Arrhythmogenic response to isoproterenol testing vs. exercise testing in arrhythmogenic right ventricular cardiomyopathy patients.

Aims: To compare the arrhythmic response to isoproterenol and exercise testing in newly diagnosed arrhythmogenic right ventricular cardiomyopathy (ARVC) patients. Methods and results: We studied isoproterenol [continuous infusion (45 µg/min) for 3 min] and exercise testing (workload increased by 30 W every 3 min) performed in consecutive newly diagnosed ARVC patients. Both tests were evaluated with regard to the incidence of (i) polymorphic premature ventricular contractions (PVCs) and couplet(s) or (ii) sustained or non-sustained ventricular tachycardia (VT) with left bundle branch block [excluding right ventricular outflow tract VT]; and compared to a control group referred for the evaluation of PVCs without structural heart disease. Thirty-seven ARVC patients (63.5% male, age 38 ± 16 years) were included. The maximal sinus rhythm heart rate achieved during isoproterenol testing was significantly lower compared to exercise testing (149 ± 17 bpm vs. 166 ± 19 bpm, P < 0.0001). However, the incidence of polymorphic ventricular arrhythmias was much higher during isoproterenol testing compared to exercise testing [33/37 (89.2%) vs. 16/37 (43.2%), P < 0.0001]. Interestingly, isoproterenol testing was arrhythmogenic in all 15 patients in whom baseline PVCs were reduced or suppressed during exercise testing. During both isoproterenol and exercise testing, control group presented a low incidence of ventricular arrhythmias compared to ARVC patients (8.1% vs. 89.2%, P < 0.0001 and 2.7% vs. 43.2%, P < 0.0001, respectively). Conclusions: The incidence of polymorphic ventricular arrhythmias is significantly higher during isoproterenol compared to exercise testing in newly diagnosed ARVC patients, suggesting its potential utility for the diagnosis.

Prevalence, characteristics, and prognosis role of type 1 ST elevation in the peripheral ECG leads in patients with Brugada syndrome.

BACKGROUND: Despite isolated reports of Brugada syndrome (BrS) in the inferior or lateral leads, the prevalence and prognostic value of ST elevation in the peripheral electrocardiographic (ECG) leads in patients with BrS remain poorly known. OBJECTIVE: To study the prevalence, characteristics, and prognostic value of type 1 ST elevation and ST depression in the peripheral ECG leads in a large cohort of patients with BrS. METHODS: ECGs from 323 patients with BrS (age 47 ± 13 years; 257 men) with spontaneous (n = 141) or drug-induced (n = 182) type 1 ECG were retrospectively reviewed. Two hundred twenty-five (70%) patients were asymptomatic, 72 (22%) patients presented with unexplained syncope, and 26 (8%) patients presented with sudden death (12 patients) or appropriated implantable cardioverter-defibrillator therapies (14 patients) at diagnosis or over a mean follow-up of 48 ± 34 months. RESULTS: Thirty (9%) patients presented with type 1 ST elevation in at least 1 peripheral lead (22 patients in the aVR leads, 2 in the inferior leads, 5 in both aVR and inferior leads, and 1 in the aVR and VL leads). Patients with type 1 ST elevation in the peripheral leads more often had mutations in the SCN5A gene, were more often inducible, had slower heart rate, and higher J-wave amplitude in the right precordial leads. Twenty-seven percent (8 of 30) of the patients with type 1 ST elevation in the peripheral leads experimented sudden death/appropriate implantable cardioverter-defibrillator therapy, whereas it occurred in only 6% (18 of 293) of other patients (P < .0001). In multivariate analysis, type 1 ECG in the peripheral leads was independently associated with malignant arrhythmic events (odds ratio 4.58; 95% confidence interval 1.7-12.32; P = .0025). CONCLUSIONS: Type 1 ST elevation in the peripheral ECG leads can be seen in 10% of the patients with BrS and is an independent predictor for a malignant arrhythmic event.

[Catheter ablation for atrial fibrillation]. / Ablation par radiofréquence de la fibrillation atriale.

The mainstay of treatment for atrial fibrillation (AF) remains pharmacological, however, catheter ablation, since an early attempt in 1994 has undergone many evolutions up to the present day whereby it has taken an increasing place in the management of this arrhythmia. In paroxysmal AF, the most recent studies report a success rate of more than 80% at 1 year of follow-up after a single procedure (free of symptoms without antiarrhythmic drugs). In persistent AF the technique continues to evolve with a success rates between 70% and 95% even if several long and complex procedures are often needed, which are not without risk, to achieve these results. With constant improvement in this field catheter ablation has become a valuable tool in the management strategy of AF.

[Risks of pulmonary vein isolation by radiofrequency for the treatment of paroxysmal atrial fibrillation: a single centre experience of the first 200 patients]. / Risques liés a l'isolement par radiofréquence des veines pulmonaires pour le traitement de la fibrillation auriculaire paroxystique: expérience monocentrique des 200 premiers patients.

The authors report the initial experience of an electrophysiological laboratory starting ablation for atrial fibrillation, a promising technique which is not yet widely practiced because of the risks related to the procedure. The incidence of severe complications (tamponade, pulmonary vein stenosis, ischaemic events) did not appear to be different in the first 100 procedures compared with the next 100 procedures: 3% in the two groups. The selection of patients, strict perioperative management and the initial support by confirmed operators seem to be the factors which minimise the complications rate of the procedure.

[Characterization of premature ventricular contraction initiating ventricular fibrillation]. / Caractéristiques morphologiques des extrasystoles ventriculaires initiatrices des fibrillations ventriculaires.

UNLABELLED: The aim of this study is to characterize the electrocardiographic features of premature ventricular contractions (PVC) from different anatomical region that trigger ventricular fibrillation (VF). METHODS AND RESULTS: 36 consecutives patients (20 males, 42+/-14 yrs) undergoing VF ablation from 7 centres were studied (22 with idiopathic VF, 4 associated with a long QT syndrome, 3 with Brugada syndrome, 4 with ischaemic cardiomyopathy and 3 associated with other substrate). Mapping of these PVC showed 2 different origins, which were then confirmed by ablation: right ventricular outflow tract (RVOT) (22%) and peripheral Purkinje network (81%). One patient had PVC from both origins (Brugada). RVOT PVC were frequent but had triggered only 5+/-5 episodes of VF for 26+/-33 months. Purkinje PVC were more likely to be present during electrical storm with 18+/-28 episodes of VF for 33+/-45 months. Right Purkinje PVC have a left bundle branch block with superior axis morphology whereas left Purkinje ones have a right bundle branch block. The axis of activation showed variation from inferior to superior depending on the area of origin from the Purkinje network and the exit site to the myocardium. However Purkinje PVC were characterized by short QRS duration (126+/-18 vs 145+/-13ms for RVOT PVC; p=0.05). In addition the coupling interval was significantly shorter compared to RVOT PVC (292+/-45 vs 358+/-37ms respectively; p=0.005). CONCLUSION: PVC initiating VF demonstrate specific electrocardiographic features that facilitate determination of their origin. Ablation of these typical PVC is feasible in order to reduce ICD shock.

Echocardiographic advances in atrial fibrillation and supraventricular arrhythmias.

Advances in echocardiography have paved the way for the development of intracardiac catheters with ultrasound transducers mounted on its tip. With this technology it has become possible for the interventional electrophysiologist to perform continuous echocardiographic examination during a procedure without the need for general anaesthesia or additional staff. Intracardiac echocardiography (ICE) allows the monitoring of catheter movement in real-time, assessment of catheter-tissue contact and potentially prevents and recognizes complications like thrombus formation and pericardial effusion. In addition recent technologies allow acquiring the full spectrum of Doppler-imaging permitting evaluation of haemodynamic data during the procedure. All these advances have made ICE an ideal tool for the interventional electrophysiologist, serving as a diagnostic and imaging tool during invasive electrophysiological procedures. This review will summarize currently available technology of ICE and its indications and applications in electrophysiological procedures.

Electrical storms in Brugada syndrome: review of pharmacologic and ablative therapeutic options.

Electrical storm occurring in a patient with the Brugada syndrome is an exceptional but malignant and potentially lethal event. Efficient therapeutic solutions should be known and urgently applied because of the inability of usual antiarrhythmic means in preventing multiple recurrences of ventricular arrhythmias. Isoproterenol should be immediately infused while oral quinidine should be further administrated when isoproterenol is not effective. In case of failure of these therapeutic options, ablation of the triggering ventricular ectopies should be attempted.

[Mapping and ablation of malignant ventricular arrhythmias]. / Cartographie et ablation des arythmies ventriculaires malignes.

Endocavitary investigations showed that the ventricular extrasystoles originated in the common ventricular myocardium (pulmonary infundibulum) in only 9 cases whereas the majority arose from the Parkinje system either on the anterior wall of the right ventricle or in septal region of the left ventricle. The extrasystoles arising from the Parkinje system and pulmonary infundibulum differed in their duration and polymorphism (128 +/- 18 ms vs 145 +/- 13 ms, p = 0.05; 3.3 +/- 2.7 morphologies vs 1.1 +/- 0.4, p < 0.001, respectively). During the extrasystoles, the local Pukinje potential preceded the ventricular activation by variable intervals, some of which were very long, up to 150 ms. Seven applications of radiofrequency were delivered on average per patient on the most distal part of the Purkinje system leading to ablation of the specific activation. The clinical results were spectacular: 88% of patients had no further episodes of ventricular fibrillation as demonstrated by analysis of the defibrillator with an average follow-up period of more than 34 months.

Catheter ablation for atrial fibrillation.

Recent advancements in our understanding of atrial fibrillation have led to the development of catheter ablation techniques that feasibly could achieve a cure for AF.

[The place of ablation in the treatment of atrial fibrillation: where are we and where are we going?]. / Place de l'ablation dans le traitement de la fibrillation auriculaire: où en sommes-nous? où allons-nous?

Atrial fibrillation, the most common arrhythmia, is frequently disabling and drug resistant and is associated with significant complications, especially thromboembolic events. Non-pharmacological approaches including surgery and catheter-based ablation have been developed for the most symptomatic patients. These new treatment strategies have dramatically increased our knowledge of the pathophysiology of this arrhythmia but most importantly have demonstrated that atrial fibrillation is curable. Since 1994, 2 different concepts have been used, aiming to modify the substrate responsible for AF maintenance using linear lesions, or to ablate the triggers located from within the pulmonary veins (PV) in about 90% of cases. The vast majority of the laboratories in the world are now using approaches centred on isolation of the PV. These approaches are far from being perfect but good enough to be offered in routine practice to selected patients in experienced centres. The importance of PVs in the initiation of AF has been clearly demonstrated and they also have a possible role in the maintenance of AF. However, the existence of non venous foci or a prominent substrate for AF maintenance limits the success rate to about 70%. As a consequence, a combination of PV isolation and linear lesions is commonly used. This more complex procedure carries a significantly higher success rate however with an increased risk of tamponade. As a consequence, we need to identify which patients will require linear lesions in addition to PV isolation. At the present time, AF ablation is restricted to symptomatic patients who have failed at least 1-2 antiarrhythmic drugs but future technical improvements based on presently applied concepts are likely to widen the indications for ablation therapy of AF.

Mapping and ablation of ventricular fibrillation.

Sudden cardiac death frequently results from ventricular fibrillation (VF). While VF is frequently the eventual mode of death in patients with abnormal ventricular substrates, it has also been described in patients with structurally normally hearts. Until recently, the management of patients who have survived sudden cardiac death has focused on treating the consequences by implantation of a defibrillator. However, such therapy remains restricted in many countries, is associated with a prohibitive cost to the community, and may be a cause of significant morbidity in patients with frequent episodes or storms of arrhythmia. Evidence emerging from the study of fibrillation both in the atria and the ventricle suggests an important role for triggers arising from the Purkinje network or the right ventricular outflow tract in the initiation of VF. Initial experience in patients with idiopathic VF and even those with VF associated with abnormal repolarization syndromes (LQT or Brugada syndrome) or myocardial infarction suggests that long term suppression of recurrent VF may be feasible by the elimination of these triggers. With the development of new mapping and ablation technologies, and greater physician experience, catheter ablation of VF, with the ultimate aim of curing such patients at risks of sudden cardiac death, may not be an unrealistic goal in the future.

[Catheter ablation of paroxysmal atrial fibrillation]. / Ablation endocavitaire des fibrillations atriales paroxystiques.

UNLABELLED: Catheter ablation techniques for atrial fibrillation have undergone an extensive evolution, starting with linear lesions in the right, then the left atria before being superseded by ablation of triggers, mainly from the pulmonary veins. We investigate the feasibility and results of combined pulmonary vein and linear ablation utilizing a specific linear lesion connecting the lateral mitral annulus to the left inferior pulmonary vein (left isthmus). METHODS: 115 patients (101 M: 54 +/- 9 years) with paroxysmal atrial fibrillation (7 +/- 5 years) resistant to 4 +/- 1.6 anti-arrhythmic drugs were studied. After electrophysiologically guided disconnection of all four pulmonary veins, the left isthmus line was performed with an irrigated tip catheter. Complete linear block was demonstrated during coronary sinus pacing by local mapping looking for widely separated double potentials and confirmed by differential pacing. Mapping and ablation from within the coronary sinus was performed if an epicardial gap was detected after unsuccessful endocardial radiofrequency delivery. RESULTS: 100% of pulmonary veins were successfully disconnected and the left isthmus line was complete with bi-directional block in 88% after a mean of 22 +/- 12 min of endocardial radiofrequency delivery in 44 patients. In 58 patients, additional radiofrequency delivery was required from within the coronary sinus for 5 +/- 5 min. After a follow-up of 6.5 +/- 2.6 months and a mean of 1.4 +/- 0.6 procedures/patient, 79% were in stable sinus rhythm without antiarrhythmic drugs. CONCLUSION: the left isthmus line is feasible and safe and when performed in addition to pulmonary veins isolation can contribute to an increased success rate.

[Radiofrequency ablation of atrial fibrillation]. / Ablation par radiofréquence de la fibrillation auriculaire.

The possibility of curing patients suffering from paroxysmal atrial fibrillation using a radiofrequency ablation treatment is a major change in the management of this arrhythmia. Pulmonary vein disconnection is efficient and safe after a learning curve of the operator. This pulmonary vein isolation is the first and mandatory step allowing disappearance of atrial fibrillation in 70% of the patients. Modification in fibrillatory substrate using linear lesions increases the rate success to 75% in chronic atrial fibrillation and to 82% in paroxysmal atrial fibrillation. The radiofrequency ablation of atrial fibrillation should be considered as a surgical treatment without an open heart, isolating structures and cutting tissues are technical improvements (new radiofrequency catheters) will probably facilitate in the future. Some comparative studies with medical treatment are currently evaluating their efficacy, safety and respective cost and they may lead to a considerable increase in the number of patients who could benefit from these curative treatments.

Atrial fibrillation can cause major hyperglycemia.

We report the case of a 66 years old woman with a well controlled, insulin-treated, type 2 diabetes, who experienced a ten-fold increase of her daily insulin needs (from 21 to 215 U/day) after the onset of a symptomatic atrial fibrillation. Check-up for another cause of insulin resistance was negative, and insulin doses could be decreased to preceding values only after electric cardioversion. Symptomatic atrial fibrillation should be considered as a potential cause of hyperglycemia.

[Role of radiofrequency ablation in atrial fibrillation]. / Place de l'ablation par radiofréquence dans la fibrillation auriculaire.

Atrial fibrillation is the most frequently encountered arrhythmia in the human species. Its danger is widely appreciated but it remains for certain patients and their practitioners an awkward or even exasperating problem. Only surgery and radiofrequency ablation allow certain patients to be cured. The surgical approach is of course warranted in the case of an otherwise necessary cardiac intervention. In the absence of a surgical indication, endovenous ablation, which is less aggressive, is preferred. The procedure consists of disconnecting the pulmonary veins which "house" 80 to 95% of the foci, together with the ablation of further non-venous foci, which are always difficult to treat. Side effects in experimental centres are rare and 70% of patients are cured, which allows cessation of antiarrhythmic and anticoagulant treatments. The procedure is currently offered to symptomatic patients having had at least one episode every ten days in spite of antiarrhythmics.

Electrogram polarity reversal as an additional indicator of breakthroughs from the left atrium to the pulmonary veins.

OBJECTIVES: We assessed the anatomical distribution and electrogram characteristics of breakthrough from the left atrium (LA) to the pulmonary veins (PVs). BACKGROUND: Localization of LA-PV breakthrough is an important technique for PV ablation in patients with atrial fibrillation (AF). METHODS: A total of 157 patients with paroxysmal AF underwent PV disconnection guided by mapping with a circumferential 10-electrode catheter. Radiofrequency (RF) current was delivered ostially at the site(s) of earliest activation (113 patients) or electrogram polarity reversal defined by opposite polarity across adjacent bipoles (44 patients). Breakthrough sites were proved by changes in pulmonary vein potential activation sequence occurring as a result of localized RF delivery and were classified into four segments around the ostium (top, bottom, anterior, posterior). Results of mapping and ablation were compared between the two groups. RESULTS: A total of 99% of 411 targeted PVs were successfully disconnected in both groups. Breakthroughs were most frequent at the bottom of superior PVs (85% prevalence) and the top of inferior PVs (75% prevalence). A wide activation front (>5 synchronous bipoles) indicating broad breakthrough was observed in 18% of PVs. Polarity reversal occurred with 88% sensitivity and 91% specificity at breakthrough sites. Polarity reversal was restricted to fewer bipoles (2.0 +/- 0.4 bipoles vs. 3.4 +/- 2.0 bipoles, p < 0.01) compared with earliest activation. Shorter RF application time was required to disconnect PVs with wide synchronous activation using polarity reversal compared with using conventional earliest activity (10.3 +/- 3.0 min vs. 12.3 +/- 3.4 min, p < 0.05). CONCLUSIONS: Bipolar electrogram polarity reversal allows more precise localization of breakthrough compared with the earliest activation, particularly in cases of wide synchronous PV activation.

Morphological characteristics of P waves during selective pulmonary vein pacing.

OBJECTIVES: We sought to assess the value of 12-lead electrocardiogram (ECG) P-wave morphology to recognize the paced pulmonary vein (PV). BACKGROUND: Prediction of arrhythmogenic PVs producing ectopy or initiating atrial fibrillation (AF) using 12-lead ECG may facilitate curative ablation. METHODS: In 30 patients P-wave configurations were studied during sinus rhythm and during pacing at six sites from the four PVs: top and bottom of each superior PV and both inferior PVs. The P-wave amplitude, duration and morphology were assessed, and predictive accuracies were calculated for the most significant parameters. An algorithm predicting the paced PV was developed and prospectively evaluated in a different population of 20 patients. RESULTS; Three criteria were used to distinguish right from left PV: 1) a positive P-wave in lead aVL and the amplitude of P-wave in lead I > or =50 microV indicated right PV origin (specificity 100% and 97%, respectively); 2) a notched P-wave in lead II was a predictor of left PV origin (specificity 95%); and 3) the amplitude ratio of lead III/II and the duration of positivity in lead V(1) were also helpful in distinguishing left versus right PV origin. In addition, superior PVs could be distinguished from inferior according to the amplitude in lead II (> or =100 microV). In prospective evaluation, an algorithm based on the above four criteria identified 93% of left versus right PV and totally 79% of the specific PVs paced. CONCLUSIONS: Pacing from the different PVs produced a P-wave with distinctive characteristics that could be used as criteria in an algorithm to identify the PV of origin with an accuracy of 79%.