Biomedical subjects

F Fillette

Publications and source records attributed to F Fillette.

At least 19 recordsLinked to original sources

PubMed1996

Effects of bisoprolol on heart rate variability in heart failure.

Analysis of heart rate variability (HRV) provides a non-invasive index of autonomic nervous system activity. HRV has been shown to be reduced in heart failure. Preliminary data indicate that beta blockers improve clinical status in patients with heart failure, but HRV improvement remains to be demonstrated. Fifty-four patients from the randomized double-blind, placebo-controlled Cardiac Insufficiency Bisoprolol Study were included in the HRV study. The bisoprolol daily dose was 5 mg once daily. We assessed HRV during 24-hour Holter recordings before randomization and after 2 months of treatment. HRV as measured in the time domain by root-mean-square successive differences (rMSSD), the percentage of adjacent RR differences >50 ms (pNN50), and the SD of RR intervals (SDNN), and in the frequency domain by high-frequency (0.16 to 0.40 Hz) and low-frequency (0.04 to 0.15 Hz) power. Most patients were in New York Heart Association functional class III. The mean left ventricular ejection fraction was 27 +/- 7%, and heart failure was idiopathic or ischemic. After 2 months, the patients receiving bisoprolol had a reduced mean heart rate compared with that in placebo patients (p=0.0004). Bisoprolol increased 24-hour rMSSD (p=0.04) and 24-hour pNN50 (p=0.04), daytime SDNN (p=0.05), and daytime high-frequency power (p=0.03) power. Bisoprolol induced a significant increase in HRV parameters related to parasympathetic activity in heart failure. Increased vagal tone may contribute to the protective effect of beta blockers and may have prognostic implications.

Adrenergic beta-Antagonists↗

PubMed1996

Persistent transient myocardial ischemia despite beta-adrenergic blockade predicts a higher risk of adverse cardiac events in patients with coronary artery disease.

OBJECTIVES: We evaluated the prevalence and prognostic significance of transient myocardial ischemia despite beta-adrenergic blockade in patients with coronary artery disease. BACKGROUND: Persistence of transient ischemia despite therapy may correspond to a subset of high risk patients with coronary disease. The impact of beta-blocker withdrawal in these patients remains unknown. METHODS: Patients (n = 313) with documented coronary artery disease and beta-blocker therapy, with (group I, n = 84) or without (group II, n = 229) transient ischemia on ambulatory electrocardiographic monitoring, were followed up during 21 +/- 9 months for cardiac events (death, myocardial infarction, percutaneous transluminal coronary angioplasty, coronary artery bypass surgery and worsening angina). Occurrence of events was compared by log-rank test. RESULTS: The number of coronary stenoses did not differ significantly between groups I and II. Beta-blocker therapy was discontinued more frequently during follow-up in group II (25% vs. 14% in group I, p = 0.04). Cumulative percentage of death or myocardial infarction, or both, tended to be higher in group I a 30 months (17% vs. 5% in group II, p = 0.09). Coronary angioplasty and bypass surgery were significantly more frequent in group I (p = 0.01 and 0.0008, respectively). Transient ischemia was associated with a higher cumulative probability of adverse events (p = 0.004). The number of coronary stenoses, presence of transient ischemia and beta-blocker withdrawal were the only significant prognostic factors of cardiac events in the Cox model. In group I patients, the relative hazard of cardiac events was increased threefold when beta-blocker therapy was interrupted. CONCLUSIONS: These data suggest that 1) the occurrence of transient ischemia despite beta-blocker therapy identifies a subset of high risk patients with coronary artery disease, and 2) the interruption of beta-blocker therapy increases the risk of adverse cardiac events.

Adrenergic beta-Antagonists↗

PubMed1995

Effects of amlodipine on transient myocardial ischaemia in patients with a severe coronary condition treated with a beta-blocker. Amlor-Holter Study Investigators.

The purpose of this trial was to study the additional anti-ischaemic effects of amlodipine in coronary patients with ambulant ischaemia despite beta-blocker therapy. Beta-blockers are the most effective drug therapy for reducing the frequency and duration of ambulatory ischaemic episodes. However, the therapeutic advantage of combined calcium antagonist-beta-blocker treatment remains questionable. Three hundred and thirteen patients with documented coronary artery disease, a positive exercise test within 6 months before entry and background beta-blocker therapy, were screened. Inclusion criteria (> or = 4 episodes of transient ST segment depression of > or = 1.0 mm and/or > or = 20 min of ischaemia) were demonstrated in a 48 h ECG during the placebo run-in period in 84 (25%) of the patients. Eighty-nine percent of the ischaemic episodes were silent. The eligible patients were then randomized in a 2-week, double-blind, parallel group study comparing placebo to amlodipine 10 mg daily added to the beta-blocker. The anti-ischaemic efficacy of the combination therapy was assessed by 48 h ECG monitoring and exercise tests. Compared to placebo, amlodipine did not significantly reduce either the frequency (3.7 +/- 4.3 vs 4 +/- 4.8 episodes in the amlodipine group) or the duration of ambulatory ischaemia (mean duration: 43.9 +/- 57.1 vs 39.6 +/- 65.7 min, total duration 3.1 +/- 6.7 vs 2.8 +/- 6.1 h). Exercise-induced ST segment depression tended to decrease with amlodipine (58% vs 73% in the placebo group) and the ischaemia-free workload capacity was increased (+1.7 stage vs 0.7 stage in the placebo group, P = 0.08). These results suggest that 2 weeks treatment with amlodipine may not provide any additional anti-ischaemic benefit in patients with ambulant ischaemia resistant to a beta-blocker therapy.

Adrenergic beta-Antagonists↗

PubMed1991

[Nosologic frontiers of arrhythmogenic dysplasia. Quantitative variations of normal adipose tissue of the right heart ventricle].

The increasing number of arrhythmogenic idiopathic cardiomyopathies with available histological studies by biopsy or peroperative sampling has prompted the need for data about the normal structure of the right ventricle. A retrospective study of right ventricular tissues was undertaken in 148 autopsies. The quantity of adipose tissue was scored 0 (only epicardial fat visible) to 4 (total replacement of the myocardium by adipose tissue). The topography of the adipocytes was also coded 0 to 4 according to the degree of intermyocytic penetration, irrespective of the total quantify of fat. The amount and extension of adipose tissue in the right ventricular wall was striking. Fifty called "normal" appearances with a myocytic wall of normal thickness and a separate layer of epicardial fat, were only present in 61 of the 148 cases. Adipocytes were present in variable numbers, often unexpectedly high in the majority of cases, with no relationship to the age or gender of the patient with frequent individualization of the myocardial bundles. These surprising findings in normal right ventricles should be born in mind when considering the diagnosis of arrhythmogenic right ventricular dysplasia (ARVD). The histopathological appearances of ARVD are very similar but also differ very significantly, at least in typical cases. The adipocytes are often present in large numbers but this is banal and non-specific. On the other hand, the bundles which penetrate the epicardial fat are usually fibro-muscular and not purely myocytic. In addition, arterioles suggesting segmental diversions are present within the fatty layer with non-specific inflammatory cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1990

[Electrophysiology in evaluating the treatment of sustained monomorphic ventricular tachycardia: criteria for efficacy].

The authors studied the influence on recurrence and mortality of induced ventricular arrhythmias during electrophysiological studies performed to assess the efficacy of treatment of sustained monomorphic ventricular tachycardia. One hundred and twenty-six consecutive patients investigated from 1981 to 1988 were included. The underlying pathology was chronic myocardial infarction (N = 56), dilated cardiomyopathy (N = 24), right ventricular dysplasia (N = 31) and there were 15 idiopathic cases. All these tachycardias could be induced during the control study. A second test was performed after instituting treatment. This was maintained whatever the result of the electrophysiological study except in patients in whom the tachycardia rate was over 130/mn and/or poorly tolerated. Recurrences were defined as the observation of tachycardia with the same morphology and/or the occurrence of sudden death. Follow-up averaged 29 +/- 21 months. The absence of recurrence and survival were assessed by the Kaplan-Meier method and Logrank's test. It was not possible to induce any arrhythmia after treatment in 52 patients (41%). The prevalence of absence of recurrence in this group was 0.863. If the induction of ventricular fibrillation, doublets or short runs of VT (N less than 6 with no recurrences) are included, the value increased to 0.877. These patients were considered to be non-inducible. The prevalence of absence of recurrence of arrhythmia in patients in whom it was possible to induce sustained ventricular tachycardia of the same morphology as the clinical arrhythmia was 0.512 (p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1990

[Value and limitations of Holter monitoring and electrophysiologic testing in the evaluation of the treatment of sustained monomorphic ventricular tachycardia].

The authors studied the value and limitations of Holter monitoring and electrophysiological investigation in the evaluation of treatment of sustained monomorphic ventricular tachycardia (VT). One hundred and twenty-four consecutive patients were included in the study from January 1981 to February 1988. The etiologies were chronic myocardial infarction (N = 54), dilated cardiomyopathy (N = 24), right ventricular dysplasia (N = 31), and idiopathic VT (N = 15). All the tachycardias could be induced during baseline electrophysiological investigations and presented as complex ventricular arrhythmias on the Holter recordings. The investigations were repeated after treatment which was maintained irrespective of the results, unless the tachycardia which was induced or recorded was over 130 cycles/min and/or poorly tolerated. Recurrence was defined as the recording of VT in the absence of a change of treatment and/or the occurrence of sudden death. The follow-up period averaged 29 +/- 21 months. The Kaplan-Meier method was used to study the prevalence of absence of recurrence and survival rates. We observed 28 recurrences of VT and there were 21 deaths. Eighty-five per cent of patients had normal Holter monitoring after treatment. The prevalence of absence of recurrence was 0.751 when the Holter was normal and 0.485 when an arrhythmia was recorded (p = 0.03). The sensitivity was 25 per cent and the specificity 88 per cent. The survival rates were 0.66 and 0.585 respectively (p = 0.008). Fifty-three per cent of patients remained inducible after treatment with a prevalence of absence of recurrence of 0.572. This value rose to 0.877 when VT could not be induced (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗

PubMed1989

[Type I and II heart block].

Second degree blocks are divided into type I blocks, with an increment in conduction time for two consecutive conducted impulses, and type II blocks which present with constant conduction times for consecutive conducted impulses. This distinction is not only of theoretical interest but also of practical interest, since type I blocks located in the node are benign as a rule, whereas type I blocks in other locations and type II blocks are of poor natural prognosis and require pacing. Major increments of the PR interval, occurrence at night and young age are in favour of type I blocks. 2/1 blocks without 2 consecutive impulses sometimes raise difficult problems. Carotid massage and change from supine to upright posture may display two consecutive conducted P waves. If this does not happen, Holter recordings will show, in almost every case, two consecutive waves which enable the block to be typed. Whenever a doubt persists, electrophysiological exploration makes it possible to determine the exact location of the block. Type I blocks imply the presence of a decremental conduction and therefore of varying conduction velocities which decrease with consecutive impulses. This is compatible with the normal functioning of the atrioventricular node which has calcium-dependent potentials, b ut everywhere else it implies a pathological state of tissues that have sodium-dependent potentials and give an all-or-nothing response. This explains why extranodal type I blocks, like types II blocks, make it necessary to fit the patients with a pacemaker, whereas type I blocks usually are of good prognosis.

Electrocardiography↗

PubMed1988

[Long-term course of conduction disorders in 97 patients with an HV interval superior or equal to 70 milliseconds].

The natural history of disorders of conduction is imperfectly known. The presence of an HV interval of 70 milliseconds or more, which is regarded as pathological, usually results in pacemaker implantation. In this study the course of symptoms and disorders of conduction was investigated in 97 patients with an HV interval of 70 ms or more, and therefore equipped with a pacemaker, followed up for a mean period of 26.5 +/- 19.5 months. Among these 97 patients, 65 had presented with one or several syncopes, 14 had experienced feelings of faintness and 18 were asymptomatic. Among patients with symptoms, these totally disappeared in 63 and became milder in the remaining 12 patients. Complete and permanent AV block was observed in 11 patients. The actuarial incidence of complete permanent AV block was about 5 p. 100 per annum until 4 years. The only predictive parameter for such a course was the occurrence of a second degree type 2 or a third degree paroxysmal block prior to pacemaker implantation (significantly associated with the absence of symptoms).

Adult↗

PubMed1988

[Morphologic study of cardiac cells in sheep before and after electric shock].

A combined electrophysiological and histopathological study was conducted on sheep myocardium fragments rich in easily identifiable conduction cells subjected to electric shocks of varying intensity. Tissue fragments were immersed in a thermostatically-controlled bath at 37 degrees C, perfused with a carbonated standard tyrode solution at the rate of 30 ml/min and stimulated at a constant bipolar 1 C/sec tension twice as high as the threshold of diastolic excitability. After measurement of reference values, electric shocks of 2 to 80 joules were delivered between two electrodes placed on both sides of the tissue fragment. The electrophysiological part of the study showed disorders of conduction which, depending on the energy delivered, were more or less complete and reversible. The histopathological part of the study showed that conduction tissue was extremely fragile, even to low-energy shocks. This fragility was in glaring contrast with the relatively modest damage suffered by myocytes. Liquefaction and/or coagulation of Purkinje's cells was also striking, as it extended over an area much wider than that subjected to the shock. Thus, with medium intensity shocks destroyed conduction bundles were seen to creep between myocytes that often were perfectly normal or showed rare hypercontraction bands. Some myocytes were in the process of degeneration or even eosinophilic necrosis, but except in case of violent shock these were more or less isolated elements in the vicinity of the stimulated area. The fragility of conduction tissue and its selective damage by low-intensity shocks may be explained partly by its low impedance which allows preferential passage of the electric current.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

[Cellular electrophysiological and histopathological study of the effects of continuous electric current on the sheep heart].

The energy released in electrode catheter ablation is spent on thermal, mechanical and electrical effects. The relative importance of these effects and their role in the adverse reactions of the method are controversial. Low-energy shocks have been shown to modify cellular electrophysiological and histopathological parameters in the sheep heart. The purpose of this study was to individualized the effects of the electric current itself, using an isolated electrode to suppress barotrauma and reduce the amount of energy delivered. Three fragments of epicardium, seven false tendons and eight loop-shaped strips were placed in an electrophysiology bath perfused with Tyrode's solution and subjected to an electric field induced by an 18 V battery without discharge from a condenser, so that all mechanical effects were suppressed. The electric field was supplied via an isolated electrode, thus preventing the current from leaking through the Tyrode's solution and forcing it across the fragments studied. The electrophysiological parameters were studied by the microelectrode method on both sides of the area subjected to the electric field. This was followed by a histological study. The current intensity was 15 mAmp, and the energy delivered in one second was 270 mJ. Membrane depolarization was constant, and no automatic of post-depolarization activity was observed after the electric current was applied. The two-dimensional conduction accounted for the absence of block in the epicardial fragments. In the false tendons a conduction block constantly appeared between the two electrodes, associated with a decrease in conduction velocity in the recovery phase (2.1 +/- 0.24 vs 1.8 +/- 0.23 m/s, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

[Current and future application of the microcomputer in cardiology].

The present and forthcoming applications of micro data processing in cardiology are reviewed. Heart signals benefit from the digital approach which reduces distortions and permits mass storage. Electrocardiography and, notably, Holter systems, as well as ultrasonic or radiological cardiac and vascular imaging begin to profit from these remarkable advances. Data banks will in due course be constituted which, among other things, will provide a better knowledge of the incidence of some diseases or pathological associations and of their natural history and course under treatment. Such banks will also form the basis of an objective evaluation of therapeutic effectiveness.

Angiocardiography↗

PubMed1988

[Intracellular microelectrode study of the electrophysiological effects of contrast media].

Intracellular microelectrodes were used to study the electrophysiological effects on action and resting potentials, refractory periods and conduction velocities of four contrast media administered either as 1/100 and 1/1000 solutions or as 20 mg bolus injections. The products studied were Telebrix, which has high osmolality (2100 mOsm/kg) and three other contrast media with lower osmolatity (700 mOsm/kg), including Hexabrix, which contains sodium, and Iopamidol and Iohexol which are sodium-free. The parameters measured were not modified by Hexabrix and Telebrix, whereas Omnipaque and Iopamiron induced varied and significant changes in these parameters, notably in concentrations of 1/100 and as bolus injections. It is suggested that the latter contrast media should be used in non-cardiovascular explorations and in patients without confirmed heart disease.

Action Potentials↗

PubMed1987

[Factors in sudden and non-sudden death after myocardial infarction].

Attempts at preventing total and sudden cardiac death after myocardial infarction can only succeed if its mechanisms and its contributing of determinant factors are known. It is now well established that sudden deaths account for one-half of mortality cases and that in the vast majority of cases these deaths are due to malignant ventricular arrhythmia. Several sudden death risk factors have been identified, including ventricular dysrhythmias, left ventricular dysfunction and myocardial ischaemia. A number of therapeutic trials on the prevention of post-infarction death have been conducted, but so far only beta-blockers have proved effective in reducing the incidence of total and sudden cardiac death. It is permissible to think, however, that other, discerningly selected treatments might also be effective.

Adrenergic beta-Antagonists↗

PubMed1987

A study of electrical activation of the heart by laser spectrometry. An optical study of cellular action potentials.

The action potentials of working myocardium and conduction tissues, traditionally recorded by intracellular glass microelectrodes, may also be studied at a distance without physical contact using an optical system. The tissues have to be stained with a dye which fluoresces when illuminated by a laser beam, and the spectrum of the fluorescence must be sensitive to variations of the transmembrane action potential. The responses obtained by the microelectrode and the optical systems were tested on several different preparations (sheep and mouse myocardium). Three types of signals were obtained: asynchronous, synchronous and mixed, related to myocardial contraction, the action potential and the excitation-contraction couple, respectively. The use of continuous and pulsed mode laser measurements by optoelectronic methods (photomultiplier, monochromator), and imaging of the electrical activation by a CCD video camera may lead to the development of high definition mapping of myocardial activation which would be used for studying arrhythmias in experimental and even clinical models.

Action Potentials↗

PubMed1987

[Cellular effects of electric shock. Definitions, physical principles, cellular electrophysiology and morphological analysis of the shocked areas].

In this experimental study the electrophysiological changes induced by electric discharges such as used clinically in some arrhythmias refractory to the usual treatments were investigated. With energies comprised between 2 and 80 joules profound modifications of the electrophysiological properties of muscle cells and conduction were observed. These modifications included loss of resting potential, inactivation of the fast sodium flux, increase in refractory periods of conduction and disorders of conduction through the shocked areas with, at most, complete block sometimes reversible when low-energy currents were used. With the same amounts of energy these effects were maximal when the current traversed tissues positioned between the electrodes and decreased in all other cases. Usually, with currents of 10 joules or more all electric activity ceased in a radius of about one centimetre around the shocked area.

Animals↗

PubMed1987

[Cellular electrophysiological effects of fulguration by low energy shock].

In spite of the increasing use of catheter ablation in the treatment of refractory ventricular and supraventricular arrhythmias, little information is available on the basic electrophysiological effects of the treatment. Although high-energy shocks are still usually delivered, the current trend is toward lower energies. We studied the electrophysiological effects of non-deflagrating anodic shocks of 2 joules on preparations of sheep ventricular myocardium and Purkinje's fibers. The shocks were delivered by a standard defibrillator between a small-area catheter electrode and a wide-area inert electrode. Action potentials were recorded by the standard microelectrode technique. After the shocks were delivered, the Purkinje's cells that were 5 mm distant from the shocked area on either side were depolarized in the -30 to -40 mV zone, but they progressively reverted to an almost normal resting potential. Recovery was bi-exponential, with time constants of about 1 min and 10 min respectively. Similarly, the conduction block induced by the electric shock in 100% of the cases was reversible in 50%. It must be noted that at the time of conduction recovery the pattern observed was that of electrotonic conduction where the distal action potential conducted was preceded by a pre-potential. This pattern always regressed progressively, with gradual disappearance of the pre-potential in the distal cells, suggesting that the unexcitable area had vanished or become smaller. Although a normal 1/1 conduction and normal action potentials returned in the cells that were 5 mm distant from the shocked area, recordings performed at a distance of 1 to 4 mm from that area disclosed alterations of action potentials that were usually irreversible.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗

PubMed1987

Electrophysiological effects of contrast media.

The effect of two low osmolar contrast media (sodium ioxitalamate and sodium ioxaglate) and two nonionic media (iohexol and iopamidol) on cellular electrophysiological properties of sheep myocardium and Purkinje fibres was studied at two concentrations of each medium. Neither sodium ioxitalamate nor ioxaglate had significant effects on any of the parameters measured. Iohexol (10 mL/L) caused a loss of resting potential, a decrease in action potential and duration, and a decrease in refractory period of the myocardium. No change in Purkinje fibres was observed. Iopamidol induced an increase in relative refractory period in both myocardium and Purkinje fibres at 1 mL/L and had a significant effect on all parameters studied at 10 mL/L. Automaticity was not observed after perfusion with any agent at either concentration.

Animals↗

PubMed1986

[A new technic for recording cardiac action potentials. Laser spectrometry].

The new technique described rests on analysis of the fluorescence emitted by a potential-sensitive dye after excitation by a laser light of suitable wavelength. This technique, which requires no physical contact with tissues, should also be applied to the study of surface activation, using more potent pulsed laser rays and video methods.

Action Potentials↗