A rare complication after radiofrequency catheter ablation in an adolescent case: skin burn.

Radiofrequency catheter ablation is a preferred treatment method for cardiac arrhythmias in children due to its high success rate and low complication risk. We present an adolescent patient who underwent radiofrequency catheter ablation for Wolff-Parkinson-White syndrome and developed a skin burn at the site of the electrode patch. Skin burns can catastrophic consequences, especially in patients with life-threatening arrhythmias; therefore, clinicians should be aware of this complication.

Drug-Induced Loss of Preexcitation in Pediatric Patients with WPW Pattern During Electrophysiologic Study.

Ablation of accessory pathways (AP) is one of the most often performed procedures in pediatric electrophysiology. In pediatric patients these procedures are mostly performed in anaesthesia or sedation. In some of these patients who are referred for electrophysiologic (EP) study, we could observe disappearance of the preexcitation, i.e. antegrade conduction of an AP during introduction of sedation. As a suppression of AP conduction capacities has been reported as negative side effect of propofol and other anaesthetics, the aim of this study was to evaluate risk factors for drug-induced suppression of AP conduction properties. Consecutive, pediatric patients with Wolff-Parkinson-White (WPW) pattern referred for EP study in the period of 2016-2017 were reviewed in retrospect. Patients with complex congenital heart disease were excluded. An entire chart review including ECG, bicycle stress testing, and periprocedural data was performed. In 4 of 37 patients included into the study, loss of preexcitation could be observed during sedation. Data analysis showed weaker conduction capacities of the AP as a risk factor (p = 0.009). Interestingly, absolute (p = 0.11) or adjusted to body weight (p = 0.92) drug doses were not a relevant risk factor. Patients with WPW and weaker conduction capacities of the AP, as implied by an early disappearance of preexcitation during exercise stress testing, seem to be more prone to drug-induced suppression of an AP.

Wolff-Parkinson-White syndrome presenting with steroid-induced bradycardia in a patient with acute rheumatic fever.

Steroids are used in the treatment of acute rheumatic fever with moderate-to-severe carditis. Corticosteroids have several cardiovascular side affects that are more common in adults than in children. Corticosteroid-related bradycardia is a rarely seen side effect. Children with bradycardia following oral corticosteroid use are rarely reported previously. We present a child who developed bradycardia after oral corticosteroid treatment and concurrent Wolff-Parkinson-White pattern.

Exome analysis of a family with Wolff-Parkinson-White syndrome identifies a novel disease locus.

Wolff-Parkinson-White (WPW) syndrome is a common cause of supraventricular tachycardia that carries a risk of sudden cardiac death. To date, mutations in only one gene, PRKAG2, which encodes the 5'-AMP-activated protein kinase subunit γ-2, have been identified as causative for WPW. DNA samples from five members of a family with WPW were analyzed by exome sequencing. We applied recently designed prioritization strategies (VAAST/pedigree VAAST) coupled with an ontology-based algorithm (Phevor) that reduced the number of potentially damaging variants to 10: a variant in KCNE2 previously associated with Long QT syndrome was also identified. Of these 11 variants, only MYH6 p.E1885K segregated with the WPW phenotype in all affected individuals and was absent in 10 unaffected family members. This variant was predicted to be damaging by in silico methods and is not present in the 1,000 genome and NHLBI exome sequencing project databases. Screening of a replication cohort of 47 unrelated WPW patients did not identify other likely causative variants in PRKAG2 or MYH6. MYH6 variants have been identified in patients with atrial septal defects, cardiomyopathies, and sick sinus syndrome. Our data highlight the pleiotropic nature of phenotypes associated with defects in this gene.

A 2-year-old child with coronary sinus diverticulum and Wolff-Parkinson-White syndrome.

A 2-year-old child having Wolff­Parkinson­White syndrome presented with recurrent drug-refractory tachycardia episodes. On electrophysiological analysis, a coronary sinus diverticulum was discovered. The accessory pathway was successfully eliminated by radiofrequency ablation within the diverticulum.

Cryoablation of para-Hisian and mid-septal accessory pathways: long-term outcomes of a specific stepwise cryoablation protocol.

BACKGROUND: Although cryoablation (CA) of septally located accessory pathways (APs) is an established treatment for Wolff-Parkinson-White Syndrome, its major limitation is the lack of data regarding long-term follow-up (FU). The present study sought to investigate long-term outcomes of a specific CA protocol targeting para-Hisian (P-H) and mid-septal (M-S) APs. METHODS: Twenty-six patients who previously underwent CA of PH or MS APs from 2004 to 2014, were prospectively considered to receive a FU during 2021. All subjects received an outpatient control visit, performing an exercise stress test and a 24-h ECG Holter monitoring. RESULTS: Acute success was achieved in 22 patients (85%). One case of recurrence was reported at short-term FU. Long-term FU, performed after a mean time of 150±37 months, did not show ventricular preexcitation recurrences, with a success rate of 81%, and without late adverse events. Symptoms reduction (12% vs. 96%, P<.001) and lower rates of antiarrhythmic drug use (12% vs. 62%, P<.001) were observed at long term-FU with respect to baseline. This clinical outcome was detected also among patients who underwent unsuccessful CA at baseline. CONCLUSIONS: Our CA protocol confirmed remarkable safety and efficacy throughout a long-term FU. Significant clinical improvement in terms of antiarrhythmic therapy discontinuation and symptoms reduction was also shown among patients who experienced acute failure of CA.

Emergency treatment of Wolff-Parkinson-White syndrome.

This article describes the aetiology of Wolff-Parkinson-White syndrome and discusses the benefits and disadvantages of some of the available cardioversion medications with which it can be treated.

Incidental dual atrioventricular nodal physiology in children and adolescents: clinical follow-up and implications.

BACKGROUND: Dual atrioventricular (AV) nodal physiology is a substrate for the development of AV nodal reentrant tachycardia (AVNRT). However, the risk of developing AVNRT in patients with dual AV nodal physiology is not known. The purpose of this study is to identify the risk of developing AVNRT in children and adolescents with incidental findings of dual AV nodal physiology after accessory pathway ablation. METHODS: This is a single center retrospective study of patients who underwent intracardiac electrophysiology study at The Children's Hospital, Denver, from March 1993 to August 2008, with findings of dual AV nodal physiology after successful ablation of an accessory pathway. Follow-up was obtained by chart review with the primary outcome of recurrent supraventricular tachycardia. Extended clinical follow-up was also achieved through phone contact with patients or parents of patients. RESULTS: Mean age at initial electrophysiology study was 12.8 years (±3.7 years). Follow-up was obtained on all 66 patients for a mean duration of 3.1 years (±2.8 years). Mean age at follow-up was 15.8 years (±4.6 years). Recurrent supraventricular tachycardia occurred in nine of the 66 patients (13.6%). AVNRT was induced in two of the 66 patients (3.0%). CONCLUSION: This study supports the hypothesis that incidental dual AV nodal physiology does not predict AVNRT in children and adolescents with after successful accessory pathway ablation.

Arrhythmias in children having a single left superior vena cava and minimal structural heart disease.

BACKGROUND: The presence of a single left superior vena cava in the absence of complex congenital heart disease is uncommon, and, in the absence of hemodynamic consequences, it would not be expected to result in cardiovascular signs or symptoms. Single case reports and our anecdotal experience suggested to us that this anomaly is highly associated with cardiac arrhythmias. OBJECTIVE: We sought to describe the clinically important arrhythmias in a population of young patients having this anomaly. METHODS: A retrospective chart review was performed from all patients <20 years old and who were determined by echocardiography over an 11-year-period to have a single left superior vena cava and minor or no coexisting congenital heart defects. The prevalence of nonsinus pacemaker, age-corrected sinus rate percentile, and prevalence of brady- or tachyarrhythmias was compared with a control group of patients having bilateral superior vena cavae. RESULTS: Eight patients having a single left and 55 patients having bilateral superior vena cava(e) were identified. The existence of this anomaly tended to be associated with a lower age-corrected sinus rate percentile (17.5% vs 75%, P = 0.09), and was associated with a higher prevalence of arrhythmias (50% vs 7%, P = 0.014) compared with the control group. In the study group, one patient each had clinically relevant sinus node dysfunction, third-degree AV block, Wolff-Parkinson-White syndrome and atrial fibrillation, and AV nodal reentrant tachycardia. CONCLUSION: Even in the absence of symptoms, patients found to have a single left superior vena cava should be monitored long-term for clinically important arrhythmias.

Chronic mad honey intoxication syndrome: a new form of an old disease?

AIMS: Although cases of acute mad honey intoxication have been reported earlier, chronic mad honey intoxication (CMHI) syndrome has not been described and we address this issue only in this study. METHODS AND RESULTS: We prospectively evaluated the history of non-commercial honey intake in all patients referred to our institution for investigation of slow heart rate or atrioventricular (AV) conduction abnormalities. Between April 2008 and December 2008, 173 patients were referred to our institution for assessment of sinus bradycardia and various degrees of AV block and/or permanent pacemaker implantation. All patients were questioned about history of honey intake. Detailed evaluation revealed a history of daily honey intake for a long period of time in five of the patients (2.8%). This non-commercial honey was made by different amateur beekeepers in eastern Back Sea region of Turkey. Discontinuation of honey intake resulted in prompt normalization of conduction and significant symptomatic improvement. None of the patients were admitted to hospital and all were asymptomatic during 3 months follow-up. Holter monitoring for 24-h revealed no abnormality at first and third month. CONCLUSIONS: This is the first report of CMHI. This issue should be suggested during assessment of patients with unexpected conduction abnormalities, because abandonment of honey intake results in prompt symptomatic and electrocardiographic improvement.

Wolff-Parkinson-White Syndrome after Fontan-Bjork operation and its Successful Ablation from Coronary Sinus.

Wolff-Parkinson-White (WPW) syndrome causes paroxysmal supraventricular tachycardia in which short PR intervals and delta waves are seen in electrocardiography, which may cause sudden cardiac death. A 19-year female presented with increasing episodes of wide and narrow QRS complex tachycardia for the past 5 years. She had tricuspid atresia and Fontan Bjork operation in her past history. She was then diagnosed with narrow QRS complex tachycardia; and WPW syndrome was discovered when she returned to sinus rhythm. Ablation was performed from the coronary sinus ostium region via the left subclavian vein. Fontan Bjork procedure leading to accessory connections stemming from the surgery in the atrio-infundibular anastomosis may be one reason for WPW syndrome. In this case, since the ablation area was close to the Fontan anastomotic line, it could not be determined clearly whether WPW syndrome was secondary to Fontan anastomosis or it was congenital occult WPW syndrome, which became overt following Fontan surgery.

Clinical Findings and Prognosis of Danon Disease. An Analysis of the Spanish Multicenter Danon Registry.

INTRODUCTION AND OBJECTIVES: Danon disease (DD) is caused by mutations in the LAMP2 gene. It is considered a multisystemic disease characterized by hypertrophic cardiomyopathy with pre-excitation and extreme hypertrophy, intellectual disability, myopathy, childhood presentation, and worse prognosis in men. There are scarce data on the clinical characteristics and prognosis of DD. METHODS: We analyzed the clinical records of patients with DD from 10 Spanish hospitals. RESULTS: Twenty-seven patients were included (mean age, 31 ± 19 years; 78% women). Male patients showed a high prevalence of extracardiac manifestations: myopathy (80%), learning disorders (83%), and visual alterations (60%), which were uncommon findings in women (5%, 0%, and 27%, respectively). Although hypertrophic cardiomyopathy was the most common form of heart disease (61%), the mean maximum wall thickness was 15 ± 7 mm and dilated cardiomyopathy was present in 12 patients (10 women). Pre-excitation was found in only 11 patients (49%). Age at presentation was older than 20 years in 16 patients (65%). After a median follow-up of 4 years (interquartile range, 2-9), 4 men (67%) and 9 women (43%) died or required a transplant. Cardiac disease and adverse events occurred later in women (37 ± 9 vs 23 ± 16 and 36 ± 20 vs 20 ± 11 years, respectively). CONCLUSIONS: The clinical characteristics of DD differ substantially from traditional descriptions: age at presentation of DD is older, the disease is not multisystemic in women, and pre-excitation is infrequent.

Molecular Pathogenesis of Familial Wolff-Parkinson-White Syndrome.

Familial Wolff-Parkinson-White (WPW) syndrome is an autosomal dominant inherited disease and consists of a small percentage of WPW syndrome which exhibits ventricular pre-excitation by development of accessory atrioventricular pathway. A series of mutations in PRKAG2 gene encoding gamma2 subunit of 5'AMP-activated protein kinase (AMPK) has been identified as the cause of familial WPW syndrome. AMPK is one of the most important metabolic regulators of carbohydrates and lipids in many types of tissues including cardiac and skeletal muscles. Patients and animals with the mutation in PRKAG2 gene exhibit aberrant atrioventricular conduction associated with cardiac glycogen overload. Recent studies have revealed "novel" significance of canonical pathways leading to glycogen synthesis and provided us profound insights into molecular mechanism of the regulation of glycogen metabolism by AMPK. This review focuses on the molecular basis of the pathogenesis of cardiac abnormality due to PRKAG2 mutation and will provide current overviews of the mechanism of glycogen regulation by AMPK. J. Med. Invest. 65:1-8, February, 2018.

Doppler predictors of inducibility of atrial fibrillation in patients with WPW syndrome and atrioventricular re-entrant tachycardia.

BACKGROUND: Atrial fibrillation (AF) in patients with Wolff-Parkinson-White syndrome (WPW) may induce complex ventricular arrhythmias resulting in sudden cardiac death. It is essential to find an effective non-invasive diagnostic method allowing to select patients at risk of life-threatening arrhythmias. Our objective was to examine Doppler predictors of AF in patients with WPW and atrioventricular re-entrant tachycardia (AVRT). MATERIAL AND METHODS: 65 patients with WPW and AVRT (33 men, mean age 39 +/- 11 y) were prospectively studied. In all patients TTE was performed with measurements of left ventricle (LV) diameters, volumes and parameters of systolic and diastolic function. TTE was followed by invasive electrophysiology study (EPS) and radiofrequency current ablation of accessory pathway.AF lasting at least 30 s was induced in 29 (44.6%) patients during EPS. Reduction of right upper pulmonary vein (RUPV) systolic velocity (P < 0.005) and systolic to diastolic velocity ratio (P < 0.005) and increase in atrial reversal velocity (P < 0.05) of RUPV flow and difference between duration of RUPV atrial reversal flow and A wave of mitral profile (P < 0.05) were associated with increased risk of AF in patients with WPW syndrome and AVRT. Systolic and atrial reversal velocities were identified as independent predictors of AF in those patients. CONCLUSIONS: Systolic and atrial reversal right upper pulmonary vein flow velocities have been shown to be independent predictors of AF inducibility in patients with Wolff-Parkinson-White syndrome and atrioventricular re-entrant tachycardia.

Long term risk of Wolff-Parkinson-White pattern and syndrome.

For years, conventional wisdom has held that patients with asymptomatic ventricular pre-excitation (asymptomatic WPW or WPW pattern) were at low risk for adverse outcomes. This assumption has been challenged more recently in a number of observational/natural history studies as well as in prospective trials in which patients were more aggressively studied via invasive electrophysiology study (EPS) and more aggressively treated, in some cases, with pre-emptive catheter ablation, despite the lack of symptoms. In sum, the data do not definitively support one approach (early, up-stream EPS and/or ablation) vs. the other (watchful waiting with close monitoring). The most recent pediatric and adult guidelines reflect this ambiguity with a broad spectrum of approaches endorsed.

Danon disease as an underrecognized cause of hypertrophic cardiomyopathy in children.

BACKGROUND: Some patients with hypertrophic cardiomyopathy (HCM) or left ventricular hypertrophy also present with skeletal myopathy and Wolff-Parkinson-White (WPW) syndrome; mutations in the gene encoding the lysosome-associated protein-2 (LAMP-2) have been identified in these patients, suggesting that some of these patients have Danon disease. In this study we investigated the frequency of LAMP2 mutations in an unselected pediatric HCM population. METHODS AND RESULTS: LAMP2 was amplified from genomic DNA isolated from peripheral lymphocytes of 50 patients diagnosed with HCM and analyzed by direct DNA sequencing. In 2 of the 50 probands (4%), nonsense mutations were identified. In 1 family the proband initially presented with HCM as a teenager, which progressed to dilated cardiomyopathy (DCM) and heart failure. Skeletal myopathy and WPW were also noted. The teenage sister of the proband is a carrier of the same LAMP2 mutation and has HCM without skeletal myopathy or WPW. The other proband presented with HCM, WPW, and skeletal myopathy as a teenager, whereas his carrier mother developed DCM during her 40s. Skeletal and cardiac muscle sections revealed the absence of LAMP-2 on immunohistochemical staining. CONCLUSIONS: LAMP2 mutations may account for a significant proportion of cases of HCM in children, especially when skeletal myopathy and/or WPW is present, suggesting that Danon disease is an underrecognized entity in the pediatric cardiology community.