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Patients with the Wolff-Parkinson-White syndrome may experience benign and malignant arrhythmias, the most common being atrioventricular reentrant tachycardias. This arrhythmia may degenerate into atrial fibrillation, which can be conducted over an accessory pathway capable of exceptionally fast conduction to the ventricles and degenerate into ventricular fibrillation, leading to sudden cardiac death. These life-threatening events generally affect symptomatic patients in their third or fourth decade. Although rare, ventricular fibrillation may be the first clinical manifestation in subjects who are asymptomatic or unaware of their conditions. Electrophysiologic study may be useful to identify subjects at high risk of sudden cardiac death.

Spine diseases are common and exhibit several causes, including degeneration, trauma, congenital issues, and other specific factors. Most people experience a variety of symptoms of spine diseases during their lifetime that are occasionally managed with conservative or surgical treatments. Accurate diagnosis of the spine pathology is essential for the appropriate management of spine disease, and various imaging modalities can be used for the diagnosis, including radiography, computed tomography (CT), magnetic resonance imaging (MRI), and other studies such as EOS, bone scan, single photon emission CT/CT, and electrophysiologic test. Patient (or case)-specific selection of the diagnostic modality is crucial; thus, we should be aware of basic information and approaches of the diagnostic modalities. In this review, we discuss in detail, about diagnostic modalities (radiography, CT, MRI, electrophysiologic study, and others) that are widely used for spine disease.

The known mechanisms for cardiac arrhythmias are disorders of impulse formation, disorders of impulse conduction, or combinations of both. However, in many cases, a combination of mechanisms is responsible for arrhythmia initiation or perpetuation. Sometimes arrhythmia caused by one mechanism could initiate another arrhythmia, such as one PAC with an automaticity mechanism could initiate a macroreentrant atrial tachycardia. The risk of different types of arrhythmia is various; some of them such as VF are very hazardous. AF may be sometimes silent and sometimes cause CVA. There are different diagnostic approaches for diagnosis of arrhythmia, such as ECG, Holter monitoring, SAECG, and invasive electrophysiologic study (EPS). Therapy for cardiac arrhythmia includes antiarrhythmic drugs, electrical cardioversion, radiofrequency ablation of the source of the arrhythmia (RFA), freezing of the culprit site of the arrhythmia, and surgical ablation.

INTRODUCTION AND OBJECTIVES: Multiparametric scores have been designed for better risk stratification in Brugada syndrome (BrS). We aimed to validate 3 multiparametric approaches (the Delise score, Sieira score and the Shanghai BrS Score) in a cohort with Brugada syndrome and electrophysiological study (EPS). METHODS: We included patients diagnosed with BrS and previous EPS between 1998 and 2019 in 23 hospitals. C-statistic analysis and Cox proportional hazard regression models were used. RESULTS: A total of 831 patients were included (mean age, 42.8±13.1; 623 [75%] men; 386 [46.5%] had a type 1 electrocardiogram (ECG) pattern, 677 [81.5%] were asymptomatic, and 319 [38.4%] had an implantable cardioverter-defibrillator). During a follow-up of 10.2±4.7 years, 47 (5.7%) experienced a cardiovascular event. In the global cohort, a type 1 ECG and syncope were predictive of arrhythmic events. All risk scores were significantly associated with events. The discriminatory abilities of the 3 scores were modest (particularly when these scores were evaluated in asymptomatic patients). Evaluation of the Delise and Sieira scores with different numbers of extra stimuli (1 or 2 vs 3) did not substantially improve the event prediction c-index. CONCLUSIONS: In BrS, classic risk factors such as ECG pattern and previous syncope predict arrhythmic events. The predictive capabilities of the EPS are affected by the number of extra stimuli required to induce ventricular arrhythmias. Scores combining clinical risk factors with EPS help to identify the populations at highest risk, although their predictive abilities remain modest in the general BrS population and in asymptomatic patients.

Ablation of ganglionated plexuses (GPs) is a relatively new technique in patients with vasovagal syncope. Due to individual variation of GP settlement, reproducible GP detection methods are needed to during electrophysiologic study. In the present case, fractionation mapping software of Ensite system was tested to detect localization of GPs and first compared with previously validated fractionated electrograms based strategy.

Background To investigate the relationship between the location of accessory pathways, electrophysiologic characteristics, and ablation success in Wolfe-Parkinson-White (WPW) syndrome. Methods Electrophysiologic study was performed in 178 patients for a pre-excitation syndrome. Accessory pathway location, anterograde or retrograde conduction, ablation success, and recurrence rate were evaluated. Results Among 178 patients with WPW syndrome, the most frequent location of the accessory pathway was left lateral (39.3%) which had high ablation success rate (97%) and low recurrence rate (1%). A meaningful relationship exists between accessory pathway location and electrophysiologic characteristics. Ablation success rate was 89.7% and was statistically related to accessory pathway location. Recurrent occurred in 2.9% of our patients and was more frequent in right free wall and PJRT. Conclusions The location of accessory pathways has a great impact on conductivity, ablation success, and recurrence rate in WPW syndrome.

Introducao O desenvolvimento de dor precordial associada ao bloqueio de ramo esquerdo (BRE) intermitente na ausencia de doenca arterial coronariana tem sido descrito na literatura como sindrome do bloqueio de ramo esquerdo doloroso. O mecanismo responsavel pela dor precordial e desconhecido, mas a principal hipotese atualmente esta relacionada a dissincronia cardiaca aguda. Nessa sindrome, o BRE ocorre quando a duracao do ciclo e igual ou inferior ao periodo refratario do ramo esquerdo, principalmente durante o esforco fisico. A dor toracica [...]

Background The value of eletrophisiologic study (EPS) with programmed ventricular stimulation for risk stratification in patients with Brugada Syndrome (BS) remains controversial. Purpose The aim of this study is to determine the clinical and electrocardiographic predictors of positive EPS and to evaluate whether the induction of malignant ventricular dysrhythmias in the EPS is a predictor of events Methods A retrospective study was carried out of patients with spontaneous type 1 Brugada pattern followed up in Arrhythmology consultation at our Hospital. From this population, patients who underwent EPS for stratification of dysrhythmic risk were selected. Clinical and electrocardiographic variables were analyzed. Hospital records and monitoring data from cardiac devices were consulted. Statistical analysis was performed using SPSS 20.0. Results Fourty nine patients were included, with a mean age at the beginning of follow-up of 45±14 years, 40 (82%) of whom were male. In 16 individuals (33%) the EPS was positive with induction of malignant ventricular dysrhythmias. All patients with positive EPS implanted an implantable cardioverter-defibrillator and of the 32 patients with negative EPS, 10 implanted an implantable event recorder. The group of patients with positive EPS had a higher proportion of male patients (88% vs 78%). The median follow-up time was 31 months. The family history of sudden death, family history of BS, or identification of a genetic variant classified as pathogenic or probably pathogenic did not present any relationship with EPS positivity. Of the analyzed electrocardiographic markers, PR interval (178±29 vs 171±27) and QRS duration (119±24 vs 113±15) tended to be longer in patients with positive EPS. Additionally, it was found that 74% of patients with a QRS of less than 120 ms had a negative EPS. In the analysis of the value of EPS in the stratification of dysrhythmic risk, it was found that of all the patients who suffered events (4), 75% had positive EPS. Of the patients with negative EPS, only 3% (1) presented events in the follow-up. However, there was no significant association between these variables. Conclusion In this population, the analysed clinical elements did not correlate with the EPS result. Although there was no statistical significance, there was a tendency for patients with narrower QRS to be more likely to have negative EPS. Accordingly with published data, it was found that the EPS result was not a predictor of events during the follow-up period, which highlights the difficulty of risk stratification in patients with BS. Funding Acknowledgement Type of funding sources: None.

Introduction The arrhythmic risk stratification of patients with repaired Tetralogy of Fallot (TOF) is still controversial. The performance of an electrophysiologic (EP) study before pulmonary valve replacement (PVR), regardless of patient's risk factors, is an extended practice in some centers that is not recommended in current guidelines. The aim of our study was to explore the differences in ventricular tachycardia (VT) inducibility in patients with TOF during programmed ventricular stimulation (PVS) depending on the clinical indication. Methods All patients with repaired TOF who underwent an EP study with PVS between January 2001 and October 2020 were included. EP studies performed in the context of ventricular or supraventricular tachycardia ablations that had been previously diagnosed were excluded. We defined two clinical scenarios for performing the EP study: pre-PVR (performed previous to pulmonary valve replacement) or diagnostic EP study (performed due to high risk symptoms which included palpitations, syncope or presyncope). Baseline clinical information, electrocardiogram, echocardiogram and cardiac MRI parameters were retrospective recorded. Results A total of 139 EP studies with PVS were included; 87 in the pre-PVR group and 52 in the diagnostic EP study group. There was a greater incidence of palpitations, syncope and presyncope in the “Diagnostic EP study” group. Moreover, there were statistical significant differences in right ventricle dimensions and function between groups. The repair surgical approach was similar in both groups. It was detected a statistical significant difference in VT induction between the pre-PVR group and the diagnostic indicated group (16,1% vs 34,6%, p=0,012). Conclusions Differences in VT induction are observed during PVS performing in TOF patients depending on the clinical indication. Symptomatology is an important parameter that must be taken into account in order to decide whether to perform an EP study in this population. Funding Acknowledgement Type of funding sources: None.

(1) Background: The exact anatomic localization of the accessory pathway (AP) in patients with Wolff–Parkinson–White (WPW) syndrome still relies on an invasive electrophysiologic study, which has its own inherent risks. Determining the AP localization using a 12-lead ECG circumvents this risk but is of limited diagnostic accuracy. We developed and validated an artificial intelligence-based algorithm (location of accessory pathway artificial intelligence (locAP AI)) using a neural network to identify the AP location in WPW syndrome patients based on the delta-wave polarity in the 12-lead ECG. (2) Methods: The study included 357 consecutive WPW syndrome patients who underwent successful catheter ablation at our institution. Delta-wave polarity was assessed by four independent electrophysiologists, unaware of the site of successful catheter ablation. LocAP AI was trained and internally validated in 357 patients to identify the correct AP location among 14 possible locations. The AP location was also determined using three established tree-based, ECG-based algorithms (Arruda, Milstein, and Fitzpatrick), which provide limited resolutions of 10, 5, and 8 AP locations, respectively. (3) Results: LocAP AI identified the correct AP location with an accuracy of 85.7% (95% CI 79.6–90.5, p &lt, 0.0001). The algorithms by Arruda, Milstein, and Fitzpatrick yielded a predictive accuracy of 53.2%, 65.6%, and 44.7%, respectively. At comparable resolutions, the locAP AI achieved a predictive accuracy of 95.0%, 94.9%, and 95.6%, respectively (p &lt, 0.001 for differences). (4) Conclusions: Our AI-based algorithm provided excellent accuracy in predicting the correct AP location. Remarkably, this accuracy is achieved at an even higher resolution of possible anatomical locations compared to established tree-based algorithms.

Cannabis usage is increasing throughout the world for both medicinal and recreational purposes. Several countries and states have legalized cannabis, and physicians can expect to encounter more patients who use or abuse cannabis. Adverse cardiovascular effects of cannabis like myocardial infarction, cardiomyopathy, and arrhythmias have been well described but bradyarrhythmia is rare and the mechanisms are not well pronounced. A 26-year-old male with a history of chronic cannabis smoking presented with complaints of dizziness and recurrent syncope. The heart rate at presentation was 42 beats per minute and the rest of the physical examination was unremarkable. There was an atrioventricular (AV) block in the ECG and a subsequent electrophysiological study (EPS) showed a high-grade supra-Hisian (nodal) AV block with prolonged His-ventricular (HV) interval. The urinary screen was positive for tetrahydrocannabinol metabolite (11-Nor-9-carboxy THC). After ruling out other possible causes, a diagnosis of high-grade AV block due to chronic cannabis use was made. A dual-chamber pacemaker was implanted and the patient was discharged in stable condition. The arrhythmia did not improve completely at the three-month follow-up. We report a novel finding in cannabis-induced bradyarrhythmia. High-grade AV block with the electrophysiologic determination of the site of conduction blockade has not been reported previously. The mechanism of bradyarrhythmia is thought to be mediated by increased vagal tone. However, prolonged HV interval and persistent nature of block indicate that direct toxic effects of cannabis, through cannabinoid receptors 1 (CB1R), on the cardiac conduction system cannot be ruled out. Also, the possibility of cannabis arteritis involving microvasculature should be kept.

A 27-year-old male was referred for further assessment after being evaluated by his general practitioner for isolated palpitations. A twelve-lead electrocardiogram was performed in which sinus rhythm with ventricular pre-excitation were observed. Electrophysiologic study demonstrated the presence of a fasciculoventricular accessory pathway.

Background: The long-term predicted value of microvolt T-wave alternans (MTWA) for ventricular tachyarrhythmia in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) remains unclear. Our study explored the characteristics of MTWA and its prognostic value when combined with an electrophysiologic study (EPS) in patients with ARVC. Methods: All patients underwent non-invasive MTWA examination with modified moving average (MMA) analysis and an EPS. A positive event was defined as the first occurrence of sudden cardiac death, documented sustained ventricular tachycardia (VT), ventricular fibrillation, or the administration of appropriate implantable cardioverter defibrillator therapy including shock or antitachycardia pacing. Results: Thirty-five patients with ARVC (age 38.6 ± 11.0 years; 28 males) with preserved left ventricular (LV) function were recruited. The maximal TWA value (MaxValt) was 17.0 (11.0–27.0) μV. Sustained VT was induced in 22 patients by the EPS. During a median follow-up of 99.9 ± 7.7 months, 15 patients had positive clinical events. When inducible VT was combined with the MaxValt, the area under the curve improved from 0.739 to 0.797. The receiver operating characteristic curve showed that a MaxValt of 23.5 μV was the optimal cutoff value to identify positive events. The multivariate Cox regression model for survival showed that MTWA (MaxValt, hazard ratio [HR], 1.06; 95% confidence interval [CI], 1.01–1.11; P = 0.01) and inducible VT (HR, 5.98; 95% CI, 1.33–26.8; P = 0.01) independently predicted positive events in patients with ARVC. Conclusions: MTWA assessment with MMA analysis complemented by an EPS might provide improved prognostic ability in patients with ARVC with preserved LV function during long-term follow-up. Key words: Modified moving average analysis; Microvolt T-wave alternans; Electrophysiologic study; Ventricular tachyarrhythmia; Arrhythmogenic right ventricular cardiomyopathy

Implantable loop recorders allow prolonged and continuous single-lead electrocardiogram recording, with the pivotal addition of remote monitoring. They have significantly shortened time to electrocardiographic diagnosis and appropriate therapy of many bradyarrhythmias/tachyarrhythmias and proved helpful in arrhythmia burden definition, offering invaluable information in the diagnostic workup for syncope and atrial fibrillation. Advanced cardiac signal recording is also possible by transesophageal catheters. They have been used to orient diagnosis during wide and narrow QRS complex tachycardias and also to perform minimally invasive pacing. Intracardiac electrophysiologic study remains, however, essential for diagnosis of several arrhythmias in the perspective of curative catheter ablation.

Graphical abstract, Highlights • EA is a distinct entity on echocardiography. • Accessory pathways are commonly seen with EA. • Mahaim fiber tachycardia is a rare accessory pathway–mediated tachycardia.

Yeni, S. Naz/0000-0001-7372-5430 WOS:000462164600002 Objective: Autonomic nervous system dysfunction during the interictal period of epileptic seizures is still poorly understood. We assessed sympathetic and parasympathetic functions during the interictal period using sympathetic skin response (SSR) and R-R interval variability (RR-IV) methods in patients with epilepsy. Methods: We questioned the presence of autonomic symptoms in 50 patients with epilepsy and 42 healthy controls. We also measured SSR and RR-IV percentage (RR-IV%) at rest, deep inspiration, and during the Valsalva maneuver. Orthostatic hypotension (OH) was also evaluated. Results: Of the 50 patients with epilepsy, 21 patients had temporal lobe epilepsy (TLE) and 29 had extratemporal lobe epilepsy. Autonomic symptoms (orthostatic intolerance, gastromotor, pupillomotor, vasomotor, secretomotor symptoms) and OH were significantly more common in patients with TLE (p

Objective: There are clinical similarities between akathisia and restless legs syndrome (RLS). Thus, we aimed to investigate the functional changes of the brainstem and its rostral connections in akathisia in comparison with RLS. Materials and Methods: Seven patients with akathisia were included in the study. We also included a group of patients with RLS (n=14), and a control group was formed including healthy volunteers (n=39). Blink reflex (BR), auditory startle reflex (ASR), and somatosensory startle (SSS) reflexes were studied in all participants. Onset latency, probability of response, amplitude, pattern and duration of responses were compared between the 3 groups. Results: Mean onset latencies of bilateral R2 and R2c were longer in the akathisia group compared with patients with RLS and healthy individuals. The mean latencies of responses after auditory stimulation were similar among the groups. The total ASR probability was higher in the akathisia and RLS groups compared with healthy subjects and this difference showed borderline significance (p=0.047). Duration of responses after auditory stimulation was longer in the akathisia group. Presence and latency of SSS were similar among the three groups. Conclusion: Longer-onset latencies and the higher probability of ASR in the akathisia group suggest that there is a hypodopaminergic state in this group. On the other hand, the longer latencies of R2-BR in patients akathisia suggest a delayed transmission in its pathway, indirectly showing involvement of serotoninergic pathways in the absence of a structural lesion. Thus, in akathisia, there are findings suggestive of serotoninergic involvement, differing from RLS, whereas findings attributed to dopaminergic deficits were quite similar to patients with RLS.

Regular atrial tachycardia (AT) is one of the most important proarrhythmic complications that may occur following left atrial pulmonary vein isolation (PVI). These tachycardias that develop after atrial fibrillation ablation may lead to worse symptoms than those from the original arrhythmia existing prior to the index ablation procedure. Ablation of various types of supraventricular tachycardias without the use of fluoroscopy has been shown to be feasible in both children and adults using three-dimensional mapping systems. We describe the case of a 71-year-old woman who developed a focal AT after a successful PVI procedure. The initial ablation failed with one mapping system. Repeat electrophysiologic study despite antiarrhythmic medications revealed the same focal AT, which was successfully ablated with a different mapping system. Both ablations were performed without fluoroscopy.

Background: The existence of atypical fast-slow (F/S) atrioventricular (AV) nodal reentrant tachycardias (NRT) using slow pathway (SP) variants connected to the right atrial (RA) inferolateral (inf) free wall (FW) along the tricuspid annulus (TA), has been neither confirmed nor precisely characterized. Methods and Results: We studied 7 patients (mean age, 48±16 years; 5 men) with F/S-AVNRT with long RP intervals and an earliest atrial activation at the RA inf-FW along the TA (inf-F/S-AVNRT). AV reentrant tachycardia was excluded on observation of the transition zone criteria in all 7 patients. Atrial tachycardia was excluded on the observation of a V-A-V activation sequence after the induction or entrainment of the tachycardia from the right ventricle in all. During the tachycardia, low-frequency, fractionated potentials (LP) preceding the local atrial electrogram were recorded near the site of the earliest atrial activation in 6 patients. Observations of conduction delay and block of the LP during ventricular entrainment or ablation of the tachycardia indicated that LP reflect retrograde activation via the inf-SP. Retrograde SP conduction was interrupted at the site of earliest atrial activation in 3 patients, and in the right posterior septum in 4 patients. Conclusions: inf-F/S-AVNRT are distinct supraventricular tachycardia incorporating an SP variant connected to the RA inf-FW along the TA in the retrograde direction, which were eliminated by ablation.

The overall aim of an invasive electrophysiological (EP) evaluation is to accurately diagnose the mechanism and substrate responsible for a documented or suspected arrhythmia to treat the patient’s symptoms or improve his/her prognosis. Significant developments in the understanding of arrhythmias as well as technological advances have allowed electrophysiology studies to be considered as a diagnostic first line option. This chapter discusses the fundamental principles of invasive electrophysiology and provides an essential guide in terms of establishing the correct diagnosis and ablation strategy.

Background: The recurrent laryngeal nerve (RLN) can be injured during thyroid surgery, which can negatively affect a patient's quality of life. The impact of intraoperative anatomic variations of t...

Syncope in patients with Brugada electrocardiogram pattern may represent a conundrum in the decision algorithm because incidental benign forms, especially neurally mediated syncope, are very frequent in this syndrome similarly to the general population. Arrhythmic syncope in Brugada syndrome typically results from a self-terminating sustained ventricular tachycardia or paroxysmal ventricular fibrillation, potentially leading to sudden cardiac death. Distinguishing syncope due to malignant arrhythmias from a benign form is often difficult unless an electrocardiogram is recorded during the episode. We performed a review of the existing literature and propose a practical approach for diagnosis and treatment of the patients with Brugada syndrome and syncope.

The electrophysiologic study is performed by inserting electrode-tipped catheters into the body and positioning them within the heart. In a typical diagnostic study, the baseline intracardiac intervals, RR, AH, and HV, are measured, and the responses to pacing from different sites in the atria and ventricles are analyzed. Precise measurements of AV conduction can be performed with intracardiac recording. In addition to the basic surface ECG measurements of the PR, QRS, QT, PP, and RR intervals, in an electrophysiologic study, atrioventricular conduction can be further analyzed by quantifying the AH and HV intervals. Significantly prolonged AH intervals in the lack of reversible factors may represent high vagal tone, intrinsic AV nodal disease, or conduction down the slow pathway of the atrioventricular node. Retrograde conduction, measured by the VA interval, the time between ventricular depolarization to the earliest atrial depolarization is also helpful in the study of supraventricular tachycardias.

At 22 years following heart transplantation, a patient presented with incessant atrial flutter. During electrophysiologic study, 2 simultaneous atrial…, At 22 years following heart transplantation, a patient presented with incessant atrial flutter. During electrophysiologic study, 2 simultaneous atrial arrhythmias were mapped, 1 from the donor and 1 from the recipient’s heart. High-density mapping allowed for rapid identification of electrically abnormal areas, which were successfully ablated, thus restoring sinus rhythm. (Level of Difficulty: Advanced.), Graphical abstract

Background Mitral valve prolapse has been associated with increased risk of ventricular arrhythmias. We aimed to examine whether certain cardiac imaging characteristics are associated with papillary muscle origin of ventricular arrhythmias in these patients. Methods and results We screened electronic medical records of all patients documented to have mitral valve prolapse on either transthoracic echocardiogram (TTE) or cardiac magnetic resonance imaging (CMR) in our center, who also underwent an electrophysiologic study (EPS) between 2007 and 2016. Anterior and posterior mitral leaflet thickness and prolapsed distance were measured on TTE and late gadolinium enhancement (LGE) was assessed on CMR. Patients were categorized as papillary muscle positive (pap (+)) or negative (pap (-)) using EPS. Eighteen patients were included in this study. Of the 15 patients who underwent TTE, a significantly higher proportion of patients in the pap (+) group had an anterior to posterior leaflet prolapse ratio of >0.45 indicating more symmetric leaflet prolapse. There were no differences in anterior or posterior leaflet thickness or prolapse distance between the groups. Patients in the pap (+) group were more likely to be women. Of the 7 patients who underwent CMR, those who were pap (+) were more likely to have LGE in the region of the papillary muscles than those who were pap (-). Conclusion Female gender, more symmetric bileaflet prolapse on TTE, and the presence of papillary muscle LGE on CMR may be associated with papillary muscle origin of ventricular arrhythmias in patients with mitral valve prolapse.

Background The differential diagnosis of a supraventricular tachycardia (SVT) is accomplished using a number of pacing maneuvers. The incidence and mechanism of a single ventricular premature beat (VPB) on initiation and termination of tachycardia were evaluated during programmed electrical stimulation (PES) of the heart in patients with the two most common regular SVTs: atrioventricular re-entrant tachycardia (AVNRT) and orthodromic atrioventricular tachycardia (AVRT). Methods Three hundred and thirty-seven consecutive patients aged above 18 years with an inducible sustained AVNRT or AVRT were prospectively enrolled. Patients with more than one tachyarrhythmia mechanism were excluded. Two hundred and seventeen patients (64.4%) had typical slow/fast AVNRT and 120 (35.6%) had an orthodromic AVRT using a rapidly conducting accessory pathway for V-A conduction. In this cross-sectional study, we specifically report the analysis of tachycardia induction and termination by a single VPB. Results Tachycardia induction with a single VPB during sinus rhythm was seen in 7 of 120 AVRT and in only one of the 217 patients with AVNRT, (5.8% vs. 0.3%, p

A 14-year-old girl with a history of recurrent palpitations and documented wide QRS complex tachycardia was referred for electrophysiologic study and catheter ablation.

Rationale: Amiodarone, a broad-spectrum antiarrhythmic drug, is widely used for the clinical treatment of tachyarrhythmias because of its safety and efficacy. Patient concerns: A 30-year-old woman presented with known paroxysmal atrial tachycardia and severe preeclampsia. Two days before admission, she had given birth to twins. She described her symptoms as a sudden palpitation at 10:20 accompanied by chest tightness and shortness of breath. Diagnosis: Cardiac arrhythmia and acute left heart failure. Interventions: Furosemide and sodium nitroprusside were administered to control the heart failure. At 16:20, 150 mg amiodarone (15 mg/min) was injected intravenously and continued at 1 mg/min. At 16:50, her electrocardiogram showed possible atrial tachycardia or atrial flutter with a ventricular rate of 206 beats/min. Administration of amiodarone was stopped at 17:23, and the medication was changed to esmolol. Outcomes: After 3 minutes, the palpitations stopped, the heart rate changed to a sinus rhythm, and the ventricular rate was 100 beats/min. Four days later, the patient underwent an electrophysiologic study and radiofrequency ablation. Lessons: When amiodarone is used to treat atrial arrhythmia, the ventricular rate may accelerate, which can cause patients with borderline heart failure to develop acute heart failure or further deterioration of acute heart failure. For heart failure induced or mediated by atrial arrhythmias, short-term β-blockers may be used to control the ventricular rate more quickly and effectively and to prevent the progression of heart failure.

Background: Refractory periods are measured by the extrastimulus technique, whereby a single extrastimulus is introduced at progressively shorter coupling intervals until a response is no longer elicited. Purpose: As refractoriness of cardiac tissues depends on prior cycle length, refractory periods should be determined at a fixed cycle length within the physiologic range. The extrastimulus is delivered after a train of 8 to 10 paced complexes to allow time for reasonable stabilization of refractoriness, which is usually accomplished after the first 3 or 4 paced beats. Objectives: We conducted this study to compare the effect of 6 vs 8 stimuli in basic cycle length (BCL) in measurement of effective refractory period (ERP). Materials and Methods: During electrophysiologic study (EPS) of 100 consecutive patients, anterograde and retrograde ERP of atrioventricular node (AVN) were measured by introduction of 6 vs 8 stimuli in BCL and premature beat, then the results were compared. Results: Recorded anterograde and retrograde ERP of AVN applying 6 vs 8 stimuli in BCL were compared and no difference was detected. Conclusion: We concluded that for ERP measurement of AVN, 6 stimuli in BCL is comparable to 8 stimuli in reaching the steady state.

We present a case of incessant wide-complex tachycardia in a patient with left-ventricular assist device, and discuss the differential diagnosis with an in-depth analysis of the intracardiac tracings during the invasive electrophysiologic study, including interpretation of the relative timing of the fascicular signals during tachycardia and in sinus rhythm, and interpretation of pacing and entrainment maneuvers.

For older patients with unexplained syncope and chronic bifascicular block (BFB), ACC/HRS and ESC guidelines recommend empiric permanent pacemaker (PPM) implantation, or electrophysiologic study (EPS) and/or implanted loop recorder (ILR) to identify high-degree AV block. Single-center retrospective

Electrodiagnostic medicine is a specific area of physical medicine and rehabilitation in which a physiatrist uses clinical history, physical examination, and the techniques of electrophysiologic study to diagnose and treat neuromuscular disorders. The roles of electrodiagnosis include (1) determining the localization and distribution of a lesion and severity of a disease, (2) characterizing the evolution of a disease, (3) estimating prognosis, (4) differentiating neuropathy and myopathy, and (5) monitoring the response to a treatment. For these to be achieved, a logical approach during every step of testing is needed, followed by data interpretation and clinical correlations.

International audience; Background: Accessory pathway (AP) ablation is not always easy. Our purpose was to assess the age-related prevalence of AP location, electrophysiological and prognostic data according to this location.Methods: Electrophysiologic study (EPS) was performed in 994 patients for a pre-excitation syndrome. AP location was determined on a 12 lead ECG during atrial pacing at maximal preexcitation and confirmed at intracardiac EPS in 494 patients.Results: AP location was classified as anteroseptal (AS)(96), right lateral (RL)(54), posteroseptal (PS)(459), left lateral (LL)(363), nodoventricular (NV)(22). Patients with ASAP or RLAP were younger than patients with another AP location. Poorly-tolerated arrhythmias were more frequent in patients with LLAP than in other patients (0.009 for ASAP, 0.0037 for RLAP

Background Atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) often terminate spontaneously, presumably due to changes in the electrophysiological properties of the reentrant circuit. However, the mechanism of spontaneous termination of these arrhythmias is incompletely understood. Methods We included 70 consecutive patients with reentrant supraventricular tachycardias (35 AVNRT, 35 AVRT) in whom the arrhythmia ended spontaneously during the electrophysiologic study. We determined in each patient the duration of the induced arrhythmia, site of block, beat-to-beat oscillations in tachycardia cycle-length (CL), A-H, H-V, H-A and V-A intervals. Results In 21/34 (62%) patients with AVNRT and 19/30 (63%) with orthodromic AVRT, tachycardia termination was preceded by progressive increase in tachycardia CL due to prolongation of the A–H interval (Mobitz type-I pattern). In 13/34 patients with AVNRT (38%) and 11/30 with orthodromic AVRT (37%), termination occurred suddenly without a preceding change in CL, with block ensuing retrogradely either in the fast AV nodal pathway or the accessory pathway (Mobitz type-II pattern). In 4/5 patients with antidromic AVRT the tachycardia ended at the retrograde limb with previous prolongation of the VA interval. Conclusion Spontaneous termination of AVNRT and AVRT is a time-related phenomenon. Despite different pathways being involved in these two reentrant tachycardias, termination can follow antegrade or retrograde block in similar ratio (60% antegradely and 40% retrogradely). Antegrade block is preceded by prolongation of the AH interval (Mobitz type-I), whereas retrograde block occurs unexpectedly in the retrograde limb (Mobitz type-II). Fatigue of conduction appears to be involved in this phenomenon.

There are three major types of syncope: neurally mediated (the most common), orthostatic hypotensive, and cardiac (the most worrisome). Several studies have shown a normal long-term survival rate in patients with syncope who have no structural heart disease, which is the most important predictor of death and ventricular arrhythmia. The workup of unexplained syncope depends on the presence or absence of heart disease: electrophysiologic study if the patient has heart disease, tilt-table testing in those without heart disease, and prolonged rhythm monitoring in both cases if syncope remains unexplained.

BACKGROUND Ventricular ectopy (VE) originating in the right ventricular outflow tract (RVOT) is a common arrhythmia. Mechanisms triggering or eliminating VE from RVOT are not entirely understood. METHODS AND RESULTS A patient with frequent, symptomatic VE underwent an electrophysiologic study: VE origin was mapped by NavX 3D navigation (St. Jude Medical, Inc., St. Paul, MN, USA). Incidental pressure applied manually to the sternum reproducibly eliminated VE for the time of exposure. Radiofrequency-ablation was successfully performed in the posterior RVOT. CONCLUSION The mechanism resulting in VE suppression remains speculative, since a mechanical alteration of the substrate for VE in the posterior RVOT by sternal pressure seems unlikely. "Mechano-electrical feedback" might have been the mechanism operative in this case.

Key Clinical Message A 53‐year‐old man presented with heart palpitations while swallowing. Electrophysiologic study (EPS) and immunohistochemical results of his esophageal leiomyoma suggested that swallowing‐induced atrial tachycardia is related with neural reflex. S100‐immunopositive nerve fibers are demonstrated sympathetic nerves which possibly explain the mechanism. Metoprolol tartrate tablets are effective in our patient.

This article provides a case study of a patient with exercised-induced near syncope. Intracardiac electrophysiologic study confirmed an intra-His block and a pacemaker was implanted.

This article discusses the case of a 69-year-old man with hypertension and diabetes who was admitted for recurrent palpitations and documented atrial flutter. The authors describe the electrophysiologic study and ablation of this case.

BACKGROUND: Detailed information on the profile of patients with Brugada syndrome (BrS) presenting their first arrhythmic event (AE) after prophylactic implantation of an implantable cardioverter-defibrillator (ICD) is limited. OBJECTIVES: The objectives of this study were (1) to compare clinical, electrocardiographic, electrophysiologic, and genetic profiles of patients who exhibited their first documented AE as aborted cardiac arrest (group A) with profiles of those in whom the AE was documented after prophylactic ICD implantation (group B) and (2) to characterize group B patients' profile using the class II indications for ICD implantation established by HRS/EHRA/APHRS expert consensus statement in 2013. METHODS: A survey of 23 centers from 10 Western and 4 Asian countries enabled data collection of 678 patients with BrS who exhibited their AE (group A, n = 426; group B, n = 252). RESULTS: The first AE occurred in group B patients 6.7 years later than in group A (mean age 46.1 ± 13.3 years vs 39.4 ± 15.1 years; P < .001). Group B patients had a higher incidence of family history of sudden cardiac death and SCN5A mutations. Of the 252 group B patients, 189 (75%) complied with the HRS/EHRA/APHRS indications whereas the remaining 63 (25%) did not. CONCLUSION: Patients with BrS with the first AE documented after prophylactic ICD implantation exhibited their AE at a later age with a higher incidence of positive family history of sudden cardiac death and SCN5A mutations as compared with those presenting with aborted cardiac arrest. Only 75% of patients who exhibited an AE after receiving a prophylactic ICD complied with the 2013 class II indications, suggesting that efforts are still required for improving risk stratification.