[New energy sources for ablative methods]. / Nouvelles sources d'énergie dans les méthodes ablatives.

Radiofrequency current is the reference energy source for endocavitary ablation of arrhythmias. It is particularly well adapted for the ablation of focal arrhythmogenic substrates such as accessory pathways or foyers of automatism. Technological advances have made the lesions larger but the extension of the indications of percutaneous ablation to more complex substrates such as atrial fibrillation have justified the evaluation of alternative energies. The production of linear transmural lesions or deeper lesions which respect the parietal myocardial architecture and endocardial structure are a challenge for these energies. The capacity of functional mapping specific to cryogenics has provided this energy source with a clinical application for ablation of high risk structures whereas other energies, despite the chronicity of their experimental evaluation, are still at the stage of preliminary clinical trials with the sophisticated catheters in special indications.

[Long-term evaluation of endocavitary cryoablation of nodal reentry]. / Evaluation à long terme de la cryoablation endocavitaire dans le traitement des réentrées nodales.

Radiofrequency ablation is the reference treatment of refractory nodal reentry. Cryoablation has the advantage of having more modulable effects and minimises the risk of permanent atrioventricular block (AVB). Its immediate efficacy seems comparable to that of radiofrequency ablation but the long-term results are not well known. Endocavitary cryoablation of the slow pathway was undertaken in 26 patients (18 women) with an average age of 47.7 +/- 72.8 years with re-entrant nodal tachycardia refractory to medical therapy. The primary success rate was 92% (24 out of 26). On average, 2.6 +/- 2.2 (1 to 10) cryoablations at - 70 degrees C were delivered and were preceded by 6.4 +/- 4.5 (1 to 16) cryomappings to locate the site of the slow pathway. During cryomapping, 8 episodes of AVB were observed in 6 patients (6 second or third degree), all of which were revertible on rewarming. No cases of permanent AVB were observed. An oesophageal stimulation test of inducibility was performed on the 4th day in 21 patients, 16 of which were not reinducible. During follow-up of 355 +/- 194 days, 22 of the 26 patients (85%) had no recurrence of the arrhythmia. Two of the 24 primary successes had a recurrence, in addition to the two primary failures. Two of the four recurrences occurred in a non-sustained form which was less disabilitating for the patient and the recurrences were controlled in the 4 patients by antiarrhythmic therapy. These results suggest that cryoablation may be a reliable and effective long-term treatment of re-entrant nodal tachycardias. If confirmed in larger series in terms of efficacy and safety, cryoablation could become the treatment of choice of re-entrant nodal tachycardia.

Red blood cell polyamine level changes following heart transplantation in man.

Follow-up of orthotopic heart transplanted patients has revealed the existence of abnormally high red blood cell (RBC) spermidine (Spd) levels during the first two months after surgical procedure (A-period). From the third month after heart transplantation (B-period), RBC Spd concentrations went back to normal values in early cardiac rejection (ECR) patients. During A- and B-periods, significantly higher Spd levels and Spd/Spm ratios were observed in late cardiac rejecting (LCR) patients than in ECR ones. The lack of a direct relationship between the histological grade of rejection and RBC Spd levels leads us to consider these polyamine blood levels as a new biological instrument in the diagnosis of heart rejection.

[Radiofrequency catheter ablation: theoretical and technical aspects]. / Ablation par courants de radiofréquence; aspects théoriques et techniques.

Radiofrequency currents produce circumscribed tissue necrosis by progressive and localised heating. Endocardial application via the percutaneous approach with a specific electrophysiological catheter enables destruction of the anatomical substrate of many cardiac arrhythmias. The technique is well tolerated due to the absence of barometric phenomena and general anaesthesia, and the possibility of modulating the energy delivered, which explains why it has supplanted fulguration in most indications. The technological evolution aims to increase the lesional power and decrease the number of complications. This implies the development of catheters capable of delivering greater currents without the risk of thrombus formation and of generators dependent on electrical or thermal parameters. The low incidence of complications reported by centres using the technique is based on an excellent understanding of the technique, the use of appropriate material, the surveillance of parameters which allow detection of unwanted effects and the respect of a strict operation protocol. In the absence of these precautions, the wide diffusion of this technique, favored by its low cost and relative simplicity, may be associated with an increase in the number of side effects which could be lethal. This cannot be accepted in a technique with such wide indications, including arrhythmias with a usually benign long-term prognosis.

[Radiofrequency ablation: physical bases and principles]. / Ablation par courants de radiofréquence; bases physiques et principes.

Radiofrequency currents are the reference physical agent for endocavitary ablation, especially of supraventricular tachycardias. They are delivered in a continuous mode or sinusoidal waves. Because of the high frequency between 200 and 3,000 kHz there is no stimulation of the neuromuscular cells. The mechanism of the resulting lesion is essentially related to heating of the biological surroundings of the active electrode. The temperature increase remains localised around the active electrode and its kinetics are progressive, which implies close and stable contact between the active electrode and the tissues. The lesional effect is obtained 60 to 90 degrees C in order to avoid the deleterious effects induced by temperatures of over 100 degrees C: boiling, coagulation, vaporization and carbonization of the tissues leading to an increase in impedence. The volume of lesions depends on many factors which are sometimes difficult to control in vivo. It is more closely correlated to the temperature of the active electrode than to the parameters of delivery (power, duration ...). The histological lesions correspond to scar tissue which respects the surrounding architecture. The major technological innovations of this method have resulted in an increase in the volume of the lesions produced, a reduction in the frequency of undesirable effects such as the formation of coagulum and in an immediate evaluation of the anatomic lesional effect. They have consisted in the introduction of specific electrodes and of systems of monitoring the electrical and thermal effects with the use of imaging techniques such as endovascular and transoesophageal echocardiography and angioscopy. New indications will require development of specific catheter-generator equipment to create lesions of size and shape adapted to the arrhythmogenic substrate.

[Struma cordis: right intraventricular ectopic thyroid]. / Struma cordis: Thyroïde ectopique intraventriculaire droite.

The authors report the case of a benign tumour composed of hyperplasic thyroid tissue in the right ventricle, diagnosed in a 43 year old woman by echocardiography after a syncopal episode. The outcome was favourable with a 13 year follow-up after surgery.

[Corynebacterium diphtheriae endocarditis complicated by septic arthritis and cerebral abscess]. / Endocardite à Corynebacterium diphtheriae compliquée d'arthrites septiques et d'abcès cérébral.

The authors report a rare case of the mitis type Corynebacterium diphteriae endocarditis on a prosthetic valve complicated by septic arthritis and cerebral abscess. The authors underline the importance of regular transoesophageal echocardiographic control and underline the diagnostic value of ultrafast computed tomography for the diagnosis of aortic annular and interventricular septal abscesses in patients with mechanical prosthetic valves.

[Percutaneous ablation of atrioventricular junction by radiofrequency current in resistant atrial arrhythmia. Results of a series of 24 patients]. / Ablation percutanée de la jonction auriculo-ventriculaire par courants de radiofréquence en cas d'arythmies atriales rebelles. Résultats d'une série de 24 patients.

Catheter ablation of the atrioventricular junction may be proposed for the treatment of certain atrial arrhythmias resistant to antiarrhythmic therapy. One of the methods currently being evaluated uses radio-frequency energy which has certain advantages compared with direct current ablation because of the progressive and limited lesions it produces. This technique was used in 24 patients with atrial arrhythmias resistant to antiarrhythmic therapy. The radio-frequency energy was delivered without general anaesthesia with HAT 100 and 200 (OSYPKA) generators in the unipolar mode (average 17.4 watts) for an average period of 22.3 +/- 8 seconds. The catheter (8F USCI suction catheter in the first 18 patients and a 7F Polaris Mansfield, deflectable catheter with a large distal electrode in the remainder) was positioned at the nodo-hisian junction at a point where the two distal electrodes recorded a large atrial deflection and the smallest possible hisian potential. The conduction defects induced during the acute phase generally remain stable in cases of complete atrioventricular block and tend to regress in cases of incomplete atrioventricular block despite initial control of atrioventricular conduction. During follow-up (21 +/- 16 months), 14 patients (58%) remained in complete atrioventricular block, 4 patients (17%) had controlled atrioventricular conduction with an acceptable ventricular rate with associated previously ineffective antiarrhythmic therapy. Radio-frequency ablation was a failure in 6 patients (25%). There were no haemodynamic, rhythmic or ischaemic complications during the acute phase or during follow-up. These results suggest radio-frequency energy is a seductive alternative to direct current ablation for percutaneous modification of atrioventricular conduction in patients with refractory atrial arrhythmias. However, simple modulation of atrioventricular conduction gives aleatory results due to the tendency to regression during follow-up. On the other hand, complete atrioventricular blocks created by radio-frequency energy are generally definitive and are associated with a junctional escape rhythm which is usually stable.

[Wolff-Parkinson-White syndrome in a case of acute rejection of cardiac transplantation]. / Apparition d'un syndrome de Wolff-Parkinson-White lors d'un rejet aigu de transplantation cardiaque.

A Wolff-Parkinson-White syndrome was observed during acute rejection in a patient who had undergone orthotopic cardiac transplantation. The sometimes intermittent nature of this syndrome could explain its postoperative appearance in this patient; the relationship with the episode of rejection is discussed.

[Left ventricle-right atrium communications acquired in bacterial endocarditis]. / Communications ventricule gauche-oreillette droite acquises au cours des endocardites bactériennes.

Three cases of acquired LV-RA communication during bacterial endocarditis are reported. The causal organisms were Staphylococcus aureus and Streptococcus. The endocarditis complicated aortic valve disease in 2 patients and a congenital aneurysm of the membranous interventricular septum in the third case. Perforation of the septal abscess was preceded by 1st and 2nd degree AVB in all cases associated with bursts of intrahisian tachycardia in 1 case. The clinical presentation was that of an acute VSD; LV-RA communication was diagnosed by the radiological demonstration of systolic expansion of the RA, by 2D echocardiography using constant and Doppler techniques which gave the exact diagnosis in 1 case, by oximetry showing a large left-to-right shunt situated in the RA, and finally by selective left ventriculography. Surgery is essential and urgent and comprises repair of the fistula by two patches, one atrial shown on via a right atrial approach and the other ventricular via aortotomy associated with correction of the valvular lesions. Third degree AVB is observed in all cases, due to the anatomical location of the His bundle and requires permanent pacing. Good results were observed in 2 cases with follow-up periods of 14 and 48 months respectively.

[Proximal migration of a caval filter. Apropos of a case]. / Migration proximale d'un filtre cave (LEM). A propos d'une observation.

We are reporting of proximal migration, intracardiac, of a percutaneous caval filter (LEM type), resulting in the death of the patient. It is a true, early (1st week) migration after accurate positioning, opposite L4, and not an incident of insertion.

[Fissuration of post-infarction left ventricular aneurysms. 2 surgically treated cases]. / Fissurations d'anévrysmes ventriculaires gauches post-infarctus. Deux cas opérés.

The authors report two cases of fissures of a left ventricular aneurysm diagnosed on the 8th and 21st days following an anterior myocardial infarction. In both cases, the clinical presentation consisted of a new episode of pain associated with a low cardiac output syndrome and adiastole. The diagnosis was confirmed by the simultaneous discovery of a pericardial effusion and a left ventricular aneurysm on echocardiography and cardiac catheterisation. An emergency operation, with circulatory assistance by means of intra-aortic counter-pressure, was performed and the infarcted area was excised. The post-operative course was uncomplicated in one case, but the other patient developed a false aneurysm of the left ventricle, requiring a second operation. The long term results were excellent with a follow-up of 30 months and 12 months respectively.

[Auriculoventricular block disclosed in the exercise test]. / Les blocs auriculo-ventriculaires démasqués à l'épreuve d'effort.

Sixteen patients, 14 of whom described stress related symptoms, present a severe atrio-ventricular block (A-V B), identified during a stress test while the ECG at rest showed a 1/1 atrioventricular conduction (AV). The electrophysiological study (EPS) creates the A-B Block through atrial stimulation and specifies the location of the A-V B: intra-hissian in 8 patients (7 with small QRS an 1 with widened QRS) and infra-hissian in 8 patients (all with widened QRS). Non-invasive methods constitute the prime approach in the diagnostic work-up of stress symptoms. The ideal treatment consists of a dual-chamber cardiac stimulation.

Transverse energy fluctuations and the pattern of J/psi suppression in Pb-Pb collisions.

The NA50 Collaboration has recently observed that the J/psi production rate in Pb-Pb collisions decreases more rapidly as a function of the transverse energy for the most central collisions than for less central ones. We show that this phenomenon can be understood as an effect of transverse energy fluctuations in central collisions. A good fit of the data is obtained using a model which relates J/psi suppression to the local energy density. Our results suggest that the J/psi is completely suppressed at the highest densities achieved in Pb-Pb collisions.

Single infusion of intravenous cibenzoline in the treatment of supraventricular tachyarrhythmias following heart surgery. A double-blind placebo-controlled parallel study.

The efficacy and safety of a single infusion of cibenzoline, a class I antiarrhythmic drug, were assessed in 86 patients presenting with a supraventricular tachyarrhythmia following heart surgery in a placebo-controlled double-blind parallel study. Cibenzoline was effective in 13 patients (30%) vs three patients (6.9%) with placebo (P < 0.05). In the non-converted patients, ventricular rate was significantly slowed by cibenzoline (P < 0.05), which also significantly increased the duration of QRS and QT intervals. Transient adverse events were seen in nine patients receiving cibenzoline: moderate hypotension, sweating, right bundle branch block. One patient with decreased left ventricular function had an increased ventricular rate and QRS duration associated with hypotension. There were no severe adverse events. These results suggest that cibenzoline is effective for the treatment of postoperative supraventricular tachyarrhythmias in patients without impairment of ventricular function.

Physiological relationship between AV interval and heart rate in healthy subjects: applications to dual chamber pacing.

The purpose of this paper is to specify the mathematical relationship between spontaneous AV interval (AVI) and heart rate (HR), the amplitude and rate of variation of AVI, and the physiological factors likely to affect these characteristics. Ten patients with healthy hearts were studied. Two catheter electrodes were positioned in the right atrium and at the tip of the right ventricle respectively, allowing the detection of endocardial signals. The AV and AA intervals for each heart cycle were digitized to an accuracy of +/- 1 msec. Measurements were made at rest, then during a stress test on an exercise bicycle, and finally during the recovery phase. The results show that adaptation is very precise and takes place instantly. Any variation in heart rate causes an immediate, inversely proportional variation in AVI. Adaptation follows a linear pattern, generally with relatively low amplitude and an average AVI reduction of 27.5 +/- 11.2 msec for an average HR increase of 78.7 +/- 22.5 bpm, i.e., a decrease of 4 +/- 2.1 msec for an HR variation of 10 bpm. The amplitude and variation rate of AVI seem to be independent of the age and base value of the PR interval. These observations may be useful for designing new VDD or DDD pacemakers that automatically adapt the AV interval to the instantaneous heart rate. The hemodynamic benefits of this adaptation were also demonstrated.

Failure of the exercise test to predict the anterograde refractory period of the accessory pathway in Wolff Parkinson White syndrome.

Modifications of the delta wave on the surface ECG during an exercise stress test were compared to electrophysiological variations in accessory pathway (AP) refractoriness and in AV node conduction, during intravenous isoproterenol infusion in ten patients with WPW syndrome. In one patient, the delta wave persisted unchanged at the end of exercise and, with isoproterenol, there was a greater reduction in the AP anterograde effective refractory period (AERP) than in AV node conduction time. In three patients, the delta wave became less and less apparent but without completely disappearing; in these patients, the slight reduction of the AERP in the accessory pathway with isoproterenol was comparable to the reduction in AV node conduction time, explaining the progressive fusion between the two activation fronts. In the six other patients, the delta wave completely disappeared during exercise: in two cases, suddenly from one cycle to the next with strong concordance between the measured (isoproterenol) and the estimated (exercise test) AERP in the AP; in four cases, the disappearance was progressive with a significantly greater reduction in the AV node conduction time than in the measured AERP of AP which was nonetheless very short, 190 to 225 ms, during isoproterenol infusion. These findings confirm the limitations of the exercise test to predict the AERP of the AP. In addition, they demonstrate that modifications in the delta wave during exercise result from a balance between the relative effects of sympathetic stimulation on refractoriness of AP and normal AV conduction.

Temporal and geographical trends in indications for implantation of cardiac defibrillators in Europe 1993-1998. Medtronic ICD System Investigators.

Despite the demonstrated efficacy of implantable cardioverter defibrillators (ICDs) in reducing sudden and total mortality in selected populations, their implantation rates vary greatly between countries. The aim of our study was to analyze temporal and geographical trends in ICD implantations in countries with similar health related expenditure in Western Europe. A total of 2,257 patients from ten European evaluation studies of Medtronic defibrillators and defibrillation electrodes, conducted between 1993 and 1998, representing 12 countries, was included in this analysis. Rates of implantation and clinical characteristics were compared between countries and years of implantation. Rates of implantation differed greatly between Western European countries and did not correlate with indices of health related expenditure (i.e., number of patients per physician and number of patients per hospital bed). However, there was a strong and statistically significant negative correlation between the use of amiodarone and the rates of implantation (r = -0.66, P = 0.02). Temporal trends showed a significant increase in the age of the patients receiving an ICD between 1993 and 1998 (57 +/- 14 vs 61 +/- 12 years, mean +/- SD, P < 0.001). There was also a temporal trend towards an increased incidence of coronary artery disease and a significant decrease in the incidence of cardiomyopathy. There was a temporal increase in implantations in patients with a history of ventricular tachycardia. Despite a general scientific agreement that ICDs are a first line treatment for patients at high risk of sudden cardiac death, their acceptance remains low in several developed countries. This low acceptance may not be entirely related to budget constraint but may also be related to their perceived efficacy by physicians and health authorities.