Search PubMed⌕ Search

Biomedical subjects

N Sadoul

Publications and source records attributed to N Sadoul.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Which patients at risk of sudden death after myocardial infarction? Critical study of prognostic factors].

A lot of acquired data concerning the prognostic factors of post-infarction mortality dates from the pre-thrombolysis era. This mortality has considerably decreased since the active management of the acute phase of myocardial infarction. This has made it more complex to evaluate the post-infarction electrical risk and may have reduced the need. However, it is not less true that the assessment of the post-infarction risk necessitates a study of each factor predisposing to severe ventricular arrhythmias and sudden death: myocardial ischaemia, left ventricular dysfunction and electrical instability. The latter parameter may be assessed by non-invasive (ventricular extrasystoles, late ventricular potentials, heart rate variability, the baroreflex and the QT interval) and invasive methods (programmed ventricular stimulation). The association of these results has an excellent negative predictive value, and also improves the positive predictive value which, nevertheless, remains insufficient for expensive prophylactic measures associated with a certain morbidity, for example the implantation of a defibrillator device, to be taken.

Death, Sudden, Cardiac↗
PubMed1995

[Atrial electrophysiological study of unexplained ischemic cerebrovascular disorders].

The aim of this study was to search for the presence of atrial vulnerability by programmed atrial stimulation in patients with unexplained ischaemic cerebrovascular strokes and to evaluate the effects of intravenous flecainide acetate on the electrophysiological parameters and on the induction of atrial arrhythmias. Thirty-eight patients (20 men, 18 women) with a mean age of 38.4 +/- 11 years were investigated. Programmed atrial pacing triggered a sustained (> 1 min) atrial arrhythmia with 1 or 2 extrastimuli in 23 of the 38 patients (61%), in these patients, there was a significant shortening of the effective refractory periods (ERP: 193 +/- 23 vs 218 +/- 30 ms; p < 0.02) and of the functional refractory periods (FRP: 228 +/- 25 vs 253 +/- 27 ms; p < 0.01) with lengthening of the A2 auriculogramme (99.7 +/- 22 vs 76.1 +/- 16 ms; p < 0.05). A combined study of the refractory periods and conduction defects provides a means of calculating an index of latent vulnerability which is greatly shortened when an atrial arrhythmia is induced (2 +/- 0.5 cm vs 3 +/- 0.6 cm; p < 0.001). Atrial arrhythmias could not be initiated after intravenous 3 mg/kg of flecainide acetate in 4 subjects (17%) with initially positive atrial stimulation tests. This study confirms the high frequency of atrial vulnerability in patients with unexplained ischaemic cerebrovascular strokes. In their population, the authors observed a low efficacy of flecainide acetate in the prevention of reinduction of atrial arrhythmias. The indication of long-term antiarrhythmic drugs in these patients are questionnable and should be assessed by a prospective long-term multicentre trial.

Adult↗
PubMed1994

[Coronary artery surgery after 70 years: an analysis of the risk factors of operative mortality].

The risk factors of operative mortality after coronary bypass surgery in patients over 70 years of age were studied in a consecutive series of 109 patients operated in our department between January 1990 and June 1992. The anginal pain was classified stage III or IV in 92 cases. Seventy-nine patients had triple vessel disease, 36 patients had left main stem stenosis and 57 had previous myocardial infarction. Twenty-six patients had ejection fractions of less than 50% and 6 were less than 30%. The average number of bypass grafts was 2.35. Associated procedures included 9 endarteriectomies of the left main coronary, one endarteriectomy of the left anterior descending and right coronary arteries, 2 myotomies involving the left anterior descending artery, 3 ventricular remodeling procedures and 3 carotid endarteriectomies. Non-lethal postoperative complications were mainly pulmonary infections (19 cases). The operative mortality was 5.1% in the group with stable angina. On the other hand, the mortality was 31.2% in the group with unstable angina operated as an emergency or semi-emergency. The causes of death were mainly postoperative low output states (16 cases) and polyarteriopathy (mesenteric infarction: 6 cases). Although age was related to operative risk, the main prognostic factor was the preoperative cardiovascular status. The degree of emergency, unstable angina, left main coronary disease, duration of cardio-pulmonary bypass and the necessity for inotropic or mechanical support in the postoperative phase were significant risk factors for death. Sex, cardiovascular risk factors, previous myocardial infarction and duration of aortic clamping were not correlated to mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1994

[Influence of gender and size on parameters measured by signal-averaged electrocardiography in healthy subjects: preliminary study].

The aim of this study was to determine the influence of electrocardiographic and biomorphometric factors on the parameters measured by signal averaged electrocardiography (SA-ECG) in normal subjects. The study population comprised 40 Caucasian students (20 men, 20 women). The SA-ECG measured 6 parameters: total duration of the averaged QRS, the root mean square of the voltage of the last 40 ms of the QRS (RMS 40) and the length duration of the terminal signal of under 40 microV (LAS), each parameter being measured with a band pass filter of 25 and 40 Hz. The echocardiographic recording included measurement of 12 parameters including left ventricular mass and ventricular volumes. Five morphological parameters were measured, including height, weight and body surface area. The duration of QRS measured with a 25 Hz band pass filter was significantly longer by 9.7 ms in men than in women (102.9 +/- 8.5 ms versus 93.2 +/- 8.1 ms; p < 0.001). Similarly, QRS duration measured with the 40 Hz band pass filter was longer in men by 11.4 ms than in women (102.1 +/- 9.6 ms versus 90.7 +/- 7.5 ms; p < 0.001). Multiple linear regression analyses showed that in both men and women, the duration of the QRS measured with either a 25 or 40 Hz band pass filter was correlated to size: the taller the subject, the longer the QRS duration. A negative correlation was observed between size and RMS 40 measured with both 25 and 40 Hz band pass filters: the taller the subject, the smaller the value of RMS 40.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Value of permanent cardiac pacing in hypertrophic and obstructive cardiomyopathies resistant to medical treatment].

The authors report their experience of long-term dual-chamber pacing in the treatment of hypertrophic and obstructive cardiomyopathy. Between August 1990 and March 1993, 16 patients (8 men, average age 53.5 +/- 18.9 years, range 21 and 79 years) with symptomatic hypertrophic obstructive cardiomyopathy resistant to medical therapy underwent electrophysiological investigation to assess atrioventricular conduction and the effects of temporary atrioventricular pacing on the intraventricular pressure gradient before implantation of a dual-chamber pacing system. The decision to implant was taken if the endocavitary studies showed severe atrioventricular conduction defects and/or if temporary pacing reduced the systolic pressure gradient by more than 30%. Temporary dual-chamber pacing led to a decrease of 48% of the systolic pressure gradient from 78.6 +/- 21.3 to 40.1 +/- 23.6 mmHg (p < 0.0005), a regression observed in 15 of the 16 patients. After an average follow-up period of 18.7 +/- 9.5 months (range 6 and 37 months), all 15 patients who received a dual-chamber pacing system were alive and were clinically improved. The systolic pressure gradient continued to decrease during the follow-up period (24.4 +/- 17.2 mmHg at the 6th month compared with 36.5 +/- 18.6 mmHg at the time of implantation; p = 0.014). The clinical improvement was dependent on careful adjustment of the atrioventricular delay which was programmed at relatively short values (65.6 +/- 14 ms, range 47 and 75 ms) to obtain permanent right ventricular capture. The authors conclude that dual-chamber pacing is an effective means of treating symptomatic hypertrophic obstructive cardiomyopathy resistant to medical therapy, even in the absence of preexisting conduction defects.

Adult↗
PubMed1994

[Results, complications and long-term follow-up of percutaneous ablation of atrioventricular conduction. Apropos of 85 cases].

This retrospective study reports the immediate and long-term results of percutaneous ablation of atrioventricular conduction. Between July 1983 and January 1992, 85 consecutive patients (51 men, age 64 +/- 10 years, range 43-84 years) presenting with supraventricular arrhythmias (atrial fibrillation n = 53; atrial flutter n = 50; atrial tachycardia n = 17; junctional tachycardia n = 6) resistant to antiarrhythmic therapy (number of drugs used: 4 +/- 1.3, range 1-6) underwent interruption of atrioventricular conduction by fulguration (n = 65) or radiofrequency energy (n = 13) or by an association of the two methods (n = 7). The 75 pacemakers implanted (10 patients had pacemakers before the procedure) comprised 55 VVIR, 11 VVI, 5 DDD and 4 DDDR units. The immediate results included two sudden deaths at the 4th and 7th day in patients undergoing fulguration and three complications with a favourable outcome (staphylococcal septicaemia, pulmonary embolism and haematoma at the site of implantation of the pacemaker). None of the patients was lost to follow-up and the average follow-up was 31 +/- 18 months (range 2-108 months). During follow-up, 15 patients died and there was a recurrence of symptoms in 11 patients after 1 to 9 months requiring a repeat procedure. In the 68 survivors, the follow-up is now 38 +/- 18 months (range 12-108 months). Sixty one patients have 2nd (2) or 3rd (59) degree atrioventricular block, giving 90% good electrocardiographic results.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Clinical aspects of implantable defibrillators: indication].

The rapidity of technological progress has now made available a device which was only a dream a few years ago, a nearly ideal implantable defibrillator. Despite the persistence of a number of technical and clinical problems, the fourth generation defibrillators are multiprogrammable, with antitachycardia and antibradycardia functions, implantable by the endocavitary approach in most cases thanks to the introduction of biphasic shocks, fitted with constantly improving systems of telemetry, and are progressively smaller in size. The selection of a defibrillator device requires consideration of the patient's needs and the technical characteristics of the defibrillator. Apart from special situations in which the indications of the implantable defibrillator are generally accepted, it is only possible in the absence of results of prospective clinical trials, to use data accumulated on the place of defibrillation compared with other forms of management of severe ventricular arrhythmias. As there is a wide choice of treatment of these ventricular arrhythmias, the role of each must be defined for each individual patient. With regards to the implantable defibrillator, it is essential to take into consideration a number of clinical and paraclinical factors such as the clinical preservation of the arrhythmia, the underlying cardiac disease, left ventricular function and the type of arrhythmia induced by programmed ventricular stimulation.

Arrhythmias, Cardiac↗
PubMed1994

[Left-sided His bundle ablation after failure of right-sided approach: technique and initial results].

Although interruption of atrioventricular conduction has been widely used over the last decade in patients with supraventricular arrhythmias and rapid conduction resistant to antiarrhythmic therapy, the incidence of atrioventricular block obtained by delivering the energy at the tricuspid ring ranges from 45 to 92%. Failure of this technique is usually related to the inhability to record endocavitary electrogrammes compatible with probable success by the right-sided approach. The authors report four cases of interruption of atrioventricular conduction in 4 men (average age 61.5 +/- 10 years) by the retrograde arterial catheterisation after one or more (1 to 3) failures by the right-sided approach. After arterial puncture, the ablation catheter is positioned against the interventricular septum below the aortic cusps to record the His bundle electrogram. His bundle ablation was obtained after an average of 2 radio frequency energy applications (range 1 to 3). At the time of effective application, the average amplitude of the endocavitary electrogram was as follows: auriculogram 0.09 mV (range 0.05 to 0.2 mV), His bundle electrogram 0.19 mV (0.15-0.22 mV), ventriculogram 1.36 mV (1.0 to 1.7 mV). No complications were observed. After an average follow-up of 4 months, the 4 patients were still in complete atrioventricular block. This preliminary series shows that left-sided interruption of atrioventricular conduction is effective and safe. It may be proposed after failure of a right-sided attempt.

Aged↗
PubMed1993

[Atrial activity and its effects].

The initiation of cardiac impulse is located in the sinus node, in the upper anterior part of the right atrium. The importance of the atrium is not only linked to the regulation of heart rate, but also to its haemodynamic function. Indeed, atrial depolarization leads to atrial contraction which can be responsible for up to 30% of cardiac output by way of ventricular filling. Supraventricular arrhythmias are related to one of the following mechanisms: abnormal automaticity, triggered activity, and reentry. Most of supraventricular tachycardias are due to a reentrant phenomenon (intranodal reentrant tachycardia, orthodromic circusmovement tachycardia, atrial flutter and atrial fibrillation). At the onset of a supraventricular tachycardia, the loss of efficacious atrial contraction as well as the increased heart rate may abruptly decrease ventricular filling. As a consequence, stroke volume is reduced, leading to a decrease in cardiac output and in arterial blood pressure, explaining that the patient may experience syncope. Usually, blood pressure reduction resumes within 30 seconds after activation of the autonomic adrenergic nervous system. In case of an underlying heart disease, the supraventricular tachycardia may lead to acute cardiac failure. When reentry is concerned, the tachycardia is going around a specific circuit. The existence of such a circuit in most of supraventricular tachycardias has led to the development of ablation therapy, the goal of which is to destroy a critical portion of the circuit hence making the recurrence of reentrant tachycardia impossible.

Arrhythmias, Cardiac↗
PubMed1993

Effects of sotalol and d-sotalol on ventricular tachycardia and fibrillation induced by programmed electrical stimulation.

It is only in the last few years that the broad-spectrum antiarrhythmic properties of sotalol have become increasingly recognized. Racemic sotalol has potent beta-blocking and class III antiarrhythmic properties, and it has been reported that this drug is able to control supraventricular and ventricular arrhythmias. Recently, several studies performed with the d-sotalol isomer, which is almost devoid of the beta-blocking effects compared to the racemate, suggest significant antiarrhythmic efficacy and good tolerance of the dextro-isomer. In this paper we review and discuss the effects of sotalol and d-sotalol in patients with ventricular tachycardia (VT), ventricular fibrillation (VF) or cardiac arrest in whom VT or VF was induced by programmed electrical stimulation (PES).

Adrenergic beta-Antagonists↗
PubMed1993

[Correlation between parameters measured by high amplification ECG and results of programmed ventricular stimulation after myocardial infarct].

The presence of late ventricular potentials and the induction of sustained ventricular tachycardia (SVT) by programmed ventricular stimulation (PVS) after myocardial infarction are markers of the risk of serious ventricular arrhythmias. The authors studied the value of signal averaged electrocardiography (SAECG) compared with induction of SVT by PVS in 118 consecutive patients 4 to 8 weeks after myocardial infarction. In addition to this study population, a control group of 22 patients with spontaneous SVT after myocardial infarction was also considered. Three parameters were measured after averaging 200 QRS complexes: the duration of the filtered QRS complex (QRSd), the duration of signals not exceeding 40 microV (LAS) and the root mean square of the voltage of the last 40 milliseconds (RMS). Abnormal values were defined as: QRSd > or = 120 ms, LAS > or = 39 ms, RMS < or = 20 microV. Patients in the study population were subdivided into 3 groups: Group I (n = 17) inducible SVT; Group II (n = 72) no inducible arrhythmias; Group III (n = 29) induction of sustained ventricular flutter or primary ventricular fibrillation requiring immediate cardioversion. The results showed a good correlation between SAECG and induction of SVT. The sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV) were as follows: 1) QRSd > 120 ms: Se = 82%, Sp = 80%, PPV = 41%, NPV = 96%; 2) LAS > 39 ms: Se = 59%, Sp = 85%, PPV = 38%, NPV = 92%; 3) RMS < 20 V: Se = 59%, Sp = 88%, PPV = 43%, NPV = 93%.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1993

[Implantable defibrillator using epicardial and endocardial leads. Results of 36 implantations].

The authors report their experience of implantable defibrillators over a 5 year period. Between February 1988 and July 1992, 36 patients (25 men, 11 women, average age 51 +/- 11 years, range 18 +/- 71 years) underwent implantation of an automatic defibrillator with epicardial (n = 13, Group I) or endocardial leads (n = 23, Group II) without patch electrodes (n = 7), with subcutaneous patch electrodes (n = 12) or epicardial patch electrodes (n = 4). Three serious early complications were observed: 2 cardiogenic shocks in Group I, one of which died on Day 1 and one case of infection which required explanation of the defibrillator on Day 23 in Group II. Late complications in Group I included one case of disactivation of the defibrillator, 2 losses of output, one of which required replacement of the defibrillator and 2 increases of threshold treated by implantation of an endocardial lead. In Group II, 2 patients had inappropriate shocks due to overdetection (n = 1) and double counting (n = 1). During an average follow-up period of 28.5 +/- 9 months in group I and 13 +/- 6 months in Group II, 4 patients died, 2 from sudden death. Ninety seven shocks were delivered in 19 patients (56%), 5.1 shocks per patient. In the 17 patients with an antitachycardia function, 14 (82%) developed 947 episodes of VT treated successfully by antitachycardia pacing in 917 cases. This retrospective study confirms the efficacy of implantable defibrillators in the treatment of malignant ventricular arrhythmias. The efficacy of endocardial and epicardial leads seems to be the same but there seems to be a lower immediate mortality and morbidity with the endocardial system.

Adult↗
PubMed1993

[Radiofrequency ablation of Kent's pathways. Apropos of 30 cases].

Radiofrequency catheter ablation is a modern radical treatment of the Wolff-Parkinson-White (WPW) syndrome. The authors report their experience of this method in 30 consecutive patients (12 women, 18 men, mean age 34.2 +/- 13 years, range 14 and 63 years) with the WPW syndrome poorly controlled by antiarrhythmic therapy in 27 out of 30 cases. An average of 10.1 applications (1-33) was necessary to suppress anterograde and retrograde conduction in 26 of the 30 patients during the first session (87% success rate). At the time of effective ablation, the average atrioventricular interval was 41 ms (35-55) and in the two patients with a retrograde Kent bundle, the average ventriculoatrial interval was 72 ms (70 and 75 ms). The average duration of the procedure was 3.5 hours (45 mins to 7 hours) with an average fluoroscopy time of 61.6 minutes (9-182 minutes). There were four complications: one pneumothorax, one subacute femoral arterial obstruction and in two patients with a left Kent bundle, one TIA which regressed within 1 hour and one hemiplegia which regressed in 24 hours. After an average follow-up period of 8.3 months (2-16 months) the 26 patients are asymptomatic without any treatment. Radiofrequency catheter ablation therefore seems to be an effective method with a low morbidity for the radical treatment of symptomatic or high risk WPW syndromes.

Adolescent↗
PubMed1993

[Atrioventricular block induced by radiofrequency: electrophysiological criteria of success].

In a retrospective series of 18 consecutive patients (10 men, average age: 61.6 +/- 9.2 years) who underwent His bundle ablation by radiofrequency current, the authors analyzed the electrophysiological criteria predictive of complete atrioventricular block. A total of 82 radiofrequency bursts were analyzed (average: 4.5 +/- 3.1 bursts/patient) and classified as effective (N = 14, definitive atrioventricular block), ineffective (N = 55, no effect on atrioventricular conduction) or transiently effective procedures (N = 13, reversible Mobitz II atrio-ventricular block). Seven electrophysiological parameters were measured: HV interval, amplitude of atrial (A), Hisian (H) and ventricular (V) potentials, and the A/H, A/V, and V/H ratios before each radiofrequency burst. At the end of the ablation, 14 patients were in complete atrioventricular block and during the following 24 hours, a complete atrioventricular block developed in 3 other patients. The average value of the H potential was comparable in the effective and transiently effective procedures (0.28 +/- 0.20 mV and 0.27 +/- 0.19 mV respectively) and significantly higher than the same parameters in the ineffective group of procedures (0.65 +/- 0.14 mV, p = 0.008). The V/H ratio was progressively greater in effective (5.43 +/- 2.51), transiently effective (8.07 +/- 6.90) and ineffective procedure (14.32 +/- 13.35), p = 0.02; the average value of the A amplitude tended to be higher in the effective procedures (1.03 +/- 0.75 mV) and the transiently effective procedures (0.98 +/- 0.72 mV) than in the ineffective procedures (0.58 +/- 0.79 mV), p = 0.06. On the other hand, the other parameters were comparable in the three groups of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

[Primary ventricular fibrillation].

In the absence of autopsy studies, the etiological diagnosis of this form of ventricular fibrillation (VF) depends on the exclusion of cardiac disease by all available invasive and non-invasive diagnostic methods. Primary VF is rare and affects young adults. There are few clinical markers and published electrophysiological data indicates that sustained ventricular tachycardia or VF is unlikely to be induced by programmed ventricular stimulation. The underlying mechanism of the arrhythmia is poorly understood. However, a possible arrhythmogenic substrate has been suggested in small zones of fibrosis within normal Purkinje tissues, as encountered in some minor forms of arrhythmogenic right ventricular dysplasia. Also, the role played by the autonomic nervous system in triggering VF seems to be particularly important. Some described cases resemble curiously "torsades de pointes" with a short coupling interval. The "cardiac" prognosis of resuscitated patients is usually good. However, arrhythmic recurrences are common, and, classically, antiarrhythmic drugs are usually ineffective. The indication for implantation of an automatic defibrillator is therefore justified in patients surviving primary VF. The lack of understanding of this condition is an argument in favour of setting up a French register of patients with primary VF in order to establish its clinical features.

Arrhythmias, Cardiac↗
PubMed1992

[Electric stability of the heart after myocardial infarction: role of anti-arrhythmia agents during postinfarction].

Electrical instability of the heart after myocardial infarction threatens surviving patients with sudden death from a severe ventricular arrhythmia. These arrhythmic complications are usually the result of several factors: an arrhythmogenic substrate corresponding to the ischaemic myocardium, a trigger factor (usually a ventricular extrasystole) and other predisposing factors (autonomic nervous system, electrolyte imbalance, activation of the renin-angiotensin system). Risk stratification of electrical instability combines noninvasive (Holter, exercise testing, signal averaged electrocardiography, study of the variability of the heart rate, radionuclide or echocardiographic evaluation of the left ventricular ejection fraction) and invasive investigations (coronary angiography and even programmed ventricular stimulation). The presence of late ventricular potentials, a low ejection fraction and/or a ventricular arrhythmia on Holter monitoring identifies a high risk subgroup. Although the assessment of electrical instability is better than it used to be, pharmacological prevention remains disappointing. Class I antiarrhythmics are ineffective or dangerous. The efficacy of Class III antiarrhythmics is uncertain and only the betablockers seem to have any beneficial effects on this post-infarction electrical instability.

Adrenergic beta-Antagonists↗
PubMed1992

[Ablation of Kent pathways by radiofrequency. An initial study apropos of 3 cases].

This paper reports the initial results of radio-frequency ablation of accessory pathways in 3 consecutive patients with left lateral bundles of Kent and indications for accessory pathway ablation. A modified Polaris catheter was used with a wide distal tip through which the radio-frequency current was delivered by a generator with an intensity of 0.5 Ampères and a potential of 50 Volts, i.e. power of 25 Watts. The appearances of ventricular preexcitation disappeared in all cases and did not reappear during follow-up of 7 to 28 days. These preliminary results are encouraging. Further studies with longer follow-up are required to confirm the safety and efficacy of this new promising technique of ablation.

Adult↗