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Biomedical subjects

P Ricard

Publications and source records attributed to P Ricard.

At least 37 records · Page 2Linked to original sources
PubMed1997

Multicenter low energy transvenous atrial defibrillation (XAD) trial results in different subsets of atrial fibrillation.

OBJECTIVES: This prospective, multicenter trial was aimed at defining efficacy and safety of low energy shocks during atrial fibrillation in a diverse cohort of patients. BACKGROUND: Experimental studies in sheep and preliminary data in humans have suggested that low energy internal shocks delivered between right atrial and coronary sinus electrode catheters may terminate atrial fibrillation. METHODS: Biphasic 3/3-ms R wave synchronous shocks were delivered between two electrode catheters in the right atrium and coronary sinus. The defibrillation protocol started with a test shock of 20 V, and shocks increased in 40-V steps until restoration of sinus rhythm or a maximum of 400 V. Shock delivery was withheld after short RR intervals. In 141 patients with atrial fibrillation, the protocol was carried out under sedation in case the shock was associated with discomfort. The atrial arrhythmia was paroxysmal (< or = 7 days) in 50 patients, chronic (> 30 days) in 53, intermediate (> 7 days, < or = 30 days) in 18 and induced in 20. Underlying heart disease was present in 88 patients (62%). RESULTS: Paroxysmal atrial fibrillation was successfully terminated in 46 (92%) of 50 patients, chronic atrial fibrillation in 37 (70%) of 53, intermediate in 16 (89%) of 18 and induced in 16 (80%) of 20. Mean conversion threshold was 1.8 J (213 V) in the induced group, 2.0 J (229 V) in the paroxysmal group, 2.8 J (272 V) in the intermediate group and 3.6 J (311 V) in the chronic group. The conversion voltage was significantly (p < 0.001) higher in the chronic group than in the other groups of atrial fibrillation and increased significantly with the duration of atrial fibrillation and with left atrial size (p < 0.05). Of 1,779 R wave synchronized shocks delivered with a mean (+/-SD) preceding RR interval of 676 +/- 149 ms, no ventricular arrhythmia was induced. The latter may occur after unsynchronized shocks. CONCLUSIONS: Low energy transvenous shocks in patients with atrial fibrillation are effective and safe, provided that shocks are properly synchronized to R waves with preceding RR intervals that meet appropriate cycle length criteria. This study provides data that may be useful in the development of an implanted atrial defibrillator.

Adolescent↗
PubMed1997

Transvenous cardioversion of atrial fibrillation using low-energy shocks.

Recent reports have suggested that transvenous cardioversion of atrial fibrillation is feasible using low-energy shocks and a right atrium coronary sinus electrode configuration. We evaluated in a prospective study the efficacy and safety of low-energy internal cardioversion of atrial fibrillation in 104 consecutive patients. Sixty-two patients presented with chronic atrial fibrillation (group I), 16 had paroxysmal atrial fibrillation (group II), and 26 had an induced atrial fibrillation episode (group III). The mean duration of the presenting episode of atrial fibrillation was 9 +/- 19 months for group I, 4 +/- 2 days for group II, and 18 +/- 7 minutes for group III. Atrial defibrillation was performed using two intracardiac catheters: one was placed in the right atrium (cathode) and the other in the coronary sinus or in the left branch of the pulmonary artery (anode). The catheters were connected to a customized external defibrillator capable of delivering 3/3-ms biphasic waveform shocks with a voltage programmable between 10 and 400 volts. The shocks were synchronized to the R wave. Sinus rhythm was restored in 44 of the 62 patients in group I (70%), in 12 of the 16 patients in group II (75%), and in 20 of 26 patients in group III (77%). The mean voltage and energy required for cardioversion were respectively 300 +/- 68 V and 3.5 +/- 1.5 J, for group I, 245 +/- 72 V and 2.0 +/- 0.9 J for group II, and 270 +/- 67 V and 2.6 +/- 1.2 J for group III. The leading-edge voltage required for sinus rhythm restoration was significantly higher (p < 0.05) in the chronic atrial fibrillation group than in the paroxysmal or induced groups. No proarrhythmic effects occurred for the delivered 686 R-wave synchronized shocks. This study of a large group of patients confirms and extends the results of previous reports. Such findings may have clinical implications for elective cardioversion of atrial fibrillation and the development of an implantable atrial defibrillator.

Aged↗
PubMed1997

Using the right drug: a treatment algorithm for regular supraventricular tachycardias.

Despite the recent advent of and the successful results from catheter ablation, pharmacological therapy is still used by most clinicians as the first line therapy in patients with regular supraventricular tachycardias. Before prescribing an antiarrhythmic agent, documentation of the arrhythmia using a 12-lead electrocardiogram (ECG) is necessary to identify the type of tachycardia. The ECG diagnosis is based on the presence and polarity of the P wave, the P to QRS relationship, the presence of QRS alternation and the effect of bundle branch block on tachycardia rate. Most regular supraventricular tachycardias use the atrioventricular node either passively, as in atrial tachycardias or flutter, or actively, as paroxysmal junctional tachycardias. The Sicilian Gambit approach attempted to introduce some rationale in the choice of an antiarrhythmic agent, taking into account tachycardia mechanism, by defining the critical components of the tachycardia and the vulnerable parameter, i.e. the component that may readily be affected by an appropriate antiarrhythmic agent. For this approach, an electrophysiological study is particularly useful. The most common regular paroxysmal supraventricular tachycardias include atrioventricular nodal re-entrant tachycardias and atrioventricular re-entrant tachycardias which use an overt or concealed accessory atrioventricular connection (Kent bundle) or atriofascicular connection (Mahaim). For acute termination of paroxysmal junctional tachycardia, intravenous adenosine is the drug of choice. For the prevention of the tachycardia attacks in atrioventricular nodal re-entrant tachycardia, the agents with a depressive effect on the antegrade slow pathway, such as calcium channel blockers or beta-blockers, are likely to be effective. If they fail, sodium channel blockers (propafenone or flecainide) may be indicated. In tachycardias involving accessory connections, agents that affect fast channel dependent tissue (propafenone, flecainide, cibenzoline, disopyramide or hydroquinidine) are effective. Potassium current blockers, such as sotalol or amiodarone, represent an alternative therapy. In atrial tachycardias, the use of propafenone, flecainide or sotalol constitute a logical choice. In drug-resistant cases, amiodarone is the most potent agent. Radiofrequency ablation of the slow atrioventricular nodal pathway, of an accessory connection or of an atrial focus, is indicated in drug-resistant or drug-intolerant patients and is increasingly offered as an alternative therapy.

Algorithms↗
PubMed1997

[Radiofrequency ablation of resistant atrial flutter: a new anatomical approach].

Several reports have suggested that radiofrequency ablation could prevent atrial flutter resistant to antiarrhythmic therapy. The usual recommendation is to apply the radiofrequency current in a zone situated between the tricuspid valve and orifice of inferior vena cava. The aim of this study was to assess the efficacy of another site of ablation of flutter extending from the tricuspid valve to the orifice of the coronary sinus, either alone or associated with a site between the coronary sinus and the lateral wall of the right atrium. Twenty patients aged 42 to 78 years (mean : 6 +/- 11 years) were included. Atrial flutter was paroxysmal in 15 patients and chronic in 5 patients. Each patients had documented failure of 1 to 5 antiarrhythmic agents (average 3.1 +/- 1.6). The site of ablation was localised by anatomical criteria alone. During follow-up of 7 +/- 5 months (range 1 to 18 months), 13 patients had no recurrence of atrial flutter after ablation, 5 patients had recurrence and 2 patients had paroxysmal atrial fibrillation alone: the success rate was 15/20 (75%). This study suggests that the zone between the tricuspid valve and coronary sinus may be a site for radiofrequency ablation of atrial flutter. It is valuable alternative to the usually recommended technique.

Adult↗
PubMed1997

[Identification of 5 variants of the hemoglobin beta chain using DNA analysis (amplification, sequencing and restriction enzymes)].

PURPOSE: To confirm the conventional techniques for studying structural haemoglobinopathies and to show off the simplicity and efficacy of new methods based on the study of DNA. PATIENTS AND METHODS: Peripheral blood samples of 17 patients with 5 haemoglobin variants detected by conventional and shown off by means of sequencing according to Sanger's method, plus PCR-RFLP, were studied. RESULTS: Five structural haemoglobin variants were found, which distributed as follows: 7 cases of Hb Complutense (beta 127 Gln-->Glu), 1 Hb D-Punjab (beta 121 Glu-->Gln), 3 Hb Hofu (beta 126 Val-->Glu), 3 Hb J-Baltimore (beta 16 Gly-->Asp) and 3 Hb San Diego (beta 109 Val-->Met). CONCLUSIONS: These results allow us to stress the simplicity and usefulness of DNA analysis (sequencing , amplification and enzymatic digestion) to identify haemoglobin variants as opposed to laborious analysis of the primary structure by means of HPLC peptide separation.

DNA Mutational Analysis↗
PubMed1997

[Cardioversion of atrial fibrillation with low energy internal electric shock].

The efficacy and safety of low internal cardioversion for the reduction of atrial fibrillation was assessed prospectively in 104 consecutive patients. Sixty-two patients had chronic atrial fibrillation (Group I). 16 patients had paroxysmal atrial fibrillation (Group II) and 26 patients had induced atrial fibrillation (Group III). The average duration of the current episode of atrial fibrillation was 9 +/- 19 months in Group I, 4 +/- 2 days in Group II and 18 +/- 7 minutes in Group III. Two intracardiac defibrillation catheters were used, one (the cathode) in the right atrium and the other in the coronary sinus or left branch of the pulmonary artery (anode). These catheters were connected to an external defibrillator delivering biphasic 3/3 ms shocks with a voltage which could be programmed from 10 to 400 volts. The shocks were synchronised on the R wave. Sinus rhythm was restored in 44 of the 62 patients in Group I (70%), 12 of the 16 patients in Group II (75%) and 20 of the 26 patients in Group III (77%). The average voltages and energies restoring sinus rhythm were 300 +/- 68 volts and 3.5 +/- 1.5 joules respectively in Group I, 245 +/- 72 volts and 2.0 +/- 2.9 joules in Group II, and 270 +/- 67 volts and 2.6 +/- 1.2 joules in Group III. These results show that the energy required to restore sinus rhythm is significantly greater in patients with chronic atrial fibrillation than in patients with paroxysmal or induced atrial fibrillation. There were no ventricular proarrhythmic effects in the 686 shocks synchronised on the R wave. This study shows that internal cardioversion of atrial fibrillation is feasible with low energies under simple sedation. These results support the concept of an implantable atrial defibrillator.

Adult↗
PubMed1996

[Antiarrhythmic drugs in paroxysmal atrial fibrillation. When and how?].

Atrial fibrillation (AF), carries a serious risk of systemic embolic complications, especially cerebral. Antiarrhythmic therapy is the most used method for restoring or maintaining sinus rhythm, and for preventing recurrences or of controlling the ventricular response. A clinical classification was recently suggested to define when to use antiarrhythmic drugs. In a first episode of symptomatic AF (Class I), it is not possible to assess the chances of recurrence and preventive antiarrhythmic therapy would not seem justified. In recurrent paroxysmal AF, the arrhythmias may be asymptomatic (Class IIa) and antiarrhythmic therapy may be questionned. When the attacks are infrequent (< 1 every 3 months, Class IIb), episodic pharmacological intervention to restore sinus rhythm or to slow the ventricular rate may be valuable, but the efficacy and safety of such treatment should be assessed. In Class IIc, appropriate antiarrhythmic treatment to prevent recurrence is often indicated. Atrial fibrillation resistant to one or more antiarrhythmic drugs (Class III) may also be subdivised into three subgroups as for Class II. In addition to the use of alternating of antiarrhythmic drugs not previously used, it is justifiable to consider investigations to determine the mechanism of resistant AF use only drugs of the which slow the ventricular rate. The choice of antiarrhythmic drug may be guided by the concepts of the Silician Gambit, taking into consideration the mechanism of AF and the therapeutic objective. In AF, the mechanism is reentry, the vulnerable parameter the atrial refractory period. To increase the refractory period, the target should be the sodium or potassium currents. The status of left ventricular function is an important parameter in the choice of an antiarrhythmic agent.

Anti-Arrhythmia Agents↗
PubMed1995

Intravenous cibenzoline in the management of acute supraventricular tachyarrhythmias.

Intravenous cibenzoline was evaluated in 37 patients with acute supraventricular tachyarrhythmias and a ventricular rate > 120 beats/min. The presenting arrhythmia was atrial fibrillation in 15 patients, atrial flutter in 5, ectopic atrial tachycardia in 11, and paroxysmal atrioventricular (AV) junctional reentrant tachycardia in 6 patients. Intravenous cibenzoline was administered as a bolus given over 2 minutes, at a dose of 1 mg/kg in the first 26 patients and 1.2 mg/kg in the subsequent 11 patients, 15 minutes following failure of placebo (isotonic glucose). The results were evaluated 15 minutes after the intravenous injection. Restoration of sinus rhythm was obtained in 3 out of 6 patients with paroxysmal AV junctional tachycardia (50%) and in 7 out of 31 patients (23%) with atrial tachyarrhythmias (5 out of 15 patients with atrial fibrillation and 2 out of 16 patients with ectopic atrial tachycardia or atrial flutter). Five additional patients with atrial tachyarrhythmias had slowing of ventricular rate below 100 beats/min. Therefore, a satisfactory result, that is, restoration of sinus rhythm or slowing of ventricular rate, occurred in 15 patients (40.5%). Side effects were transient, including visual disturbance (one patient), asymptomatic widening of QRS complex (three patients), incessant reciprocating tachycardia (one patient), and acceleration of ventricular rate (eight patients), resulting in 1:1 flutter, with poor tolerance in two patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Paroxysmal atrial fibrillation: a need for classification.

UNLABELLED: Classification of Atrial Fibrillation. INTRODUCTION: Clinical aspects of paroxysmal atrial fibrillation are heterogeneous. The attacks of atrial fibrillation may differ in their duration frequency and presence and severity of symptoms. Therefore, a proposal for a clinical classification of paroxysmal atrial fibrillation may be helpful. We tested a new classification system in a cohort of 51 consecutive hospitalized patients with paroxysmal atrial fibrillation. METHODS AND RESULTS: Paroxysmal atrial fibrillation was subdivided into three classes. Class I included a first attack of symptomatic atrial fibrillation either with spontaneous termination (IA) or requiring cardioversion because of poor tolerance (IB). Class II included recurrent attacks in untreated patients within three subgroups: IIA with no symptoms, IIB with < 1 symptomatic attack per 3-month period, and IIC > with 1 symptomatic attack per 3-month period. Class III included recurrent atrial fibrillation unresponsive to one or more antiarrhythmic agents for prevention of recurrences. Class III also consisted of three subgroups: IIIA with no or mild symptoms, IIIB with < 1 symptomatic attack per 3-month period, and IIIC with > 1 symptomatic attack per 3-month period. The criteria for paroxysmal atrial fibrillation (episode > 2 minutes and < 7 days in duration) were fulfilled by 51 patients (29 men, 22 women; mean age 61 +/- 14 years). Structural heart disease was present in 31 patients; the atrial fibrillation was idiopathic in 18 (35%). All 51 patients could be classified within the three classes and their subgroups: 14 patients (27%) in Class I, 13 (25%) in Class II, and 24 (47%) in Class III. The incidences of idiopathic atrial fibrillation were 21%, 30%, and 45% of the patients in Classes I, II, and III, respectively. CONCLUSIONS: Based on this new classification system, all hospitalized patients with paroxysmal atrial fibrillation could be classified. This classification may be useful to delineate better the clinical subgroups of patients with paroxysmal atrial fibrillation, to characterize better the patient population in future studies, and to improve treatment strategies.

Aged↗
PubMed1993

[Pharmacological treatment of ventricular tachycardia].

Pharmacological antiarrhythmic therapy is the treatment of first intention for the prevention of ventricular tachycardia (VT). In sustained VT, electrophysiological investigations without treatment enable the induction of VT, the demonstration of its reproducibility, the confirmation of diagnosis (if necessary), the determination of its mechanism and the choice of treatment. In an effort to standardise the technique, a minimum acceptable protocol of stimulations was agreed upon: at least 2 cycles (600 milliseconds and 400 milliseconds) and 3 extrastimuli (S2, S3, S4). The percentage of inducibility (sensitivity) depends on the underlying heart disease and is of the order of 90-95% in coronary artery disease with a history of infarction. Serial electrophysiological studies show non-inducibility of VT with treatment in 20-60% of cases. This result is influenced by the ejection fraction, the type of ventricular arrhythmia (fibrillation or tachycardia) and the antiarrhythmic agent tested. A Class IA, then a Class IC antiarrhythmics or sotalol (if the ejection fraction is over 40%) are evaluated by this technique. Empiric therapy has no place in the management of malignant poorly tolerated arrhythmias. In recurrent, well tolerated arrhythmias which are non-inducible, treatment may be guided by the results of Holter monitoring, providing the patient has a sufficient number of extrasystoles. Exercise stress tests may be useful in effort or catecholamine-induced tachycardias. There is no consensus about the management of non-sustained VT. When these arrhythmias are associated with syncope or cardiac arrest, programmed ventricular stimulation seems indicated. The choice of antiarrhythmic drugs and their results are reviewed.

Anti-Arrhythmia Agents↗
PubMed1992

Cloning, functional expression, and regulation of two K+ channels in human T lymphocytes.

Low stringency screening of a Jurkat cDNA library with a rat brain K+ channel (RCK1) probe has resulted in the isolation of HLK3, a voltage-gated K+ channel. In Xenopus oocytes, the HLK3 clone directs the expression of a rapidly activating transient outward K+ current similar to the type n K+ current recorded in Jurkat T cells. The HLK3 gene is located on the short arm of human chromosome 1 (p13.3). Polymerase chain reaction was used to clone HIsK from Jurkat cDNA. The HIsK clone shares the same sequence with a previously described genomic clone (Murai, T., Kazikuka, A., Takumi, T., Ohkubo, H., and Nakanishi, S. (1989) Biochem. Biophys. Res. Commun. 161, 176-181). In Xenopus oocytes, it encodes a slowly activating, noninactivating K+ channel which cannot be recorded in Jurkat cells by conventional patch-clamp techniques. Transcripts of both clones are present at a similar level before and after activation of purified human T lymphocytes and Jurkat cells, reflecting a constitutive expression of K+ channel messages. This finding is in good agreement with the electrophysiological results for type n K+ current density on the same cells. HLK3 current is very sensitive to the scorpion toxin charybdotoxin (IC50 = 0.8 nM). HIsK current is totally insensitive to this toxin but is blocked by the antiarrhythmic clofilium (IC50 = 80 microM). While charybdotoxin has no effect on interleukin 2 mRNA induction, clofilium potently inhibits interleukin 2 mRNA expression upon mitogen-induced T cell activation. It is concluded that the HLK3 channel is not an important component of the T cell mitogenic response. Other targets for K+ channel blockers, such as the HIsK protein, could be involved in the activation process.

Amino Acid Sequence↗
PubMed1991

Cloning, expression, pharmacology and regulation of a delayed rectifier K+ channel in mouse heart.

Neonatal mouse cardiac poly(A)+ mRNA microinjection into Xenopus oocytes directed the expression of a delayed rectifier K+ current. A cDNA encoding this channel, called mIsK, was cloned from a neonatal mouse heart cDNA library whose properties were studied after expression of the complementary RNA in Xenopus oocytes. Among the different known K+ channel blockers, only the class III antiarrhythmic clofilium inhibited mIsK in the 10-100 microM range. The channel was completely insensitive to other antiarrhythmics such as quinine, quinidine, sotalol or amiodarone. mIsK was enhanced by increasing intracellular Ca2+ and by microinjected Ca(2+)-calmodulin dependent protein kinase II. These stimulations were reversed by the calmodulin antagonist W7. Conversely, the phorbol ester PMA, the diacylglycerol analog OAG and microinjected purified protein kinase C inhibited mIsK. This inhibitory effect could be prevented by the protein kinase C inhibitor staurosporine. These results were consistent with the presence of consensus sequences for kinase II and kinase C in the mIsK structure. Cultured newborn mouse ventricular cardiac cells exhibited a delayed rectifier K+ current which had biophysical properties similar to those of cloned mIsK and which was inhibited by clofilium and protein kinase C activators. In situ hybridization experiments revealed that mIsK mRNA was homogeneously distributed in the cardiac tissue. Neonatal mouse heart expressed the most mIsK mRNA compared with various other rat and mouse tissues. Since this K+ channel generates a current which appears to be involved in the control of both the action potential duration and the beating rate, these results suggest an important role for the mIsK channel in cardiac cell physiology and cardiac pathology.

Amino Acid Sequence↗
PubMed1990

[Intraoperative and postoperative analgesia in pediatric surgery. 1 years' experience].

Operative and postoperative analgesia has become in a few years a major concern for pediatric anesthesiologists. The fact that pain can have dramatic metabolic and hemodynamic consequences has been well documented. This study shows the activity in our department in the field of analgesia during 1989. 82% of the 2,675 children having undergone surgery have received analgesia during the operative period either by the way of an i.v. narcotic or an regional block. No morbidity or mortality resulted from these techniques during the operative period. When a regional block was prolonged by the mean of a catheter, there were no major complication (2 seizures). The use of oral, rectal and i.v. analgesics follows the classic recommendations. Morphine by all routes of administration is used increasingly in our department. Two moderate respiratory depressions occurred in 1989 due to error in dosage with no consequence for the child. The authors underline the importance of well established protocols which have been discussed and approved by all, the importance of emergency procedures and treatment, which only can guaranteed the necessary safety.

Acetaminophen↗
PubMed1989

[Hemolytic anemia caused by pyrimidine 5'-nucleotidase (P5N) deficiency 15 years later. Apropos of 2 new cases of hereditary deficit and another one of lead poisoning].

Congenital pyrimidin 5'nucleotidase deficiency manifests as hemolytic anemia with basophilic stippling. In lead poisoning, anemia, basophilic stippling and inhibition of erythrocyte pyrimidin 5' deficiency are also observed. In the present work, we report two cases of hemolytic anemia secondary to congenital deficiency of pyrimidin 5' nucleotidase and another case secondary to lead poisoning. Since 1974, when pyrimidin 5' nucleotidase deficiency was isolated, is known that hemolysis is related to the accumulation of pyrimidin nucleotides within the erythrocytes that behave as metabolic inhibitors. However, the precise metabolic process whose inhibition leads to the shortening of erythrocytes half life has not been elucidated yet.

5'-Nucleotidase↗
PubMed1989

Characterization of a new alpha-thalassemia-1 deletion in a Spanish family.

A new type of alpha-thalassemia-1 was characterized in one Spanish patient with Hb H disease and in her mother. The restriction map of this deletion suggests that the deletion of 22 kb has occurred on a chromosome carrying a zeta-globin triplication. The resulting chromosome lacks the alpha 2- and alpha 1-globin genes, the psi alpha 2- and psi alpha 1-globin genes, and one of the three zeta-globin genes, while the other two zeta-globin genes and the theta 1-globin gene have been retained.

Adult↗
PubMed1985

Protection of indwelling vascular catheters: incidence of bacterial contamination and catheter-related sepsis.

We compared the incidence of catheter contamination and catheter-related sepsis in 200 noninfected patients admitted postoperatively to the surgical ICU. Four methods of catheter fixation were used: (a) povidone-iodine ointment (Betadine) with a sterile gauze and adhesive dressing (Elastoplast); (b) Op-Site film; (c) Op-Site spray followed by Op-Site film; and (d) Beta-dine and Op-Site film. Of 708 catheters used for 200 patients, 516 (72.8%) were cultured. There was no catheter-related septicemia but 13 (2.52%) catheters were contaminated. However, these were evenly distributed among the four groups. We, therefore, conclude that aseptic insertion of catheters, daily inspection of puncture site, and replacement of tubing are the determining factors in preventing catheter-related sepsis.

Bacterial Infections↗