Martin J. LaPage

Multi-Institutional Study of Implantable Defibrillator Lead Performance in Children and Young Adults Results of the Pediatric Lead Extractability and Survival Evaluation (PLEASE) Study

Background— Implantable cardioverter-defibrillator (ICD) therapy in children and congenital heart disease patients is hampered by poor long-term lead survival. Lead extraction is technically difficult and carries substantial morbidity. We sought to determine the outcomes of ICD leads in pediatric and congenital heart disease patients. Methods and Results— The Pediatric Lead Extractability and Survival Evaluation (PLEASE) is a 24-center international registry. Pediatric and congenital heart disease patients with ICD lead implantations from 2005 to 2010 were eligible. Study subjects comprised 878 ICD patients (44% congenital heart disease). Mean±SD age at implantation was 18.6±9.8 years. Of the 965 total leads, 54% were thin (⩽7F), of which 57% were Fidelis, and 23% were coated with expanded polytetrafluoroethylene. There were 139 ICD lead failures (14%) in 132 patients (15%) at a mean lead age of 2.0±1.4 years, causing shocks in 53 patients (40%). Independent predictors of lead failure included younger implantation age and Fidelis leads. Actuarial analysis showed an incremental risk of lead failure with younger age at implantation: <8 years compared with >18 years (P=0.015). The actuarial yearly failure rate was 2.3% for non-Fidelis and 9.1% for Fidelis leads. Extraction was performed on 143 leads (80% thin, 7% expanded polytetrafluoroethylene coated), with lead age as the only independent predictor for advanced extraction techniques. There were 6 major extraction complications (4%) but no procedural mortality. Conclusions— This study demonstrates that ICD leads in children and congenital heart disease patients have an age-related suboptimal performance, further compounded by a high failure rate of Fidelis leads. Advanced extraction techniques were common and correlated with older lead age. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00335036.Background— Implantable cardioverter-defibrillator (ICD) therapy in children and congenital heart disease patients is hampered by poor long-term lead survival. Lead extraction is technically difficult and carries substantial morbidity. We sought to determine the outcomes of ICD leads in pediatric and congenital heart disease patients. Methods and Results— The Pediatric Lead Extractability and Survival Evaluation (PLEASE) is a 24-center international registry. Pediatric and congenital heart disease patients with ICD lead implantations from 2005 to 2010 were eligible. Study subjects comprised 878 ICD patients (44% congenital heart disease). Mean±SD age at implantation was 18.6±9.8 years. Of the 965 total leads, 54% were thin (≤7F), of which 57% were Fidelis, and 23% were coated with expanded polytetrafluoroethylene. There were 139 ICD lead failures (14%) in 132 patients (15%) at a mean lead age of 2.0±1.4 years, causing shocks in 53 patients (40%). Independent predictors of lead failure included younger implantation age and Fidelis leads. Actuarial analysis showed an incremental risk of lead failure with younger age at implantation: 18 years ( P =0.015). The actuarial yearly failure rate was 2.3% for non-Fidelis and 9.1% for Fidelis leads. Extraction was performed on 143 leads (80% thin, 7% expanded polytetrafluoroethylene coated), with lead age as the only independent predictor for advanced extraction techniques. There were 6 major extraction complications (4%) but no procedural mortality. Conclusions— This study demonstrates that ICD leads in children and congenital heart disease patients have an age-related suboptimal performance, further compounded by a high failure rate of Fidelis leads. Advanced extraction techniques were common and correlated with older lead age. Clinical Trial Registration— URL: . Unique identifier: [NCT00335036][1]. # Clinical Perspective {#article-title-15} [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00335036&atom=%2Fcirculationaha%2F127%2F24%2F2393.atom

Catecholaminergic Polymorphic Ventricular Tachycardia in Children Analysis of Therapeutic Strategies and Outcomes From an International Multicenter Registry

Background—Catecholaminergic polymorphic ventricular tachycardia is an uncommon, potentially lethal, ion channelopathy. Standard therapies have high failure rates and little is known about treatment in children. Newer options such as flecainide and left cardiac sympathetic denervation are not well validated. We sought to define treatment outcomes in children with catecholaminergic polymorphic ventricular tachycardia. Methods and Results—This is a Pediatric and Congenital Electrophysiology Society multicenter, retrospective cohort study of catecholaminergic polymorphic ventricular tachycardia patients diagnosed before 19 years of age. The cohort included 226 patients, including 170 probands and 56 relatives. Symptomatic presentation was reported in 176 (78%). Symptom onset occurred at 10.8 (interquartile range, 6.8–13.2) years with a delay to diagnosis of 0.5 (0–2.6) years. Syncope (P<0.001), cardiac arrest (P<0.001), and treatment failure (P=0.008) occurred more often in probands. &bgr;-Blockers were prescribed in 205 of 211 patients (97%) on medication, and 25% experienced at least 1 treatment failure event. Implantable cardioverter defibrillators were placed in 121 (54%) and was associated with electrical storm in 22 (18%). Flecainide was used in 24% and left cardiac sympathetic denervation in 8%. Six deaths (3%) occurred during a cumulative follow-up of 788 patient-years. Conclusions—This study demonstrates a malignant phenotype and lengthy delay to diagnosis in catecholaminergic polymorphic ventricular tachycardia. Probands were typically severely affected. &bgr;-Blockers were almost universally initiated; however, treatment failure, noncompliance and subtherapeutic dosing were often reported. Implantable cardioverter defibrillators were common despite numerous device-related complications. Treatment failure was rare in the quarter of patients on flecainide. Left cardiac sympathetic denervation was not uncommon although the indication was variable.

Heterogeneity of genetic modifiers ensures normal cardiac development

Background— Mutations of the transcription factor Nkx2-5 cause pleiotropic heart defects with incomplete penetrance. This variability suggests that additional factors can affect or prevent the mutant phenotype. We assess here the role of genetic modifiers and their interactions. Methods and Results— Heterozygous Nkx2-5 knockout mice in the inbred strain background C57Bl/6 frequently have atrial and ventricular septal defects. The incidences are substantially reduced in the Nkx2-5+/− progeny of first-generation (F1) outcrosses to the strains FVB/N or A/J. Defects recur in the second generation (F2) of the F1×F1 intercross or backcrosses to the parental strains. Analysis of >3000 Nkx2-5+/− hearts from 5 F2 crosses demonstrates the profound influence of genetic modifiers on disease presentation. On the basis of their incidences and coincidences, anatomically distinct malformations have shared and unique modifiers. All 3 strains carry susceptibility alleles at different loci for atrial and ventricular septal defects. Relative to the other 2 strains, A/J carries polymorphisms that confer greater susceptibility to atrial septal defect and atrioventricular septal defects and C57Bl/6 to muscular ventricular septal defects. Segregation analyses reveal that ≥2 loci influence membranous ventricular septal defect susceptibility, whereas ≥2 loci and at least 1 epistatic interaction affect muscular ventricular and atrial septal defects. Conclusions— Alleles of modifier genes can either buffer perturbations on cardiac development or direct the manifestation of a defect. In a genetically heterogeneous population, the predominant effect of modifier genes is health.

Safety and Results of Cryoablation in Patients <5 Years Old and/or <15 Kilograms

Current recommendations discourage elective radiofrequency ablation in patients <5 years old and/or weighing <15 kg, primarily because of the greater complication rate. To describe the current use, complications, and immediate outcomes of cryoablation in this patient population, a multicenter retrospective review of all patients <5 years old and/or weighing <15 kg who were treated with cryoablation for arrhythmia was performed. Eleven centers contributed data for 68 procedures on 61 patients. Of those, 34% were elective and 24% (n = 16) were both cryoablation and radiofrequency ablation. The median age and weight at ablation was 3.5 years (range 8 days to 9.9 years) and 15.2 kg (range 2.3 to 23), respectively. Congenital heart disease was present in 23% of the patients. The immediate success rate of cryoablation alone was 74%. No major complications occurred with cryoablation only; however, 2 of the 16 patients who underwent cryoablation and radiofrequency ablation had major complications. Of the 50 patients receiving cryoablation, 8 (16%) had variable degrees of transient atrioventricular block. The recurrence rate was 20% after cryoablation and 30% after cryoablation plus radiofrequency ablation. In conclusion, cryoablation appears to have a high safety profile in these patients. Compared to older and larger patients, the efficacy of cryoablation in this small, young population was lower and the recurrence rates were higher. Cryoablations effect on the coronary arteries has not been fully elucidated and requires additional research.

Update on rhythm mapping and catheter navigation

Purpose of review Rhythm mapping in electrophysiology is a critical step in the catheter ablation of arrhythmia substrates. The past decade has seen major advances in the technology used by electrophysiologists to visualize and treat arrhythmias. This review will summarize the most recent developments in three-dimensional electroanatomic mapping and in catheter navigation. Recent findings Three-dimensional contact and noncontact mapping systems have a proven efficacy in multiple clinical studies. Advances in technology have led to the integration of imaging and mapping to produce an increasingly realistic representation of arrhythmias. These systems have been used both to improve success in the treatment of arrhythmias and to enhance our understanding of cardiac electroanatomy and electrophysiology. Additionally, remote catheter mapping technology, although not widely used in pediatrics, may be an important tool to decrease procedural risks to both the patient and physician. Summary Technological developments have occurred rapidly over the past several years. Three-dimensional electroanatomic mapping has proven to be a key tool for the success of complex arrhythmia ablations, especially in patients with congenital heart disease. The integration of imaging technology and arrhythmia mapping technology has greatly enhanced the understanding and visualization of arrhythmias. Remote catheter navigation may become an important tool to improve safety.

Verapamil in infants: An exaggerated fear?

The use of intravenous verapamil for tachyarrhythmia in infants is widely considered contraindicated due to the perceived risk of hemodynamic collapse after administration. This article reviews the relatively limited evidence that led to this well-known contraindication and highlights the interesting process by which medical practice may evolve in the absence of persuasive science.

Cardiac implantable electronic device remote monitoring surveillance in pediatric and congenital heart disease: Utility relative to frequency

BACKGROUND Heart Rhythm Society expert consensus provides recommendations for surveillance monitoring of cardiac implantable electronic devices (CIEDs), but limited data are available for the pediatric and congenital heart disease population. OBJECTIVE The purpose of this study was to determine the rate of actionable events during CIED surveillance in this population, assess the utility of routine CIED remote monitoring, and assess the potential benefit from more frequent monitoring. METHODS This was a retrospective cohort study of all CIED patients followed at a pediatric and congenital heart center and enrolled in the Medtronic Carelink system with either (1) a chronic (implanted for >6 months) CIED followed between July 1, 2010, and July 1, 2012, on a bimonthly schedule; or (2) a new CIED (implanted <6 months) between July 1, 2008, and July 1, 2012, followed on a monthly schedule. RESULTS Aggregate mean age was 20 ± 13.7 years. There were 608 interrogations on newly implanted CIEDs with an actionable event rate of 11 per 100 patient-years. There were 2614 interrogations of chronic CIEDs with an actionable event rate of 22 per 100 patient-years. The odds of an actionable event on an asymptomatic remote monitoring transmission was lower than if symptomatic (odds ratio 0.04, 95% confidence interval 0.03-0.07). Tachyarrhythmia was the most common event. Predictors of actionable events were identified. CONCLUSION In this population of pediatric and congenital heart disease patients, the rate of actionable events was low, especially on asymptomatic interrogations. Most actionable events were due to tachyarrhythmia. A more frequent than every 90-day monitoring schedule does not appear to be of significant benefit.

Utility of intrathoracic impedance monitoring in pediatric and congenital heart disease.

The utility of cardiac device‐based intrathoracic monitoring (OptiVol, Medtronic Inc., Minneapolis, MN, USA) for congestive heart failure (CHF) exacerbation has not been evaluated in pediatric or congenital heart disease patients.

Novel Ryanodine Receptor 2 Mutation Associated with a Severe Phenotype of Catecholaminergic Polymorphic Ventricular Tachycardia

An adolescent girl with a history of anxiety associated seizure-like episodes was ultimately diagnosed with catecholaminergic polymorphic ventricular tachycardia. She tested positive for a novel mutation of the ryanodine receptor. The report underscores how genetic arrhythmia syndromes may be mistaken for neurologic disorders.

Development and impact of arrhythmias after the Norwood procedure: A report from the Pediatric Heart Network

Objectives: The study objective was to determine the predictors of new‐onset arrhythmia among infants with single‐ventricle anomalies during the post‐Norwood hospitalization and the association of those arrhythmias with postoperative outcomes (ventilator time and length of stay) and interstage mortality. Methods: After excluding patients with preoperative arrhythmias, we used data from the Pediatric Heart Network Single Ventricle Reconstruction Trial to identify risk factors for tachyarrhythmias (atrial fibrillation, atrial flutter, supraventricular tachycardia, junctional ectopic tachycardia, and ventricular tachycardia) and atrioventricular block (second or third degree) among 544 eligible patients. We then determined the association of arrhythmia with outcomes during the post‐Norwood hospitalization and interstage period, adjusting for identified risk factors and previously published factors. Results: Tachyarrhythmias were noted in 20% of subjects, and atrioventricular block was noted in 4% of subjects. Potentially significant risk factors for tachyarrhythmia included the presence of modified Blalock–Taussig shunt (P = .08) and age at Norwood (P = .07, with risk decreasing each day at age 8‐20 days); the only significant risk factor for atrioventricular block was undergoing a concomitant procedure at the time of the Norwood (P = .001), with the greatest risk being in those undergoing a tricuspid valve procedure. Both tachyarrhythmias and atrioventricular block were associated with longer ventilation time and length of stay (P < .001 for all analyses). Tachyarrhythmias were not associated with interstage mortality; atrioventricular block was associated with mortality among those without a pacemaker in the unadjusted analysis (hazard ratio, 2.3; P = .02), but not after adding covariates. Conclusions: Tachyarrhythmias are common after the Norwood procedure, but atrioventricular block may portend a greater risk for interstage mortality.