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Background Arrhythmogenic ventricular cardiomyopathy (AC) is a genetic progressive disease characterized by fibro-fatty replacement of either ventricles in isolation or in combination. Arrhythmogenic ventricular cardiomyopathy is frequently associated with ventricular tachycardia (VT) having a left bundle branch block (LBBB) morphology and much more rarely with VT having right bundle branch block (RBBB) morphology even when the left ventricle is involved. Cardiac magnetic resonance (CMR) imaging plays a key role in the diagnosis of AC. Sustained VT in AC may occur in the concealed stage of the disease before the manifestation of morphological abnormalities on echocardiogram; however, they almost always are accompanied by structural abnormalities of the ventricles on CMR. Case summary A 54-year-old man presented with sustained VT of LBBB configuration consistent with the diagnosis of AC but with no right ventricular (RV) anomalies at repeat CMR. Ten years later, he developed sustained VT with RBBB morphology and structural changes at CMR compatible with RV involvement in the setting of AC. Two years later, he suffered from recurrent identical sustained RBBB-VT with typical CMR signs of left ventricular involvement. Genetic analysis was negative for any known mutation. Discussion In the present report, we describe a patient with AC who first exhibited LBBB- and 10 years later RBBB-sustained VT. Contrasting with what is usually observed in patients with AC, documentations of the VT’s arising from either ventricle were found to precede the structural anomalies in the respective cardiac chambers. This case highlights that normal CMR does not exclude underlying AC contrary to the perceptions of many clinicians. In addition, it strongly encourages repeating CMR after 1–2 years when the diagnosis of AC is highly suspected.

Introduction : A new imaging software (CARTO® Segmentation Module, Biosense Webster) allows pre-procedural 3-D reconstruction of all heart chambers based on cardiac CT. We describe our initial experience with the new module during ablation of ventricular arrhythmias. Methods and Results : Eighteen consecutive patients with idiopathic ventricular arrhythmias or ischemic ventricular tachycardia (VT) were studied. In the latter group, a combined endocardial and epicardial ablation was performed. Of the 14 patients with idiopathic arrhythmias, 12 were ablated in the outflow tract (OT), 1 in the midseptal left ventricle and 1 at the left posterior fascicular area; acute successful ablation was achieved in 11 (78.6%) patients. The procedure was discontinued due to close proximity of the arrhythmia origin to the coronary arteries (CA) in 2 patients. Acute successful uncomplicated ablation was achieved in all 4 patients with ischemic VT. During ablation in the coronary cusps commissures, the CARTO® Segmentation Module accurately defined the cusps anatomy. The precise anatomic location provided by the module assisted in successfully ablating when information from activation mapping was not optimal, by ablating at the opposite side of the cusps. In addition, by demonstrating the precise location of the CA, it allowed safe ablation of arrhythmias that originated in close proximity to the CA both in the OT area and the epicardium, eliminating the need for repeat angiography. Conclusions : The CARTO® Segmentation Module is useful for accurate definition of the exact anatomic location of ventricular arrhythmias and for safely ablating them especially in close proximity to the CA. This article is protected by copyright. All rights reserved

Background A few series of focal atrial tachycardia (AT) originating from the noncoronary sinus of Valsalva (NCSV) have been reported in the literature during the last decade. Methods and results Of 147 patients with AT referred for radiofrequency ablation (RFA), we identified nine (6%) originating in the vicinity of the NCSV. Clinical AT was induced during electrophysiological study in all patients without (n = 6) and with (n = 3) isoproterenol infusion. Mean cycle length of the induced tachycardia was 399 ± 85 ms. Mapping of the right atrium and of the left atrium (LA) was initially performed in all nine patients and in four patients, respectively. Earliest tachycardia activation occurred at the His bundle area in all cases. Earliest activations in the LA were at the low paraseptal regions. In two patients with antegrade dual atrioventricular (AV) node physiology that rendered difficult accurate distinction between atrial and ventricular activation, slow pathway ablation was necessary. A retrograde aortic approach was used for mapping the aortic cusps. The earliest local atrial activation in the NCSV preceded the atrial activation in the His area in all patients by 27 ± 8 ms. RFA was performed in all nine patients and was acutely successful in eight. Two patients required radiofrequency (RF) energy outputs of 50 W in order to terminate the arrhythmia. In one patient, successful AT ablation was associated with complete AV block requiring implantation of permanent pacemaker. Conclusions Focal AT can be successfully mapped and ablated in the NCSV. Higher than usual RF energy levels are sometimes required. Complete AV block is a possible complication.

The incidence, characteristics, and clinical significance of catheter-induced mechanical suppression (trauma) of ventricular arrhythmias originating in the outflow tract (OT) area have not been thoroughly evaluated.To determine these variables among our patient cohort.All consecutive patients with right ventricular OT (RVOT) and left ventricular OT (LVOT) arrhythmias ablated at two medical centers from 1998 to 2014 were included. Patients were observed for catheter-induced trauma during ablation procedures. Procedural characteristics, as well as response to catheter-induced trauma and long term follow-up, were recorded.During 288 ablations of OT arrhythmias in 273 patients (RVOT n=238, LVOT n=50), we identified 8 RVOT cases (3.3%) and 1 LVOT (2%) case with catheter-induced trauma. Four cases of trauma were managed by immediate radiofrequency ablation (RFA), three were ablated after arrhythmia recurrence within a few minutes, and two were ablated after30 minutes without arrhythmia recurrence. Patients with catheter-induced trauma had higher rates of repeat ablations compared to patients without: 3/9 (33%) vs. 12/264 (0.45%), P = 0.009. The three patients with arrhythmia recurrence were managed differently during the first ablation procedure (immediate RFA, RFA following early recurrence, and delayed RFA). During the repeat procedure of these three patients, no catheter trauma occurred in two, and in one no arrhythmia was observed.Significant catheter-induced trauma occurred in 3.1% of OT arrhythmias ablations, both at the RVOT and LVOT. Arrhythmia suppression may last30 minutes and may interfere with procedural success. The optimal mode of management following trauma is undetermined.

Limited information exists about detailed clinical characteristics and management of the small subset of Brugada syndrome (BrS) patients who had an arrhythmic event (AE).To conduct the first nationwide survey focused on BrS patients with documented AE.Israeli electrophysiology units participated if they had treated BrS patients who had cardiac arrest (CA) (lethal/aborted; group 1) or experienced appropriate therapy for tachyarrhythmias after prophylactic implantable cardioverter defibrillator (ICD) implantation (group 2).The cohort comprised 31 patients: 25 in group 1, 6 in group 2. Group 1: 96% male, mean CA age 38 years (range 13-84). Nine patients (36%) presented with arrhythmic storm and three had a lethal outcome; 17 (68%) had spontaneous type 1 Brugada electrocardiography (ECG). An electrophysiology study (EPS) was performed on 11 patients with inducible ventricular fibrillation (VF) in 10, which was prevented by quinidine in 9/10 patients. During follow-up (143 ± 119 months) eight patients experienced appropriate shocks, none while on quinidine. Group 2: all male, age 30-53 years; 4/6 patients had familial history of sudden death age50 years. Five patients had spontaneous type 1 Brugada ECG and four were asymptomatic at ICD implantation. EPS was performed in four patients with inducible VF in three. During long-term follow-up, five patients received ≥ 1 appropriate shocks, one had ATP for sustained VT (none taking quinidine). No AE recurred in patients subsequently treated with quinidine.CA from BrS is apparently a rare occurrence on a national scale and no AE occurred in any patient treated with quinidine.

Background During radiofrequency (RF) ablation of paroxysmal atrial fibrillation, a circular multielectrode recording "lasso" catheter is generally positioned within each pulmonary vein (PV) to determine when pulmonary vein potentials (PVPs) are present and when they have been ablated. The new irrigated multipolar nMARQ circular ablation catheter is positioned within the left atrium to create contiguous circular ablation lines around each PV ostium. Objective To determine whether the recordings obtained from the nMARQ catheter position around the PV ostium accurately reproduce the recordings obtained from a lasso catheter positioned within that vein. Methods In 10 patients undergoing RF ablation of paroxysmal atrial fibrillation, we placed an nMARQ and a lasso catheter around and within each PV, respectively. Recordings obtained from both catheters at baseline and after RF ablation were compared. Results At baseline, recordings of PVPs in both catheters were concordant in 92% of all PVs. However, after RF delivery, the concordance between the nMARQ and lasso recordings was poor. The discordant result most commonly observed was disappearance of "PVPs" from the nMARQ catheter with persistence of PVPs in the lasso catheter (12 of 39 [30%]). Conversely, the delivery of RF frequently resulted in fragmented electrograms (pseudo-PVPs) on the nMARQ catheter despite evidence of PV isolation by lasso catheter recordings. Conclusions The use of an nMARQ catheter alone, as currently recommended, may lead to underestimation and overestimation of the number of RF applications required to achieve PV isolation.

One of the most controversial issues debated by cardiac electrophysiologists during the past decade has been whether programmed ventricular stimulation (PVS) plays any role in the arrhythmic risk stratification of the Brugada syndrome (BrS).1–5 The results of the multicenter study published in 2003 by the Brugada brothers were unequivocal.6 In a study involving 408 BrS individuals with no previous cardiac arrest, inducibility of ventricular fibrillation (VF) was found to be a marker of poor prognosis: individuals with inducible VF had a 6 times higher risk of having sudden death because of VF during the subsequent 2 years compared with the patients with noninducible VF. Subsequent multicenter studies from Europe7,8 and Japan,9,10 as well as 2 meta-analyses studies,11,12 failed to confirm these results,6 leading to downgrade in class indication of PVS for risk stratification from IIa in 200513 to IIb in 2013.14 However, in the latest reported meta-analysis of the prognostic value of PVS in BrS, Fauchier et al15 found that PVS actually may be useful in patients with syncope and in asymptomatic patients. The strength of that meta-analysis when compared with the first 2 reported11,12 is that it distinguished the prognostic role of PVS according to the initial clinical presentation (syncope versus asymptomatic). However, this meta-analysis did not include the results of PRogrammed ELectrical stimUlation preDictive valuE registry8 because that study did not provide data discriminating between these 2 patient groups. Article see p 777 In this issue of Circulation: Arrhythmia and Electrophysiology , Sieira et al16 analyzed the experience of Pedro Brugada laboratories in Belgium (Alst and Brussels) during the past 20 years. They reported a cohort of 404 patients with type 1 Brugada ECG (spontaneous in …

This international consensus statement is the collaborative effort of three medical societies representing electrophysiology in North America, Europe, and Asian-Pacific area: the Heart Rhythm Society (HRS), the European Heart Rhythm Association (EHRA), and the Asia Pacific Heart Rhythm Society. The objective of the consensus document is to provide clinical guidance for diagnosis, risk stratification, and management of patients affected by inherited primary arrhythmia syndromes. It summarizes the opinion of the international writing group members based on their own experience and on a general review of the literature with respect to the clinical data on patients affected by channelopathies. This document does not address the indications of genetic testing in patients affected by inherited arrhythmias and their family members. Diagnostic, prognostic, and therapeutic implications of the results of genetic testing are also not included in this document because this topic has been covered by a recent publication1 coauthored by some of the contributors of this consensus document, and it remains the reference text on this topic. Guidance for the evaluation of patients with idiopathic ventricular fibrillation, sudden arrhythmic death …

A few series of focal atrial tachycardia (AT) originating from the noncoronary sinus of Valsalva (NCSV) have been reported in the literature during the last decade.Of 147 patients with AT referred for radiofrequency ablation (RFA), we identified nine (6%) originating in the vicinity of the NCSV. Clinical AT was induced during electrophysiological study in all patients without (n = 6) and with (n = 3) isoproterenol infusion. Mean cycle length of the induced tachycardia was 399 ± 85 ms. Mapping of the right atrium and of the left atrium (LA) was initially performed in all nine patients and in four patients, respectively. Earliest tachycardia activation occurred at the His bundle area in all cases. Earliest activations in the LA were at the low paraseptal regions. In two patients with antegrade dual atrioventricular (AV) node physiology that rendered difficult accurate distinction between atrial and ventricular activation, slow pathway ablation was necessary. A retrograde aortic approach was used for mapping the aortic cusps. The earliest local atrial activation in the NCSV preceded the atrial activation in the His area in all patients by 27 ± 8 ms. RFA was performed in all nine patients and was acutely successful in eight. Two patients required radiofrequency (RF) energy outputs of 50 W in order to terminate the arrhythmia. In one patient, successful AT ablation was associated with complete AV block requiring implantation of permanent pacemaker.Focal AT can be successfully mapped and ablated in the NCSV. Higher than usual RF energy levels are sometimes required. Complete AV block is a possible complication.

Left ventricular outflow tract (LVOT) arrhythmias are increasingly recognized. Data regarding the distribution of the sites of origin (SOO) of the arrhythmias are sparse.To describe the clinical characteristics of patients with LVOT arrhythmias and the distribution of their SOO.All 42 consecutive patients with LVOT arrhythmias who underwent radiofrequency (RF) ablation during the period 2000-2014 were included. SOO identification was based on mapping activation, pace mapping and a 3D mapping system in eight patients.The study group comprised 28 males (66.7%) and 14 females, the mean age was 55 ± 15.4 years. Most patients (76%) were symptomatic. All suffered from high grade ventricular arrhythmias. Left ventricular (LV) dysfunction (ejection fraction ≤ 50%) was observed in 15 patients (35.7%), of whom 14 (93.3%) were males. The left coronary cusp (LCC) was the most common arrhythmia SOO (64.3%). Other locations were the right coronary cusp (RCC), the junction of the RCC-LCC commissure, aortic-mitral continuity, endocardial-LVOT, and a coronary sinus branch. Acute successful ablation was achieved in 29 patients (69%) and transient arrhythmia abolition in 40 (95.2%). There was a trend for a higher success rate using cooled tip ablation catheters as compared to standard catheters. The ablation procedure significantly improved LV function in all patients with tachycardiomyopathy.LVOT arrhythmias mostly originate from the LCC and are associated with LV dysfunction in 36% of patients. Knowledge regarding the prevalence of the anatomic origin of the LVOT arrhythmias may help achieve successful ablation. The use of cooled tip ablation catheters might have beneficial effects on the success rate of the procedure.

Objectives The goal of this study was to establish a patient-specific human-induced pluripotent stem cells (hiPSCs) model of catecholaminergic polymorphic ventricular tachycardia (CPVT). Background CPVT is a familial arrhythmogenic syndrome characterized by abnormal calcium (Ca2+) handling, ventricular arrhythmias, and sudden cardiac death. Methods Dermal fibroblasts were obtained from a CPVT patient due to the M4109R heterozygous point RYR2 mutation and reprogrammed to generate the CPVT-hiPSCs. The patient-specific hiPSCs were coaxed to differentiate into the cardiac lineage and compared with healthy control hiPSCs-derived cardiomyocytes (hiPSCs-CMs). Results Intracellular electrophysiological recordings demonstrated the development of delayed afterdepolarizations in 69% of the CPVT-hiPSCs-CMs compared with 11% in healthy control cardiomyocytes. Adrenergic stimulation by isoproterenol (1 μM) or forskolin (5 μM) increased the frequency and magnitude of afterdepolarizations and also led to development of triggered activity in the CPVT-hiPSCs-CMs. In contrast, flecainide (10 μM) and thapsigargin (10 μM) eliminated all afterdepolarizations in these cells. The latter finding suggests an important role for internal Ca2+ stores in the pathogenesis of delayed afterdepolarizations. Laser-confocal Ca2+ imaging revealed significant whole-cell [Ca2+] transient irregularities (frequent local and large-storage Ca2+-release events, broad and double-humped transients, and triggered activity) in the CPVT cardiomyocytes that worsened with adrenergic stimulation and Ca2+ overload and improved with beta-blockers. Store-overload–induced Ca2+ release was also identified in the hiPSCs-CMs and the threshold for such events was significantly reduced in the CPVT cells. Conclusions This study highlights the potential of hiPSCs for studying inherited arrhythmogenic syndromes, in general, and CPVT specifically. As such, it represents a promising paradigm to study disease mechanisms, optimize patient care, and aid in the development of new therapies.

Background: Quinidine is very effective in preventing the reinduction of sustained ventricular fibrillation (VF) during electrophysiologic study (EPS) in patients with idiopathic VF and Brugada syndrome. However, there are no data on the long-term reproducibility of this EP efficacy. Methods and Results: Nine patients (seven males and two females, aged 21‐72 years), who suffered from aborted cardiac arrest (n = 8) or recurrent syncope (n = 1) due to Brugada syndrome (n = 5) or idiopathic VF (n = 4), comprised the study. All patients had inducible sustained VF at baseline that was prevented by quinidine therapy and underwent another EPS on medication after 1.7‐23.6 (9.8 ± 6.8) years (>5 years in eight patients). Two patients underwent two late EPS on quinidine. The goal of repeat EPS on quinidine was to ensure persistent long-term drug efficacy (n = 6) or to elucidate the reason of syncopal episodes during therapy (n = 3). The EPS protocol significantly evolved over the years as it became more aggressive (more pacing sites and/or more ventricular extrastimuli). All nine patients tolerated the medication well and had no recurrent documented arrhythmic events during long-term follow-up (mean 15 ± 7 years). No sustained ventricular tachyarrhythmias could be induced in any patient during repeat late EPS. In six patients, a more aggressive stimulation protocol could be tested at repeat EPS. Conclusion: The long-term reproducibility of the EP efficacy of quinidine in patients with idiopathic VF and Brugada syndrome is excellent. EP-guided quinidine therapy represents a valuable long-term alternative to ICD therapy in these patients. (PACE 2009; 32:294‐301)

Objectives The purpose of this study was to determine whether J-point elevation is a marker of arrhythmic risk. Background J-point elevation has been considered an innocent finding among healthy young individuals (the “early repolarization” pattern). However, this electrocardiogram (ECG) finding is increasingly being associated with idiopathic ventricular fibrillation (VF). Methods In a case-control study, the ECG of 45 patients with idiopathic VF were compared with those of 124 age- and gender-matched control subjects and with those of 121 young athletes. We measured the height of J-point and ST-segment elevation and counted the presence of slurring in the terminal portion of the R-wave. Results J-point elevation was more common among patients with idiopathic VF than among matched control subjects (42% vs. 13%, p 0.001). This was true for J-point elevation in the inferior leads (27% vs. 8%, p 0.006) and for J-point elevation in leads I to aVL (13% vs. 1%, p 0.009). J-point elevation in V4 to V6 occurred with equal frequency among patients and matched control subjects (6.7% vs. 7.3%, p 0.86). Male subjects had J-point elevation more often than female subjects and young athletes had J-point elevation more often than healthy adults but less often than patients with idiopathic VF. The presence of ST-segment elevation or QRS slurring did not add diagnostic value to the presence of J-point elevation. Conclusions J-point elevation is found more frequently among patients with idiopathic VF than among healthy control subjects. The frequency of J-point elevation among young athletes is intermediate (higher than among healthy adults but lower than among patients with idiopathic VF). (J Am Coll Cardiol 2008;52:1231‐8) © 2008 by the American College of Cardiology Foundation

ObjectivesThe purpose of this study was to define the electrocardiographic (ECG) predictors of torsade de pointes (TdP) during acquired bradyarrhythmias.BackgroundComplete atrioventricular block (CAVB) might lead to downregulation of potassium channels, QT interval prolongation, and TdP. Because potassium-channel malfunction causes characteristic T-wave abnormalities in the congenital long QT syndrome (LQTS), we reasoned that T-wave abnormalities like those described in the congenital LQTS would identify patients at risk for TdP during acquired bradyarrhythmias.MethodsIn a case-control study, we compared 30 cases of bradyarrhythmias complicated by TdP with 113 cases of uncomplicated bradyarrhythmias. On the basis of the criteria used for the congenital LQTS, T waves were defined as LQT1-like (long QT interval with broad T waves), LQT2-like (notched T waves), and LQT3-like (small and late) T waves.ResultsNeither the ventricular rate nor the QRS width at the time of worst bradyarrhythmia predicted the risk of TdP. However, the QT, corrected QT (QTc), and Tpeak–Tend intervals correlated with the risk of TdP. The best single discriminator was a Tpeak–Tend of 117 ms. LQT1-like and LQT3-like morphologies were rare during bradyarrhythmias. In contrast, LQT2-like “notched T waves” were observed in 55% of patients with TdP but in only 3% of patients with uncomplicated bradyarrhythmias (p < 0.001). A 2-step model based on QT duration and the presence of LQT2-like T waves identified patients at risk for TdP with a positive predictive value of 84%.ConclusionsProlonged QT interval, QTc interval, and Tpeak–Tend correlate with increased risk for TdP during acquired bradyarrhythmias, particularly when accompanied by LQT2-like notched T waves.

Summary The efficacy and safety of flumazenil in reversing midazolam-induced paradoxical reaction in a child suffering from paroxysmal supraventricular tachycardia (PSVT) and undergoing radiofrequency ablation procedure has not been described before. We report a boy who had suffered for years from poorly controlled PSVT because of noncompliance to medications and was being sedated by midazolam and morphine (4 mg each) and prepared for radiofrequency ablation when he began attempting to speak, writhing and flailing his arms, for which physical restraint was required. We also review the current knowledge on the subject. Two doses of flumazenil 0.05 mg i.v. swiftly halted the untoward episode. The child opened his eyes and was calm, coherent and able to answer simple questions. All haemodynamic and respiratory parameters remained stable throughout this event, except for a temporary increase in heart rate (from 68 to 83 b·min−1). The aberrant behaviour did not resume when he was allowed to fall asleep during the ablation of a concealed left lateral accessory pathway. After that procedure, he awoke calm and pain free with no recollection of the aggressive episode. He was kept for 24 h in an intermediate cardiac care unit and was then discharged home. This apparent first report on the efficacious use of flumazenil for the reversal of a paradoxical reaction to midazolam during an electrophysiological study suggests that it neither induces abnormal heart rate nor interferes with the electrophysiological study or the ablation procedure.

Recent studies have shown that the pathogenesis of accessory connections (AC) formation may have a genetic component.The purpose of the study was to examine whether AC location differs by gender in a large cohort of patients with AC undergoing radiofrequency ablation (RFA) in two Israeli electrophysiology (EP) laboratories.All consecutive patients who underwent RFA of single ACs in Tel Aviv Sourasky Medical Center between 1992 and 2009 (n = 574) as well as the first consecutive 230 patients who underwent RFA in Sheba Medical Center between 1992 and 2001 were included in this study.The 804 patients in the two centers included 511 males (63.6 %) and 293 (36.4 %) females, mean age 34 + 16 years old. The AC was located in the left free wall, posteroseptal, right free wall, right anteroseptal, and in other areas in 57.8, 22.8, 9.3, 7 and 3.1 % of patients, respectively. The anatomical AC distribution was similar in the two EP laboratories. A right free wall location was more frequent in females (13 %) than in males (7.2 %; p = 0.008). A right anteroseptal location was more frequent in males (8.4 %) than in females (4.4 %) (p = 0.043). The left free wall and posteroseptal locations were similarly encountered in males (58.1 and 23.1 %, respectively) and in females (57.3 and 22.2 %, respectively).In our Israeli population, females more commonly have right free wall ACs and males more commonly have right anteroseptal ACs. These findings support the possible role of a genetic component in the pathogenesis of AC formation.

In 1992 two Spanish cardiologist brothers, Pedro and Josep Brugada reported eight patients with aborted cardiac arrest and no demonstrable heart disease who exhibited in sinus rhythm right bundle branch block (RBBB) with prominent STsegment elevation in precordial leads V 1‐V3. 1 Despite initial controversy about the diagnosis, especially concerning the possibility of a subtle arrhythmogenic right ventricular dysplasia, the repeated lack of right ventricular involvement along with consistent clinical, electrocardiographic (ECG), and electrophysiological features convinced the cardiological community that the Brugada syndrome was actually a new and important cause of sudden cardiac death (SCD) in ostensibly healthy patients. 2 During the last decade an increased awareness among physicians has resulted in a growing number of patients reported worldwide. In 1998, Chen et al. 3 were first to establish that the Brugada syndrome was a genetic disease with an autosomal dominant pattern of transmission. These investigators described mutations all affecting the cardiac sodium channel SCN5A on chromosome 3. More recently, a novel gene locus on chromosome 3, distinct from SCN5A has been identified. 4 The genetic pattern of transmission of the disease has lead to the increased detection of asymptomatic patients affected by the disease among families of cardiac ar

Background: There is limited information regarding characteristics of patients with Brugada syndrome (BrS) who received a prophylactically implantable cardioverter-defibrillator (ICD) that delivered appropriate therapy. We sought to compare patients’ characteristics and indications of prophylactic

Stage A 35-year-old woman was referred to the arrhythmia clinic because of palpitations and a finding of ventricular extrasystoles on a Holter recording. She had no history of heart disease, and her electrocardiogram (Figure 1) and echocardiogram were interpreted as normal. Response Extrasystoles are common in otherwise healthy young patients. For the majority, this is a harmless condition that does not require therapy. However, the rare patient who is at risk for lethal arrhythmias must be identified. The fact that the echocardiogram is normal is the most consequential information, because arrhythmias are generally benign in the absence of heart disease. . . .

Electrophysiologic Drug Testing in Idiopathic VF. Introduction: Implantation of a implantable cardioverter defibrillator (ICD) is viewed universally as the “gold standard” therapy for patients with idiopathic ventricular fibrillation (VF). We sought to study the long-term value of electrophysiologic (EP)-guided therapy with Class IA antiarrhythmic drugs in patients with idiopathic VF with or without the Brugada syndrome. Methods and Results: We performed EP studies in 34 consecutive patients who had idiopathic VF with (n = 5) or without (n = 29) the Brugada syndrome. All patients with inducible sustained polymorphic ventricular tachycardia (SPVT) or VF underwent repeated EP evaluation after oral administration of a Class IA antiarrhythmic drug (mainly quinidine). Patients rendered noninducible received this therapy on a long-term basis. SPVTA/VF were induced in 27 (79.4%) patients at baseline studies. Class IA drugs effectively prevented induction of SPVTA'F in 26 (96%) patients. Of the 23 patients treated with these medications, no patient died or had a sustained ventricular arrhythmia during a mean follow-up period of 9.1 ± 5.6 years (7 to 20 years in 15 patients). Two deaths occurred in patients without inducible SPVTA'F at baseline studies who had been treated empirically. Conclusion: Our results suggest that EP-guided therapy with Class IA agents is a reasonable, safe, and effective approach for the long-term management of patients with idiopathic VF. A randomized prospective study of EP-guided Class IA therapy in patients with ICDs seems warranted.

Stage A 22-year-old man was apparently in good health until, suddenly and without warning, he lost consciousness in the back seat of a car. The patient was rushed to a nearby clinic, where he was found to be apneic and to have no pulse. Electrocardiographic monitoring revealed ventricular fibrillation. Cardiopulmonary resuscitation was carried out, and after repeated direct-current shocks, sinus rhythm was restored. The patient was hospitalized. Response The causes of sudden death are many and are usually presented in double-page, small-print tables in textbooks. The absence of symptoms before the catastrophic event in this case allows me to concentrate . . .

Important data have recently been added to our understanding of sustained ventricular tachyarrhythmias occurring in the absence of demonstrable heart disease. Idiopathic ventricular tachycardia (VT) is usually of monomorphic configuration and can be classified according to its site of origin as either right monomorphic (70% of all idiopathic VTs) or left monomorphic VT. Several physiopathological types of monomorphic VT can be presently individualized, according to their mode of presentation, their relationship to adrenergic stress, or their response to various drugs. The long-term prognosis is usually good. Idiopathic polymorphic VT is a much rarer type of arrhythmia with a less favorable prognosis. Idiopathic ventricular fibrillation may represent an underestimated cause of sudden cardiac death in ostensibly healty patients. A high incidence of inducibility of sustained polymorphic VT with programmed ventricular stimulation has been found by our group, but not by others. Long-term prognosis on Class IA antiarrhythmic medications that are highly effective at electrophysiologic study appears excellent.

A 15-year-old girl with no obvious heart disease and frequent episodes of paroxysmal supraventricular tachycardia (PSVT) underwent electrophysiological study with radiofrequency ablation. Her resting electrocardiogram showed prominent R waves in right precordial leads without obvious pre-excitation (PR=0·16 s) [Fig. 1(a)]. Both right atrial and coronary sinus pacing showed exclusive antegrade conduction over the atrioventricular (AV) node. Sustained AV re-entrant tachycardia (AVRT) at a rate of 220 bpm was reproducibly induced with atrial pacing. The sequence of atrial activation during AVRT suggested the existence of a concealed left lateral accessory pathway. Radiofrequency ablation of the pathway was attempted via a patent foramen ovale during AVRT using a temperaturecontrolled ablation catheter (temperature set at 72 C). At the fifth radiofrequency pulse, AVRT terminated after 4·5 s due to retrograde block in the accessory pathway. A wide QRS complex tachycardia immediately developed upon termination of AVRT (Fig. 2). This tachycardia had a right bundle branch block morphology with right axis, was regular at 190 bpm [Fig. 1(b)], and persisted as long as the radiofrequency pulse lasted (60 s). A few minutes later, conduction over the accessory pathway resumed and AVRT was induced again. Another radiofrequency pulse was administered at the mitral valve annulus at a site very close to the previous site. Again, AVRT terminated after 2·5 s and a regular, wide QRS complex tachycardia, identical in morphology, rate and regularity to that induced previously, was observed and persisted as long as the radiofrequency pulse lasted (60 s). Subsequent right and left ventricular pacing showed exclusive retrograde AV nodal

The purpose of this study was to determine whether J-point elevation is a marker of arrhythmic risk.J-point elevation has been considered an innocent finding among healthy young individuals (the "early repolarization" pattern). However, this electrocardiogram (ECG) finding is increasingly being associated with idiopathic ventricular fibrillation (VF).In a case-control study, the ECG of 45 patients with idiopathic VF were compared with those of 124 age- and gender-matched control subjects and with those of 121 young athletes. We measured the height of J-point and ST-segment elevation and counted the presence of slurring in the terminal portion of the R-wave.J-point elevation was more common among patients with idiopathic VF than among matched control subjects (42% vs. 13%, p = 0.001). This was true for J-point elevation in the inferior leads (27% vs. 8%, p = 0.006) and for J-point elevation in leads I to aVL (13% vs. 1%, p = 0.009). J-point elevation in V(4) to V(6) occurred with equal frequency among patients and matched control subjects (6.7% vs. 7.3%, p = 0.86). Male subjects had J-point elevation more often than female subjects and young athletes had J-point elevation more often than healthy adults but less often than patients with idiopathic VF. The presence of ST-segment elevation or QRS slurring did not add diagnostic value to the presence of J-point elevation.J-point elevation is found more frequently among patients with idiopathic VF than among healthy control subjects. The frequency of J-point elevation among young athletes is intermediate (higher than among healthy adults but lower than among patients with idiopathic VF).

We present an unusual mechanism of preexcited tachycardia--atypical AV nodal reentry with bystander AP. It can be differentiated from other preexcited tachycardias by its variable degree of preexcitation (either spontaneous or in response to atrial pacing), higher degree of preexcitation with pacing near the origin of the AP than during tachycardia, inability to preexcite the tachycardia by either late atrial or ventricular premature beats, the presence of nonpreexcited atypical AV nodal reentry tachycardia following successful AP ablation, and by exclusion of atrial tachycardia.