Patterns of Electrocardiographic Abnormalities in Children with Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM), a common cardiomyopathy in children, is an important cause of morbidity and mortality. Early recognition and appropriate management are important. An electrocardiogram (ECG) is often used as a screening tool in children to detect heart disease. The ECG patterns in children with HCM are not well described.ECGs collected from an international cohort of children, and adolescents (≤ 21 years) with HCM were reviewed. 482 ECGs met inclusion criteria. Age ranged from 1 day to 21 years, median 13 years. Of the 482 ECGs, 57 (12%) were normal. The most common abnormalities noted were left ventricular hypertrophy (LVH) in 108/482 (22%) and biventricular hypertrophy (BVH) in 116/482 (24%) Of the patients with LVH/BVH (n = 224), 135 (60%) also had a strain pattern (LVH in 83, BVH in 52). Isolated strain pattern (in the absence of criteria for hypertrophy) was seen in 43/482 (9%). Isolated pathologic Q waves were seen in 71/482 (15%). Pediatric HCM, 88% have an abnormal ECG. The most common ECG abnormalities were LVH or BVH with or without strain. Strain pattern without hypertrophy and a pathologic Q wave were present in a significant proportion (24%) of patients. Thus, a significant number of children with HCM have ECG abnormalities that are not typical for "hypertrophy". The presence of the ECG abnormalities described above in a child should prompt further examination with an echocardiogram to rule out HCM.

Impact of Obesity on Left Ventricular Thickness in Children with Hypertrophic Cardiomyopathy.

Obesity is associated with additional left ventricular hypertrophy (LVH) in adults with hypertrophic cardiomyopathy (HCM). It is not known whether obesity can lead to further LVH in children with HCM. Echocardiographic LV dimensions were determined in 504 children with HCM. Measurements of interventricular septal thickness (IVST) and posterior wall thickness (PWT), and patients' weight and height were recorded. Obesity was defined as a body mass index (BMI) ≥ 99th percentile for age and sex. IVST data was available for 498 and PWT data for 484 patients. Patient age ranged from 2 to 20 years (mean ± SD, 12.5 ± 3.9) and 340 (68%) were males. Overall, patient BMI ranged from 7 to 50 (22.7 ± 6.1). Obesity (BMI 18-50, mean 29.1) was present in 140 children aged 2-19.6 (11.3 ± 4.1). The overall mean IVST was 20.5 ± 9.6 mm and the overall mean PWT was 11.0 ± 8.4 mm. The mean IVST in the obese patients was 21.6 ± 10.0 mm and mean PWT was 13.3 ± 14.7 mm. The mean IVST in the non-obese patients was 20.1 ± 9.5 mm and mean PWT was 10.4 ± 4.3 mm. Obesity was not significantly associated with IVST (p = 0.12), but was associated with increased PWT (0.0011). Obesity is associated with increased PWT but not IVST in children with HCM. Whether obesity and its impact on LVH influences clinical outcomes in children with HCM needs to be studied.

Risk factors for lethal arrhythmic events in children and adolescents with hypertrophic cardiomyopathy and an implantable defibrillator: An international multicenter study.

BACKGROUND: Predictors of risk of lethal arrhythmic events (LAE) is poorly understood and may differ from adults in children with hypertrophic cardiomyopathy (HCM). OBJECTIVE: The purpose of this study was to determine predictors of LAE in children with HCM. METHODS: A retrospective data collection was performed on 446 children and teenagers 20 years and younger (290 [65%] male; mean age 10.1 ± 5.7 years) with idiopathic HCM from 35 centers. Patients were classified as group 1 (HCM with LAE) if having a secondary prevention implantable cardioverter-defibrillator (ICD) or primary prevention ICD with appropriate interventions or group 2 (HCM without LAE) if having a primary prevention ICD without appropriate interventions. RESULTS: There were 152 children (34%) in group 1 and 294 (66%) in group 2. Risk factors for group 1 by univariate analysis were septal thickness, posterior left ventricular (LV) wall thickness, lower LV outflow gradient, and Q wave > 3 mm in inferior electrocardiographic leads. Factors not associated with LAE were family history of SCD, abnormal blood pressure response to exercise, and ventricular tachycardia on ambulatory electrocardiographic monitoring. Risk factors for SCD by multivariate analysis were age at ICD placement (hazard ratio [HR] 0.9; P = .0025), LV posterior wall thickness z score (HR 1.02; P < .005), and LV outflow gradient < 30 mm Hg (HR 2.0; P < .006). LV posterior wall thickness z score ≥ 5 was associated with LAE. CONCLUSION: Risk factors for LAE appear different in children compared to adults. Conventional adult risk factors were not significant in children. Further prospective studies are needed to improve risk stratification for LAE in children with HCM.

Insights on Atrial Fibrillation in Congenital Heart Disease.

Patients with congenital heart disease (CHD) have been surviving late into adulthood, with atrial arrhythmias being the most common long-term complication. In recent reports, atrial fibrillation (AF) tended to be the most common form of arrhythmias among groups of patients with adult CHD (ACHD) older than 50 years of age. When compared with their adult counterparts without CHD, AF in patients with ACHD has been characterized by a higher incidence and prevalence, younger age of onset, and a greater risk of progression to persistent AF. Risk factors for the development of AF are not well known but include older age, left atrial dilation, systemic hypertension, and multiple cardiac surgeries. Data on management options such as optimal antiarrhythmic drug therapy, indications for anticoagulation, and efficacy and safety of catheter ablation are limited. There is a crucial need for further research exploring management, prevention, and monitoring strategies for the growing ACHD patient population with AF. This report will provide a contemporary review of the epidemiology, pathophysiology, and management options for AF in this complex patient population.

Current management of focal atrial tachycardia in children: a multicenter experience.

BACKGROUND: Focal atrial tachycardia (FAT) is an uncommon cause of supraventricular tachycardia in children. Incessant FAT can lead to tachycardia-induced cardiomyopathy. There is limited information regarding the clinical course and management of FAT. This study characterizes current management strategies for FAT in children including the prevalence of spontaneous resolution and the role of catheter ablation. METHODS AND RESULTS: This is a retrospective chart review of pediatric patients with FAT managed between January 2000 and November 2010 at 10 pediatric centers. There were 249 patients with a median age at diagnosis of 7.2 (95% confidence interval, 5.8-10.4) years. Cardiomyopathy was observed in 28%. Resolution of FAT occurred in 89%, including spontaneous resolution without catheter ablation in 34%. Antiarrhythmic medications were used for initial therapy in 154 patients with control of FAT in 72%. Among first-line medications, ß-blockers were the most common (53%) and effective (42%). Catheter ablation was successful in 80% of patients. FAT recurrence was less common with electroanatomic mapping compared with conventional mapping techniques (16% versus 35%; P=0.02). Patients were followed for a median of 2.1 (95% confidence interval, 1.8-2.6) years. CONCLUSIONS: FAT is managed successfully in most children. Current approaches are variable. Many patients have control of FAT with medications; however, catheter ablation is used for most patients. Spontaneous resolution is common for young children, emphasizing the role for delayed ablation in this group. Ablation is successful for all ages. Lower recurrence occurs when electroanatomic mapping techniques are used.

Permanent junctional reciprocating tachycardia in children: a multicenter experience.

BACKGROUND: Permanent junctional reciprocating tachycardia (PJRT) is an uncommon form of supraventricular tachycardia in children. Treatment of this arrhythmia has been considered difficult because of a high medication failure rate and risk of cardiomyopathy. Outcomes in the current era of interventional treatment with catheter ablation have not been published. OBJECTIVE: To describe the presentation and clinical course of PJRT in children. METHODS: This is a retrospective review of 194 pediatric patients with PJRT managed at 11 institutions between January 2000 and December 2010. RESULTS: The median age at diagnosis was 3.2 months, including 110 infants (57%; aged <1 year). PJRT was incessant in 47%. The ratio of RP interval to cycle length was higher with incessant than with nonincessant tachycardia. Tachycardia-induced cardiomyopathy was observed in 18%. Antiarrhythmic medications were used for initial management in 76%, while catheter ablation was used initially in only 10%. Medications achieved complete resolution in 23% with clinical benefit in an additional 47%. Overall, 140 patients underwent 175 catheter ablation procedures with a success rate of 90%. There were complications in 9% with no major complications reported. Patients were followed for a median of 45.1 months. Regardless of treatment modality, normal sinus rhythm was present in 90% at last follow-up. Spontaneous resolution occurred in 12% of the patients. CONCLUSION: PJRT in children is frequently incessant at the time of diagnosis and may be associated with tachycardia-induced cardiomyopathy. Antiarrhythmic medications result in complete control in few patients. Catheter ablation is effective, and serious complications are rare.

Lone atrial fibrillation in the pediatric population.

BACKGROUND: There are few reports of pediatric studies of atrial fibrillation (AF). We sought to describe the clinical characteristics, management strategies, and recurrence rates and to identify predictors of AF recurrence in a contemporary pediatric population. METHODS: A retrospective review was performed of patients ≤ 18 years with lone AF who were seen at 4 pediatric institutions from 1996-2011. Patients with AF in the setting of thyroid disease, ventricular pre-excitation, coexisting congenital heart disease, or a history of cardiac surgery were excluded. Demographics, clinical presentation, investigations, treatment, and follow-up were analyzed. RESULTS: Forty-two patients were diagnosed with a first episode of lone AF, and 4 of these cases were later classified as persistent AF. Thirty-one (74%) were male patients, median age was 15.3 years, and median (interquartile range [IQR]) duration of AF episode was 12 (IQR, 7-24) hours. AF recurred in 39% (15 of 38) of patients. The Kaplan-Meier median time to estimated recurrence was 19 months. By univariate analysis, initial AF episode duration was associated with a higher risk of recurrence (hazard ratio [HR], 1.01; 95% confidence interval [CI], 1-1.02; P = 0.034). Sex, age, family history, size of the left atrium, and history of cardioversion were not associated with recurrence. Recurrence with another supraventricular tachyarrhythmia (SVT) was observed in 6 of 38 (16%) patients, and 12 patients underwent electrophysiology (EP) study, with 6 patients receiving ablation. CONCLUSIONS: Our reported rate of recurrence of 39% is important when counseling pediatric patients and their parents on the expected course and treatment goals.

Efficacy of implantable cardioverter defibrillators in young patients with catecholaminergic polymorphic ventricular tachycardia: success depends on substrate.

BACKGROUND: The effectiveness of implantable cardioverter-defibrillator (ICD) therapy for the management of catecholaminergic polymorphic ventricular tachycardia (VT) in young patients is not known. ICD discharges are not always effective and inappropriate discharges are common, both resulting in morbidity and mortality. METHODS AND RESULTS: This is a multicenter, retrospective review of young patients with catecholaminergic polymorphic VT and ICDs from 5 centers. ICD discharges were evaluated to determine arrhythmia mechanism, appropriateness, efficacy of therapy, and complications. A total of 24 patients were included. Median (interquartile range) ages at onset of catecholaminergic polymorphic VT symptoms and ICD implant were 10.6 (5.0-13.8) years and 13.7 (10.7-16.3) years, respectively. Fourteen patients received 140 shocks. Ten patients (42%) experienced 75 appropriate shocks and 11 patients (46%) received 65 inappropriate shocks. On actuarial analysis, freedom from appropriate shock at 1 year after ICD implant was 75%. Of appropriate shocks, only 43 (57%) demonstrated successful primary termination. All successful appropriate ICD discharges were for ventricular fibrillation. No episodes of polymorphic VT or bidirectional VT demonstrated successful primary termination. The adjusted mean (95% confidence interval) cycle length of successful discharges was significantly shorter than unsuccessful discharges (168 [152-184] ms versus 245 [229-262] ms; adjusted P=0.002). Electrical storm occurred in 29% (4/14) and induction of more malignant ventricular arrhythmias in 36% (5/14). There were no deaths. CONCLUSIONS: ICD efficacy in catecholaminergic polymorphic VT depends on arrhythmia mechanism. Episodes of ventricular fibrillation were uniformly successfully treated, whereas polymorphic and bidirectional VT did not demonstrate successful primary termination. Inappropriate shocks, electrical storm, and ICD complications were common.

Dynamic changes of myocardial oxygen consumption at pacing increased heart rate - the first observation by the continuous measurement of systemic oxygen consumption.

OBJECTIVES: To assess dynamic changes in myocardial oxygen consumption (myoVO(2)) during atrial pacing increased heart rate by continuous measurement of systemic oxygen consumption (sysVO(2)). METHODS: Six mechanically ventilated pigs were atrially paced to increase heart rate from baseline 98 ± 9 to 120-140-160-180 bpm for 10 minutes at each stage, with 10 minute intervals without pacing between stages. sysVO(2) was continuously measured with a respiratory mass spectrometer. Left anterior descending coronary arterial flow, aorta and coronary sinus blood gases were measured to calculate index of whole heart myoVO(2). RESULTS: sysVO(2) peaked at the initiation of pacing in the first two to three minutes, followed by a decrease and subsequent stabilization. As heart rate increased, sysVO(2) increased by 0.08 ± 0.06 ml/kg/min, 0.14 ± 0.05 ml/kg/min and 0.17 ± 0.10 ml/kg/min, representing a 1.2 ± 0.9%, 2.1 ± 0.7% and 3.0 ± 1.8% increase of sysVO(2) respectively; myoVO(2) increased by 0.16 ± 0.12 to 0.31 ± 0.14 to 0.36 ± 0.24 ml/100 g/min, representing a 11 ± 9%, 21 ± 9% and 26 ± 12% increase of myoVO(2), respectively. The absolute and relative increases in sysVO(2) were significantly correlated with the increases in myoVO(2). CONCLUSIONS: On-line continuous sysVO(2) monitoring by respiratory mass spectrometry allows non-invasive assessments of dynamic changes in myoVO(2) in vivo. The mechanism for the peaked increase in sysVO(2) at the initiation of pacing remains to be explored.

Short- and long-term outcomes in children undergoing radiofrequency catheter ablation before their second birthday.

BACKGROUND: Tachyarrhythmias can cause substantial morbidity and mortality in infants and very young children. Our objective was to assess early and late outcomes in children undergoing radiofrequency catheter ablation before their second birthday. METHODS: This is a retrospective review of medical records from 1995 till 2009 at a single institution with a large referral base. RESULTS: Thirty-four children younger than 2 years of age were brought to the electrophysiology laboratory for catheter ablation for tachyarrhythmia. Radiofrequency ablation (42 procedures) was performed in 31 children (mean weight, 7.4 kg; range, 2.6-12.3 kg). Tachyarrhythmias were atrioventricular re-entry tachycardia (19), ectopic or multifocal atrial tachycardia (6), atrial flutter (1), ventricular tachycardia (3), and congenital junctional ectopic tachycardia (2). Seventeen children presented with tachycardia-induced cardiomyopathy and heart failure. Three patients required extracorporeal life support prior to the procedure. Radiofrequency catheter ablation was successful in 74% of these very young children vs 91% in a comparison group of children older than 2 years (n = 447). Among patients with initially successful ablations, there was no tachyarrhythmia recurrence during medium- to long-term follow-up (1.4-15.0 years; mean, 7.3 years). Major complications occurred in 4 very young children. Eight of 11 patients in whom ablation failed or could not be done required another form of continued aggressive treatment. CONCLUSION: Catheter ablation is indicated and successful in critically ill infants with life-threatening tachyarrhythmia refractory to medical therapy. Initially successful procedures are associated with excellent long-term outcomes, but significant complication rates require that such procedures be reserved for carefully selected patients and performed by highly skilled staff.

Atrio-ventricular conduction following radiofrequency ablation for atrio-ventricular node reentry tachycardia in children.

AIMS: The study was designed to assess atrio-ventricular (AV) conduction with non-invasive methods at least 1 year after radiofrequency ablation (RFA) of the slow pathway for AV node reentry tachycardia. METHODS AND RESULTS: Medical records of all patients who underwent RFA before their 18th birthday were reviewed. Patients were brought back for clinical evaluation, an electrocardiogram, an exercise stress test, and ambulatory Holter monitoring. Radiofrequency ablation of the slow pathway above the ostium of the coronary sinus was done in 106 children. No procedure resulted in high degree AV block. Follow-up evaluation was possible in 67 patients (63% of the total cohort) who were brought back to the clinic 1-13.7 years, mean 4.7+/-3.0 years after the procedure. Dizzy spells were reported by 36% of examined patients and 2 patients reported syncope. PR intervals were normal in all but two patients when compared with published normal values. One patient presented with persistent, post-procedural first-degree AV block and another developed new onset, symptomatic second degree AV block 2 years after the procedure and required pacemaker implantation. CONCLUSION: Non-invasive testing showed normal PR intervals in a cohort of patients who underwent RFA of the slow pathway in childhood or adolescence. Late AV block occurred in one child. Clinical evaluation more than a year after the procedure is warranted in symptomatic patients.

Torsades de Pointes ventricular tachycardia in a pediatric patient treated with fluconazole.

Fluconazole is an antifungal medication that has been reported to cause prolongation of the QT interval and Torsades de Pointes (TdP) ventricular tachycardia in adults. We describe the case of an 11-year-old child treated with fluconazole who developed ventricular arrhythmia culminating in TdP. We discuss the possible roles played by genetic and environmental factors in this child's rhythm disturbances. After briefly summarizing similar cases from the adult literature, we outline the putative mechanism by which fluconazole may cause arrhythmia. This case should alert pediatricians to the possible risks of fluconazole use, especially in the presence of electrolyte abnormalities, diuretic use, therapy with other pro-arrhythmic agents, or suspicion of congenital Long-QT Syndrome.

Direct intracardiac placement of an automatic implantable cardioverter defibrillator coil lead in a small child.

A 3.5-year-old child with hypertrophic obstructive cardiomyopathy and recurrent syncope underwent surgical left-ventricular outflow tract myectomy and implantation of a single-chamber automatic cardioverter defibrillator. A single-coil active fixation lead was introduced via a purse-string suture in the right atrial appendage and the lead tip positioned and fixed in the right-ventricular apex under direct visualization via a small right atriotomy incision. Described configuration may be considered in small children undergoing intracardiac surgery at the time of defibrillator implantation.

Right ventricular outflow tract tachycardia in children.

OBJECTIVE: To assess the clinical spectrum of right ventricular outflow tract tachycardia and its management in children. STUDY DESIGN: Five centers identified patients for retrospective review. Patients (age <18 years) demonstrating ventricular tachycardia with an inferior axis and left bundle branch block were included. Patients with structural heart disease, myocarditis, cardiomyopathy, or long QT syndrome were excluded. Demographics, clinical presentation, investigations, and treatment were analyzed. Holter data were used to quantify ectopy. RESULTS: Patients (n = 48) were referred for evaluation of incidental findings (39/48), near syncope or syncope (7/48), or other (2/48). Investigations included magnetic resonance imaging (51%), endomyocardial biopsy (25%), and angiography (23%). Medical treatment was initiated in 26 of the 48 patients. The most common indications for treatment were frequent ectopy and symptoms. Medical treatment (P <.007) and observation alone (P <.02) were both associated with a reduction in ectopy. Symptoms persisted in 3 of 13 patients who were treated medically and in all untreated patients. At follow-up, there were no deaths and no difference in ectopy (P <.46) between patients who were treated medically and patients who were observed. Ablation was attempted in 6 of the 48 patients (successful in 4/6). CONCLUSION: The clinical spectrum and management of right ventricular outflow tract tachycardia in children are diverse. Both medical therapy and observation alone were associated with a reduction in ectopy.

The significance of cardiac surgery scars in adult patients with congenital heart disease.

BACKGROUND: Scars resulting from heart surgery mark patients for life, yet their effect on patients' well-being is unknown. AIM: To determine what spheres of life may be affected by surgical chest scarring. METHODS: A preliminary questionnaire asked 10 random patients at our adult congenital heart disease clinic to describe personal consequences (if any) of having a cardiac surgery scar. Results provided the basis to design another questionnaire which asked specific questions and attempted to rate the effect of scars on identified areas of concern. RESULTS: One hundred consecutive patients attending the clinic (53 males) aged 18 to 50 (mean 27 years) participated. Sixty percent reported that the scar affected them less now than in adolescence. The body was perceived as disfigured by 58%. The scar was concealed by 48% of patients. Attention to the scar made 19% of patients feel negative, 58% neutral and 23% positive. Chest scarring was associated with decreased self-esteem in 20% and decreased self-confidence in 18% of patients. Patients reported less effect of chest scarring on their choice of career, success in life, friendships, sexual relationships and choice of recreation. Sixty-one percent reported a positive effect on appreciation of health. CONCLUSION: Scars resulting from heart surgery may have a considerable effect on patients' body image and several aspects of everyday life.

Supraventricular tachycardia in children.

Several different mechanisms are responsible for paroxysmal supraventricular tachycardia in children. Different forms of tachycardia occur at different age. Atrio-ventricular reentry tachycardia results from the presence of congenital atrio-ventricular bypass tracts and is frequently encountered at all ages. Infants may present with ectopic atrial tachycardia or atrial flutter. Atrio-ventricular node reentry tachycardia becomes more frequent in adolescence. Atrial scarring resulting from open heart surgery predisposes to complex intra-atrial reentry. Certain forms of congenital and acquired heart disease are associated with specific types of arrhythmia. Many children with paroxysmal supraventricular tachycardia do not require any therapy. The decision to proceed with treatment should be based on the frequency and severity of symptoms and on the effect of arrhythmia on the quality of life. Infants require medical treatment because of the difficulty to recognize symptoms of tachycardia and a risk of heart failure. Patients with Wolff-Parkinson-White syndrome as well as those with significant heart disease are at risk of sudden death. Syncope in children with paroxysmal tachycardia may indicate a severe fall in cardiac output from extremely rapid heart rate. Patients with potentially life-threatening arrhythmia should not participate in competitive physical activities. Treatment options have undergone significant evolution over the past decade. Indications for the use of specific antiarrhythmic medications have been refined. Contemporary catheter ablation procedures employ different forms of energy allowing for safe and effective procedures. Catheter ablation is the treatment of choice for symptomatic paroxysmal tachycardia in school children and in some infants who failed medical treatment. Surgery is the preferred treatment in few selected cases. The goal of this review is to present the state of the art approach to the diagnosis and management of paroxysmal supraventricular tachycardia in infants, children and adolescents.

How much do parents know about their children's heart condition and prophylaxis against endocarditis?

BACKGROUND: Caregivers are frequently expected to serve as a conduit for information between heath care providers; however, few previous studies showed inadequate parental knowledge about their children's heart disease. OBJECTIVES: To assess parental knowledge regarding their children's congenital heart disease, risk of bacterial endocarditis (BE) and requirement for BE prophylaxis. METHODS: Parents of 65 consecutive children with heart disease, aged from two months to 16 years, were asked to complete a survey while awaiting their ambulatory appointment. RESULTS: On average, patients had been seen by 1.7 cardiologists and had attended 7.8 clinic appointments before the study, with 55% having undergone heart surgery and 18% currently taking cardiac medications. In general, caregivers felt they had received full explanation of their child's condition (89%) and were informed sufficiently about ongoing care (91%), yet only 71% knew the specific name of their child's heart defect, with 65% being able to correctly explain the condition in layman's terms. Of the 55 children whose heart defects fulfilled risk criteria for BE, only 47% of their parents declared to have ever heard of the disease, with just 25% able to correctly define it. Although 71% of the children's parents knew that special medication was required when seeing a dentist, only 29% were aware of any other situations when they would also require it. As many as 27% of the children who required BE prophylaxis had had significant dental problems in the past, including root canals, extracted teeth, braces, caps and gingivitis. CONCLUSION: Many parents are not familiar with their child's heart disease and do not understand the risks of BE or the need for BE prophylaxis. Results of this study and several other queries published over the past 20 years point to the need for continuous education of patients and their parents by physicians, nurses and allied health care providers.

A pacemaker for asystole in breath-holding spells.

Two cases of young children with frequent severe breath-holding spells complicated by prolonged asystole and seizures are reported. A ventricular pacemaker was implanted in each child, and both have subsequently remained free of syncope, although they continue to exhibit breath-holding behaviour.