on the diagnostic yield. Symptomatic patients as well as patients without structural heart disease showed higher diagnostic yield. Patients with a positive diagnosis underwent pacemaker/implantable cardioverter-defibrillator implantation (13%), pharmacological treatment (10.5%), or catheter ablation (1.5%). CONCLUSIONS: In a large cohort of 200 children and young adults, ICMs with remote monitoring showed a high diagnostic yield (63%), especially in symptomatic patients and in patients without structural heart disease.

When Should Premature Ventricular Contractions Be Considered as a Red Flag in Children with Cardiomyopathy?

Premature ventricular contractions (PVCs) are common and generally benign in childhood and tend to resolve spontaneously in most cases. When PVCs occur frequently, an arrhythmia-induced cardiomyopathy may be present requiring medical or catheter ablation. PVCs are only rarely the manifestation of a cardiomyopathy. The purpose of this review is to provide some tips and tricks to raise the suspicion of a cardiac disease based on the presence and characteristics of PVCs in children.

Comparison of cryoablation with 3D mapping versus conventional mapping for the treatment of atrioventricular re-entrant tachycardia and right-sided paraseptal accessory pathways.

UNLABELLED: Aim Transcatheter cryoablation is a well-established technique for the treatment of atrioventricular nodal re-entry tachycardia and atrioventricular re-entry tachycardia in children. Fluoroscopy or three-dimensional mapping systems can be used to perform the ablation procedure. The aim of this study was to compare the success rate of cryoablation procedures for the treatment of right septal accessory pathways and atrioventricular nodal re-entry circuits in children using conventional or three-dimensional mapping and to evaluate whether three-dimensional mapping was associated with reduced patient radiation dose compared with traditional mapping. METHODS: In 2013, 81 children underwent transcatheter cryoablation at our institution, using conventional mapping in 41 children - 32 atrioventricular nodal re-entry tachycardia and nine atrioventricular re-entry tachycardia - and three-dimensional mapping in 40 children - 24 atrioventricular nodal re-entry tachycardia and 16 atrioventricular re-entry tachycardia. RESULTS: Using conventional mapping, the overall success rate was 78.1 and 66.7% in patients with atrioventricular nodal re-entry tachycardia or atrioventricular re-entry tachycardia, respectively. Using three-dimensional mapping, the overall success rate was 91.6 and 75%, respectively (p=ns). The use of three-dimensional mapping was associated with a reduction in cumulative air kerma and cumulative air kerma-area product of 76.4 and 67.3%, respectively (p<0.05). CONCLUSIONS: The use of three-dimensional mapping compared with the conventional fluoroscopy-guided method for cryoablation of right septal accessory pathways and atrioventricular nodal re-entry circuits in children was associated with a significant reduction in patient radiation dose without an increase in success rate.

Sinus bradycardia, junctional rhythm, and low-rate atrial fibrillation in Short QT syndrome during 20 years of follow-up: three faces of the same genetic problem.

We describe the case of an asymptomatic girl with sinus bradycardia and short QT interval at birth, junctional bradycardia in infancy requiring single-chamber pacemaker, atrial fibrillation in adolescence, and V141M mutation in the KCNQ1 gene. Atrial fibrillation recurred and became unresponsive to electrical or anti-arrhythmic therapy. During 20 years of follow-up, a progressive evolution from sinus node dysfunction to low-rate atrial fibrillation was observed.

Results of remote follow-up and monitoring in young patients with cardiac implantable electronic devices.

BACKGROUND: Remote monitoring is increasingly used in the follow-up of patients with cardiac implantable electronic devices. Data on paediatric populations are still lacking. The aim of our study was to follow-up young patients both in-hospital and remotely to enhance device surveillance. METHODS: This is an observational registry collecting data on consecutive patients followed-up with the CareLink system. Inclusion criteria were a Medtronic device implanted and patient's willingness to receive CareLink. Patients were stratified according to age and presence of congenital/structural heart defects (CHD). RESULTS: A total of 221 patients with a device - 200 pacemakers, 19 implantable cardioverter defibrillators, and two loop recorders--were enrolled (median age of 17 years, range 1-40); 58% of patients were younger than 18 years of age and 73% had CHD. During a follow-up of 12 months (range 4-18), 1361 transmissions (8.9% unscheduled) were reviewed by technicians. Time for review was 6 ± 2 minutes (mean ± standard deviation). Missed transmissions were 10.1%. Events were documented in 45% of transmissions, with 2.7% yellow alerts and 0.6% red alerts sent by wireless devices. No significant differences were found in transmission results according to age or presence of CHD. Physicians reviewed 6.3% of transmissions, 29 patients were contacted by phone, and 12 patients underwent unscheduled in-hospital visits. The event recognition with remote monitoring occurred 76 days (range 16-150) earlier than the next scheduled in-office follow-up. CONCLUSIONS: Remote follow-up/monitoring with the CareLink system is useful to enhance device surveillance in young patients. The majority of events were not clinically relevant, and the remaining led to timely management of problems.

Cryoablation of typical atrioventricular nodal reentrant tachycardia in children: six years' experience and follow-up in a single center.

BACKGROUND: Cryoablation is an effective and safe treatment for children with supraventricular tachycardias when the reentry circuit is located near the atrioventricular (AV) junction. We retrospectively reviewed consecutive cryoablation procedures for the treatment of atrioventricular nodal reentrant tachycardia (AVNRT) in children and young adults in a single pediatric center. METHODS: From October 2002 to October 2008, cryoablation was attempted in 76 pediatric patients (mean age 11.3 +/- 2.4 years, range: 6-16.4 years) with symptomatic typical AVNRT. Cryomapping, used to identify the tissue site for safe arrhythmia ablation, was performed at -30 degrees C for a maximum of 60 seconds. The efficacy of the cryomapping procedure was assessed in terms of disappearance of dual-AV node physiology and noninducibility of AVNRT. RESULTS: Cryoablations were from 4 to 8 minutes long at -75 degrees C. A single "bonus" cryoapplication (-75 degrees C for minimum 6 minutes) was delivered to consolidate the acutely successful cryoablation for 64 consecutive patients. After the cryoablation procedure, patients were assessed at 1, 3, 6, 12, 18, and 24 months (and then every year thereafter) by a clinical evaluation and standard electrocardiogram, Holter monitoring, and exercise stress testing. No permanent cryo-related complications were reported. Seventy-four (97.4%) patients were successfully acutely ablated. During a mean follow-up of 29.5 months (range 2-74 months), five (6.8%) acutely successful pediatric patients experienced arrhythmia recurrence. We did not identify any predictive factors of AVNRT recurrence. CONCLUSIONS: Acute and long-term results demonstrate that cryoablation of AVNRT can be considered a safe and effective procedure in pediatric patients. (PACE 2010; 475-481).

Outcome of young patients with abandoned, nonfunctional endocardial leads.

BACKGROUND: Transvenous leads may fail and may be extracted or abandoned. There are no reports of the outcome of children with abandoned nonfunctional leads. METHODS: We evaluated retrospectively the outcome of these patients, in our population of pacemaker (PM) patients. Data are reported as median (range). RESULTS: In 18 patients (of 245, 7%) with endocardial pacing systems implanted at 4 (0.3-19) years of age (15 VVIR and 3 DDD PM), 19 leads (16 ventricular, 3 atrial) failed (abnormal threshold increase in seven leads; exit block in nine including three atrial leads; insulation break in three) after 10 (3-15) years, and were abandoned. At 13 (6-30) years of age, seven patients received VDD PM, seven VVIR, three DDD, and one patient an epicardial system. Median number of abandoned leads is one (two in two patients). Final cross-sectional area (CSA) of the implanted leads is eight (2-14) mm(2). All the procedures were successfully completed. Follow-up (FU) duration is 4 (1-10) years. All new leads are functioning normally. No tricuspid valve dysfunction or new venous occlusion occurred. Two cases of lead endocarditis occurred after 5 and 10 years of follow-up in patients with two ventricular leads. No specific risk factors for endocarditis were identified. CONCLUSIONS: Abandonment of a nonfunctioning lead is a palliative procedure, technically feasible, with no short-term complication. Two patients experienced late endocarditis of the leads.

Circadian pattern of atrial pacing threshold in the young.

AIM: The aim of this study was to evaluate the circadian variation of atrial pacing threshold in young patients. METHODS AND RESULTS: Atrial Capture Management (ACM) algorithm is a Medtronic EnPulse pacemaker (PM) feature that uses two algorithms: atrioventricular conduction (AVC) (atrial pacing and spontaneous AVC) and atrial chamber reset (ACR) [intrinsic atrial activity with atrioventricular block (AVB)]. For this prospective, non-randomized study, ACM automatically measured and recorded thresholds every 4 h. Data are reported as median (range) or mean +/- SD. In 2004-05, 14 consecutive patients (11 males, 79%), aged 12 years (1 day-24 years) received an EnPulse DDD/R PM for AVB (eight patients, 57%) or sinus node dysfunction. A new pacing system was implanted in eight patients (57%) and a replaced PM in six patients. Epicardial leads were implanted in 10 patients (71%). The follow-up duration is 11 (1-18) months: 9742 threshold measurements were attempted (6328 AVC, 3414 ACR), of which 3797 (39%) were successful (1807 AVC, 29%, 1990 ACR, 58%) in 11 (79%) patients. Three infants had no successful measurements. Measurement success was 42 +/- 34% (AVC 27 +/- 39%, ACR 41 +/- 29%). Higher thresholds were found between 00.00 and 12.00 a.m. and lower between 12.00 and 20.00. CONCLUSION: Young patients show a circadian variability of atrial threshold with higher thresholds between 00.00 and 12.00.

Closed loop stimulation improves ejection fraction in pediatric patients with pacemaker and ventricular dysfunction.

BACKGROUND: The aim of this prospective study was to evaluate the effect of the closed loop stimulation (CLS) on the ejection fraction in pediatric patients, affected by complete atrioventricular block (CAVB) or CAVB and sinus node dysfunction (SND), with a previously implanted pacemaker (PM) and ventricular dysfunction. The role of electrical therapy in the treatment of pediatric patients with congenital atrioventricular (AV) blocks has been shown. Conventional right ventricular pacing seems to affect ventricular function. Up to now, the feasibility and the long-term results of biventricular pacing in pediatric patients were not entirely clear. METHODS: In eight pediatric patients with a previously implanted single or dual chamber PM, ventricular dysfunction, and CAVB or SND and CAVB, a dual chamber PM INOS(2+)-CLS (Biotronik GmbH, Berlin, Germany) was implanted. The effect of the physiological modulation of CLS pacing mode on the ejection fraction was evaluated by Echo-Doppler examination. Measurements were performed before the substitution of the old PM and for up to 2 years of follow-up. RESULTS: All patients showed correct electrical parameters at implantation and during follow-up. The mean value of the ejection fraction measured before the replacement of the old PM was 36 +/- 7%, while after 2 years it was 47 +/- 1% (P < 0.003). No patient showed any worsening of the ejection fraction, while only one showed no improvement. CONCLUSIONS: DDD-CLS pacing seems to improve ventricular function in pediatric patients with CAVB and/SND in spite of the use of the apical right conventional stimulation.

Upgrading of VVIR pacemakers with nonfunctional endocardial ventricular leads to VDD pacemakers in adolescents.

BACKGROUND: In some children with ventricular rate responsive demand (VVIR) pacemakers (PM), transvenous leads fail for technical reasons or patient's growth. AIM: The aim of this study is to describe our experience in adolescents with a nonfunctional ventricular lead in whom the lead was abandoned and an additional VDD lead was implanted. Of the 136 children who received a VVIR PM with an endocardial lead in our center, seven patients aged 7 (0.3-12) years [median (range)] at initial implantation, after 10 (5-15) years showed lead malfunction and underwent atrial synchronous ventricular inhibited pacing (VDD) PM upgrading at 16 (10-20) years. RESULTS: The VDD lead was inserted through the ipsilateral subclavian vein in five patients, the contralateral in two (venous occlusion in one and for operator choice in the first patient). The tip was positioned into the right ventricular apex, the atrial dipole along the lateral atrial wall. Fluoroscopy times were not significantly different from those measured in SSI PM implantation and in VVIR dual-chamber demand pacing (VVIR-DDD) upgrading. There were no intraprocedural complications. Follow-up duration is 12 (6-62) months. The VDD PM showed good function, no undersensing or oversensing. Tricuspid damage, new venous occlusion, and "twisting" of the two leads at x-ray were not documented. The first patient showed an infection of the old PM pocket after 1 year, local pain after 3 years, and endocarditis of the leads after 5 years. CONCLUSION: The upgrading of VVIR PM to VDD PM with the abandonment of the nonfunctional lead is feasible, with no intraprocedural complications and good PM function. Lead endocarditis occurred in one patient.

Atrioventricular nodal reentrant tachycardia in children.

The purpose of this study was to identify the clinical and electrophysiological characteristics of children with atrioventricular reentry tachycardia (AVNRT) and to define the prognosis and the treatment strategy. Sixty-two children (28 males and 34 females mean age, 10.2 +/- 3.2 years) with AVNRT ("slow-fast" type) were included in the study. Patients were divided into two groups: 47 patients with severe symptoms (group A) and 15 with mild symptoms (group B). The severity of the symptoms was not related to the electrophysiological parameters. Females were more symptomatic than males. Patients in group B did not receive any treatment (except 1 because of parents' choice) nor did they develop symptoms, and 5 patients had resolution of palpitations. Forty-one of 46 patients in group A were successfully treated with medical therapy as initial treatment. Thirty-one patients in group A underwent slow pathway ablation. There were late recurrences of AVNRT in 6 patients. Typical AVNRT in young patients does not appear to be life threatening. Patients with mild or no symptoms do well without therapy. Medical therapy and slow pathway ablation appear to be effective in the more symptomatic patients. Age and electrophysiological variables are not related to the symptoms or response to treatment. Females with AVNRT are more symptomatic and more likely to present with syncope.

Ventricular capture management in pediatric pacing: efficacy and safety.

BACKGROUND: The Ventricular Capture Management (VCM) of Medtronic Kappa 700 series pacemakers (PM) performs automatic threshold detection and optimization of pacing output that may enhance generator longevity. We evaluated efficacy and safety of this algorithm in children. METHODS: The study was prospective, non-randomized, involving 50 consecutive patients (mean age 5.6 +/- 6.6 years, median 4 years), enrolled at first PM implant. VCM was active from the implant, with nominal values of safety margin, minimum adapted pulse amplitude and width. Leads were endocardial and epicardial, all unipolar. Thresholds and pacing outputs were registered with telemetric PM interrogation. Endocardial and epicardial thresholds and outputs were also compared. Follow-up duration was 27 +/- 13 months (range 6-49 months). RESULTS: A significant reduction in pulse amplitude was evident since the sixth month. Thresholds and outputs were lower in endocardial than in epicardial pacing. A false negative capture detection occurred during the "acute phase" in 3 patients (6.0%), with incorrect automatic output increase to 5 V/1 ms. After this phase, the problem was still detected in 2 patients (4.0%). VCM correctly identified threshold increases in 2 patients (1%). No pacing defect was documented. VCM was not performed in 4 infants (8.0%) for pacing rate > or = 100 b/min. CONCLUSIONS: VCM function is safe and effective in reducing pacing output in pediatric patients; this may increase PM longevity. Epicardial pacing shows higher thresholds and outputs than endocardial pacing.

Transvenous cryothermal catheter ablation of re-entry circuit located near the atrioventricular junction in pediatric patients: efficacy, safety, and midterm follow-up.

OBJECTIVES: We investigated the safety and efficacy of cryoablation in the treatment of pediatric patients with accessory pathways (APs) located near the atrioventricular junction and with atrioventricular nodal re-entrant tachycardia (AVNRT). BACKGROUND: Few studies concern cryoablation in a significant number of pediatric patients involving treatment for supraventricular tachycardias (SVTs) with the reentry circuit located near the atrioventricular junction. METHODS: Twenty-six pediatric patients (age range: 5 to 20 years) were treated; 14 had AVNRT, 10 had Wolff-Parkinson-White syndrome, and 2 had re-entrant SVT due to a concealed AP. Electrophysiologic study was performed with diagnostic catheters, and cryoablations were performed with a 7-F 4-mm-tip catheter (Freezor, CryoCath Technologies Inc., Kirkland, Canada). Cryomapping, used to identify the tissue site for safe arrhythmia ablation, was performed at -30 degrees C for a maximum of 60 s. Cryoablations were from 4 to 8 min long at -75 degrees C. Acute end points were noninducibility of AVNRT by programmed atrial stimulation at baseline or during isoproterenol performed 30 min after procedure, as well as noninducibility and conduction block over the AP. The chronic end point was arrhythmia recurrence after intervention. RESULTS: No permanent cryo-related complications or adverse outcomes were reported. Twenty-four (92%) patients were acutely successful. During follow-up (range: 1 to 22 months), seven (29%) acutely successful pediatric patients experienced arrhythmia recurrence. CONCLUSIONS: Acute results demonstrate cryoablation of SVTs with the reentry circuit located near the atrioventricular junction to be safe and efficacious in pediatric patients. However, the etiology of recurrences reported after intervention need further investigation.