Impact of transesophageal electrophysiologic study to elucidate the mechanism of arrhythmia on children with supraventricular tachycardia and no preexcitation.

An electrophysiologic study (EPS) of children and teenagers with paroxysmal supraventricular tachycardia (SVT) and normal electrocardiography (ECG) in sinus rhythm was evaluated. Generally, EPS is performed only before paroxysmal SVT ablation in these patients. In this study, 140 patients (mean age, 15 ± 3 years) with normal ECG in sinus rhythm were studied for SVT by a transesophageal route in baseline state and after isoproterenol. Idiopathic left or right ventricular tachycardia was diagnosed in four patients (3 %). Anterograde conduction over an atrioventricular (AV) left lateral (n = 10) or septal (n = 9) accessory pathway (AP) was noted in 19 patients (13.5 %) at atrial pacing. Orthodromic AV reentrant tachycardia (AVRT) was induced in these children. Five of the patients had a high rate conducted over AP (>240 bpm in baseline state or >290 bpm after isoproterenol). Two of the patients (a 10-year-old girl with well-tolerated SVT and a 17-year-old with syncope-related SVT) had the criteria for a malignant form with the induction of atrial fibrillation conducted over AP at a rate exceeding 290 bpm in baseline state. Of the 140 patients, 74 (53 %) had typical AV node reentrant tachycardia (AVNRT), nine had atypical AVNRT (6 %), 1 had atrial tachycardia (0.7 %), and 33 (23.5 %) had AVRT related to a concealed AP with only retrograde conduction. Electrophysiologic study is recommended for children with paroxysmal SVT and normal ECG in sinus rhythm. The data are helpful for guiding the treatment. Ventricular tachycardia or atrial tachycardia can be misdiagnosed. Masked preexcitation syndrome with anterograde conduction through AP was present in 13.5 % of the patients, and 1.4 % had a malignant preexcitation syndrome.

Is ablation of atrial flutter always safe?

BACKGROUND: Radiofrequency ablation of typical atrial flutter is largely used and is considered as safe. The purpose of the study was to evaluate the prevalence and the causes of severe adverse event (AE) following atrial flutter ablation. METHODS: Ablation of typical flutter was performed by conventional method with an 8-mm-tip electrode catheter, a maximum power of 70 W, and a maximum target temperature of 70° for 60 seconds in 883 patients, (685 males and 198 females aged from 18 to 93 years [64 ± 11.5]; 664 had heart disease [HD]). RESULTS: AE occurred in 44 patients (5%). AE was life threatening in 14 patients: poorly tolerated bradycardia (transient complete atrioventricular block [AVB] or sinus bradycardia [SB] <40 beats per minute) associated with cardiac shock and acute renal failure in five patients, tamponade (n = 1), bleeding leading to death (n = 1), various AE-related deaths (n = 2), ventricular tachycardia-related death (n = 1), definitive complete AVB (n = 3), and right coronary artery occlusion-related complete AVB (n = 1). Less serious AE occurred in 30 patients: transitory major SB or second- or third-degree AVB (n = 23), bleeding (n = 4), transient ischemic attack (n = 1), and various AE (n = 2). Most of the bradycardia was related to ß-blockers or other antiarrhythmic drugs used to slow atrial flutter. Factors of AE were female gender (36% vs 22%, P < 0.02) and the presence of ischemic (P < 0.03) or valvular HD (P < 0.01). CONCLUSIONS: AE following atrial flutter ablation occurred in 5% of patients. Most of them are avoidable by control of anticoagulants and arrest of rate-control drugs used to slow the rate of atrial flutter.

Supraventricular tachyarrhythmia as a cause of sudden cardiac arrest.

INTRODUCTION: Supraventricular tachyarrhythmias (SVTA) are an accepted cause of cardiac arrest in patients with Wolff-Parkinson-White syndrome (WPW) and hypertrophic cardiomyopathy but their participation in other conditions is less well understood. The purpose of the study was to examine the role of SVTA in sudden cardiac arrest (SCA) by comprehensive evaluation of patients successfully resuscitated from SCA. METHODS: A total of 169 survivors of SCA in the absence of acute myocardial infarction underwent systematic evaluation that included echocardiography, Holter monitoring, coronary angiography and electrophysiological study (EPS) with additional testing in selected cases using provocative drug testing with isoproterenol, ajmaline or ergonovine. RESULTS: SVTA was found as the only possible cause or as the cause facilitating SCA in 29 patients: (1) 3 had a WPW syndrome related to accessory pathway with short refractory period; (2) for 12 patients, SVTA was the cause of cardiovascular collapse; heart disease (HD) was present in 11 cases, but disappeared in two of four with dilated cardiomyopathy after the restoration of sinus rhythm; (3) in 14 patients, SVTA degenerated either in a VF or ventricular tachycardia (VT); HD was present in 12 cases, but disappeared in one; two had no HD and recurrent similar arrhythmia was documented by cardiac defibrillator in one of them. SVTA induced coronary ischemia was the main cause of SCA. CONCLUSION: Rapid SVTA was a cause of SCA, either by cardiovascular collapse or by the degeneration in VT or VF. The complication generally occurred in patients with advanced HD or with rapid SVTA-induced cardiomyopathy and rarely in patients without HD. The incidence of SVTA as the only cause or the facilitating cause of SCAs is probably underestimated, because it is difficult to prove.

[Association of Wolff-Parkinson-White syndrome with isolated non-compaction of the left ventricle: a case report]. / Association du syndrome de Wolff-Parkinson-White a une non-compaction isolée du ventricule gauche. A propos d'un cas.

The Wolff-Parkinson-White syndrome (WPW) may be associated with a number of cardiac pathologies, especially congenital disease, in 7.5 to 17% of cases. The authors report a rare association of the WPW syndrome with two Kent bundles, right and left septal, with non-compaction of the left ventricle in a 52 year old man. This was a chance finding during systematic echocardiography after ablation, and confirmed by cardiac MRI. The patient was asymptomatic.

Long-term prediction of major ischemic events by exercise thallium-201 single-photon emission computed tomography. Incremental prognostic value compared with clinical, exercise testing, catheterization and radionuclide angiographic data.

OBJECTIVES: This study sought to evaluate the prognostic role of exercise thallium-201 (Tl-201) single-photon emission computed tomography (SPECT) in patients with known or suspected coronary artery disease. BACKGROUND: Compared with planar Tl-201 scintigraphy, Tl-201 SPECT allows enhanced assessment of myocardial perfusion abnormalities. However, the long-term prognostic value of exercise Tl-201 SPECT has not been ascertained and compared with that of other techniques of investigation. METHODS: Predictors of ischemic events were sought in 217 patients with known or suspected coronary artery disease who underwent exercise Tl-201 SPECT, coronary angiography and rest radionuclide angiography and who initially received medical therapy. Predictive values were determined using Cox proportional hazards regression models. RESULTS: During a mean (+/- SD) follow-up period of 70 +/- 19 months, 29 patients had a major ischemic event (cardiac death or myocardial infarction). Total extent of exercise defects was the best independent predictor by Tl-201 SPECT of major events (p < 0.001) and provided additional prognostic information compared with clinical, exercise testing and catheterization variables (p < 0.02). Extent of reversible Tl-201 SPECT perfusion defects provided additional prognostic information compared with extent of irreversible defects (p < 0.001) and was the sole Tl-201 SPECT variable providing additional prognostic information compared with radionuclide left ventricular ejection fraction (p < 0.02). CONCLUSIONS: Total extent of exercise Tl-201 SPECT defects is a powerful long-term predictor of major ischemic events that enhances the prediction provided by clinical, exercise testing and coronary angiographic data. In view of its prognostic significance, extent of reversible Tl-201 SPECT defects might provide original information about improving prognosis by coronary revascularization.

[Feasibility and significance of a transoesophageal electrophysiological investigation in children and adolescents with Wolff-Parkinson-White syndrome]. / Faisabilité et intérêts de l'étude électrophysiologique par voie transoesophagienne dans le syndrome de Wolff-Parkinson-White de l'enfant et de l'adolescent.

UNLABELLED: An electrophysiological investigation is the most reliable means of detecting malignant forms of Wolff-Parkinson-White syndrome (WPW). However, an endocavity investigation is an invasive procedure, especially in young subjects with few symptoms. The aim of this study was to examine the feasibility and results of an electrophysiological study performed by the transoesophageal route in children with WPW. The study was performed in 70 children aged between 11 and 19 years (mean 15 +/- 3) with an obvious ECG appearance of WPW: 13 had dizziness or syncope (group I), 25 had tachycardia (group II) and 32 were asymptomatic (group III). The ages were similar in all three groups. The transoesophageal electrophysiological investigation without premedication consisted of atrial stimulation at increasing frequencies and programmed atrial stimulation using one and two extra stimuli delivered in the basal state and after infusion of 2 to 5 microg of isoproterenol. RESULTS: The investigation was completed in all the children except one in group II. A paroxysmal junctional tachycardia was induced in 7 group I children (54%), 22 in group II (92%) and 4 in group III (12.5%). Atrial fibrillation lasting more than one minute was induced in 7 group I children (54%), 6 in group II (25%) and 6 in group III (19%). The percentage of malignant forms combining rapid conduction in the bundle of Kent at a rate of more than 240/min in the basal state or more than 300/min with isoproterenol, and atrial fibrillation was 54% in group I, 21% in group II, and 22% in group III. In conclusion, a transoesophageal electrophysiological investigation was possible as an outpatient procedure in children older than 10 years, and allowed the detection of potentially serious forms whatever the indication for the investigation, with nevertheless a significantly higher incidence in those presenting with dizziness or syncope. The incidence of 22% for potentially malignant forms in asymptomatic children provides an incentive to recommend an ECG in all children older than 10 years participating in an active sport in order to detect WPW and to propose oesophageal investigation.

Incidence and mechanism of presyncope and/or syncope associated with paroxysmal junctional tachycardia.

The objectives of this study were to: (1) define the incidence of presyncope and/or syncope in patients with paroxysmal junctional tachycardias, (2) determine their causes, and (3) determine the outcome of symptoms. Syncope is a frequent problem and is often caused by paroxysmal tachycardia. The mechanism of hemodynamic instability is unknown. The population study consisted of 281 patients, consecutively recruited because they had paroxysmal tachycardia and a sinus rhythm on a normal electrocardiogram. Fifty-two patients (group I) had presyncope and/or syncope associated with tachycardia. The remaining patients (group II) had no loss of consciousness. Transesophageal programmed atrial stimulation used 1 and 2 atrial extrastimuli, delivered in a control state, and if necessary, after infusion of 20 to 30 microg of isoproterenol. Arterial blood pressure was monitored. Vagal maneuvers and echocardiogram were performed in all patients. Paroxysmal tachycardia was induced in 51 group I patients and 227 group II patients. Comparisons of groups I and II revealed that age (50 +/- 21 vs 49 +/- 17 years), presence of heart disease (10% vs 10%), mechanism of tachycardia with a predominance of atrioventricular nodal reentrant tachycardia (70.5% vs 76%), and rate of tachycardia (196 +/- 42 vs 189 +/- 37 beats/min) did not differ between the groups. However, there were differences in both groups with regard to significantly higher incidences of positive vasovagal maneuvers (35% vs 4%, p <0.01), isoproterenol infusion required to induce tachycardia (55% vs 17%, p <0.001), and vasovagal reaction at the end of tachycardia (41% vs 4%, p <0.05). Thirty-seven group I patients underwent radiofrequency ablation of the reentrant circuit, which suppressed presyncope and/or syncope in 36 of the 37 patients. Thus, presyncope and/or syncope frequently complicated the history of patients with paroxysmal junctional tachycardia (18.5%). Several mechanisms are implicated, but vasovagal reaction was the most frequent cause. Treatment of the tachycardia typically suppressed presyncope and/or syncope.

The signal-averaged electrocardiogram is of limited value in patients with bundle branch block and dilated cardiomyopathy in predicting inducible ventricular tachycardia or death.

An abnormal signal-averaged electrocardiogram (SAECG) has predictive value for arrhythmic events in patients with idiopathic dilated cardiomyopathy and a normal conduction. The purpose of this study was to investigate whether the presence of a complete bundle branch block (BBB) affects prognostic information of the SAECG. We prospectively obtained SAECGs in 128 patients with idiopathic dilated cardiomyopathy. Forty-three of them had BBB and 85 had a normal QRS duration. According to their clinical history and results of ventricular programmed stimulation, patients were divided into 4 groups: (1) group IA with BBB and ventricular tachycardia (VT) (n = 18); (2) group IB with BBB but without VT (n = 25); (3) group IIA without BBB but with VT (n = 40); (4) group IIB without BBB and without VT (n = 45). Patients were compared with 129 patients without heart disease and without VT. Fifty-seven of them had BBB (group III) and 72 had normal conduction (group IV). The filtered QRS duration was longer in group IB than in group III (175 +/- 21 vs 149 +/- 16 ms, p <0.001), and in group IIB than in group IV (111 +/- 19 vs 96 +/- 12 ms, p <0.05). QRS duration was similar in groups IA and IB (176 +/- 24 vs 175 +/- 21 ms) but longer in group IIA than in group IIB (131 +/- 24 vs 111 +/- 19 ms, p <0.001). The low-amplitude signal duration (LAS) and the root-mean-square voltage (RMS) of the last 40 ms of the filtered QRS did not differ between groups IB and III and IA and IB. LAS and RMS were, respectively, longer (44 +/- 20 vs 31 +/- 13 ms, p <0.01) and lower (21 +/- 20 vs 43 +/- 33 microV, p <0.001) in groups IIA and IIB. In groups IA and IB the combination of 2 of the 3 available criteria: QRS duration >170 ms, RMS <20 microV, LAS >45 ms lead up to the best overall statistical result, with a sensitivity and specificity of 78% and 56%, respectively. In groups IIA and IIB, using conventional late potential criteria, the sensitivity and specificity of the SAECG for VT detection were 65% and 73%, respectively. The risk of sudden death was not predicted by the SAECG, and total cardiac mortality was only dependent on left ventricular ejection fraction. In conclusion, QRS duration was prolonged in all of the patients with a dilated cardiomyopathy compared with those without heart disease. BBB did not change the sensitivity but decreased the specificity of the SAECG to predict any VT risk in dilated cardiomyopathy. The risk of sudden death and total cardiac mortality could not be predicted by the SAECG.

Hypertrophic cardiomyopathy: value of atrial programmed electrical stimulation in patients with or without syncope with special reference to the role of atrial arrhythmias.

Hypertrophic cardiomyopathy may be associated with both supraventricular and ventricular arrhythmias, which may play a role in the genesis of syncope. The aim of this study was to assess the findings of electrophysiological study and programmed atrial and ventricular stimulation and their possible role in syncope. Programmed atrial and ventricular stimulation using up to two extrastimuli in right atrium and three in right ventricle at three cycle lengths (600, 400 ms and spontaneous) was systematically performed in 56 patients with hypertrophic cardiomyopathy. Thirty seven had unexplained dizzinesses or syncopes (group I) and 19 did not present loss of consciousness (group II). Patients with syncopes had a higher prevalence of induced sustained supraventricular tachyarrhythmia (73%) than those of group II (16%) (P<0.05). Inducible supraventricular tachycardia was the only finding in 16 patients with syncopes. During the follow-up (3 years+/-6 months), empirical antiarrhythmic therapy suppressed the symptoms, except in two patients who developed atrial fibrillation despite therapy. The high incidence of inducible atrial tachycardia of these patients was not correlated with particular Holter findings or echocardiographic data. However, their mean age was rather high (58+/-12 years). In conclusion, atrial tachyarrhythmias may play a role in syncopes of middle-aged patients with hypertrophic cardiomyopathy. Moreover programmed atrial stimulation is an useful means to identify this syncope mechanism.

Predictors of atrial flutter with 1:1 conduction in patients treated with class I antiarrhythmic drugs for atrial tachyarrhythmias.

OBJECTIVES: The purpose of the study was to look for the predictor factors of atrial proarrhythmic effects of class I antiarrhythmic drugs. BACKGROUND: Class I antiarrhythmic drugs may induce or exacerbate cardiac arrhythmias. The predictors of ventricular proarrhythmia are known. The predictors of atrial flutter with 1:1 conduction are unknown. METHODS: Clinical history, EGG, signal-averaged EGG (SAECG) and electrophysiologic study were analysed in 24 cases of 1:1 atrial flutter with class I AA drugs and in 100 control patients without history of 1:1 atrial flutter with class I AA drugs. RESULTS: The ages of patients varied from 46 to 78 years. Underlying heart disease was present in nine patients. The surface EGG revealed the presence of a short PR interval (PR<0.13 ms), visible in leads V5, V6 in eight (35%) patients with normal P wave duration; in other patients with prolonged P wave duration, PR seemed normaL On SAECG recording, there was a pseudofusion between P wave and QRS complex. The electrophysiologic study revealed some signs indicating a rapid AV nodal conduction (short AH interval or rate of 2nd degree AV block at atrial pacing >200 beats/mm) in 19 of the 23 studied patients. All patients, except one, had at least one sign indicating a rapid AV nodal conduction (short PR and/or P wave-QRS complex continuity on SAECG). In the control group, seven patients (7%) had a short PR interval (P<0.01) and 11 (11%) had a pseudofusion between P wave and QRS complex on SAECG (P<0.001). The P wave-QRS complex pseudofusion on SAECG had a sensitivity of 100% and a specificity of 89% for the prediction of an atrial proarrhythmic effect with class I antiarrhythmic drug. CONCLUSION: We recommend avoiding class I AA drugs in patients with a short PR interval on surface EGG and to record SAECG in those with apparently normal PR interval to detect a continuity between P wave and QRS complex, which could indicate a rapid AV nodal conduction, predisposing to 1:1 atrial flutter with the drug.

Influence of age on the electrophysiological mechanism of paroxysmal supraventricular tachycardias.

The purpose of this study was to evaluate the influence of age on the mechanism of paroxysmal supraventricular tachycardia (PSVT). Previous studies have shown age and sex differences between certain arrhythmias and especially changes in electrophysiological characteristics of Wolff-Parkinson-White syndrome. Four hundred and eighty five patients aged 9-86 years, with PSVT and without Wolff-Parkinson-White syndrome in sinus rhythm, were studied. The esophageal or intracardiac electrophysiological study used a standardized atrial pacing protocol. Paroxysmal junctional tachycardia was induced in 475 patients. The mechanism of tachycardia was not influenced by age and atrioventricular nodal reentrant tachycardia (AVNRT) was found as the main cause of PSVT in all ranges of age. Atrioventricular reentrant tachycardia (AVRT) using a concealed accessory pathway (AP) had a similar incidence from youth to elderly. The ratio male/female (M/F) and the inducibility of other arrhythmias (atrial flutter/fibrillation) (AF/AFl) were also found to be similar in all ranges of age. The age of the patients did not influence the mechanism of the tachycardia. Most of PVST were related to a AV nodal reentrant tachycardia. Concealed accessory pathway was identified with a similar incidence in young and old patients.

Programmed ventricular stimulation in survivors of acute myocardial infarction: long-term follow-up.

The prognostic significance of ventricular tachyarrhythmias induced by programmed ventricular stimulation was evaluated in 492 consecutive survivors of acute myocardial infarction (AMI). Holter monitoring, signal-averaged electrocardiogram (ECG) and measurement of left ventricular ejection fraction (EF) were also performed. The protocol used up to 3 extrastimuli. Sustained monomorphic ventricular tachycardia (VT) < 270 beats/min, > 270 beats/min (ventricular flutter) (VFI), and ventricular fibrillation (VF) were induced in 99, 66 and 52 patients, respectively. Long term follow-up (mean 3.7 +/- 2.2 years) showed that most episodes of VT occurred during the first months following AMI (n = 14), but some patients (n = 6) could develop VT as late as 4 years after AMI. Sudden death (SD) (n = 22) always occurred during the first year following AMI. Multivariate analysis demonstrated that EF < 30% and induction of a VT < 270 beats/min were the only predictors for total cardiac death (P < 0.001). EF < 30%, induction of a VT < 270 beats/min and also of VFI (P < 0.05) were predictors for VT and SD: the risk was 4% in patients without inducible VT, 12% in those with inducible VF1, and 21% in those with inducible VT < 270 beats/min. In conclusion, induction of a sustained monomorphic VT < 270 beats/min or > 270 beats/min is a predictor of arrhythmic events during the first year as well as 4 years after myocardial infarction. However the risk of arrhythmic sudden death decreases after the first year, while the risk of VT persists. Because of the low positive predictive value of programmed stimulation (respectively 21% and 12% for the induction of a sustained VT and VFI), we recommended the indication of programmed stimulation in only the patients with one abnormal non-invasive investigation.

Wide QRS complex tachycardia. Rapid method of prognostic evaluation.

UNLABELLED: A wide QRS complex tachycardia suggests a ventricular tachycardia (VT); but supraventricular tachycardia (SVT) is also possible. Some authors reported on the electrocardiographic signs for the differential diagnosis of VT and SVT with aberrancy. Frequently these signs are debatable and the diagnosis is uncertain. The purpose of the study was to evaluate the interest of a non-invasive study by transesophageal route for the evaluation of the nature of a wide QRS complex tachycardia in which a reliable ECG algorithm does not permit to distinguish VT from SVT with aberrancy. METHODS: Esophageal electrophysiologic study (EPS) was performed in 53 patients, aged from 16 to 85 years without bundle branch block (BBB) in sinus rhythm, but with wide-QRS tachycardia. The protocol consisted of atrial pacing at progressively higher rates and then programmed stimulation with one and two extrastimuli in control state and after isoproterenol infusion. Intracardiac EPS was performed in 49 of them. RESULTS: (1) Study was negative in nine patients; intracardiac EPS remained negative in four of them, induced a VT in five; (2) clinical tachycardia was induced in 44 patients: (a) in 29 of them, atrial pacing induced a BBB similar to aberrancy noted in tachycardia and the diagnosis of SVT with aberrancy was made; (b) in 15 patients, QRS complex remained narrow during atrial pacing; the diagnosis of VT was made in presence of AV dissociation and confirmed by intracardiac study. VT was induced by atrial or ventricular stimulation or was spontaneous during isoproterenol infusion. VT mechanism were bundle branch reentry [Am. J. Cardiol. 65 (1990) 322], verapamilsensitive VT [Am. J. Cardiol. 65 (1990) 322], catecholamine-sensitive VT [J. Cardiovasc. Electrophysiol. 7 (1996) 2]. Two patients had tachycardias of both natures either supraventricular or ventricular. CONCLUSION: Esophageal EPS was a safe, rapid and economic means to evaluate the mechanism of wide QRS tachycardia in 84% of patients; atrial pacing at progressively higher rates is very simple to reproduce the aberrancy of similar morphology in those patients who had wide-QRS tachycardia related to a SVT with aberrancy. If atrial pacing did not exactly reproduce the aberrancy in tachycardia, a VT should be suspected.

Significance and prevalence of inducible atrial tachyarrhythmias in patients undergoing electrophysiologic study for presyncope or syncope.

The purpose of the study was to report the prevalence of inducible supraventricular tachyarrhythmias (SVTA) in 827 consecutive patients aged 17 to 90 years who did not have spontaneous documented SVTA and who had unexplained presyncope and/or syncope. The electrophysiologic study (EPS) included programmed atrial and ventricular stimulation up to two extrastimuli at three cycle lengths, and the study of sino-atrial and AV conduction. The results were as follows. EPS was normal in 386 patients. Inducible junctional tachycardia or atrial flutter and fibrillation was the only finding in 187 patients (23%). In the remaining patients we found ventricular tachycardia in 103 (12%), heart block in 67 (8%), sick sinus syndrome in 56 (7%) and increased vagal tone in 28 (3%). The presence of an underlying heart disease (47%) and salvos of atrial premature beats on Holter monitoring (39%) were significantly correlated with the induction of SVTA. However, the comparison with similar groups without syncope indicates that only the induction of SVTA in patients with hypertrophic cardiomyopathy and mitral valve prolapse was significantly correlated with the history of syncope. In patients without heart disease or with prior myocardial infarction or decreased left ventricular function, the induction of SVTA, which is not associated with hypotension in the supine position, could require an induction after head-up tilting, because of the lack of specificity of programmed stimulation in these patients. Programmed atrial stimulation should be systematically performed in patients with unexplained syncope, in particular in those with hypertropic cardiomyopathy and mitral valve prolapse, who require a specific treatment, if a SVTA is induced. In other patients the results of programmed atrial stimulation should be interpreted cautiously.

Effects of radiofrequency catheter ablation on patients with permanent pacemakers.

The objective of this study was to assess the effects of radiofrequency energy application on implanted pacemaker functions. Radiofrequency (RF) catheter ablation may cause pacemaker dysfunction due to electromagnetic interferences. The effects of RF on pacemaker behavior were studied in a series of 38 pacemakers, implanted 18 +/- 26 months prior to a RF procedure using either a right ventricular approach (AV node ablation, n = 35) or a left ventricular approach (left concealed accessory pathway ablation, n = 1; VT ablation, n = 2). The 38 patients (mean age 65 +/- 9 years) included 20 men and 18 women. Before energy applications, the 23 different pacemaker models were programmed to the VVI mode at the lowest available rate. The continuous surface ECG was recorded throughout the procedure. Thorough testing of the devices was performed before and after each RF delivery. Unusual pacemaker responses occurred in 20 of the 38 cases studied (53%). The impact of RF delivery was unpredictable, and variable dysfunctions were observed at different times for a given patient or could vary for a given model. Unusual pacemaker responses included pacemaker inhibition (n = 8), untoggled backup mode (n = 3), electromagnetic interference noise mode (n = 3), temporary RF-induced pacemaker tachycardia (n = 2), erratic behavior (n = 1), oversensing of RF onset and offset (n = 8), and transient loss of ventricular capture, (n = 1). Postablation, most devices automatically toggled back to full functionality. The three devices in the untoggled backup mode had to be reprogrammed to obtain normal operations. At the end of the procedure, pacing thresholds remained unchanged in all but one patient, in whom the increase in ventricular threshold was due to a nicked lead. In conclusion, implanted pacemakers frequently exhibit transient, unpredictable responses to RF energy application. Although all pacemaker functions were restored postablation, some devices had to be reset manually. The anomalies observed during the RF application argue for the simultaneous use of an external pacemaker in pacing-dependent patients.

Incomplete bundle-branch block and ST-segment elevation: syndrome associated with sustained monomorphic ventricular tachycardia in patients with apparently normal heart.

This paper reports on three cases of patients with an apparently normal heart admitted for sustained monomorphic ventricular tachycardia. The only abnormal finding showed in the electrocardiogram (ECG) in sinus rhythm that exhibited an entity associated with incomplete right bundle-branch block and persistent ST-segment elevation. The ECG entity was variable and disappeared transiently. Spontaneous ventricular tachycardia in one patient was inducible by programmed stimulation. There was no underlying heart disease. The origin of the ventricular tachycardia in one patient was located by pace mapping in the left ventricle at the left ventricular basal septum. The follow-up (from 6 months up to 6 years) demonstrated a good prognosis. This particular ECG entity associated with monomorphic ventricular tachycardia could have been missed because of the variations in the ECG in sinus rhythm and was associated with a favorable prognosis.

[Is the transesophageal approach preferable to endocavitary approach in the evaluation of Wolff-Parkinson-White syndrome?]. / La voie oesophagienne est-elle préférable à la voie endocavitaire pour évaluer le syndrome de Wolff-Parkinson-White?

Now that the radical treatment of the Wolff-Parkinson-White syndrome is established, it is essential to evaluate the prognosis of this condition accurately. Initiation of atrial fibrillation is one of the factors which influence the prognosis. The aim of this study was to compare the results of electrophysiological studies performed by the endocavitary and transoesophageal approaches in the measurement of the initiation of atrial fibrillation. Twenty-six patients with a patent Wolff-Parkinson-White syndrome were studied by the two methods with a similar protocol: incremental atrial pacing to the Wenckebach point, programmed atrial stimulation using up to two extrastimuli, repeated with an infusion of 20 to 30 ug of isoproterenol. Sixteen patients had reciprocating nodal tachycardia or were asymptomatic (group I) and the other 10 had spontaneous atrial fibrillation (group II). In group I, atrial fibrillation was induced in 9 cases (56%) by the endocavitary and in two cases (12.5%) by the transoesophageal method. In group II, spontaneous atrial fibrillation was reproduced in all cases by the endocavitary and transoesophageal protocols. None of the patients in group I developed atrial fibrillation during follow-up (average 2 years +/- 9 months). The authors observe that all spontaneous atrial fibrillation of the Wolff-Parkinson-White syndrome can be triggered by oesophageal stimulation. The prevalence of atrial fibrillation was overestimated by endocavitary studies in asymptomatic or paucisymptomatic patients. The assessment of atrial vulnerability of a Wolff-Parkinson-White syndrome may therefore be performed by transoesophageal electro-physiological studies.

[Does radiofrequency ablation of the bundle of Kent results in a lower risk of atrial fibrillation?]. / L'ablation par radiofréquence du faisceau de Kent fait-elle régresser le risque de fibrillation auriculaire?

Radiofrequency ablation of the Bundle of Kent is a common method of treating malignant forms of the Wolff-Parkinson-White syndrome and the paroxysmal junctional tachycardia which may complicate this condition. The aim of this study was to investigate the effects of ablation of a latent or patent Bundle of Kent on the prevention of atrial fibrillation. One hundred and thirty eight patients aged 15 to 81 years of age with one or more patent (Group I) (n = 96) or latent Bundles of Kent (Group II) (n = 42) underwent successful ablation of the Bundle of Kent. Five patients in Group I (5%) and 4 in Group II (9.5%) had spontaneous paroxysmal atrial fibrillation before ablation. During electrophysiological investigation, AF was induced in 7 patients, 2 of whom had spontaneous AF in Group I and 3 in Group II. During follow-up (3 +/- 1 years), 3 patients of Group I went on to develop AF: 2 of them had never had the arrhythmia before: 4 patients of Group II, including 2 with previous AF, went on to develop AF. The risk of spontaneous AF was correlated to older ages. The authors conclude that persistence of the risk of spontaneous AF after ablation of a Bundle of Kent should be investigated especially in patients over 45 years of age.

[Does radiofrequency ablation of the slow pathway prevent atrial fibrillation in cases of re-entrant intranodal junctional tachycardia?]. / L'ablation de la voie lente par radiofréquence dans les tachycardies jonctionnelles par réentrée intranodale prévient-elle le développement d'une fibrillation auriculaire?

The aim of this study was to assess the effects of ablation of the slow pathway on the eventual occurrence of atrial fibrillation (AF) in cases of intranodal junctional tachycardia (INJT). Two hundred and fifty seven patients were admitted for recurrent paroxysmal junctional tachycardia. The ages ranged from 15 to 87 years (average 54 +/- 16 years). Tachycardia was induced in all patients and the mechanism shown to be INJT in 215 patients. Twelve of these (6%) also had spontaneous paroxysmal AF. It was possible to induce INJT and AF in 23 patients during electrophysiological study (11%): of these patients, 4 had a history of AF associated with INJT. Radiofrequency ablation of the slow pathway was successfully carried out. Patients were followed up for 1 to 6 years (average 3 +/- 2 years). None were prescribed antiarrhythmic drugs. The results showed that of the 12 patients with spontaneous AF before ablation, 8 had recurrence of paroxysmal AF which required reintroduction of an antiarrhythmic treatment and a ninth patient is currently in chronic atrial fibrillation. All but one of the patients were over 65 years of age. The AF recurred 1 month to 4 years after ablation. Of the 19 patients without previous AF but with inducible AF, 2 developed spontaneous paroxysmal AF. Of the patients without previous AF and without inducible AF, 4 aged over 65 went on to develop paroxysmal AF. The authors conclude that radiofrequency ablation of the slow pathway of patients with INJT does not seem to prevent future development of AF in elderly subjects.

[Paroxysmal atrial fibrillation: main cause of syncope in hypertrophic cardiomyopathy]. / La fibrillation auriculaire paroxystique: principale cause de syncope dans la cardiomyopathie hypertrophique?

The aim of this retrospective study was to determine the mechanism of syncope in idiopathic hypertrophic cardiomyopathy (HCM). An electrocardiographic study was undertaken in 43 patients with HCM: 27 (Group I) had a history of syncope and 16 (Group II) had no history of syncope but were investigated for conduction defects (n = 7) or unsustained ventricular tachycardia (VT) (n = 9). The stimulation protocol used programmed atrial pacing with 1 and 2 extrastimuli and ventricular pacing using up to 3 extrastimuli delivered at 2 sites. The following results were obtained: sustained atrial fibrillation (AF) (> 1 min) was induced in 21 patients in Group I (78%), 4 in Group II (25%); VT was induced in 3 patients in Group I (11%), and 3 in Group II (19%); infra-Hisian block was detected in 1 patient in Group I. The mechanism of syncope was elucidated in 23 patients in Group I (85%): one atrioventricular block 1 sinus node dysfunction, 18 atrial fibrillations, 2 associations of AF-VT and 1 VT. The authors conclude that the prevalence of inducible AF was higher in patients with HCA and syncope than in controls and HCM without syncope: this was the only detectable difference in 67% of patients with unexplained syncope. Paroxysmal AF could therefore explain malaise or syncope in up to 2/3 of cases of HCM.