Orthodromic Atrioventricular Reentrant Tachycardia Research Articles

Artificial intelligence in cardiology: a machine learning model for supraventricular tachycardia discrimination

Abstract Background Distinguishing atrioventricular nodal reentrant tachycardia (AVNRT) from orthodromic atrioventricular reentrant tachycardia (AVRT) presents a diagnostic challenge, with clinical and electrocardiogram (ECG) features playing a crucial role in differential diagnosis. Purpose The aim of this study was to devise and validate a predictive algorithm that utilises basic clinical and ECG parameters to accurately classify AVNRT versus AVRT. Furthermore, this algorithm was integrated into a user-friendly, web-based tool to support clinical decision-making. Methods We conducted a prospective analysis of 704 patients (median age: 53.6 years; 59.7% female) with electrophysiologically confirmed AVNRT (n=535) or AVRT (n=169). A comprehensive evaluation was performed using a structured questionnaire tailored to arrhythmia-specific symptoms. The study utilised advanced machine learning techniques for classification, employing feature selection methods to enhance predictive accuracy. The analysis included 19 demographic, clinical, and ECG variables, adopting an 80-20% split for training and internal validation. The algorithm's performance was evaluated against a model comprising all variables (Full Model), expert ECG interpretations (ExpertECG), objective ECG criteria (ECG model), and a baseline dummy classifier, with efficacy assessed by the Area Under the Receiver Operating Characteristic curve (AUC) and the Area Under the Precision-Recall Curve (AUPRC). Results The optimised model, utilising the XGBoost algorithm with six critical variables (initial age at first episode, biological sex, presence of neck palpitations, pseudoR wave in lead V1/pseudoS wave in inferior leads, visibility of retrograde P-waves, and tachycardia cycle length), exhibited superior performance, achieving an AUC of 0.916 and an AUPRC of 0.823. This model significantly outperformed other comparative models in terms of predictive accuracy (Figure 1). Implementation of the model into a web-based interface was accomplished using Shiny, enhancing its accessibility for clinical application (Figure 2). Conclusions This study illustrates the efficacy of employing machine learning algorithms to utilise bedside clinical and ECG variables for accurately differentiating between AVNRT and AVRT. The creation of a web-based calculator marks a significant advancement, empowering clinicians, especially non-specialists, with a potent tool for providing personalised diagnostic insights. Future research should focus on external validation to ascertain the model's generalisability and its applicability in broader clinical settings.Figure 1Figure 2

Analysis of ST segment depression in supraventricular tachycardia and its relationship with underlying mechanism

BackgroundElectrocardiographic diagnosis of causes of supraventricular tachycardia (SVT) is sometimes difficult and application of routine algorithms can lead to misdiagnosis in as many as 37 % of patients. ST segment depression may be useful in diagnosing the nature of SVT. MethodsWe reviewed surface electrocardiogram (ECG) characteristics of 300 patients having SVT with 1:1 AV relationship and correlated findings with electrophysiology study (EPS) findings. Final diagnosis of AVNRT (Atrioventricular nodal reentrant tachycardia), Orthodromic AVRT (atrioventricular reentrant tachycardia) and atrial tachycardia (AT) was correlated with ECG parameters like heart rate, ST segment depressions and QRS morphology. ResultsOut of 300 patients, majority patients included in study, were having AVNRT or AVRT. ST depression predicted AVRT if the ST depression was ≥ 2 mm (overall sensitivity of 38.3 % and specificity of 93.8 % to predict AVRT) and was downsloping in morphology (sensitivity of 36.9 % and specificity of 94.7 % to predict AVRT). At heart rates ≥214 beats per minute (bpm) as measured by 7 small squares of ECG at 25 mm/s, downsloping ST depression ≥2 mm had a sensitivity 37.9 % of and specificity of 89.2 % to predict AVRT. At heart rate <214 bpm, downsloping ST depression ≥2 mm had sensitivity of 37.2 % and specificity of 96.5 % to predict AVRT. Downsloping ST depression of ≥2 mm helps to differentiate AVNRT from AVRT. ConclusionA downsloping ST segment depression ≥2 mm predicted SVT being an AVRT and can be used as a useful criteria in diagnosing the tachycardia.

Unexpected Response of Parahisian Resetting During an Orthodromic Atrioventricular Re-Entrant Tachycardia

Unexpected Response of Parahisian Resetting During an Orthodromic Atrioventricular Re-Entrant Tachycardia

Abstract 13210: A Hidden Right Atrial Lipoma in a Patient With Recurrent Sustained Supraventricular Tachycardias

Introduction: Cardiac lipomas, known for their benign nature, compose 8 percent of primary cardiac tumors. Advanced imaging modalities allow improved diagnosis, yet little of their potential complications involving the heart's conduction system is known. Case: A 65-year-old male presented to the Emergency Department with palpitations. History was significant for recurrent sustained orthodromic atrioventricular reentrant tachycardia using a concealed left posterior accessory pathway from a prior EP study. He was treated with ablation twice in the past. The patient was hemodynamically stable on evaluation. ECG showed supraventricular tachycardia (SVT) involving orthodromic re-entry with a ventricular rate of 227 bpm. Computer tomography (CT) of the chest revealed a large, low-attenuated lesion with -102 Hounsfield unit (HU) attached to the right atrial roof, extending to both SVC and IVC. No sparing of foramen ovale was seen. Findings suggest right atrial lipoma. A transthoracic echocardiogram (TTE) visualized the same echo-dense structure without increased vascularity. The patient responded to intravenous Adenosine. We discussed the case with the Cardiothoracic surgery team. Outpatient cardiac MRI and elective surgery were planned. Discussion: The case presented clinically significant atrial arrhythmia in a patient with a massive right atrial lipoma. Although most cardiac lipomas remain asymptomatic, arrhythmias coinciding with the location of involved chambers have been reported. In addition, the recurrence of orthodromic tachycardia despite previous ablation suggests the potential benefit of surgical intervention.

The Case Files

The Case Files

AP-452681-4 UNUSUAL INITIATION OF ORTHODROMIC ATRIOVENTRICULAR REENTRANT TACHYCARDIA WITH A JUNCTIONAL BEAT

Spontaneous initiation of orthodromic atrioventricular reentrant tachycardia (AVRT) is commonly noted with premature ventricular beat (PVC). In the lab it can be initiated with programmed atrial or ventricular stimulation. We report the initiation of AVRT (with left lateral accessory pathway) with a junctional beat. Case report A 69-year-old male with history of Parkinson’s, HTN, who has had palpitations for few years. Event monitor showed narrow and wide complex tachycardia and he was scheduled for electrophysiology (EP) study and catheter ablation. He presented in sinus rhythm. EP study revealed normal AH and HV intervals with no evidence of preexcitation. Narrow complex supraventricular tachycardia (SVT) initiated spontaneously as noted in the Figure. SVT (short RP) was also initiated with ventricular and atrial extra stimuli without critical AH dependence. There was eccentric atrial activation during SVT with the earliest atrial activation on distal CS. Ventricular overdrive pacing (VOD) during SVT lead to VAV response ruling out atrial tachycardia. There was LBBB during SVT that increased the VA time from 94 ms to 170 ms. The tachycardia terminated with single fused PVC with VA block. Based on these findings a diagnosis of AVRT was made and the concealed left lateral accessory pathway was ablated at 1’o clock on mitral annulus via transseptal catheterization. This case illustrates spontaneous initiation of AVRT using a left lateral accessory pathway with a junctional beat that conducted retrogradely through the accessory pathway. This is a novel finding that has not been demonstrated prior to this. Hence a junctional beat can spontaneously initiate AVRT similar to a PVC. Similarly JPC can initiate AVNRT especially during ablation at the slow pathway region and should not be presumed to be junctional tachycardia.

Accessory pathways in monozygotic twins with different clinical phenotypes: a case report

BackgroundThe atrioventricular reentrant tachycardia (AVRT) is the most common tachycardia associated with accessory pathways (APs). Although sporadic Wolff-Parkinson-White (WPW) syndrome has been well-described, AP occurrence in identical twins with WPW syndrome remains rarely reported.Case presentationWe report a case of 14-year-old monozygotic twin brothers referred for an electrophysiology (EP) study. Twin A presented with recurrent symptomatic narrow complex tachycardia after exercise, noted for 3 years. His 12-lead surface electrocardiogram (ECG) did not show ventricular pre-excitation. However, an orthodromic AVRT utilizing a concealed right posteroseptal AP was found and successfully ablated. AVRT did not recur 12 months after the procedure. Twin B was asymptomatic. During his medical examination for firefighter volunteerism, his 12-lead ECG showed a spontaneous ventricular pre-excitation. EP study revealed a short anterograde right midseptal AP, which was then successfully eliminated by catheter ablation. His 12-lead ECG showed no ventricular pre-excitation recurrence 12 months after the procedure.ConclusionsThese identical twin brothers had a right-side AP in almost the same place but showed completely different phenotypes. This case clearly illustrates the difficulty in understanding genetic contribution in the origin of atrioventricular APs. Environmental exposure could play a role in their clinical presentations and AP electrophysiological properties.

Forward-Solution Noninvasive Computational Arrhythmia Mapping: The VMAP Study.

The accuracy of noninvasive arrhythmia source localization using a forward-solution computational mapping system has not yet been evaluated in blinded, multicenter analysis. This study tested the hypothesis that a computational mapping system incorporating a comprehensive arrhythmia simulation library would provide accurate localization of the site-of-origin for atrial and ventricular arrhythmias and pacing using 12-lead ECG data when compared with the gold standard of invasive electrophysiology study and ablation. The VMAP study (Vectorcardiographic Mapping of Arrhythmogenic Probability) was a blinded, multicenter evaluation with final data analysis performed by an independent core laboratory. Eligible episodes included atrial and ventricular: tachycardia, fibrillation, pacing, premature atrial and ventricular complexes, and orthodromic atrioventricular reentrant tachycardia. Mapping system results were compared with the gold standard site of successful ablation or pacing during electrophysiology study and ablation. Mapping time was assessed from time-stamped logs. Prespecified performance goals were used for statistical comparisons. A total of 255 episodes from 225 patients were enrolled from 4 centers. Regional accuracy for ventricular tachycardia and premature ventricular complexes in patients without significant structural heart disease (n=75, primary end point) was 98.7% (95% CI, 96.0%-100%; P<0.001 to reject predefined H0 <0.80). Regional accuracy for all episodes (secondary end point 1) was 96.9% (95% CI, 94.7%-99.0%; P<0.001 to reject predefined H0 <0.75). Accuracy for the exact or neighboring segment for all episodes (secondary end point 2) was 97.3% (95% CI, 95.2%-99.3%; P<0.001 to reject predefined H0 <0.70). Median spatial accuracy was 15 mm (n=255, interquartile range, 7-25 mm). The mapping process was completed in a median of 0.8 minutes (interquartile range, 0.4-1.4 minutes). Computational ECG mapping using a forward-solution approach exceeded prespecified accuracy goals for arrhythmia and pacing localization. Spatial accuracy analysis demonstrated clinically actionable results. This rapid, noninvasive mapping technology may facilitate catheter-based and noninvasive targeted arrhythmia therapies. URL: https://www. gov; Unique identifier: NCT04559061.

Ventricular versus atrial side ablation for treatment of atrioventricular accessory pathways: a randomized controlled clinical trial.

The earliest atrial (A)/ventricular (V) activation potentials, or fused A/V potentials, are commonly used as ablation targets for atrioventricular (AV) accessory pathways (APs). However, these targets can be achieved in a relatively wide area of the heart around AV rings at both atrial and ventricular sides. The aim of this study is to analyze the height of intracardiac A and V waves and their correlation to find the most appropriate side for successful delivery of radiofrequency energy, atrial or ventricular edge. Ninety patients diagnosed with orthodromic AV re-entrant tachycardia (AVRT) or Wolff-Parkinson-White syndrome were enrolled. Local atrial/ventricular (A/V) amplitude potentials with the earliest activation or fused AV potentials were measured. Patients were randomly assigned into two groups with a 2:1 ratio. In group 1, ablation was done at the site where A was greater than V. In group 2, V was greater than A. Primary endpoint was success at first attempt, achieving antegrade AP conduction block, AV block during right ventricle pacing, or AVRT termination with no AP conduction. Fifty-one patients (56.7%) were male. Thirty patients had an ablation at an atrial site (A > V) and 60 at a ventricular site (V > A). Ablation was more successful at the ventricular site (87% vs 100%, P = 0.011). All 30 patients in the atrial arm and 71% of the ventricular group underwent ablation via the antegrade method. Success of catheter ablation of APs is higher where V > A (ventricular site of AP), indicating the priority of the ventricular edge of the mitral ring for a better outcome.

Catheter Ablation for Atrial Fibrillation in Patients ≤30 Years of Age

Pulmonary vein (PV) automaticity is an established trigger for paroxysmal atrial fibrillation (PAF), making PV isolation (PVI) the cornerstone of catheter ablation. However, data on triggers for atrial fibrillation (AF) and catheter ablation strategy in very young patients aged <30 years are sparse. A total of 51 young patients (mean age 24.0 ± 4.2 years, 78.4% men) with drug-refractory PAF underwent electrophysiology (EP) study and ablation at 5 EP centers. None of the patients had structural heart disease or family history of AF. EP study induced supraventricular tachycardia (SVT) in 12 patients (n=12, 23.5%): concealed accessory pathway mediated orthodromic atrioventricular reentrant tachycardia in 3 patients, typical atrioventricular nodal reentrant tachycardia in 6 patients, left superior PV tachycardia in 1 patient, left atrial appendage tachycardia in 1 patient, and typical atrial flutter in 1 patient. In patients with induced SVTs, SVT ablation without PVI was performed as an index procedure, except for the patient with atrial flutter who received cavotricuspid isthmus ablation in addition to PVI. Remaining patients underwent radiofrequency (n=15, 29.4%) or second-generation cryoballoon-based PVI (n=24, 47%). There were no major complications related to ablation procedures. Follow-up was based on outpatient visits including 24-hour Holter-electrocardiogram at 3, 6, and 12 months after ablation, or additional Holter-electrocardiogram was ordered in case of symptoms suggesting recurrence. Recurrence was defined as any atrial tachyarrhythmia (ATA) episode >30 seconds after a 3-month blanking period. A total of 2 patients with atrioventricular nodal reentrant tachycardia, 1 with left atrial appendage tachycardia, experienced AF recurrence within the first 3 months and received PVI. After the 3-month blanking period, during a median follow-up of 17.0 ± 10.1 months, 44 of 51 patients (86.2%) were free of ATA recurrence. In the PVI group, 33 of 39 patients (84.6%) experienced no ATA recurrence. In conclusion, SVT substrate is identified in around a quarter of young adult patients with history of AF, and targeted ablation without PVI may be sufficient in the majority of these patients. PVI is needed in the majority and is safe and effective in this population.

567 Wolff–Parkinson–White syndrome and sport activity: a peculiar case in a young athlete

Abstract Aims Wolff–Parkinson–White (WPW) is a cardiac conduction system disorder characterized by abnormal accessory conduction pathways between the atria and the ventricles. Palpitations, presyncope, or syncope that result from supraventricular tachycardia represent classic symptoms; however, especially in young athletes, the syndrome can occur with sudden cardiac death. As result, the presence of an accessory pathway (AP) and tachycardia induced by physical activity contraindicates agonist physical activity and represents an indication to perform an electrophysiology (EP) study to stratify the arrhythmic risk, also allowing an eventual transcatheter ablation (TCA) of the AP. Methods and results An agonist football player, known since the age of 6 years for Wolff–Parkinson–White syndrome from an intermittent right midseptal parahissian AP, underwent a transesophageal EP study and subsequently ineffective TCA with radiofrequency when he was 13 years old. For evidence of intermittent ventricular preexcitation (VPE), at the age of 15 he underwent a further endocavitary EP study with documentation of poor conductive abilities of the AP. Subsequently, at the age of 17, he had a resumption of palpitation and lipotimie during effort; during another sport medical examination with an exercise stress test (EST), a persistent VPE with the start of an orthodromic atrioventricular reentrant tachycardia during the recovery phase was documented. A new EP study with isoprenaline infusion confermed the precence of the parahissian AP and the inducibility of an orthodromic atrioventricular reentrant tachycardia (Picture 1-2B); therefore, after mapping the arrhythmia, a cryoablation of AP was performed (Picture 1c-1d). Nevertheless, 12 h after the procedure, there was still evidence of intermittent VPE. The patient was then discharged and, after a month, he repeated the EST with documentation of persistent VPE which suddenly disappeared at the peak of the exercise and reappeared during the recovery phase. At the 1-year follow-up, no arrhythmic recurrence but persistence of VPE was reported and a successive EST confirmed abrupt interruption of VPE at the peak of the exercise. Due to the low arrhythmic risk, sport activity was not more restricted. Conclusions This represents an original clinical case, as it raises the question of what practical criteria should be defined as an effective TCA of AP in a competitive athlete with unfavorable anatomy. The current guidelines (Sport Cardiology and Exercise 2020) provide useful indications in linear and common cases, but may be a source of doubts in particular cases. Therefore, only the experience and the careful evaluation of the individual patient can provide the key to a correct management of the cases like this.

The Utility of a Lewis Lead for Distinguishing Atrioventricular Reentrant Tachycardia from Typical Atrioventricular Nodal Reentrant Tachycardia.

Objective The Lewis lead configuration is an alternative bipolar chest lead and it can help detect atrial activity. The utility of the Lewis lead to distinguish orthodromic atrioventricular reentrant tachycardia (AVRT) from typical atrioventricular nodal reentrant tachycardia (AVNRT) by visualizing the apparent retrogradely conducted P waves was investigated. Methods Forty-four patients with paroxysmal supraventricular tachycardia (PSVT) were included in this study. All patients had PSVT documented by an electrocardiogram (ECG) and underwent an electrophysiological study (EPS). During tachycardia, an ECG recording was performed using a Lewis lead with the electrode on the right aspect of the sternum at the second intercostal space instead of the right arm and the electrode on the fourth intercostal space instead of the left arm. The ECG parameters during tachycardia were compared between AVRT and AVNRT. Results Fourteen patients were diagnosed with AVRTs and 30 with typical AVNRTs on EPS. The positive P wave could be seen in the Lewis lead configuration in 9 of 14 patients with AVRTs and 21 of 30 patients with AVNRTs. P waves were more often visible in the Lewis lead configuration than in the standard leads (66% vs. 45%). The RP interval was significantly longer for AVRTs than for AVNRTs (88±17 vs. 154±34 ms, p<0.001), which yields 89% sensitivity and 71% specificity for distinguishing these 2 tachyarrhythmias with a cut-off point of 100 ms. Conclusion A Lewis lead configuration may help to make an accurate diagnosis among the reentrant supraventricular tachycardias prior to procedures, owing to its ability to locate P waves.

Association of age with clinical features and ablation outcomes of paroxysmal supraventricular tachycardias

ObjectiveThe role of age in clinical characteristics and catheter ablation outcomes of atrioventricular nodal re-entrant tachycardia (AVNRT) or orthodromic atrioventricular re-entrant tachycardia (AVRT) has been assessed in retrospective studies categorising...

Assessing and Managing Asymptomatic Ventricular Preexcitation in the Young Athlete

Assessing and Managing Asymptomatic Ventricular Preexcitation in the Young Athlete

Case Report: Wide-to-Narrow QRS Tachycardia in a 3-Month-Old Infant

Introduction: It is rare to find that wide QRS tachycardia automatically changes to narrow QRS tachycardia, and it is more difficult to clarify the mechanism.Case Report: A 3-month-old infant with recurrent paroxysmal supraventricular tachycardia underwent transesophageal cardiac electrophysiological examination. The wide QRS tachycardia was induced by atrial RS2 stimulation, and it soon changed to narrow QRS tachycardia automatically. By the accurate measurement of esophageal lead, it was found that the electrocardiogram changes completely conform to Coumel law. The mechanism of wide and narrow QRS tachycardia was orthodromic atrioventricular reentrant tachycardia with or without ipsilateral functional bundle branch block, and the accessory pathway was defined as the left free wall-concealed accessory pathway.Conclusion: Transesophageal cardiac electrophysiological examination can reveal some special electrophysiological phenomena, and its non-invasive nature is especially suitable for infants.

Wide complex tachycardia cycle length shorter than the narrow complex tachycardia. What is the mechanism?

15-Year-old man's cardiac event monitor showed an episode of wide complex tachycardia which transitioned into narrow complex tachycardia. The tachycardia cycle length was shorter during wide complex tachycardia compared with narrow complex tachycardia. He underwent electrophysiology study in which an orthodromic atrioventricular reentrant tachycardia (wide and narrow complex tachycardia) utilizing left posterolateral bypass tract was induced. We propose the mechanism for shorter tachycardia cycle length during wide complex tachycardia compared with narrow complex tachycardia.

P1010Electrophysiological characteristics of paroxysmal tachycardia in children with short PQ interval

Abstract Introduction It is well known that children with short PQ interval can have different types paroxysmal tachycardia (PT). Combination of short PQ interval with PT is called Lown-Ganong-Levine (LGL) syndrome. We have hypothesized that in children with short PQ interval electrophysiological types of PT do not correlate with shortening of PQ interval. Purpose The aim of the study was to assess the PT types based on results of the electrophysiological studies and radiofrequencycatheter ablation (RFA), and to estimate the AV conduction parameters and their dynamic changes before and after the procedure. Materials and methods of research: 55 children with supraventricular tachycardia (SVT) and short PQ interval were examined. The examination included:ECG, 24-hour Holter monitor, transesophageal pacing study (TEPS), intracardiac electrophysiological study (EPS). 22 children underwent RFA procedure. During the period of the study 55 children had 111 TEPS and 28 EPS studies. Results 21 (38,2%) children had orthodromic AV reentrant tachycardia with accessory pathway (AVRT), 27 (49,1%) had typical (slow-fast) AV nodal reentrant tachycardia (AVNRT), 2 (3,6%) had atypical AVNRT, 1 (1,8%) had combination of typical and atypical AVNRT, 1 (1,8%) had atrial ectopic tachycardia combined with atypical AVNRT, 4 (7,3%) had spontaneous atrial fibrillation or atrial flutter, 3 (5,4%) had combination with typical AVNRT and 1 child (1,8%) had AVRT. PQ interval measured 107,2 ms (83–120ms). 22 (40%) children underwent RFA-13 children with typical AVNRT, 9 with AVRT. In children with AVNRT tachycardia cycle length was 229–425 ms (309,8±67,6ms). Primary RFA was effective in 10 (76,9%) children. The AVNRT recurrence was found in 3 (13,6%) cases after 7,2±4,3 month from the time of procedure. After slow pathway ablation PQ interval length didn't change (107,1±9,1ms compared to 108,2±7,1ms; p=0,2). No change occurred with the maximal rate of 1:1 conduction through AV node (187,8±14,8 imp/min compared to187±12,5 imp/min; p=0,2). Effective refractory period of AV node (AVNERP) increased by a small amount (288,9±14ms, compared to 266±42,7ms; p=0,06). 9 (40,9%) children underwent RFA of the accessory pathway (AP). In all of the cases there were concealed AP with the left-sided localization. AVRT cycle length was 259–382 ms (304,2±41,2ms). After RFA of concealed AP maximal rate of 1:1 conduction through AV node increased by a small amount (220±26,4 imp/min compared to 191,2±23,6 imp/min) and AVNERP decreased (256,7±25,2ms compared to 268,6±38,9ms; p=0,09).After RFA of AP PQ interval length didn't change (110±5,9ms compared to 110±5ms; p=0,1). Conclusion In children with short PQ interval PT was associated with dual physiology of AV connection or with concealed AP. After the successful RFA in children with AVNRT and AVRT there was no PQ interval normalization, which remained short in all examinations. Thus, short PQ- interval is a co-existing phenomenon in children with AVNRT and AVRT.

Electrophysiological properties of asymptomatic children and adolescents with the Wolff-Parkinson-White electrocardiographic pattern

Optimal management in asymptomatic children and adolescents with the Wolff-Parkinson-White (WPW) electrocardiographic pattern is still debatable. The aim of this retrospective study was to evaluate the electrophysiological properties of asymptomatic children and adolescents with WPW. The medical records and procedural data of asymptomatic children and adolescents with the WPW electrocardiographic pattern who underwent invasive electrophysiological study (EPS) and catheter ablation between April 2012 and April 2018 were evaluated. In all, 149 consecutive, asymptomatic children and adolescents with WPW who underwent EPS were retrospectively investigated. In 39 (26.2%) of the patients, a shortest pre-excited R-R interval of ≤250 ms during atrial fibrillation or an accessory pathway effective refractory period of ≤270 ms was found. A total of 39 patients with high-risk antegrade conduction and 45 patients with inducible orthodromic atrioventricular re-entrant tachycardia underwent catheter ablation. In addition, 14 patients underwent catheter ablation due to family preference. High-risk antegrade conduction properties are exhibited by more than one-quarter of asymptomatic children and adolescents with WPW. Ablation should be considered as a first-line therapy in asymptomatic children and adolescents with high-risk WPW.

Coexistence of atrioventricular accessory pathways and drug-induced type 1 Brugada pattern.

Atrial arrhythmias, particularly atrioventricular nodal reentrant tachycardia, can coexist with drug-induced type 1 Brugada electrocardiogram (ECG) pattern (DI-Type1-BrP). The present study was designed to determine the prevalence of DI-Type1-BrP in patients with atrioventricular accessory pathways (AV-APs) and to investigate the clinical, electrocardiographic, electrophysiologic, and genetic characteristics of these patients. One-hundred twenty-four consecutive cases of AV-APs and 84 controls underwent an ajmaline challenge test to unmask DI-Type1-BrP. Genetic screening and analysis was performed in 55 of the cases (19 with and 36 without DI-Type1-BrP). Patientswith AV-APs were significantly more likely than controls to have a Type1-BrP unmasked (16.1vs 4.8%, P=0.012). At baseline, patients with DI-Type1-BrP had higher prevalence of chest pain, QR/rSr' pattern in V1 and QRS notching/slurring in V2 and aVL during preexcitation, rSr' pattern in V1 -V2 , and QRS notching/slurring in aVL during orthodromic atrioventricular reentrant tachycardia (AVRT) compared to patients without DI-Type1-BrP. Abnormal QRS configuration (QRS notching/slurring and/or fragmentation) in V2 during preexcitation was present in all patients with DI-Type1 BrP. The prevalence of spontaneous preexcited atrial fibrillation (AF) and history of AF were similar (15%vs 18.3%, P=0.726) in patients with and without DI-Type1-BrP, respectively. The prevalence of mutations in Brugada-susceptibility genes was higher (36.8%vs 8.3%, P=0.02) in patients with DI-Type1-BrP compared to patients without DI-Type1-BrP. DI-Type1-BrP is relatively common in patients with AV-APs. We identify 12-lead ECG characteristics during preexcitation and orthodromic AVRT that point to an underlying type1-BrP, portending an increased probability for development of malignant arrhythmias.

Clinical course and treatment of children and adolescents with the preexcitation syndrome - own studies.

IntroductionEssentially, preexcitation syndrome is the presence of an accessory pathway in the heart, which can lead to serious consequences, ranging from atrioventricular reentrant tachycardia to sudden cardiac death. Wolff-Parkinson-White syndrome is the most common preexcitation syndrome.Aim of the studyThe aim of the study was to evaluate the clinical course of the disease, as well as the treatment of children and adolescents hospitalized in the Department of Pediatric Cardiology in the years 2008-2015.Materials and methodsThe study was carried out in 45 children (62 % male, 38% female; the mean age 11 years). During the study we analyzed 12-lead ECG, 24-hour Holter ECG, echocardiography and the cycloergometric exercise test. The results of treatment were also discussed.ResultsApart from the typical features of preexcitation, the most prevalent abnormality found in ECG was atrioventricular reentrant tachycardia. In 24-hour Holter ECG the most frequently detected disorders were premature ventricular beats and premature atrial contractions. Structural heart defects were detected in 8.9% of the children. The cycloergometric exercise test was positive in 8.9% of patients. The mean duration of symptoms before the diagnosis was 2.5 years. 25% of the patients were asymptomatic. 42.2% of the children needed antiarrhythmic therapy, while 44.4% had accessory pathways ablated.ConclusionsThe most common symptom of preexcitation in the study group were heart palpitations. The most frequent type of arrhythmia in children with preexcitation syndrome was orthodromic atrioventricular reentrant tachycardia. For the majority of older children ablation of the accessory pathway was a recommended form of treatment. In younger children the standard preventive pharmacological treatment was applied for 6 to 12 months.Charakterystyczną cechą zespołów preekscytacji jest obecność dodatkowej, nieprawidłowej drogi przewodzenia w sercu. Najczęstszym typem zespołu preekscytacji jest zespół Wolffa-Parkinsona-White’a.