Supraventricular tachycardia mechanisms and their age distribution in pediatric patients

Keeping It "Current": A Review of Treatment Options for the Management of Supraventricular Tachycardia

OBJECTIVE

To review treatment options and updates that exist for the management of paroxysmal supraventricular tachycardia (PSVT).

DATA SOURCES

A literature search of PubMed was performed including articles from 1974 to June 2023 using the terms: arrhythmias, adenosine, verapamil, diltiazem, esmolol, propranolol, metoprolol, beta-blockers, amiodarone, PSVT, synchronized cardioversion, methylxanthines, dipyridamole, pediatrics, heart transplant, and pregnancy. Primary literature and guidelines were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Studies were considered if they were available in English and conducted in humans.

DATA SYNTHESIS

PSVT is a subset of supraventricular tachycardia (SVT) that presents as a rapid, regular tachycardia with an abrupt onset and termination. Due to frequent emergency department (ED) visits annually with symptoms of PSVT, appropriate and efficient management of these patients is vital. This review provides an overview of the pathophysiology of PSVT, while also describing the literature behind nonpharmacologic and pharmacologic management of PSVT.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review describes new literature regarding the improved success of the modified Valsalva maneuver as a nonpharmacologic therapy in PSVT. In addition, it describes a new technique in administration of adenosine that has improved outcomes, defines dose adjustments needed for drug interactions with adenosine, compares the utilization of nondihydropyridine calcium channel blockers with adenosine, and provides management recommendations for patients in special populations.

CONCLUSIONS

With high annual rates of ED visits for SVT, providers should be aware of the data behind management and modifications of therapy based on patient-specific factors (ie, patient preference, pharmacokinetics/pharmacodynamics, drug interactions, and special populations).

Outcomes of Infant Supraventricular Tachycardia Management Without Medication

Most infants presenting with supraventricular tachycardia (SVT) are treated with an antiarrhythmic, primarily to prevent unrecognized future episodes that could lead to tachycardia-induced cardiomyopathy. A common practice at our institution is to not treat after the first presentation of infant SVT and instead educate parents on heart rate monitoring and reasons to present to care. The goal of this study was to evaluate the outcomes of non-pharmacologic treatment of infant SVT at first presentation and compare to outcomes of infants treated with an antiarrhythmic. This was a retrospective single center study of all infants presenting with a first episode of SVT from 2014 to 2021. Excluded were patients with a non-reentry type tachyarrhythmia, atrial flutter, long-RP tachycardia, congenital heart disease, or abnormal ventricular function. Sixty-four infants were included in the study. Thirty-six were managed without an antiarrhythmic. SVT recurred in 28% of the non-treatment group vs 50% in those treated with antiarrhythmics, p = 0.12. Of the patients admitted to the hospital, those in the non-treatment group had a shorter length of stay, 1(IQR 1-1) vs 3(IQR 2-4) days, p < 0.01. Non-treated patients were less likely to present to the emergency department for recurrent SVT, 6% vs 32%, p < 0.01. Neither group had a patient develop tachycardia-induced cardiomyopathy. For infants with structurally and functionally normal hearts, non-treatment combined with parental education after the first episode of SVT does not lead to worse outcomes. This approach avoids the burden of medication administration in an infant and may have the added benefit of empowering parents to feel comfortable managing clinically insignificant tachycardia at home.

Using 2D speckle-tracking echocardiography to localize the accessory pathway and evaluate cardiac function and dyssynchrony in pediatric patients with Wolf-Parkinson-White syndrome

Wolf-Parkinson-White (WPW) accessory pathway (AP) may be associated with reentry supraventricular tachycardia (SVT) in addition to ventricular dyssynchrony and cardiac dysfunction. Electrophysiological studies (EPS) are the gold standard for the localization of the AP; however, 2D speckle-tracking echocardiography (2D-STE) may help in the localization of the AP noninvasively. Our study aims to evaluate the capability of 2D-STE for AP localization and the identification of AP-related contractile abnormalities and dyssynchrony in pediatric patients with WPW syndrome. This prospective multicenter cohort study involved 18 pediatric patients with ventricular preexcitation from January 2021 to January 2023. Tissue Doppler imaging (TDI), conventional echocardiography, and 2D-STE were done. Myocardial velocities, myocardial performance index (MPI), the global and segmental longitudinal strain of the left ventricle (LV), and time-to-peak longitudinal strain (TPLS) were measured before and after ablation. The longitudinal strain of the LV segments supplied by the AP, or the nearby segments close to the AP, was significantly impaired and improved after ablation (P = 0.0001). The abnormal strain pattern in the affected segments could predict the location of the AP. The TPLS of the affected segments significantly increased after ablation (P = 0.0001), denoting improved dyssynchrony. The ejection time and the LV MPI measured at the basal septum improved significantly after ablation.

CONCLUSIONS

2D STE may be used for noninvasive localization of the AP and to evaluate cardiac function and dyssynchrony in patients with WPW. Further research on more patients is necessary to validate this method for AP localization.

WHAT IS KNOWN

• Accessory pathways (AP) associated with the Wolf-Parkinson-White (WPW) syndrome have been linked to supraventricular tachycardia (SVT). Even without SVT, WPW can cause left ventricular dyssynchrony, contractile dysfunction, and cardiomyopathy. • Electrophysiology study is the gold standard for the localization of the AP in WPW syndrome.

WHAT IS NEW

• The combination of 2D-speckle-tracking echocardiography (2D-STE) and the modified Arruda algorithm can precisely localize the AP associated with WPW syndrome. • 2D-STE can potentially assess cardiac function and dyssynchrony related to WPW syndrome. Additionally, 2D-STE can be utilized to evaluate the effectiveness of ablation in restoring cardiac function and dyssynchrony.

Transesophageal pacing studies reduce readmission but prolong initial admission in infants with supraventricular tachycardia: A cost-comparison analysis

Background

Supraventricular tachycardia (SVT) is a common arrhythmia. Infants with SVT are often admitted to initiate antiarrhythmics. Transesophageal pacing (TEP) studies can be used to guide therapy prior to discharge.

Objective

The objective of this study was to investigate the impact of TEP studies on length of stay (LOS), readmission, and cost in infants with SVT.

Methods

This was a 2-site retrospective review of infants with SVT. One site (Center TEPS) utilized TEP studies in all patients. The other (Center NOTEP) did not. Patients with structural heart disease, patients with gestational age <34 weeks, and patients diagnosed after 6 months were excluded. At Center TEPS, repeat TEP studies were performed after titration of medication until SVT was not inducible. Primary endpoints were LOS and readmission for breakthrough SVT within 31 days of discharge. Hospital reimbursement data were utilized for cost-effectiveness analysis.

Results

The cohort included 131 patients, 59 in Center TEPS and 72 in Center NOTEP. One patient was readmitted in Center TEPS vs 17 in Center NOTEP (1.6% vs 23.6%; P ≤ .001). Median LOS was longer for Center TEPS at 118.0 (interquartile range [IQR] 74.0-189.5) hours vs Center NOTEP at 66.9 (IQR 45.5-118.3) hours (P = .001). Twenty-one patients had multiple TEP studies. Median length of readmission for Center NOTEP was 65 (IQR 41-101) hours. Including readmission costs, utilization of TEP studies resulted in a probability-weighted cost of $45,531 per patient compared with $31,087 per patient without TEP studies.

Conclusion

Utilization of TEP studies was associated with decreased readmission rates but longer LOS and greater cost compared with SVT management without TEP studies.

Combination of Slow Pathway Late Activation Maps and Voltage Gradient Maps in Guidance of Atrioventricular Nodal Reentry Tachycardia Cryoablation

BACKGROUND

The optimal strategy for electroanatomic mapping-guided cryoablation of atrioventricular nodal reentry tachycardia (AVNRT) remains unclear.

OBJECTIVE

To investigate the effectiveness of slow pathway late activation mapping (SPLAM) and voltage gradient mapping for AVNRT cryoablation.

METHODS

From June 2020 to February 2022, all consecutive patients with AVNRT underwent SPLAM to define the wave collision point and voltage gradient mapping to define the low voltage bridge (LVB). Conventional procedures performed from August 2018 to May 2020 served as control.

RESULTS

The study and control groups comprised 36 (aged 16.5±8.2 years) and 37 patients (aged 15.5±7.3 years), respectively. Total procedural times were comparable, and acute success rates were 100% in both groups. Compared to controls, number of cryomapping attempts (median 3 vs. 5, p=0.012) and cryoablation applications (median 1 vs. 2, p<0.001) were significantly lower in the study group. At a median follow-up of 14.6 and 18.3 months, recurrence rates were 5.6% (2 patients) and 10.8% (4 patients) in the study and control groups (p=0.402), respectively. Mapping of Koch's triangle took 11.8±3.6 min, in which 1562±581 points were collected. In SPLAM, wave collision points were defined and compatible with the final successful lesion sites in all patients, including those with multiple slow pathways. LVB could not be defined in 6 patients (16.7%), and LVB was not compatible with the final successful lesion in another 6 (16.7%).

CONCLUSIONS

For AVNRT cryoablation, SPLAM could effectively guide the localization of slow pathway ablation sites and was particularly beneficial in patients with multiple slow pathways.

Ambulatory Cardiac Monitoring in Infants with Supraventricular Tachycardia

Supraventricular tachycardia (SVT) is a frequent cause of tachyarrhythmia in infants < 1 year of age and ambulatory cardiac monitoring is an important tool for diagnosis and follow-up of these patients. We retrospectively reviewed 594 infants (mean age 4.05 months, SD 3.55; 54% M) who underwent ambulatory cardiac monitoring (69% 24 h Holter, 31% extended monitor) through the Pocket ECG system (MediLynx) between January 2016 and July 2020. 170 patients who had the ICD-10 code I47.1 for SVT used at enrollment were analyzed separately. 49 (8.3%) patients had sustained SVT or non-sustained SVT (nSVT) during the study period, including 20 patients (11.8%) who had the ICD-10 code I47.1 at enrollment. Extended ambulatory cardiac monitors detected 61% of all patients with nSVT or SVT and was superior when compared to 24 h Holter (p < 0.0001). In the overall group, the first episode of SVT or nSVT was detected within 24 h of monitoring in 40/49 patients (82%). 48/49 patients (98%) were diagnosed within a week of monitoring and the single remaining patient was diagnosed with nSVT at day 15 of monitoring. There was no significant difference in minimal, maximal, and average heart rate between patients with and without ICD-10 code I47.1 at enrollment or between patients with and without SVT or nSVT. Despite their low yield, ambulatory cardiac monitors are an important diagnostic tool. The ideal length of monitoring in patients with known or suspected SVT has yet to be defined, although all patients in our cohort were identified by day 15 of monitoring.

Supraventricular tachycardia associated with severe diabetic ketoacidosis in a child with new-onset type 1 diabetes mellitus

Diabetic ketoacidosis is one of the most serious and common complications of diabetes, with between 15 and 70% of new-onset type 1 diabetes mellitus worldwide presented with diabetic ketoacidosis. Supraventricular tachycardia, however, is an infrequent complication of diabetic ketoacidosis. We present the case of a child with a new-onset type 1 diabetes mellitus with supraventricular tachycardia as a complication of paediatric diabetic ketoacidosis. The patient received intravenous fluid resuscitation, insulin, and potassium supplementation and subsequently developed stable supraventricular tachycardia initially, confirmed on a 12-lead electrocardiogram despite a structurally normal heart and normal electrolytes. Vagal manoeuvers failed to achieve sinus rhythm. The patient went into respiratory distress and was intubated, for mechanical ventilation. She received one dose of adenosine with successful conversion to sinus rhythm and a heart rate decreased from 200 to 140 beats per minutes. We conclude that supraventricular tachycardia can occur as a complication of diabetic ketoacidosis, including in new-onset type 1 diabetes mellitus. Furthermore, a combination of acidosis, potassium derangement, falling magnesium, and phosphate levels may have precipitated the event. Here, we report a case of supraventricular tachycardia as a complication of paediatric diabetic ketoacidosis.

Clinical Predictors of Recurrent Supraventricular Tachycardia in Infancy

BACKGROUND

Data regarding recurrence risk among infants with supraventricular tachycardia (SVT) are limited.

OBJECTIVES

The purpose of this study was to determine incidence and factors associated with SVT recurrence.

METHODS

This was a retrospective single-center study (1984-2020) with prospective phone follow-up of infants with structurally normal hearts diagnosed at age ≤1 year with re-entrant SVT. Primary outcome was first SVT recurrence after hospital discharge. Classification and regression tree analysis was performed to determine a risk algorithm.

RESULTS

Among 460 infants (62% male), 87% were diagnosed at ≤60 days of age (median 13 days; IQR: 1-31 days). During a median follow-up of 5.2 years (IQR: 1.8-11.2 years), 33% had recurrence. On multivariable analysis, factors associated with recurrence included: fetal or late (>60 days) diagnosis (HR: 1.90; 95% CI: 1.26-2.86; and HR: 1.73; 95% CI: 1.07-2.77, respectively), Wolff-Parkinson-White (WPW) syndrome (HR: 2.46; 95% CI: 1.75-3.45), and need for multi-antiarrhythmic or second-line therapy (HR: 2.08; 95% CI: 1.45-2.99). Based on the classification and regression tree analysis, WPW incurred the highest risk. Among those without WPW, age at diagnosis was the most important factor predicting risk. Fetal or late diagnosis incurred higher risk, and if multi-antiarrhythmic or second-line therapy was also required, risk nearly doubled. Infants without WPW, who were diagnosed early (0-60 days), and who were discharged on propranolol were at lowest recurrence risk.

CONCLUSIONS

Infants with SVT are most likely to be diagnosed at ≤60 days and be male. Risk factors for recurrence (occurred in 33%), present at time of diagnosis, include WPW, fetal or late diagnosis, and multi-antiarrhythmic or second-line therapy. Infants with early diagnosis, without WPW, and discharged on first-line monotherapy are at lowest recurrence risk.

Fetal Arrhythmia Diagnosis and Pharmacologic Management

One of the most successful achievements of fetal intervention is the pharmacologic management of fetal arrhythmias. This management usually takes place during the second or third trimester. While most arrhythmias in the fetus are benign, both tachy‐ and bradyarrhythmias can lead to fetal hydrops or cardiac dysfunction and require treatment under certain conditions. This review will highlight precise diagnosis by fetal echocardiography and magnetocardiography, the 2 primary means of diagnosing fetuses with arrhythmia. Additionally, transient or hidden arrhythmias such as bundle branch block, QT prolongation, and torsades de pointes, which can lead to cardiomyopathy and sudden unexplained death in the fetus, may also need pharmacologic treatment. The review will address the types of drug therapies; current knowledge of drug usage, efficacy, and precautions; and the transition to neonatal treatments when indicated. Finally, we will highlight new assessments, including the role of the nurse in the care of fetal arrhythmias. The prognosis for the human fetus with arrhythmias continues to improve as we expand our ability to provide intensive care unit–like monitoring, to better understand drug treatments, to optimize subsequent pregnancy monitoring, to effectively predict timing for delivery, and to follow up these conditions into the neonatal period and into childhood. Coordinated initiatives that facilitate clinical fetal research are needed to address gaps in knowledge and to facilitate fetal drug and device development.

A rare cause of idiopathic right outflow tract premature ventricular contraction: Type-4 renal tubular acidosis

The premature ventricular contractions (PVCs) have usually good prognosis in patients without structural heart disease. In case of left ventricular ejection fraction depression or symptoms, antiarrhythmic drugs or cardiac ablations could be an option for management. We present a case of a patient with high burden of PVC admitted for cardiac ablation. Preoperative assessment revealed hyperkalemia and metabolic acidosis which ended up with type-4 renal tubular acidosis (RTA). Its rare cause and management may draw attention to the possibility of type -4 RTA as the cause of the PVC, and hyperkalemia.

Ripple Mapping: A precise tool for atrioventricular nodal reentrant tachycardia ablation

INTRODUCTION

Ablation for atrioventricular nodal reentrant tachycardia (AVNRT) classically utilizes evaluation of signal morphology within the anatomic region of the slow pathway (SP), which involves subjectivity. Ripple Mapping (RM) (CARTO-3© Biosense Webster Inc, Irvine, CA) displays each electrogram at its 3-dimensional coordinate as a bar changing in length according to its voltage-time relationship. This allows prolonged, low-amplitude signals to be displayed in their entirety, helping identify propagation in low-voltage areas. We set out to evaluate the ability of RM to locate the anatomic site of the slow pathway and assess its use in guiding ablation for AVNRT.

METHODS

Patients ≤18 yrs with AVNRT in the EP laboratory between 2017 and 2021 were evaluated. RM was performed to define region of SP conduction in patients from 2019-2021, whereas standard electro-anatomical mapping was used from 2017-2019. All ablations were performed using cryo-therapy. Demographics, outcomes and analysis of variance in number of test lesions until success were compared between groups.

RESULTS

A total 115 patients underwent AVRNT ablation during the study; 46 patients were in the RM group and 69 were in the control group. There were no demographic differences between groups. All procedures, in both groups, were acutely successful. In RM group, 89% of first successful lesions were within 4mm of the predicted site. There was significantly reduced variability in number of test lesions until success in the RM group (p=0.01).

CONCLUSIONS

RM is a novel technique that can help identify slow pathway location, allowing for successful ablation of AVNRT with decreased variability. This article is protected by copyright. All rights reserved.

Nonutility of Diagnostic Testing in Ambulatory Patients With Supraventricular Tachycardia

BACKGROUND

Supraventricular tachycardia (SVT) is the most common arrhythmia in the pediatric population. Patients often present to the emergency department and undergo extensive diagnostic assessment. The objective of this study is to determine the frequency of diagnostic studies obtained in such patients and to assess clinical significance of these results.

METHODS

A retrospective study was performed from 2011 to 2018 in a single-center ED, including patients 21 years of age or younger presenting with SVT without shock.

RESULTS

A total of 40 patients with 92 encounters were included for analysis. The mean age was 8.58 (±5.51) years; 55% female. A total of 67.4% underwent serologic laboratory evaluation, of which 8 (12.9%) had any abnormality. Only one was deemed clinically significant to warrant intervention. Nearly 30% of patients underwent chest radiography, with no clinically significant findings.

CONCLUSIONS

Patients undergoing ED management of uncomplicated SVT are likely to undergo laboratory investigation and unlikely to have abnormal studies impacting their care. Given the associated risk of false-positive studies, the discomfort to the patient and parent, and cost of these studies, routine laboratory or radiographic investigation in this population may be unwarranted.

Evaluation of Clinical Course and Maintenance Drug Treatment of Supraventricular Tachycardia in Children During the First Years of Life. A Cohort Study from Eastern Germany

Supraventricular tachycardia (SVT) is considered the most common cause of arrhythmia in children and infants. Regarding the likelihood of a spontaneous resolution of SVTs during the first years of life, drug treatment aims to bridge the time until children 'grow out' out of the arrhythmia. The choice of antiarrhythmic agents and the planning of maintenance therapy are mainly based on clinical experience and retrospective single- and multi-institutional analyses and databases from all over the world approaching differently to this topic. The current study aimed to evaluate the clinical course, pharmacological treatment strategies, and constellations of risk for recurrences in the management of SVTs in children aged 3 < years. The database of the Heart Center Leipzig, Department of Pediatric cardiology, was searched for pediatric patients aged < 3 years with a clinically documented SVT between 2000 and 2019 that received pharmacologic treatment. Patients with complex congenital heart disease or arrhythmias following cardiac surgery were excluded. 69 patients were included. Pharmacologic treatment, follow-up schedule, recurrences, outcomes, and risk factors for complicated courses are reported. Drug therapy of SVTs in young children remains a controversial topic with heterogeneous treatment and follow-up strategies applied. Risk factors for recurrences and/or stubborn clinical courses are difficult rhythm control with 3 or more antiarrhythmic drugs, ectopic atrial tachycardias, and a first occurrence of the SVT in the fetal period. Prospective studies are needed to sufficiently evaluate optimal treatment strategies.

Medical Management of Infants With Supraventricular Tachycardia: Results From a Registry and Review of the Literature

Background

Several medication choices are available for acute and prophylactic treatment of refractory supraventricular tachycardia (SVT) in infants. There are almost no controlled trials, and medication choices are not necessarily evidence based. Our objective was to report the effectiveness of management strategies for infant SVT.

Methods

A registry of infants admitted to hospital with re-entrant SVT and no haemodynamically significant heart disease were prospectively followed at 11 international tertiary care centres. In addition, a systematic review of studies on infant re-entrant SVT in MEDLINE and EMBASE was conducted. Data on demographics, symptoms, acute and maintenance treatments, and outcomes were collected.

Results

A total of 2534 infants were included: n = 108 from the registry (median age, 9 days [0-324 days], 70.8% male) and n = 2426 from the literature review (median age, 14 days; 62.3% male). Propranolol was the most prevalent acute (61.4%) and maintenance treatment (53.8%) in the Registry, whereas digoxin was used sparingly (4.0% and 3.8%, respectively). Propranolol and digoxin were used frequently in the literature acutely (31% and 33.2%) and for maintenance (17.8% and 10.1%) (P < 0.001). No differences in acute or prophylactic effectiveness between medications were observed. Recurrence was higher in the Registry (25.0%) vs literature (13.4%) (P < 0.001), and 22 (0.9%) deaths were reported in the literature vs none in the Registry.

Conclusion

This was the largest cohort of infants with SVT analysed to date. Digoxin monotherapy use was rare amongst contemporary paediatric cardiologists. There was limited evidence to support one medication over another. Overall, recurrence and mortality rates on antiarrhythmic treatment were low.

Empiric slow-pathway ablation results for presumed atrioventricular nodal reentrant tachycardia in pediatric patients

BACKGROUND

In pediatric patients with documented narrow QRS tachycardia that is suggestive of atrioventricular nodal reentrant tachycardia (AVNRT) and not inducible in electrophysiological study (EPS), empiric slowpathway ablation (ESPA) may be considered. There is limited data in children about this topic.

METHODS

Seventy-nine patients who underwent cryoablation and/or radiofrequency ablation (RFA) for presumed AVNRT between January 2010 and January 2020, with no inducible tachycardia and no other tachycardia mechanisms during EPS, were included in this study.

RESULTS

The age was between 6 and 18 years. All patients had no structural heart disease. Preablation exhibited sustained SP conduction for all patients. In all cases, the ablation end points were prolongation in wenckebach cycle length (WBCL) with loss of cross and/or jump, and/or echo beat. The end points were not achieved in two patients. Overall, the mean basal WBCL increased to 351 ms (240-500 ms) from 301.3 ms (180-420 ms), evident in the non-recurrence group. Nine patients had a transient AV block that improved. We followed the patients without medication for about 46.9 months (8 months to 10 years). Palpitations occurred again in 9 of 77 patients (clinical recurrence rate 9/79 - 11.3%). The documented ECG recurrence rate was 1.2% (1/79). In the non-recurrence group, WBCL prolongation was higher and mean age was lower than in the recurrence group (13.075 vs. 15.33 years).

CONCLUSION

In cases with presumed AVNRT, ESPA seems to be a reasonable and safe way. In our study, we found our procedural success rate as 97.4% and follow-up recurrence rate as 12.6% (9+1/79).

Treatment of Fetal Arrhythmias

Fetal arrhythmias are mostly benign and transient. However, some of them are associated with structural defects or can cause heart failure, fetal hydrops, and can lead to intrauterine death. The analysis of fetal heart rhythm is based on ultrasound (M-mode and Doppler echocardiography). Irregular rhythm due to atrial ectopic beats is the most common type of fetal arrhythmia and is generally benign. Tachyarrhythmias are diagnosed when the fetal heart rate is persistently above 180 beats per minute (bpm). The most common fetal tachyarrhythmias are paroxysmal supraventricular tachycardia and atrial flutter. Most fetal tachycardias can be terminated or controlled by transplacental or direct administration of anti-arrhythmic drugs. Fetal bradycardia is diagnosed when the fetal heart rate is slower than 110 bpm. Persistent bradycardia outside labor or in the absence of placental pathology is mostly due to atrioventricular (AV) block. Approximately half of fetal heart blocks are in cases with structural heart defects, and AV block in cases with structurally normal heart is often caused by maternal anti-Ro/SSA antibodies. The efficacy of prenatal treatment for fetal AV block is limited. Our review aims to provide a practical guide for the diagnosis and management of common fetal arrythmias, from the joint perspective of the fetal medicine specialist and the cardiologist.

Detection of Tachyarrhythmias in a Large Cohort of Infants Using Direct-to-Consumer Heart Rate Monitoring

OBJECTIVE

Current estimates of the incidence of tachyarrhythmias in infants rely on clinical documentation and may not reflect the true rate in the general population. Our aim was to describe the epidemiology of tachyarrhythmia detected in a large cohort of infants using direct-to-consumer heart rate (HR) monitoring.

STUDY DESIGN

Data were collected from Owlet Smart Sock devices used in infants in the US with birthdates between February 2017 and February 2019. We queried the HR data for episodes of tachyarrhythmia (HR of ≥240 bpm for >60 seconds).

RESULTS

The study included 100 949 infants (50.8% male) monitored for more than 200 million total hours. We identified 5070 episodes of tachyarrhythmia in 2508 infants. The cumulative incidence of tachyarrhythmia in our cohort was 2.5% over the first year of life. The median age at the time of the first episode of tachyarrhythmia was 36 days (range, 1-358 days). Tachyarrhythmia was more common in infants with congenital heart disease (4.0% vs 2.4%; P = .015) and in females (2.7% vs 2.0%; P < .001). The median length of an episode was 7.3 minutes (range, 60 seconds to 5.4 hours) and the probability of an episode lasting longer than 45 minutes was 16.8% (95% CI, 15.4%-18.3%).

CONCLUSIONS

We found the cumulative incidence of tachyarrhythmia among infants using direct-to-consumer HR monitors to be higher than previously reported in studies relying on clinical diagnosis. This finding may represent previously undetected subclinical disease in young infants, the significance of which remains uncertain. Clinicians should be prepared to discuss these events with parents.

Essentials of Paroxysmal Supraventricular Tachycardia for the Pediatrician

Paroxysmal supraventricular tachycardia (SVT) is the most common clinical arrhythmia in young patients. With an estimated prevalence of roughly 1 in 500 children, a pediatrician may knowingly or unknowingly see several patients who are affected each year. SVT symptoms can sometimes be vague or conflated with common pediatric complaints. Different forms of SVT are predominant at different ages, sometimes complicating timely recognition and referral. Differing pathophysiology and age distribution impact risk of complications such as heart failure, or rarely, sudden death. Treatment choices continue to evolve as new medications, monitoring devices, and ablation technologies continue to mature. This review focuses on the most common types of paroxysmal SVT: atrioventricular nodal reentrant tachycardia, atrioventricular reciprocating tachycardia, and Wolff-Parkinson White syndrome. Atrial arrhythmia mechanisms are also briefly outlined. It is meant to provide practical guidelines for the diagnosis and management of patients with SVT from infancy through adolescence. [Pediatr Ann. 2021;50(3):e113-e120.].

Care of Children with Supraventricular Tachycardia in the Emergency Department

Prior studies have characterized children with supraventricular tachycardia (SVT) in inpatient settings, however there is a paucity of data regarding pediatric SVT in the Emergency Department (ED) setting. We sought to describe pediatric ED visits for SVT and assess whether variability exists in care. We performed a cross-sectional study of ED visits for SVT among children < 18 years old from 2010 to 2017 at 33 pediatric hospitals. Visits were included if made for a primary International Disease Classification Ninth or Tenth Revision diagnosis code for SVT and intravenous (IV) adenosine was given on the initial or 2nd hospital day. We evaluated factors associated with hospital admission using multivariate logistic regression and described variability in frequency of rate of hospitalization, second-line IV antiarrhythmic medication usage, and diagnostic testing across sites. We included 2329 ED visits made by 1738 children and the median patient age was 6.3 years (IQR 1.5-11.9). There were 2 deaths (0.1% of visits). Marked variability existed between centers in rates of admission to the hospital (range 17-85%) and ICU (range 4-60%). Factors associated with admission included: younger age, male sex and presence of comorbid conditions. A second IV antiarrhythmic agent was used in 17% of visits (range 4-41% across hospitals). There was variability in rates of diagnostic testing between centers [chest x-ray (range 10-47%), complete blood count (range 10-72%), electrolytes (range 22-86%), echocardiography (range 3-68%)]. Management of SVT is variable across pediatric hospitals, suggesting an opportunity for standardization in care.

Long-Term Patient Experience Following Acutely Successful Ablation of Supraventricular Tachycardia Substrate in Children

Definitive treatment of supraventricular tachycardia (SVT) substrate involves catheter ablation. While objective success rates have been well established, long-term subjective patient experiences have not been well described. We quantify a subjective cure rate and characterize long-term patient experience after acutely successful ablation. A cross-sectional survey of pediatric patients with accessory pathways or atrioventricular nodal reentrant tachycardia who underwent acutely successful ablation from 2008 to 2012 was performed. Data were obtained from medical records and patient surveys. Patients with congenital heart disease other than patent ductus arteriosus, patent foramen ovale, or coronary artery abnormalities were excluded. Statistical analyses included Student's t-test and χ² analysis for continuous and categorical variables, respectively. Surveys were sent to 153 patients of which 147 responded with median follow-up of 7.2 (IQR 6.1-8.5) years. Of the 147 responders, 124 (84%) patients reported cure with a male predominance. Symptoms were present in 130/147 (88%) patients pre-ablation and in 53/147 (36%) post-ablation. Among those with post-ablation symptoms, 50/53 (94%) reported symptomatic improvement. Recurrence occurred in 23/147 (16%) patients and was more prevalent following cryoablation. Ablation of SVT substrate can be curative with excellent long-term results and patient satisfaction. Long-term subjective cure rate is high and there is a substantial decrease in symptoms post-ablation. Many patients continue to have symptoms following ablation; however, the majority of these patients consider themselves cured and symptoms can be attributed to other etiologies. Recurrence is uncommon and occurs more frequently following cryoablation.

Ventricular tachycardia in an adolescent with severe diabetic ketoacidosis

Diabetic ketoacidosis (DKA) occurs frequently among children and adolescents with type 1 diabetes. Although a number of complications may occur during episodes of DKA, significant cardiac arrhythmias are uncommon. We present the case of an adolescent who presented with severe DKA and wide complex tachycardia that was unresponsive to multiple doses of adenosine and ultimately required synchronized cardioversion. This case reminds the clinician of the importance of cardiac monitoring in children with DKA, particularly in the setting of hyperkalemia.

The use of a traditional nonlooping event monitor versus a loan-based program with a smartphone ECG device in the pediatric cardiology clinic

Background

A smartphone-enabled device has been developed that provides a single-lead electrocardiogram using a portable monitor. The increase in direct-to-consumer medical devices may lead to health disparities affecting members of socially disadvantaged populations.

Objective

Here we provide a single center’s experience in the use of this device in a pediatric cardiology clinic using a loan-based program. We also compare it to retrospective data from patients who received a traditional nonlooping event monitor.

Methods

Forty AliveCor Kardia monitor devices were purchased with grant support from the South Carolina TeleHealth Alliance. The devices were provided between June 2018 and August 2019 to patients presenting to the pediatric cardiology clinic who would have otherwise received a nonlooping event monitor. A retrospective chart review was performed for all patients who were given a MicroER nonlooping event monitor between May and December of 2017.

Results

Over a 15-month period, 65 patients were given the smartphone device. A total of 692 tracings were recorded by patients with 9 abnormal recordings. Of the devices expected to be returned, 35 devices have been returned to clinic (54%). Over an 8-month period, 61 patients received the traditional event monitors, accounting for a total of 142 transmissions with 3 abnormal transmissions.

Conclusion

Our results reveal adequate use of the device with reliable tracings and show more frequent utilization of the smartphone-enabled device. Utilization of these devices in a loan-based program may improve access to care with improved methods to ensure return of the devices.

Paroxysmal Supraventricular Tachycardia in Wolff–Parkinson–White Syndrome in a Newborn—Case Report and Mini-Review

Wolff–Parkinson–White (WPW) syndrome is a rare abnormal condition frequently associated with paroxysmal supraventricular tachycardia (PSVT) and is described as an arrhythmia under the form of increased heartbeat. Currently, there are various possible treatments going from medicines such as adenosine and beta-blockers to cardioversion. The unknown causes of this condition together with the different responses to treatment in each patient make it difficult to establish the best therapeutic approach. In this context, in the current paper, we were interested in reporting the therapeutic options and their efficiency in the case of associated heart or inflammatory conditions in a 13-day-old patient.

Syncope and Palpitations: A Review

Syncope and palpitations are common complaints for patients presenting to their primary care provider. They represent symptoms that most often have a benign etiology but rarely can be the first warning sign of a serious condition, such as arrhythmias, structural heart disease, or noncardiac disease. The history, physical examination, and noninvasive testing can, in most cases, distinguish benign from pathologic causes. This article introduces syncope and palpitations, with emphasis on the differential diagnoses, initial presentation, diagnostic strategy, and various management strategies.

Radiofrequency catheter ablation for supraventricular tachycardia in a paediatric population: characteristics of tachycardia mechanisms in a subpopulation with early onset

BACKGROUND

In children, the first episode of supraventricular tachycardia occurs at various ages. The aim of this study is to describe age-specific tachycardia mechanisms, clinical findings, and outcome in a contemporary cohort of paediatric patients with supraventricular tachycardia.

METHODS

Retrospective analysis of 531 consecutive patients with structurally normal hearts under the age of 18 years who underwent invasive electrophysiological study for supraventricular tachycardia. The study population was divided into two groups, early-onset group (n = 57) and late-onset group (n = 474), according to the age of the occurrence of the first tachycardia before or after the age of 12 months.

RESULTS

Accessory pathway-mediated tachycardia was more common (82.5 versus 50.1%, p < 0.001) and the proportion of left-sided accessory pathways was more pronounced (74.5 versus 53.7%, p = 0.01) in the early-onset group than in the late-onset group. The antegrade and retrograde refractory periods of the accessory pathways were similar in both groups, but pre-excitation was more common in the early-onset group (50.9 versus 31.9%, p = 0.007). Typical atrioventricular nodal re-entrant tachycardia was more common (36.7 versus 7.0%, p < 0.001) in the late-onset group. There was no difference among the two groups regarding overall outcome.

CONCLUSION

Accessory pathway-mediated re-entrant tachycardia is the most common mechanism of recurrent supraventricular tachycardia in infants with structurally normal hearts who are later referred to an electrophysiological study. These pathways often cause pre-excitation and tend to be located on the left side whereas their refractory period is not different from that of patients with late-onset tachycardia.

Management of Arrhythmias in Pediatric Emergency

Pediatricians often find it difficult to make specific diagnosis of arrhythmia based on ECG. This article is an effort to make the pediatricians understand common arrhythmias. Diagnosing arrhythmias is important as some arrhythmias, if not diagnosed or suspected, can lead to heart failure. With proper diagnosis, some of them can be cured with therapeutic ablation. Adenosine is not only a therapeutic drug but in many circumstances, it gives definite diagnosis also.

Arrhythmia Mechanisms and Outcomes of Ablation in Pediatric Patients With Congenital Heart Disease

BACKGROUND

In contrast to the adult population with congenital heart disease (CHD), arrhythmia mechanisms and outcomes of ablation in pediatric patients with CHD in recent era have not been studied in detail. Aims of this study were to determine arrhythmia mechanisms and to evaluate procedural and long-term outcomes in pediatric patients with CHD undergoing catheter ablation.

METHODS

Consecutive patients <18 years of age with CHD undergoing catheter ablation over an 11-year period (2007-2018) were included. Procedural outcome included complete or partial success, failure or empirical ablation. Long-term outcome included arrhythmia recurrence and burden according to a 12-point clinical arrhythmia severity score.

RESULTS

The study population consisted of 232 patients (11.7 years [0.01-17.8], 33.5 kg [2.2-130.1]). The most common diagnoses were Ebstein's anomaly (n=44), septal defects (n=39), and single ventricle (n=36). Arrhythmia mechanisms included atrioventricular reentry tachycardia (n=104, 90 patients), atrioventricular nodal reentry tachycardia (n=33, 29 patients), twin atrioventricular nodal tachycardia (n=3, 2 patients), macroreentrant atrial tachycardia (n=59, 56 patients), focal atrial tachycardia (n=33, 25 patients), ventricular ectopy (n=10, 8 patients), and ventricular tachycardia (n=15, 13 patients). Fifty-six arrhythmias (39 patients) were undefined. Outcomes included complete success (n=189, 81%), partial success (n=7, 3%), failure (n=16, 7%), or empirical ablation (n=20, 9%). Over 3.6 years (0.3-10.7) arrhythmia recurred in 49%. Independent of arrhythmia recurrence, arrhythmia scores decreased from 4 (0-10) at baseline to 0.5 (0-8) at 4 years follow-up (P<0.001). In 23/51 repeat procedures (45%), a different arrhythmia substrate was found. Overall adverse event rate was 9.4%, although only 1.6% (n=4) were of major severity and 0.8% (n=2) of moderate severity.

CONCLUSIONS

Pediatric patients with CHD demonstrate a broad spectrum of arrhythmia mechanisms. Despite recurrence and emergence of novel mechanisms after a successful procedure, ablation can be performed safely and successfully resulting in decreased arrhythmia burden.

Neonatal supraventricular tachycardia

Supraventricular tachycardia (SVT) is one of the most common conditions requiring emergency cardiac care in neonates. Atrioventricular reentrant tachycardia utilizing an atrioventricular bypass tract is the most common form of SVT presenting in the neonatal period. There is high likelihood for spontaneous resolution for most of the common arrhythmia substrates in infancy. Pharmacological agents remain as the primary therapy for neonates.

Fetal Arrhythmias: Genetic Background and Clinical Implications

Fetal arrhythmias are a common phenomenon of pregnancies. However, debates remain with regard to the etiologies and early treatment of choices for severe fetal arrhythmias. The gene regulatory networks govern cardiac conduction system development to produce distinct nodal and fast conduction phenotypes. The slow conduction properties of nodes that display automaticity are determined by the cardiac ion channel genes, whereas the fast conduction properties are regulated by the transcription factors. Mutations of genes specific for the developmental processes and/or functional status of cardiac conduction system including ion channel promoter (minK-lacZ), GATA family of zinc finger proteins (GATA4), the homeodomain transcription factor (Nkx2.5), the homeodomain-only protein (Hop) and the T-box transcription factors (Tbx2, Tbx3 and Tbx5), hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) and connexins, may cause fetal arrhythmias. It is expected that development of investigational antiarrhythmic agents based on genetic researches on cardiac conduction system, and clinical application of percutaneously implantable fetal pacemaker for the treatment of fetal arrhythmias would come to true.

Comparison of a smartphone-based ECG recording system with a standard cardiac event monitor in the investigation of palpitations in children

BACKGROUND

The AliveCor (Kardia) monitor attaches to a smartphone and allows a single-lead ECG to be recorded during symptoms. In 2016, we introduced the use of this smartphone device for investigating palpitations, without syncope, in children. The aim of our study was to review our experience with the smartphone device, comparing it with our previous standard conventional approach to cardiac event monitoring using the Cardiocall monitor, which uses skin electrodes and is given for a finite period.

METHODS

Over a period of 24 months, 80 smartphone monitors were issued and compared with the most recent 100 conventional event monitors. The number of ECG recordings received, arrhythmias documented, quality of ECG recordings and patient satisfaction were evaluated.

RESULTS

Median patient age was 11 years in the smartphone monitor group compared with 10 years in the conventional group. Seventy-nine of 80 (98%) patients with a smartphone monitor sent an ECG recorded during symptoms, compared with 62/100 (62%) from the conventional group. A total of 836 ECG recordings were sent from the smartphone monitors compared with 752 from the conventional group. Eight per cent of ECG recordings in each group were of inadequate quality for analysis. Twenty of 80 (25%) patients with a smartphone monitor had documented tachyarrhythmia compared with 6/100 (6%) patients with the conventional monitor (p<0.001). On comparison with the conventional approach, the smartphone monitor outperformed with respect to diagnostic yield and patient satisfaction.

CONCLUSIONS

A smartphone-based event monitor allows simple, effective, long-term ECG event monitoring in children that is highly acceptable to the patient and parent.

Reentry Tachycardia in Children: Adenosine Can Make It Worse

OBJECTIVES

We report on a rare but severe complication of adenosine use in a child with reentry tachycardia.

METHODS AND RESULTS

Treatment with adenosine, which is the standard medical therapy of atrioventricular reentry tachycardia, led to the development of an irregular wide complex tachycardia, caused by rapid ventricular response to atrial fibrillation. The girl was finally stabilized with electrical cardioversion. We analyze the pathomechanism and discuss possible treatment options.

CONCLUSIONS

Atrial fibrillation, as well as its conduction to the ventricles, can be caused by adenosine. Rapid ventricular response in children with Wolff-Parkinson-White syndrome is more frequent than previously believed. A patient history of atrial fibrillation is a contraindication for cardioversion with adenosine and needs to be assessed in children with reentry tachycardia. High-risk patients may potentially profit from prophylactic comedication with antiarrhythmic agents, such as flecainide, ibutilide, or vernakalant, before adenosine administration.

Hospitalization rate of paroxysmal supraventricular tachycardia in Sweden

INTRODUCTION

The hospitalization rate of paroxysmal supraventricular tachycardia (PSVT) in a nationwide study is not established. We determined age- and sex-specific hospitalization rates and time trends for hospitalized PSVT in the Swedish population between 1987 and 2010.

METHODS

This nationwide study is based on the Swedish Hospital Discharge Register. The patients with first PSVT diagnoses between January 1987 and December 2010 were identified.

RESULTS

A total of 42,765 individuals with PSVT were diagnosed (mean age 60 years; 44% males). The overall age- and sex-adjusted hospitalization rate was 20 per 100,000 person-years. The hospitalization rate increased with advancing age with highest hospitalization rates in individuals aged 80-84 years (67.12 per 100,000 person-years) and did not change significantly over time. A total of 20,011 (46.8%) patients had "lone" PSVT without any comorbidities. Lone PSVT patients were younger than PSVT patients with comorbidities (mean age 54 vs. 67 years, p = .0002).

CONCLUSIONS

This study showed a slight preponderance for females and stable hospitalization rate of PSVT over time; the hospitalization rate increased with age. A high proportion of PSVT patients had no comorbidities. They were affected at a younger age than patients with comorbidities, which suggests an inherent predisposition. Key messages This study represents the first extensive and nationwide hospitalization study of PSVT. Hospitalization is highest in old age but a bimodal pattern was observed with a small peak in the first years of life. Patients with lone PSVT are younger than those with comorbidities; which suggests an inherent predisposition.

Age makes a difference: Symptoms in pediatric supraventricular tachycardia

BACKGROUND

Supraventricular tachycardia is a group of rhythm disturbances that affect 1 in 300-1200 Australian children annually. The differentiation of supraventricular tachycardia (SVT) symptoms and age of onset according to their subtype is not well understood in the pediatric population. Most studies rely on ECG criteria only to characterize the subtype of the SVT, which is not applicable to all subtypes. The purpose of this study was to identify the symptoms and ages of onset of SVT subtypes, and to analyze whether ethnicity or severity correlated with the SVT subtype confirmed in an invasive Electrophysiology (EP) study.

METHODS

A retrospective analysis and prospective survey evaluated 364 patients who underwent an EP study at The Royal Children's Hospital, Melbourne between 2009 and 2015. Age of onset, symptoms, and ethnicity were collected by phone survey or medical records in addition to EP study diagnostic data, medication status, and follow-up information about their symptom status following EP procedure. Patients were grouped according to their SVT subtype. Data analysis was performed using chi-squared, Fisher's exact, and ANOVA statistical tests to determine associations between SVT substrates.

RESULTS

Two hundred and thirty-three suitable cases of SVT were identified (131 men, 102 women) aged between 0 and 18 years. Atrioventricular Reentrant Tachycardia (AVRT) (n = 153) was the most common SVT subtype, followed by Atrioventricular Nodal Reentrant Tachycardia (AVNRT) (n = 55), Atrial Tachycardia (AT) (n = 17), and other SVT subtypes (n = 8) which included Atrial Fibrillation, Atrial Flutter, and Junctional Tachycardia. There was a male predominance in all subtypes, except for AVNRT. AVNRT patients had palpitations, dyspnoea, dizziness, and anxiety more than any other group, AVRT patients complained of vomiting most and patients with AT had the most fatigue. The mean age of symptom onset varied among groups, being earlier in AVRT, later in AVNRT with a significant difference between AVRT with unidirectional retrograde accessory pathway (URAP) and AVNRT subtypes (P < 0.01).

CONCLUSION

Some specific symptoms were strong discriminators between different SVT subtypes. Ethnicity did not have strong correlations with SVT subtype incidence. This study was able to show clinical differences among children with SVT due to AVRT (URAP) compared to AVNRT, allowing the prognosis and intended management of pediatric SVT to be anticipated by less invasive means.

Treatment of left accessory cardiac pathway conduction disorders using radiofrequency catheter ablation under the guidance of the Ensite NavX 3D mapping system: a retrospective study

To investigate the effectiveness and safety of using the Ensite NavX three-dimensional (3D) mapping system during Radiofrequency catheter ablation (RFCA) of left accessory pathway (AP) disorders. A total of 227 patients having their left AP treated by RFCA, were classified into study group (n = 112) and the control group (n = 115). X-ray irradiation time and exposure doses during the course of the operations were recorded. Time taken to place the mapping catheter along with total duration of operations and procedural complications were compared. The X-ray irradiation time and exposure doses in the course of manipulating the ablation catheters were significantly lower in the study group compared to control (5.1 ± 2.3 min vs. 13.1 ± 3.1 min; P < 0.05 and 5.7 ± 2.6 mGy vs. 17.8 ± 4.3 mGy; P < 0.05, respectively). The total duration of operation was also significantly shorter in the study group compared to control (53.1 ± 18.8 min vs. 62.3 ± 20.6 min; P < 0.05). No procedural complications were reported in both groups. The irradiation time and exposure dose along with total operation duration was significantly reduced when the Ensite NavX mapping system was used during RFCA in comparison with traditional X-ray fluoroscopy method.

Apoptosis and epicardial contributions act as complementary factors in remodeling of the atrioventricular canal myocardium and atrioventricular conduction patterns in the embryonic chick heart

BACKGROUND

During heart development, it has been hypothesized that apoptosis of atrioventricular canal myocardium and replacement by fibrous tissue derived from the epicardium are imperative to develop a mature atrioventricular conduction. To test this, apoptosis was blocked using an established caspase inhibitor and epicardial growth was delayed using the experimental epicardial inhibition model, both in chick embryonic hearts.

RESULTS

Chicken embryonic hearts were either treated with the peptide caspase inhibitor zVAD-fmk by intrapericardial injection in ovo (ED4) or underwent epicardial inhibition (ED2.5). Spontaneously beating embryonic hearts isolated (ED7-ED8) were then stained with voltage-sensitive dye Di-4-ANEPPS and imaged at 0.5-1 kHz. Apoptotic cells were quantified (ED5-ED7) by whole-mount LysoTracker Red and anti-active caspase 3 staining. zVAD-treated hearts showed a significantly increased proportion of immature (base to apex) activation patterns at ED8, including ventricular activation originating from the right atrioventricular junction, a pattern never observed in control hearts. zVAD-treated hearts showed decreased numbers of apoptotic cells in the atrioventricular canal myocardium at ED7. Hearts with delayed epicardial outgrowth showed also increased immature activation patterns at ED7.5 and ED8.5. However, the ventricular activation always originated from the left atrioventricular junction. Histological examination showed no changes in apoptosis rates, but a diminished presence of atrioventricular sulcus tissue compared with controls.

CONCLUSIONS

Apoptosis in the atrioventricular canal myocardium and controlled replacement of this myocardium by epicardially derived HCN4-/Trop1- sulcus tissue are essential determinants of mature ventricular activation pattern. Disruption can lead to persistence of accessory atrioventricular connections, forming a morphological substrate for ventricular pre-excitation. Developmental Dynamics 247:1033-1042, 2018. © 2018 Wiley Periodicals, Inc.

Supraventricular tachycardias, conduction disease, and cardiomyopathy in 3 families with the same rare variant in TNNI3K (p.Glu768Lys)

BACKGROUND

Rare genetic variants in TNNI3K encoding troponin-I interacting kinase have been linked to a distinct syndrome consisting primarily of supraventricular tachycardias and variably expressed conduction disturbance and dilated cardiomyopathy in 2 families.

OBJECTIVE

The purpose of this study was to identify new genetic variants associated with inherited supraventricular tachycardias, cardiac conduction disease, and cardiomyopathy.

METHODS

We conducted next generation sequencing in 3 independent multigenerational families with atrial/junctional tachycardia with or without conduction disturbance, dilated cardiomyopathy, and sudden death. We also assessed the effect of identified variant on protein autophosphorylation.

RESULTS

In this study, we uncovered the same ultra-rare genetic variant in TNNI3K (c.2302G>A, p.Glu768Lys), which co-segregated with disease features in all affected individuals (n = 23) from all 3 families. TNNI3K harboring the TNNI3K-p.Glu768Lys variant displayed enhanced kinase activity, in line with expectations from previous mouse studies that demonstrated increased conduction indices and procardiomyopathic effects with increased levels of Tnni3k.

CONCLUSION

This study corroborates further the causal link between rare genetic variation in TNNI3K and this distinct complex phenotype, and points to enhanced kinase activity of TNNI3K as the underlying pathobiological mechanism.

Usefulness of Echocardiography in Children with New-Onset Supraventricular Tachycardia

BACKGROUND

Supraventricular tachycardia (SVT) is the most common sustained arrhythmia in children. Infants with SVT and ventricular preexcitation (Wolff-Parkinson-White syndrome) are known to have up to 30% prevalence of congenital heart disease (CHD). Infants without ventricular preexcitation who present with SVT at <1 year of age have a similar prevalence of CHD. However, for children without ventricular preexcitation who present with SVT at older ages, the prevalence of CHD is not known. The aim of this study was to determine the prevalence of CHD in older children and adolescents presenting with SVT without ventricular preexcitation, with the goal of providing guidance regarding the usefulness of echocardiography in this patient population.

METHODS

Children aged 2 to 18 years presenting with confirmed SVT between January 2011 and December 2015 were included in this retrospective review. Patients with any history of ventricular preexcitation or preexisting heart disease were excluded. Medical records were reviewed, and electrocardiographic and echocardiographic findings were classified as normal, incidental, or abnormal.

RESULTS

Two hundred ninety patients met the inclusion criteria. Echocardiographic examinations were completed on 224 patients. Only one patient was found to have CHD, a moderate primum atrial septal defect. This patient was noted to have electrocardiographic abnormalities consistent with primum atrial septal defect.

CONCLUSIONS

For older children and adolescents with no known heart disease presenting with SVT without ventricular preexcitation, echocardiography may not be a necessary part of initial evaluation when the results of physical examination and electrocardiography are normal.

Nonreentrant atrial tachycardia occurs independently of hypertrophic cardiomyopathy in RASopathy patients

Multifocal atrial tachycardia (MAT) has a well-known association with Costello syndrome, but is rarely described with related RAS/MAPK pathway disorders (RASopathies). We report 11 patients with RASopathies (Costello, Noonan, and Noonan syndrome with multiple lentigines [formerly LEOPARD syndrome]) and nonreentrant atrial tachycardias (MAT and ectopic atrial tachycardia) demonstrating overlap in cardiac arrhythmia phenotype. Similar overlap is seen in RASopathies with respect to skeletal, musculoskeletal and cutaneous abnormalities, dysmorphic facial features, and neurodevelopmental deficits. Nonreentrant atrial tachycardias may cause cardiac compromise if sinus rhythm is not restored expeditiously. Typical first-line supraventricular tachycardia anti-arrhythmics (propranolol and digoxin) were generally not effective in restoring or maintaining sinus rhythm in this cohort, while flecainide or amiodarone alone or in concert with propranolol were effective anti-arrhythmic agents for acute and chronic use. Atrial tachycardia resolved in all patients. However, a 4-month-old boy from the cohort was found asystolic (with concurrent cellulitis) and a second patient underwent cardiac transplant for heart failure complicated by recalcitrant atrial arrhythmia. While propranolol alone frequently failed to convert or maintain sinus rhythm, fleccainide or amiodarone, occasionally in combination with propranolol, was effective for RASopathy patient treatment for nonreentrant atrial arrhythmia. Our analysis shows that RASopathy patients may have nonreentrant atrial tachycardia with and without associated cardiac hypertrophy. While nonreentrant arrhythmia has been traditionally associated with Costello syndrome, this work provides an expanded view of RASopathy cardiac arrhythmia phenotype as we demonstrate mutant proteins throughout this signaling pathway can also give rise to ectopic and/or MAT.

Neonatal and Pediatric Arrhythmias: Clinical and Electrocardiographic Aspects

Arrhythmias have acquired a specific identity in pediatric cardiology, but for pediatric cardiologists it has always been difficult to recognize and treat them. Changes in anatomy and physiology result in electrocardiogram features that differ from the normal adult pattern and vary according to the age of the child. Sinus arrhythmia, ectopic atrial rhythm, "wandering pacemaker," and junctional rhythm can be normal characteristics in children (15%-25% of healthy children can have these rhythms on the electrocardiogram). Tachyarrhythmias and bradyarrhythmias must be treated according to the severity of symptoms, and the patient's age and weight.

RHOA-ROCK signalling is necessary for lateralization and differentiation of the developing sinoatrial node

Aims

RHOA-ROCK signalling regulates cell migration, proliferation, differentiation, and transcription. RHOA is expressed in the developing cardiac conduction system in chicken and mice. In early development, the entire sinus venosus myocardium, including both the transient left-sided and the definitive sinoatrial node (SAN), has pacemaker potential. Later, pacemaker potential is restricted to the right-sided SAN. Disruption of RHOA expression in adult mice causes arrhythmias including bradycardia and atrial fibrillation, the mechanism of which is unknown but presumed to affect the SAN. The aim of this study is to assess the role of RHOA-ROCK signalling in SAN development in the chicken heart.

Methods and results

ROCK signalling was inhibited chemically in embryonic chicken hearts using Y-27632. This prolonged the immature state of the sinus venosus myocardium, evidenced by up-regulation of the transcription factor ISL1, wide distribution of pacemaker potential, and significantly reduced heart rate. Furthermore ROCK inhibition caused aberrant expression of typical SAN genes: ROCK1, ROCK2, SHOX2, TBX3, TBX5, ISL1, HCN4, CX40, CAV3.1, and NKX2.5 and left-right asymmetry genes: PITX2C and NODAL. Anatomical abnormalities in pulmonary vein development were also observed. Patch clamp electrophysiology confirmed the immature phenotype of the SAN cells and a residual left-sided sinus venosus myocardium pacemaker-like potential.

Conclusions

RHOA-ROCK signalling is involved in establishing the right-sided SAN as the definitive pacemaker of the heart and restricts typical pacemaker gene expression to the right side of the sinus venosus myocardium.

Supraventricular tachycardia as a complication of severe diabetic ketoacidosis in an adolescent with new-onset type 1 diabetes

Diabetic ketoacidosis (DKA) is one of the most common causes of morbidity and mortality in new-onset type 1 diabetes (T1D). Supraventricular tachycardia (SVT), however, is a very rare complication of DKA. We present the case of a patient with new-onset T1D who presented with DKA. He received intravenous fluid resuscitation, insulin and potassium supplementation and subsequently developed SVT, confirmed on a 12-lead electrocardiograph despite a structurally normal heart. Vagal manoeuvres and adenosine failed to restore sinus rhythm, but flecainide was successful. We conclude that SVT can occur as a complication of DKA, including in new-onset T1D. Our case is the first of this phenomenon occurring in new-onset childhood diabetes, as the few prior documented cases had established diabetes. Furthermore, a combination of potassium derangement, hypophosphataemia and falling magnesium levels may have precipitated the event.

Coronary sinus morphology in pediatric patients with supraventricular tachycardia

PURPOSE

The anatomic basis of atrioventricular node reentrant tachycardia (AVNRT) remains incompletely characterized in children. Differences in coronary sinus (CS) size and morphology have been observed in adults with AVNRT but have not been well characterized in children.

METHODS

Children (< 18 years) brought to the EP lab with supraventricular tachycardia for ablation underwent CS venography. A blinded pediatric interventional cardiologist performed CS measurements, which were indexed to body surface area. Patients were excluded if they were < 25 kg or had significant congenital heart disease.

RESULTS

Forty-six patients (age 14.2 ± 3.3 years) met inclusion criteria, 17 with AVNRT and 32 with an accessory pathway (AP). CS ostium (LAO projection, end-systole) was 7.8 ± 2.9 mm/m² for the AVNRT group versus 6.0 ± 2.5 mm/m² for the AP group (p = 0.04). CS "windsock" morphology was more prevalent in the AVNRT group (16/17, 94.1%) than the AP group (11/32, 34.3%) (p < 0.001). Within the AVNRT group, there was no correlation between CS ostium size and tachycardia cycle length (R = 0.01, p = 0.96), fast-pathway ERP (FPERP) (R = 0.42, p = 0.12), or A2-H2 at the FPERP (R = 0.25, p = 0.39).

CONCLUSIONS

Children with AVNRT have larger CS ostia and more prevalent windsock morphology. CS size/morphology did not correlate with EP properties of the AVNRT substrate. These features may explain the basis for the development of the electrophysiologic substrate for dual AV node physiology in children.

Radiofrequency catheter ablation of atrioventricular nodal reentry tachycardia in children and adolescents: a single center experience

Purpose

Atrioventricular nodal reentry tachycardia (AVNRT) is less common in pediatric patients than in adult patients. Thus, data for pediatric AVNRT patients are insufficient. Hence, we aimed to analyze the patient characteristics, treatment, and any recurrences in pediatric AVNRT patients.

Methods

We reviewed the records of 50 pediatric AVNRT patients who had undergone radiofrequency catheter ablation (RFCA) between January 1998 and December 2016 at a single regional center. The patients were aged ≤18 years.

Results

Among 190 pediatric patients who underwent RFCA for tachyarrhythmia, 50 (26.3%; mean age, 13.4±2.6 years) were diagnosed as having AVNRT by electrophysiological study. Twenty-five patients (25 of 50, 50%) were male. Twenty patients (20 of 50, 40%) used beta-blockers before RFCA. All patients had no structural heart disease except 1 patient with valvular aortic stenosis and coarctation of the aorta. RFCA was performed using the anatomic approach under fluoroscopic guidance. The most common successfully ablated region was the midseptal region (25 of 50, 50%). Slow pathway (SP) ablation and SP modulation were performed in 43 and 6 patients, respectively. Complication occurred in 1 patient with complete atrioventricular block. During follow-up, 6 patients had recurrence of supraventricular tachycardia, as confirmed by electrocardiography. Among them, 5 underwent successful ablation at the first procedure. In 1 patient, induction failed during the first procedure.

Conclusion

RFCA is safe and effective in pediatric AVNRT patients. However, further research is needed for establishing the endpoints of ablation in pediatric AVNRT patients and for identifying risk factors by evaluating data on AVNRT recurrence after RFCA.