Outcomes after cryoablation vs. radiofrequency in patients with paroxysmal atrial fibrillation: impact of pulmonary veins anatomy.

AIMS: Pulmonary vein isolation is the mainstay of treatment in catheter ablation of paroxysmal atrial fibrillation (AF). Cryoballoon ablation has been introduced more recently than radiofrequency ablation, the standard technique in most centres. Pulmonary veins frequently display anatomical variants, which may compromise the results of cryoballoon ablation. We aimed to evaluate the mid-term outcomes of cryoballoon ablation in an unselected population with paroxysmal AF from an anatomical viewpoint. METHODS AND RESULTS: Consecutive patients with paroxysmal AF who underwent a first procedure of cryoballoon ablation or radiofrequency were enrolled in this single-centre study. All patients underwent systematic standardized follow-up. Comparisons between radiofrequency and cryoballoon ablation (Arctic Front™ or Arctic Front Advance™) were performed regarding safety and efficacy endpoints, according to pulmonary vein (PV) anatomical variants. A total of 687 patients were enrolled (376 radiofrequency and 311 cryoballoon ablation). Baseline characteristics and distribution of PV anatomical variants were generally similar in the groups. After a mean follow-up of 14 ± 8 months, there was no difference in the incidence of relapse (17.0% cryoballoon ablation vs. 14.1% radiofrequency, P = 0.25). We observed no interaction of PV anatomical variants on mid-term procedural success. CONCLUSION: Our findings suggest that mid-term outcomes of cryoballoon ablation for paroxysmal AF ablation are similar to those of radiofrequency, regardless of PV anatomy. The presence of anatomical variants of PVs should not discourage the referral of patients with paroxysmal AF for cryoballoon ablation.

[Rhythm control - cardioversion]. / Contrôle du rythme sinusal - Cardioversion.

In case of persistent and symptomatic atrial fibrillation, a pharmacological cardioversion under effective anticoagulation treatment may be performed according to current guidelines. In the absence of return to sinus rhythm, a Direct-Current cardioversion can be performed. After returning to sinus rhythm will arise the question of anticoagulation and antiarrhythmic drugs treatments that will be most often long-term pursued.

[How to evaluate sudden cardiac death risk after myocardial infarction?]. / Comment évaluer le risque de mort subite dans les suites d'un infarctus du myocarde ?

Sudden cardiac death is the mode of death of more than half of coronary heart disease patients. Preventing sudden cardiac death involves prevention of ventricular arrhythmias occurrence as well as the treatment by an implantable cardioverter defibrillator. The evaluation of sudden cardiac death risk should consider the underlying cardiopathy, the associated coronary risk factors and all pharmacological treatment efficient to reduce ventricular remodeling and myocardial ischemia. Only significant low ejection fraction and positive ventricular testing in some cases are now considered are now considered by the current French recommendations for cardioverter defibrillator implantation in primary prevention. However, other noninvasive markers such as heart rate variability and T wave alternans are of interest in sudden cardiac death risk stratification after myocardial infarction.

[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.

[Rhythm disorders and cardiac crypto-malformations]. / Troubles du rythme et crypto-malformations cardiaques.

Faced with a cardiac arrhythmia occuring in an apparently healthy heart, it is necessary to perform an anatomical investigation to detect any unsuspected anomalies. Congenital cardiopathy must certainly be excluded, as this is often responsible for rhythm disorders and/or cardiac conduction defects. Similarly, any acquired conditions, cardiomyopathy, or cardiac tumour must be sought. However, the possibility should always be considered of a minimal congenital malformation, which could be repsonsible for: any type of cardiac arrhythmia: rhythm disorder or conduction defect at the atrial, junctional or ventricular level, with a benign or serious prognosis. Unexpected therapeutic difficulties during radiofrequency ablation procedures or at implantation of pacemakers or defibrillators. Together with rhythm studies, the investigation of choice is high quality imaging, either the classic left or right angiography or the more modern cardiac CT or intracardiac mapping.

[Brugada syndrome and supraventricular arrhythmias]. / Syndrome de Brugada et arythmies supraventriculaires. A propos d'une observation clinique.

The author reports the case of a 46-year old patient diagnosed with idiopathic ventricular fibrillation (Brugada syndrome) further to induction of class Ic antiarrhythmic therapy for the management of paroxystic ventricular fibrillation. It would appear that this diagnosis is increasingly frequent in young patients with Brugada syndrome shown to be minimal or intermittent on electrocardiograms. Atrial arrhythmia was the only rhythmic pathology objectively evidenced in this patient and the author was consequently led to reconsider its prevalence in patients presenting this syndrome both in the literature and according to his personal experience.

Is postural tremor size controlled by interstitial potassium concentration in muscle?

OBJECTIVES: To determine whether factors associated with postural tremor operate by altering muscle interstitial K(+). METHODS: An experimental approach was used to investigate the effects of procedures designed to increase or decrease interstitial K(+). Postural physiological tremor was measured by conventional means. Brief periods of ischaemic muscle activity were used to increase muscle interstitial K(+). Infusion of the beta(2) agonist terbutaline was used to decrease plasma (and interstitial) K(+). Blood samples were taken for the determination of plasma K(+). RESULTS: Ischaemia rapidly reduced tremor size, but only when the muscle was active. The beta(2) agonist produced a slow and progressive rise in tremor size that was almost exactly mirrored by a slow and progressive decrease in plasma K(+). CONCLUSIONS: Ischaemic reduction of postural tremor has been attributed to effects on muscle spindles or an unexplained effect on muscle. This study showed that ischaemia did not reduce tremor size unless there was accompanying muscular activity. An accumulation of K(+) in the interstitium of the ischaemic active muscle may blunt the response of the muscle and reduce its fusion frequency, so that the force output becomes less pulsatile and tremor size decreases. When a beta(2) agonist is infused, the rise in tremor mirrors the resultant decrease in plasma K(+). Decreased plasma K(+) reduces interstitial K(+) concentration and may produce greater muscular force fluctuation (more tremor). Many other factors that affect postural tremor size may exert their effect by altering plasma K(+) concentration, thereby changing the concentration of K(+) in the interstitial fluid.

[Pharmacological treatment of atrial fibrillation]. / Traitement médicamenteux de la fibrillation atriale.

Although anticoagulant treatment of atrial fibrillation is now well codified, the medical treatment of the fibrillation remains controversial. Two types of medication can be proposed: drugs to slow the rhythm (digitalis, betablockers and calcium inhibitors) and anti-arrhythmic mainly Class I or Class III drugs. Some doubt was raised in the 1990's about the pertinence of antiarrhythmic therapy and four recent trials (AFFIRM, RACE, PIAF and STAF) compared the two attitudes of "rhythm control" or "rate control" in atrial fibrillation. The four trials all showed that the results of these two options were equivalent with respect to the therapeutic objectives: reduction of mortality, thromboembolic or haemodynamic risk, and regression of symptoms and improvement of the quality of life. However, these trials have not closed the debate on these two therapeutic attitudes. In fact, analysis shows that the comparison was biased because anticoagulant treatment was inadequate and, though the treatment for rate control was appropriate, the antiarrhythmic treatment was far from being satisfactory and effective. Moreover, many patients in the "rhythm control" group were in atrial fibrillation whereas a certain number of patients in the "rate control" group were, in fact, in sinus rhythm throughout the study period. In addition, the comparison was incomplete because it did not include two other particularly common populations in clinical practice: multi-relapsing paroxysmal atrial fibrillation in healthy hearts and atrial fibrillation associated with severe left ventricular dysfunction, patients with cardiac failure. Until the results of trials currently under way (AF-CHF) become available, the authors discuss the use of drugs for rate control and antiarrhythmic therapy in everyday practice.

There is no simple temporal relationship between the initiation of rapid reactive hand movements and the phase of an enhanced physiological tremor in man.

1. A postural hand tremor of enhanced size was induced in eleven subjects. There was rhythmic activity in the posturally active extensor muscles synchronised to the tremor oscillation, which implied an oscillatory modulation of motor neurones. 2. The subjects executed single rapid wrist flexion movements in response to a flash of light. The light flash was presented at an instant when the wrist was spontaneously moving in the flexion direction, extension direction or at random. The time taken to generate a movement was not significantly different or more consistent in any of the conditions. 3. Inspection of individual and averaged acceleration and EMG records strongly suggests that the movement is made at a time that is independent of the tremor cycle at the time of stimulus presentation or at the moment of movement initiation. 4. These observations suggest that the central or spinal mechanism generating tremor does not gate the central mechanism that produces voluntary movement.

Tremulousness--the perception of tremor in man.

The thresholds for detection of a tremor-like movement are described. Detection is poorest at frequencies which correspond to natural tremor. The results are in accord with the failure of persons often to notice that their hands are tremulous.

The phase of postural hand tremor is not influenced by repetitive photic brain stimulation.

Powerful photic stimulation was employed to produce driving of the EEG rhythm recorded from occipital cortex. The resulting quasi-sinusoidal signal was considerably larger than the spontaneous alpha rhythm, and Fourier analysis showed it to be sharply tuned to the frequency of the stimulation which ranged from 7-11 Hz. Physiological postural hand tremor was recorded bilaterally during the period of stimulation. Signal averaging was used to investigate the relationship of the EEG and tremor waveform to the light flashes. The EEG was clearly phasically related to the repetitive stimulus, but the waveform of the tremor was not. We conclude that this external stimulus fails to produce a detectable entrainment of motor output.