PubMed Health⌕ Search

Biomedical subjects

Y Gallais

Publications and source records attributed to Y Gallais.

At least 19 recordsLinked to original sources
PubMed2006

Transition from free to interacting composite fermions away from.

Spin excitations from a partially populated composite fermion level are studied above and below nu=1/3. In the range 2/7<nu<2/5, the experiments uncover significant departures from the noninteracting composite fermion picture that demonstrate the increasing impact of interactions as quasiparticle Landau levels are filled. The observed onset of a transition from free to interacting composite fermions could be linked to condensation into the higher order states suggested by transport experiments and numerical evaluations performed in the same filling factor range.

Journal Article↗
PubMed2002

Evidence for two distinct energy scales in the Raman spectra of YBa2(Cu1-xNix)3O6.95.

We report electronic Raman scattering from Ni-substituted YBa2Cu3O6.95 single crystals with T(c) ranging from 92.5 to 78 K. The fully symmetrical A(1g) channel and the B(1g) channel which is sensitive to the d(x(2)-y(2)) gap maximum have been explored. The energy of the B(1g) pair-breaking peak remains constant under Ni doping while the energy of the A(1g) peak scales with T(c) ( E(A(1g))/k(B)T(c) = 5). Our data show that the A(1g) peak tracks the magnetic resonance peak observed in inelastic neutron scattering yielding a key explanation to the long-standing problem of the origin of the A(1g) peak.

Journal Article↗
PubMed2001

Delivery management in a woman with thrombocytopenia of the May-Hegglin anomaly type.

Thrombocytopenia of the May-Hegglin anomaly type was diagnosed in a woman with no past history of bleeding diathesis, who had been followed during her three pregnancies. No abnormal bleeding occurred although no platelet transfusion was administered during the second and third cesarean sections. Routine platelets transfusion is unnecessary but platelets should be available for use if abnormal bleeding occurs.

Adult↗
PubMed2000

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.

Adolescent↗
PubMed2000

Low chronic pacing thresholds of steroid-eluting active-fixation ventricular pacemaker leads: a useful alternative to passive-fixation leads.

Active-fixation pacemaker leads enable pacing at various sites, have a low dislodgment rate, and are easier to extract than passive-fixation leads, though are usually not routinely implanted in the ventricle because of their higher pacing threshold. The long-term pacing threshold associated with an active-fixation steroid-eluting lead was prospectively measured in 18 women and 20 men. At a mean follow-up of 14 months (range 3-25 months), pacing threshold increased from 0.71 +/- 0.29 V to 0.96 +/- 0.28 V (P = 0.01) between implant and the first month of follow-up, then remained stable over time, consistently allowing the long-term programming of the ventricular output at 2.5 V, while lead impedance remained stable (from 647 +/- 161 omega at implant to 666 +/- 122 omega at last follow-up). If the long-term performance of this type of lead is confirmed, the routine implantation of ventricular steroid-eluting active-fixation leads should be considered since lead extraction has become a major concern.

Adult↗
PubMed1996

[Radiofrequency catheter ablation of ventricular tachycardia].

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.

Adolescent↗
PubMed1994

[Fulguration and radiofrequency in ventricular tachycardia].

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)

Adolescent↗
PubMed1994

[Ablative methods, therapeutic alternative to medical treatment for junctional tachycardia].

The clinical syndrome corresponding to junctional tachycardia is generally known as Bouveret's disease, but actually corresponds to two quite separate entities: 1) tachycardia related to a secondary atrioventricular pathway or Kent bundle; 2) intranodal tachycardia arising in the atrio-ventricular node. Until recently, anti-arrhythmics were used to treat most of the cases of accessory pathways. If this was unsuccessful or if the anti-arrhythmics induced adverse effects and in life-threatening cases affecting Kent bundles, surgical section was sometimes proposed, carrying a non-negligible risk of morbidity and mortality. Intranodal arrhythmia is not a serious, but may call for prophylactic antiarrhythmic treatment if it becomes too frequent and disabling. Before the advent of ablative treatment, there was no satisfactory alternative to antiarrhythmic treatment. Ablation of the accessory pathways or selection ablation of the slow pathway of the atrio-ventricular node (sometimes of the rapid pathway) is not achieved by applying a high-frequency current (radiofrequency), which has virtually replaced fulguration (destruction using a modified electrical current). In both types of tachycardia, a cure is obtained in 90% of cases with a low incidence of complications and virtually no risk of mortality, which contrasts favorably with long-term antiarrhythmic treatment (or surgical section of Kent bundles), which justifies the large-scale development of radiofrequency ablation.

Catheter Ablation↗
PubMed1993

[Treatment of ventricular tachycardia by endocardial fulguration. Apropos of 86 cases].

Between 1983 and 1991, 86 cases of ventricular tachycardia (VT) resistant to antiarrhythmic therapy were treated by endocardious catheter fulguration: there were 21 cases of right ventricular dysplasia (RVD), 35 chronic myocardial infarctions (MI), 11 dilated cardiomyopathies (DCM), 10 bundle branch VT, 5 idiopathic septal VT, 3 operated Fallot procedures, 1 Ebstein's anomaly. There were 69 men and 17 women aged 14 to 76 years (average 45 +/- 18 years). The ejection fraction was under 30% in 37 cases. Forty-five VTs were permanent or recurred several times daily; 6 were inducible despite drug therapy and 35 patients had monthly recurrences. A total of 141 different forms of VT were treated in 133 procedures. One session was sufficient in 49 cases; 2 sessions were required in 29 cases; 3 sessions in 6 cases and 4 sessions in 2 cases. A total of 480 DC shocks were delivered with energies of 160 to 300 joules. The CPK-MB levels were 37 +/- 30 i.u./l. The following complications were observed: 7 perioperative deaths, 2 cardiac tamponades requiring surgical drainage, 1 permanent AV block, 5 reversible left ventricular failures. Follow up concerned 79 patients: 5 were followed up for less than 3 months with death occurring from cardiac failure which had been present before the ablation procedure without recurrence of VT. Seventy-four patients were followed up from 3 to 111 months (56 +/- 33 months). Thirty-two patients were without any antiarrhythmic therapy and had no recurrence of VT. Two of these patients developed a different form of VT 2 and 6 years after the catheter ablation.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1992

[Experimental study of fulguration on a healthy ventricle. I. Acute lesions].

The effect of fulguration shocks applied to the healthy ventricular myocardium in 6 pigs weighing between 63 and 100 kg showed that for shocks with the same energy level as those used in clinical practice, the immediate effects of fulguration result in a hemorrhagic zone with a diameter of up to 15 mm. Histopathological examination revealed tearing of the cardiomyocytes which is probably related to barotraumatic phenomena. Deflagrating shocks of 90 Joules, with a short development time (non-self-inductive circuit) can lead to perforation of the myocardium in both the right and left ventricles. In this animal model, arrhythmia was rare and did not lead to sudden death in any case. No vascular damage was observed.

Acute Disease↗
PubMed1992

[Experimental study of fulguration of healthy ventricle. II. Chronic lesions].

The effect of fulguration shocks was studied using healthy ventricular myocardium of 12 pigs weighing between 63 and 100 kg. With shocks of equal energy to those used clinically, lesions seen 24 hours after the session in two pigs showed the formation of loose fibrosis and of marked cellular infiltration as well as zones of hypercontraction with calcium precipitation. The size of chronic lesions seen during periods ranging from one week to 2 months was studied in 4 pigs. Transmural plaques with a diameter of 1.5 to 2 cm were seen in the right ventricle. For the same energy levels of 240 Joules delivered to left ventricular tissue, lesions were of the same size but were never transmural. Under certain conditions, lesions were disposed in the direction of the neutral electrode.

Acute Disease↗
PubMed1989

Electrode catheter ablation of resistant ventricular tachycardia in arrhythmogenic right ventricular dysplasia: experience of 13 patients with a mean follow-up of 45 months.

Electrode catheter ablation (fulguration) is a new technique for the treatment of ventricular tachycardia resistant to medical treatment. It proved effective in our hands in a series of 65 cases of ventricular tachycardia of varied origin. This paper reports the early results in a subgroup of 13 patients suffering from arrhythmogenic right ventricular dysplasia in whom shocks ranging from 160 to 280J, single or multiple, in one or up to three sessions were delivered. In the 11 patients surviving the DC ablation procedure single or multiple monomorphic sustained VT was brought under control. However, four patients (36%) required therapeutic antiarrhythmic treatment following the fulguration therapy. During the learning phase one case of death was related to poor catheter selection and the other to poor protocol. The post-mortem study of the effect of shocks depends on the anatomical structure to which the shocks have been delivered.

Adult↗
PubMed1988

Techniques and methods for catheter endocardial fulguration.

Fulguration is a new and promising technique for the treatment of cardiac arrhythmias. This paper discusses the methods and equipment used at Jean Rostand Hospital for invasive experimental research related to fulguration. The importance of catheter testing and selection is demonstrated. The most important features of the measurement techniques for both His bundle and ventricular tachycardia recordings are described. The main components of the protocols for fulguration and early post-operative surveillance are reported. The ODAM Fulgucor is used, augmented by the incorporation of additional pieces of equipment to allow monitoring of current and voltage curves. An electromechanical relay allows for automatic switching from the recording amplifier to the energy source. The video system used includes recording of the image of the last fluoroscopic event with a character generator and an electronic pointer superimposed (when necessary). Computer programs for appropriate timing of predominant events have been developed.

Arrhythmias, Cardiac↗