[Periprocedural management of anticoagulation in patients undergoing atrial fibrillation ablation]. / Anticoagulation péri-interventionnelle lors d'ablation de fibrillation auriculaire.

Catheter ablation of atrial fibrillation (AF) has been increasingly performed and has become a standard of care treatment option for drug-refractory symptomatic patients. However, this procedure has been associated with major complications, like thromboembolic or bleeding events. Optimal periprocedural anticoagulation strategy is essential for minimizing these complications. In this article, we review current anticoagulation strategies, including use of oral anticoagulation with Vit-K-Antagonists, as well as use of direct oral anticoagulants in the periprocedural settings of AF ablation.

Microparticles in atrial fibrillation: a link between cell activation or apoptosis, tissue remodelling and thrombogenicity.

Microparticles (MPs) are small membrane vesicles that are shed from virtually all cells in response to stress. Widely described in atherothrombotic diseases, recent data suggest a role for circulating MPs in the hypercoagulable state associated with supraventricular tachyarrhythmia. During atrial fibrillation, several mechanisms, such as high ventricular heart rate, low or oscillatory shear stress, stretch, hypoxia, inflammation and oxidative stress, are potent inducers of apoptotic cell death, which leads to the shedding of procoagulant MPs within the vasculature. As key regulators of cell-cell cross-talk and important mediators of inflammatory, thrombogenic and proteolytic pathways, MPs directly or indirectly contribute to the amplification loops involved in atrial fibrillation. Because high levels of platelets and endothelial-derived MPs are identified during stroke and are associated with infarct size and clinical outcome, they are proposed to be a potent marker of ischaemic risk. During pulmonary vein isolation, the additional increases of platelet and leukocyte MP levels suggest the extent of tissue damage and reflect a transient activation of the coagulation cascade that could favour ischaemic stroke. Conversely, the observed decreases of several apoptotic markers some months after the restoration of sinus rhythm suggest that the extent of apoptotic processes is reversible and might enable restoration of haemostasis. In this review, we will summarise the current evidence supporting the roles of apoptosis and cell activation in the development of the prothrombotic state observed in atrial fibrillation, with a particular focus on procoagulant MPs.

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.

Effect of atrial overdrive pacing on pulmonary vein focal discharge in patients with atrial fibrillation.

AIMS: Recently, it has been shown that atrial fibrillation may be caused by spontaneously discharging foci located predominantly in the pulmonary veins. However, the effect of atrial overdrive pacing on these pulmonary vein foci has not been studied. METHODS AND RESULTS: In 58 patients with drug refractory paroxysmal or persistent atrial fibrillation we performed radiofrequency catheter ablation of arrhythmogenic triggers inside the pulmonary veins and/or an ostial pulmonary vein isolation with conventional mapping and ablation technology. Continuous bigeminal pattern of discharge from one or more arrhythmogenic pulmonary veins was recorded in 14 patients. Atrial overdrive pacing resulted in suppression of pulmonary vein 'focus' activity in all patients. The longest mean atrial pacing cycle length resulting in overdrive suppression was 587+/-114 ms. Independent of pacing rate and duration, bigeminal pulmonary vein focus activity reemerged 2.5+/-3.7s after cessation of pacing. Overdrive suppression of the pulmonary vein focus was incomplete in 9 pacing attempts, and resulted in induction of atrial fibrillation from the same vein in 3 of 31 pacing manoeuvres. At 2 years follow-up 79% of these patients were free of atrial fibrillation, 55% without antiarrhythmic drugs, 24% on previously ineffective antiarrhythmic drug therapy. CONCLUSION: Stable pulmonary vein 'focus' activity in patients with atrial fibrillation can be suppressed by atrial overdrive pacing. However, 'proarrhythmic' effects of atrial overdrive pacing, such as induction of atrial fibrillation, were also seen.

[Ventricular tachycardia by branch to branch re-entry. Familial case with Steinert's disease]. / Tachycardie ventriculaire par réentrée de branche à branche. Cas familial avec maladie de Steinert.

Ventricular tachycardia by branch to branch reentry is a rare arrhythmia. It occurs in cardiomyopathies associated with conduction defects. During tachycardia a His potential precedes each QRS complex which usually has a left bundle branch block appearance. The authors report two familial cases of ventricular branch to branch tachycardia (son and mother) without cardiomyopathy. The diagnosis of Steinert's disease was made post-mortem in these two patients. In cases of branch to branch ventricular tachycardia, the diagnosis of myotonic dystrophy should be excluded. Conversely, endocavitary electrophysiological investigation with ventricular stimulation should be proposed for symptomatic patients (dizzy spells, syncope) to diagnose branch to branch ventricular tachycardia, even in cases with conduction defects which could also explain the symptoms.

[Focal paroxysmal atrial fibrillation. Experiences with treatment using high frequency catheter ablation]. / Fokales paroxysmales Vorhofflimmern. Erste Erfahrungen mit der Behandlung mit Hochfrequenz-Katheterablation.

BACKGROUND AND OBJECTIVE: As has recently been discovered, paroxysmal atrial fibrillation (PAF) can be induced by focal extrasystoles or tachycardia. This raises the question of whether this form of atrial fibrillation can be cured by high-frequency catheter ablation of the focal trigger. PATIENTS AND METHODS: Seven men and eleven women (mean age 45.6 +/- 11 years) with severe symptoms and treatment-resistant PAF underwent electrophysiological tests with the aim of high-frequency catheter ablation, if long-term ECG monitoring had demonstrated frequent atrial extrasystoles or tachycardia as pointer to a focal origin. Ablation was performed at the point of earliest excitation after the origin of the ectopic focus had been localized. The end-point was reached if the atrial ectopic rhythm had ceased for more than 60 min. RESULTS: In 18 of the 20 patients an ectopic focus was found and successfully ablated (1 in the superior vena cava, 3 in the right atrium and 16 in a pulmonary vein). Atrial ectopic beats recurred within 24 hours of ablation in 6 of the 14 patients with a pulmonary vein focus: a second focus was found in two, re-emergence of the original focus in two, no re-investigation in another two. 13 of the 18 patients have had no further symptoms after a mean follow-up of 11 months without anti-arrhythmia treatment. CONCLUSION: The results indicate that focally induced paroxysmal atrial fibrillation can be cured by locally applied high-frequency ablation.

Catheter ablation of chronic atrial fibrillation targeting the reinitiating triggers.

INTRODUCTION: We assessed the mode of reinitiation of atrial fibrillation (AF) after cardioversion and the efficacy of ablating these foci of reinitiation in patients with chronic AF. METHODS AND RESULTS: Fifteen patients, 7 with structural heart disease, underwent mapping and catheter ablation of drug-resistant AF documented to be persistent for 5 +/- 4 months. In all patients, cardioversion was followed by documentation of P on T atrial ectopy and early recurrence, which allowed mapping of the reinitiating trigger or the source of ectopy. Radiofrequency (RF) ablation was performed at pulmonary vein (PV) ostia using a target temperature of 50 degrees C and a power limit of 30 to 40 W, with the endpoint being interruption of all local muscle conduction. A total of 32 arrhythmogenic PVs and 2 atrial foci (left septum and left appendage) were identified: 1, 2, and 3 or 4 PVs in 5, 3, and 6 patients. RF applications at the ostial perimeter resulted in progressively increasing delay, followed by abolition of PV potentials in 8, but potentials persisted in 6. A single ablation session was performed in 7 patients and 8 underwent two or three sessions because of recurrence of AF; ablation was directed at the same source due to recovery of local PV potential or at a different PV. No PV stenosis was noted either acutely or at repeated follow-up angiograms. Nine patients (60%) were in stable sinus rhythm without antiarrhythmic drugs at follow-up of 11 +/- 8 months. Anticoagulants were interrupted in 7 patients. CONCLUSION: PVs are the dominant triggers reinitiating chronic AF in this patient population. Elimination of PV potentials by ostial RF applications results in stable sinus rhythm in 60%. A larger group and longer follow-up are needed to investigate further the role of trigger ablation in curative therapy for chronic AF.

[Atrial fibrillation: healing by focal high frequency catheter ablation?]. / Vorhofflimmern: Heilung durch fokale Hochfrequenz-Katheterablation?

Atrial fibrillation is the most common sustained arrhythmia causing substantial morbidity and probably increasing the risk of death. Most commonly, it is divided into a paroxysmal form, when--by definition--episodes end spontaneously, or a persistent one that lasts and requires a medical or electrical intervention for its termination. It might be called permanent, when no further attempts seem to be indicated for its elimination. Until recently, therapeutic strategies aimed at preventing cardiac embolism and at restoring and maintaining sinus rhythm by antiarrhythmic drugs. Long-term efficacy of the latter approach is poor, since less than 50% of patients can be maintained in stable sinus rhythm when periods of more than 1 year are considered. Can atrial fibrillation be cured? More than ten years ago Cox and coworkers demonstrated that the surgical compartimentation of both atria (MAZE procedure) is able to abolish atrial fibrillation in up to 90% of patients with chronic paroxysmal and also persistent atrial fibrillation. However, all studies trying to imitate the MAZE procedure by electrophysiological catheter-based techniques applying radiofrequency energy to produce transmural linear lesions were either not successful or showed a non-acceptable complication rate, especially a high rate of cerebrovascular accidents. The rationale behind the principle of compartimentation of the atria is the reduction of the critical atrial muscle mass necessary to facilitate fibrillation of the atria. A different approach aiming especially at the problem of paroxysmal atial fibrillation is based on the observation that there might be a "focal trigger" responsible for the initiation of the atrial tachyarrhythmia and that by eliminating this focal trigger atrial fibrillation can be avoided. This hypothesis was first verified in patients by Haïssaguerre et al., in fact experimental creation of "focal atrial fibrillation" was presented by Moe and Abildskov more than 30 years ago. During the last 3 years the concept of curing paroxysmal atrial fibrillation by applying focal radiofrequency lesions was supported by the results of several groups in more than 200 patients: 60 to 85% of patients can be cured, but in almost half of the cases more than one procedure is necessary. Most interestingly--and this is a finding of all investigators--more than 90% of the triggering ectopic foci are located in the pulmonary veins or in the pulmonary vein/left atrial junction. This concept is also supported by surgical experience from performing pulmonary vein isolations during open heart surgery. Most recently, the concept of eliminating the trigger was extended and applied to patients with established persistent atrial fibrillation. Until now, it has not been well established how many patients with paroxysmal atrial fibrillation are "good candidates" for a focal RF ablation procedure, nor is the risk of the procedure well defined. Besides the necessity of performing a transseptal catheterization there is the risk of cardiac embolism and pulmonary vein stenosis. The endpoint of the procedure is also not well defined: instead of trying to eliminate the "trigger" located in a pulmonary vein, it might be safer to isolate the "arrhythmogenic vein". This however, is a difficult task with current catheter technologies. It can be expected that new catheter designs for mapping and ablation and--maybe--the use of alternative energy sources--e.g., ultrasound, microwave--will make the procedure easier and applicable to more patients with drug refractory atrial fibrillation.

[Radiofrequency ablation in auricular flutter. Predictive factors of primary success and medium term results]. / Ablation par radiofréquence du flutter auriculaire. Facteurs prédictifs du succès primaire et devenir à moyen terme.

Ninety-one consecutive patients underwent radiofrequency ablation of chronic or paroxysmal atrial flutter. The average age of the patients was 66. There was a previous history of atrial fibrillation in 38% of cases and of cardiac surgery in 14.3% of cases. The primary success rate was 79% (92% in cases of common flutter). The predictive factors of success were the type of flutter (p < 0.001), left ventricular (p < 0.01) and left atrial dimensions (p < 0.01) at echocardiography. The length of the cavo-tricuspid isthmus measured by echocardiography had no influence on the initial result but, in primary success, did affect the parameters of the procedure (duration and number of applications of radiofrequency energy). After an average of 11 +/- 2 months, sinus rhythm was maintained in 67% of patients. There were recurrences of flutter in 27.5% of cases and of atrial fibrillation in 5.5% of cases: 85% of these episodes occurred during the first six months after ablation. A second procedure was carried out in 12 patients for recurrence of flutter (92% primary success rate). After an average follow-up of 8.4 months, 4 patients had a recurrence and required a third procedure (100% success rate). In cases of failure of ablation, the rhythm was converted by a shock or atrial pacing: 47.3% of these patients remained in sinus rhythm with antiarrhythmic therapy with a 12 month follow-up. Radiofrequency ablation of atrial flutter is, therefore, a safe method, the difficulty of which is mainly related to anatomical factors: the medium-term results are better than those of other therapeutic methods.

AV nodal re-entry tachycardia in elderly patients: clinical presentation and results of radiofrequency catheter ablation therapy.

BACKGROUND: Modification of AV nodal conduction by means of radiofrequency catheter ablation has become the accepted mode of therapy for patients with symptomatic AV nodal re-entry tachycardias (AVN-RT). The published results demonstrate high success rates and a low incidence of severe complications. However, published series have primarily dealt with relatively young patient populations. Little is known about the efficacy and risks of radiofrequency catheter ablation of AVN-RT in the elderly. METHODS: We retrospectively analysed our data of 404 patients who underwent a catheter ablation therapy for AVN-RT between 1992 and June 1997. Nine patients were excluded from further analysis because of presence of more than one tachycardia mechanism. The ablation procedure was performed at the time of the diagnostic electrophysiologic study. RESULTS: The mean age of 395 patients undergoing catheter ablation for AVN-RT was 52.3 years (19-90 years); 85 patients were 65 years old or older. Compared with the younger subgroup, these elderly patients (mean age 70.4 years) more often had organic heart disease (coronary heart disease with or without myocardial infarction 19.3% versus 2.6%; P < 0.02), more often had syncopes or presyncopes with AVN-RT (43.2% versus 29.8%; P < 0.05), had more hospitalisations and emergency treatments because of their symptoms (56.8% versus 39.5%; P < 0.05) although the cycle length of the induced AVN-RT was significantly shorter in the younger patient group (325 ms versus 368 ms; P < 0.001). Slow pathway ablation was performed in 94% of the young and 82% of the elderly (P < 0.001). In 17.5% of the elderly patients versus 6.5% of the young (P < 0.05) the fast pathway approach was chosen as the first therapy or tried after an unsuccessful approach to the slow pathway. The overall success rate (96.8% in the young and 95.3% in the elderly) and the recurrence rate (5.8% in the elderly versus 4.9% in the young) were similar in both patient groups. There were no differences regarding the total procedure of fluoroscopy time, radiation exposure or the incidence of high-degree AV-block necessitating pacemaker implantation (2.3% in the elderly versus 1.6% in the young). CONCLUSIONS: In patients older than 65 years, AVN-RT may lead to severe, sometimes life-threatening symptoms, despite the fact that the tachycardia is not as fast as in younger patients. Radiofrequency catheter ablation can be performed effectively and safely and should be offered to these patients as first-choice therapy.

The role of endogenous opiates in thermal regulation of the body during exercise.

Naloxone abolished the rise in body temperature seen after bicycle ergometer tests performed by 10 healthy men. This suggests that endogenous opiates play a part in thermal regulation during muscular exercise.