[Relation between cavo-tricuspid isthmus anatomy studied by transesophageal echocardiography and the immediate outcome of radiofrequency ablation of common atrial flutter]. / Relation entre l'anatomie de l'isthme cavo-tricuspide étudiée par échocardiographie trans-oesophagienne et les résultats immédiats de l'ablation par radiofréquence du flutter auriculaire commun.

Radiofrequency ablation is the only curative treatment of common atrial flutter. The aim of the treatment is to create a line of bidirectional block at the level of the cavo-tricuspid isthmus. This objective can be achieved in the vast majority of the patients. However, it may difficult or even not possible to create an isthmus block. The anatomy of the right atrium is subject to important variations, especially at the isthmus level. We therefore tested the hypothesis that these anatomic variations might influence the immediate outcome of cavo-tricuspid isthmus ablation. The anatomy of cavo-tricuspid isthmus was studied by trans-oesophageal echocardiography. The shape of the isthmus (concave or not), the presence of diverticula and the degree of development of the Eustachian ridge were analysed. From these data, the cavo-tricuspid anatomy was classified as simple or complex. The immediate outcome of radiofrequency ablation was reviewed in 94 patients (mean age of 63 years) according to the anatomy, simple or complex. When the anatomy was classified as simple, the success rate of radiofrequency ablation was 95.6%; when the anatomy was complex, the success rate was 76.9% (overall success rate for the entire population equal to 90.4%). The length of the cavo-tricuspid isthmus did not influence the outcome of radiofrequency ablation. In summary, it appears that the anatomy of cavo-tricuspid isthmus seems to play a role in the immediate outcome of radiofrequency ablation of cavo-tricuspid isthmus.

[Case report and review about radiofrequency catheter ablation in a patient with dilated cardiomyopathy and an implantable cardioverter defibrillator]. / Prise en charge d'une tachycardie ventriculaire récidivante sur cardiopathie non ischémique chez un patient implanté d'un défibrillateur.

The benefit of implantable cardioverter defibrillators (ICD) on total mortality has been demonstrated in primary prevention for heart failure patients, in whom they improve clinical outcomes. However, some of these patients present incessant ventricular tachycardia and receive appropriated shocks and antitachycardia therapy. Radiofrequency catheter ablation is an efficacious method to prevent the occurrence of stable ventricular tachy-arrythmia. We present here, the case of a patient with dilated cardiomyopathy implanted with an ICD in secondary prevention (ventricular tachycardia [VT]). The ICD delivered multiple appropriated shocks for monomorphic VT. A radiofrequency catheter ablation was successfully performed and the patient receives no further shock for the whole 18 months follow-up.

[The choice of pacing sites: should we change our practice?]. / Choix des sites de stimulation cardiaque: doit-on changer notre pratique?

For the past 45 years the sites used for elective pacing have been the apex of the right ventricle and the right atrium. Although the initial objective of pacing was the "simple" correction of a conduction disorder, a more recent evolution has been to achieve a favourable haemodynamic effect, considering left ventricular filling and synchronisation of ventricular contraction as essential. Demonstration of the benefit in terms of survival brought about by pacing in atrioventricular block has not required large trials. However, it is possible that this improvement in morbidity and mortality is in part offset by the altered haemodynamics due to pacing at the right ventricular apex. At the atrial level, the prevention of AF is the holy grail of atrial pacing, but is far from being attained, perhaps because the physiopathological bases are not clear and have not really been demonstrated, casting doubt on the final objective. The choice of pacing site is essential in this context, as much in the atrium as in the ventricle. The current problem regarding this choice is the same as for all medical treatment, where the risk/benefit ratio is evaluated: if the usual sites are potentially deleterious, is it possible to continue using them or is it necessary to change implantation practices, and what level of proof is needed?

[Electrophysiologic remodeling and drug treatment of atrial fibrillation]. / Remodelage électrophysiologique et traitement médicamenteux de la fibrillation atriale.

Since 1995, a number of studies have established and detailed the mechanisms of electrical and structural atrial remodeling induced by atrial fibrillation. Atrial remodeling involves many cellular components, from ionic channels to connexins. The determination of these mechanisms may help to define a new therapeutic targets of atrial fibrillation, a frequent arrhythmia that remains difficult to treat. Atrial remodeling prevention may lead to limit the evolution of the arrhythmia (early recurrences after reduction, AF secondary to atrial tachycardia, permanent AF, decrease in atrial contractility, sinus dysfunction). Except amiodarone, the usual antiarrhythmic drugs have no effect on atrial remodeling. Calcium channel inhibitors prevent early remodeling but have no effect on prolonged remodeling. Digoxin increases remodeling. Angiotensin II receptor inhibitors have been shown to prevent early AF recurrence after reduction and are very promising in such a direction. Other methods such as the one of antioxidant therapy seem to be promising and could define soon a new antiarrhythmic therapeutic class, the antiremodeling drugs.

[Dual chamber rate responsive pacing and chronotropic insufficiency. Comparison of double and respiratory sensors]. / Stimulation double chambre à fréquence asservie et incompétence chronotrope. Comparaison d'un capteur d'activité, de ventilation et d'un double capteur.

Late responsive DDD pacemakers are the most technically advanced devices presently available. These pacemakers are particularly useful in patients with chronotropic insufficiency when the sinus node is incapable of accelerating during exercise. The latest pacemakers have two sensors to reproduce optimal physiological sinus acceleration. The aim of this study was to analyse the performances of a new rate responsive pacemaker with a double activity and respiratory sensor, the interaction of which is automatically controlled by a sophisticated algorithm, in 12 patients (8 men and 4 women) with a mean age of 75 +/- 7 years. Analysis was based on the performance of the sensors used singly or in association: during three exercise stress tests with measurement of the VO2 max; during everyday activities using the data archived by the pacemaker and the answers to a simplified questionnaire on quality of life. The results showed that during exercise stress testing with measurement of VO2 max, the best performances were obtained with the double sensor or the respiratory sensor compared with the activity sensor alone, suggesting that these two sensors are more effective in intense exercise. This tendency was also observed in the analysis of the memory bank of the pacemaker which showed that the total duration of the faster heart rates was greater with the two sensors. On the other hand, the quality of life was not significantly different, whichever sensor was studied. Longer scale trials are necessary to appreciate the real value of these new double sensor pacing devices and to identify the best indications for their usage.

Ventricular tachycardia catheter ablation in arrhythmogenic right ventricular dysplasia: a 16-year experience.

Arrhythmogenic right ventricular dysplasia (ARVD) is a structural heart disease affecting young adults that leads to cardiac rhythm disorders including supraventricular and mostly ventricular arrhythmias. Sudden death may be the first presentation of the disease. Ablation techniques have been used for the treatment of ventricular tachycardia in cases resistant to drug therapy. Radiofrequency is appropriate as a first approach for ventricular tachycardia ablation in ARVD; however, its effectiveness is less than 40% at the first session. Fulguration is effective for ventricular tachy-cardia ablation and should be used in the same session after ineffective radiofrequency ablation. However, fulguration requires expertise, general anesthesia, and more than one session in half of all patients. Radiofrequency and fulguration plus other common forms of treatment including pacemakers and automatic implantable cardioverter defibrillators provides a clinical success rate of 81% to 93% in a series of 50 consecutive patients studied during 16 years. Earlier poor reputation of fulguration was the result of poorly understood technical problems concerning the physics and biophysics of the procedure under control with presently available methods. This in-depth study of a large population over a long time period demonstrates that fulguration should be rehabilitated.

[Chronotropic incompetence: when should a pacemaker be considered? Which pacing system and which settings?]. / Incompétence chronotrope: quand faut-il envisager l'implantation d'un stimulateur cardiaque? Quel stimulateur et quels réglages?

Chronotropic incompetence is defined as the inability to increase and maintain heart rate appropriately during exercise. Intolerance to exertion is manifested by a number of clinical symptoms, and is almost obligatory if heart rate cannot be increased. Several rate-modulating pacing systems have been developed. The most obvious and reliable way to increase heart rate during exercise is to detect the sinus node. Adding an atrial lead in a patient in complete AV block and VVI pacing is the most satisfactory way to correct chronotropic incompetence in some patients. Rate-adaptive sensors include motion sensors, respiration sensors, QT interval, and right ventricular contractility. Indications for rate-adaptive pacing should be based on clinical symptoms, demonstration of a lack of cardiac acceleration during exercise, and the presence of another indication for pacing.

[Role of tilt test in the diagnostic and therapeutic management of syncopes]. / Rôle du tilt-test dans la prise en charge diagnostique et therapeutique des syncopes.

Following confirmation of one or several episodes of syncope, the most important step is identification of the cause. Unfortunately, despite a careful actiological work-up, a cause is not found in about 30 to 40% of cases, but the tilt test can attribute some of these cases to a vagal cause. The test must be performed according to a rigorous methodology and interpretation must be based on a good knowledge of abnormalities of the autonomic nervous system, particularly the pathophysiology of vagal syncope. The tilt-test can also be useful to evaluate the efficacy of drug treatment prescribed to prevent recurrent syncope.

[Radiofrequency catheter ablation of ventricular tachycardia]. / La radiofréquence dans le traitement de la tachycardie ventriculaire.

Radiofrequency energy was used for the ablation of chronic recurrent ventricular tachycardia (VT) in 58 patients who were divided into two groups: 44 cases with structural myocardial disease (36 men and 8 women: mean age 55 years; range: 14 to 85 years) with an average left ventricular ejection fraction of 38% (range: 15 to 80%): these patients had myocardial infarction (28 cases), arrhythmogenic right ventricular dysplasia (11 cases), idiopathic dilated cardiomyopathy (2 cases), operated congenital heart disease (2 cases) and operated valvular heart disease (1 case). The clinical success rate after the first session of radiofrequency ablation was 34%. When (according to our modified protocol of fulguration) 160 joule cathodal shocks were delivered to the same catheter previously used for RF ablation during the same session or secondarily (13 cases), the success rate increased to 76%. The average follow-up period of the 37 survivors was 16.7 months. The second group consists of 14 cases without structural myocardial disease (10 men and 4 women, mean age 41 years, range 14 to 69 years) with an average left ventricular ejection fraction of 61%. These patients had idiopathic ventricular tachycardia (10 cases) and verapamil-sensitive ventricular tachycardia (4 cases). The primary success of radiofrequency ablation alone was 43%. When combined with fulguration during the same of radiofrequency ablation alone was 43%. When combined fulguration during the same of at a later session, the success rate increased to 71.3%. The average follow-up period of the 13 survivors was 19 months (range 0.3 to 39 months). No significant difference was observed between the groups with or without structural myocardial disease after radiofrequency or fulguration ablation, not only with respect to global results but also after analysis of subgroups with, for example, post-infarction ventricular tachycardia or arrhythmogenic right ventricular dysplasia. However, clinical success was obtained after a single session of radiofrequency ablation alone in 8 of the 9 cases of incessant ventricular tachycardia in patients with structural myocardial disease.

Fulguraçäo e radiofrequência na taquicardia ventricular / Fulguration and radiofrequency ablation in ventricular tachycardia

Durante um período de 10 anos, 89 casos taquicardia ventricular (TV) resistentes ao antiarrítmicos foram tratados pelo método da fulguraçäo. A série foi composta por: 37 casos de enfarte do miocárdio, com fraçào de ejeçäo média de 30 por cento, onde o acompanhamento médio dos sobreviventes foi de 61 meses e a eficácia clínica foi de 87, 9 por cento; 23 casos de sisplasia arrtmogência do ventrículo direito, em que a média de idade foi de 40 anos e a fraçäo de ejeçäo média de 57 por cento, acompanhad durante 71 meses em média, com eficácia clínica de 83 por cento; 12 pacientes que apresentavam TV sensíveis ao verapamil (fasciculares), com idade média de 30 anos e fraçäo de ejeçäo média de 65 por cento, sendo o seu acompanhamento idiopática dilatada, idade média de 35 anos de fraçäo de ejeçäo média de 23 por cento que, acompanhados por 38 meses, permitiram constatar uma eficácia clínica de 80 por cento; 4 outros pacientes, com idade média de 21 anos, doenças congênitas operadas e com fraçäo de ejeçä édia de 60 por cento, em que um acompanhamento de 36 meses demonstrou eficácia clínica de 100 por cento. Por fim, 3 pacientes com taquicardia ventriculares idiopáticas infundibulares, idade média de 36 anos e fraçäo de ejeçäo média de 62 por cento, acompanhados durante um período de 72 meses, com um eficácia clínica de 67 por cento. Complicaçöes näo letais foram observadas em 16 por cento dos casos, notadamente o hemopericárdio, observado em 4,5 por cento dos casos, tendo implicado em pericardiocentese Amortalidade operatória no mês posterior à ablaçäo foi de 9,2 por cento, sendo principalmente observada durante a fase de aprendizagem. Em conclusäo, ainda que näo seja isenta de riscos, em mäos experientes a fulguraçäo obteve resultados notáveis na maioria dos casos. Continua a ser indicada nas TV resistentes à radiofrequência, o que foi observado em mais da metade dos casos numa série preliminar de 41 pacientes.

Preliminary evaluation of a dual chamber pacemaker with bradycardia diagnostic functions.

Unexplained syncope is the main indication for the implantation of a diagnostic pacemaker. Studies on those implanted have shown that in patients with unexplained syncope, the diagnosis of paroxysmal bradycardia was feasible and reliable. The present study was designed to evaluate a new bradycardia diagnosis algorithm, loaded in a dual chamber pacemaker, in 24 patients considered as candidates for diagnostic pacemakers. During a mean follow-up of 153 days, at least one bradycardia episode was recorded in 13 patients. The mean number of detected bradycardias was 6 and the median was 3. The mean delay between the algorithm activation and the first bradycardia episode was 67 days. The mechanism of bradycardia was atrioventricular block in 6 patients, sinus node dysfunction in 6 patients, and consecutive blocked atrial premature beats in 1 patient, as indicated by the event markers. In 11 patients bradycardia was recorded during the daytime only or day and night. In two patients the episodes were recorded only at night. Overall, the algorithm was well-tolerated; however, some mild symptoms were observed due to the method of bradycardia determination, allowing bradycardia. Three patients were symptomatic as a direct result of the algorithm operation, and four patients had symptoms related to the single chamber operation of the pacemaker while functioning in the diagnosis mode (VDI). These symptoms were relieved with DDD pacing.

[Preliminary study of a double chamber pacemaker with diagnostic function]. / Etude préliminaire d'un stimulateur double chambre à fonction diagnostique.

Pacemakers with diagnostic functions have been implanted for several years. The main clinical indication for these devices is unexplained syncope. Some reports of the use of diagnostic pacemakers have shown that in patients with unexplained syncope, paroxysmal bradycardia was a common finding after implantation. Until recently, diagnostic functions were only available in VVI pacemakers, which explains the limitations of this type of function in determining the mechanism of the bradycardia. The aim of this study was to assess a new dual-chamber diagnostic pacemaker functioning in the VDI mode. Twenty-three patients were implanted with this type of unit and followed up for an average of 153 days. The number of episodes of bradycardia detected was 6 +/- 10 (median: 3). The interval between the installation of the algorithm and the date of the first episode of bradycardia was 67 +/- 86 days (range: 12-306 days). The mechanisms of the bradycardia were atrioventricular block (6 patients), sinus node dysfunction (6 patients) and blocked atrial bigeminy in 1 patient. These conclusions were drawn from analysis of chains of markers. Bradycardia was recorded during the day or during the day and night in 21 patients; bradycardia was exclusively nocturnal in only 2 patients. The tolerance of the algorithm was good on the whole but 3 patients reported minor symptoms related to the relative bradycardia inherent with this type of algorithm. Four other patients had a VDI pacemaker syndrome which was completely corrected by reprogramming the pacemaker to the standard DDD mode. These new devices represent a technical advance in the field of diagnostic pacemakers.(ABSTRACT TRUNCATED AT 250 WORDS)

[Fulguration of extrasystolic ventricular focus]. / Fulguración de un foco extrasistólico ventricular.

A case is presented of symptomatic premature ventricular contractions refractory to drug therapy with right bundle branch block QRS morphology and left axis deviation in a 68-year-old female without structural heart disease. Endocardial mapping localized the extrasystolic focus at meso-inferoapical region of the left ventricular septum suggesting an origin from the Purkinje network of the left posterior fascicle. Catheter ablation with direct-current energy abolished extrasystolic complexes, without complications. The patient remained asymptomatic over a follow-up of 3 months.

Time- and frequency-domain analyses of the signal-averaged ECG in patients with arrhythmogenic right ventricular dysplasia.

BACKGROUND: Arrhythmogenic right ventricular dysplasia (ARVD) is characterized by recurrent ventricular tachycardia of right ventricular origin and a cardiomyopathy with hypokinetic areas involving the free wall of the right ventricle. Subjects have a risk of sudden cardiac death, particularly during sports and strenuous exercise. Routine clinical examinations may be normal, but fragmented or delayed electrograms are usually recorded in the right ventricle of these patients. However, the frequency with which late potentials are detected by conventional time-domain analysis of the signal-averaged ECG (SAECG) is not high. This study evaluated the usefulness of the frequency-domain analysis of the SAECG in addition to the conventional time-domain analysis for a screening test to detect patients with ARVD. METHODS AND RESULTS: SAECG was recorded by using a bipolar X, Y, and Z lead system in 28 patients with ARVD (mean age, 38 +/- 13 years) and 35 age-matched normal subjects (mean age, 35 +/- 11 years). The conventional time-domain analysis of the SAECG was performed at two different high-pass filter settings, 25 and 40 Hz, and the low-pass cutoff frequency was fixed at 250 Hz. The fast-Fourier transform analysis of SAECG was performed using a Blackman-Harris window. Area ratio 1 (area of 20 to 50 Hz)/(area of 0 to 20 Hz) and area ratio 2 (area of 40 to 100 Hz)/(area of 0 to 40 Hz) were calculated. In the conventional time-domain analysis, 20 (71%) and 18 (64%) patients had positive criteria at filter settings of 25 and 40 Hz, respectively. In the frequency-domain analysis, 18 (64%) and 20 (71%) patients had abnormal values in area ratios 1 and 2, respectively. Combining the time- and frequency-domain analyses, all patients were judged positive, with a sensitivity of 100% and a specificity of 94%. CONCLUSIONS: Each result of the time- and frequency-domain analyses revealed that both methods had equivalent value. Combining the two domain analyses improved the sensitivity without reducing the specificity. These findings suggest that combining the time- and frequency-domain analyses of the SAECG may be useful as a screening test to detect patients with ARVD.

Idiopathic ventricular tachycardia: feasibility and efficacy of catheter ablation.

Idiopathic ventricular tachycardia is a well described syndrome of both left and right ventricular origin. This study reports the feasibility and efficacy of catheter ablation in this entity. Fourteen patients (mean age 30 +/- 10 years of age) and six patients (mean age 51 +/- 9 years of age) underwent endocardial catheter ablation with either direct-current shocks and radiofrequency energy, respectively. Earliest right and left ventricular activation and endocardial mapping during tachycardia were made to localize the site of ventricular tachycardia origin. The overall clinical efficacy was 93% for direct-current method with a mean number of shocks of 3.3 +/- 0.9/patient after a mean follow-up of 38 +/- 25 months. Radiofrequency ablation achieved an overall clinical efficacy of 83.6% with a mean of 3.2 pulses/patient during a follow-up of 10.5 +/- 4 months. The isoenzyme MB fraction of peak creatine kinase after ablation was less than 5%. There were no complications in any patient who underwent radiofrequency energy. Endocardial catheter ablation is feasible in patients with idiopathic ventricular tachycardia. Both methods are highly effective but radiofrequency energy is most desirable because of its lack of barotrauma, and may be considered as early therapy.

[Value and limitations of diagnostic function of bradycardia of a ventricular pacemaker]. / Intérêts et limites de la fonction diagnostique de bradycardie d'un stimulateur ventriculaire. Groupe d'étude du registre Théorema.

The indication for permanent pacing may be confirmed by a bradycardia counter in patients without ECG or Holter recording of the causal bradycardia. The algorithm was assessed in a multicenter register with the SORIN Theorema model. The activation of the device was programmed on a double hysteresis of 2 seconds with a programmable histogramme of detections and sensing and pacing counters. One hundred and forty five patients were recruited in 50 centers over 2 years: 89 men and 56 women aged 33 to 96 years (average 72 years), 87 of whom had no other obvious cardiac disease. One hundred and ten had typical syncopal episodes, 19 had atypical or minor syncopal attacks and 16 were asymptomatic, one with sinus node dysfunction and the others with pathological prolongation of the HV interval (> or = 70 ms) during endocavitary electrophysiological investigation. The mechanism of the bradycardia was considered to be infra-hisian in 62 patients who had HV intervals > or = 70 ms. This was also the probable mechanism in 20 others who had bundle branch block and typical syncope despite a HV interval < 70 ms and in 6 patients with bundle branch block and typical syncope who did not undergo electrophysiological investigation before implantation. Twenty one patients had sinus node dysfunction during electrophysiological investigation and 8 had a carotid sinus syndrome. The remaining 28 cases had transient syncope but no ECG changes or abnormality on electrophysiological investigation. Permanent pacing was proposed when an extracardiac origin of the syncope was excluded.(ABSTRACT TRUNCATED AT 250 WORDS)

[Fulguration and radiofrequency in ventricular tachycardia]. / Fulguration et radiofréquence dans la tachycardie ventriculaire.

Eighty-nine cases of ventricular tachycardia, resistant to antiarrhythmic therapy, were treated over a 10 year period by high energy D ablation (fulguration). This series included 37 cases of myocardial infarction with a mean ejection fraction of 30%. The mean follow-up period of the survivors was 61 months and clinical efficacy was 87.9%. Twenty-three cases of arrhythmogenic right ventricular dysplasia, aged 40 years, and with an ejection fraction of 57%, followed up for 71 months, had a clinical efficacy of 83%. Twelve patients had verapamil sensitive (fascicular) ventricular tachycardia. Their age was 30, their ejection fraction 65%, the follow-up period 55 months, and the clinical efficacy was 100%. Ten patients had primary dilated cardiomyopathy. Their age was 35, their ejection fraction 23%, the follow-up period of 38 months with a clinical efficacy of 80%. Four patients, aged 21, had operated congenital heart disease with an ejection fraction of 60%, a follow-up of 36 months and a clinical efficacy of 100%. Finally, 3 patients had idiopathic infundibular ventricular tachycardia. Their age was 36, the ejection fraction 62%, the follow-up period was 72 months and the clinical efficacy was 67%. Non lethal complications were observed in 16% of cases, mainly haemopericardium requiring pericardocentesis in 4.5% of cases. The operative mortality and in the month following ablation was 9.2%, observed mainly during the learning period. These results show that fulguration is not without risk, but in skilled hands, it gives remarkable results in the majority of cases.(ABSTRACT TRUNCATED AT 250 WORDS)