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Biomedical subjects

G Fontaine

Publications and source records attributed to G Fontaine.

At least 145 records · Page 8Linked to original sources
PubMed1989

Clinical experience with fulguration and antiarrhythmic therapy for the treatment of ventricular tachycardia. Long-term follow-up of 43 patients.

Forty-three patients (mean age, 45 +/- 18 years) with drug-refractory VT of varied etiologies, including 15 cases occurring after chronic myocardial infarction, underwent fulguration procedures. With a mean follow-up of 29 +/- 12 months (range, 9 to 55 months), after one to four sessions, VT had been controlled without a need for antiarrhythmic drugs in 22 (56 percent) of the 39 patients surviving the perioperative period and was controlled in 17 patients (44 percent) with the help of drugs. No malignant arrhythmias were observed following fulguration. There were five early deaths, four deaths related to the procedure, and eight late deaths, but no death was thought to be related to the endocardial shock itself. Thus, fulguration appears to be a valuable adjunct to the treatment of drug-resistant VT.

Adolescent↗
PubMed1989

[Causes of sudden death in athletes].

Sudden death is rare in athletes, and it is only in recent years that significant series were collected, making it possible to draw the cardiological profile of athletes who died suddenly at the peak of exertion or while recovering. A study of the literature, both medical and paramedical, has yielded 53 cases in which the most frequent causes of sudden death were hypertrophic cardiomyopathy (26 p. 100), (arrhythmogenic right ventricular disease (19 p. 100), congenital abnormalities of coronary arteries (11 p. 100) and coronary atheromatous lesions (9 p. 100), to which must be added various other causes. This study clearly demonstrates the hitherto unrecognized importance of arrhythmogenic right ventricular dysplasia-a condition which, as recent data suggest, is not solely due to a myocardial development disorder but also to an infective disease, an acute of chronic myocarditis. In subjects with this condition, new exploratory methods might detect the presence of an arrhythmogenic substrate during medical screening of athletes, but in any case these causes of sudden death suggest that a fast rhythm disorder was involved in several of these deaths. This disorder could be treated if the attendants were trained to carry out cardiorespiratory resuscitation procedures or if they had access to a defibrillator which should be available on every sports field.

Adult↗
PubMed1989

[Efficacy of the combination of low doses of beta-blockers and amiodarone in the treatment of refractory ventricular tachycardia].

Thirty one patients aged 56 +/- 16 years with chronic ventricular tachycardias (VT) refractory to 4.4 +/- 1.8 antiarrhythmic drugs, used alone or in combination, were managed by low doses of beta-blocker agents combined with oral amiodarone, either after loading (1.2 g for 7 days, n : 7) or reloading (1.2 g for 4 days, n : 24) of amiodarone. All patients proved refractory to amiodarone alone. Nine VT were also refractory to endocardial catheter fulguration in 8 patients. Twenty one patients had coronary artery disease, 4 had arrhythmogenic right ventricular dysplasia, 4 had dilated cardiomyopathy, 1 had valvular disease, and 1 had no structural heart disease. Twelve patients had an ejection fraction less than 30 p. 100. Ten patients were in NYHA functional class 3. VT was permanent in 3 patients, daily in 5, weekly in 7, paroxysmal in 16. In 14 patients, VT occurred both at day and night. Oral administration of a daily low dose of a beta-blocker agent (acebutolol 100 mg, betaxolol 5-10 mg, metoprolol 50-100 mg, nadolol 20-40 mg, pindolol 2.5 mg, propranolol 30 mg, sotalol 80-160 mg, tertatolol 2.5 mg) combined with 400 mg per day of amiodarone suppressed VT episodes in all patients. None presented heart failure or collapse. The mean reduction of the heart rate was about 17 p. 100. One patient need a definite pacemaker to correct sinus bradycardia. At discharge, exercise ECG (n: 20) induced non sustained VT in 2 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Identification and catheter ablation of a zone of slow conduction in the reentrant circuit of ventricular tachycardia in humans.

Three patients who had incessant ventricular tachycardia and in whom a zone of slow conduction was identified are presented. Each patient's tachycardia was refractory to multiple antiarrhythmic drugs and was being treated with amiodarone at the time of the electrophysiologic study. The ventricular tachycardia cycle length was 500 to 580 ms. In Patients 1 and 2, a single site at the posterolateral wall or low septum in the left ventricle was identified at which overdrive pacing during ventricular tachycardia resulted in ventricular capture with a stimulus to QRS interval of 280 to 400 ms and with little or no change in the configuration of the QRS complexes during pacing as compared with during ventricular tachycardia. In Patient 3, the same phenomenon was observed at two areas in the left ventricle: at the inferior wall, overdrive pacing during ventricular tachycardia resulted in a stimulus to QRS interval of 440 to 470 ms, whereas at the posterolateral wall, the stimulus to QRS interval was 320 to 360 ms. Transcatheter shocks of 100 to 240 J delivered at the pacing sites have been successful in preventing recurrences of ventricular tachycardia over a follow-up period of 10 to 11 months. These observations may be explained by the pacing site being located within a reentrant circuit in a zone of slow conduction bounded by inexcitable tissue between the pacing site and the exit site of the reentrant circuit. In Patient 3, the variable stimulus to QRS intervals are explained by variable proximity of the pacing sites within the slow conduction zone to the exit site of the reentrant circuit.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Long-term follow-up of atrioventricular junctional transcatheter electrical ablation.

Complete data concerning long-term results of transcatheter electrical ablation of the atrioventricular junction is not available. At the request of the French Cardiac Arrhythmia Working group we undertook an inquiry in October 1983. All centers potentially able to perform such procedures were asked to report their experience. Eight centers have performed one case or more, over a period of 3 years, for a total of 91 patients. The mean follow-up completed in all patients in April 1986 was 12 +/- 10 months. The procedure was indicated for a supraventricular arrhythmia resistant to a mean of 3.9 +/- 1.3 classes of antiarrhythmic agents. Atrial flutter or fibrillation in 54 (59%) and atrioventricular nodal reentry in 17 (18%) were the most common arrhythmias. A mean of 2.6 +/- 2.3 electrical shocks (range 1-14 shocks) with a stored energy of 130-400 joules was delivered during 1-5 sessions. Complete heart block was obtained in 83 patients and persisted at the time of discharge from the hospital in 46 patients (50.5%). The immediate complication (within 24 hours after the procedure) included ventricular fibrillation successfully converted (one patient) and nonsustained ventricular tachycardia (three patients). Late complications included one death 3 days after the procedure, in a patient in whom sustained ventricular tachycardia was documented, nonsustained ventricular tachycardia in two patients, sepsis in three patients and pericardial effusion in one patient. At the time of the follow-up, there were three additional deaths related to sepsis due to pacemaker pocket infection in one patient and to preexisting congestive heart failure in two patients.(ABSTRACT TRUNCATED AT 250 WORDS)

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↗
PubMed1988

Efficacy and safety of low doses of beta-blocker agents combined with amiodarone in refractory ventricular tachycardia.

Twenty patients aged 55 +/- 16 years with 40 chronic ventricular tachycardias (VT) refractory to 4.6 +/- 1.9 antiarrhythmic drugs, used alone or in combination, were managed by low doses of beta-blocker agents combined with oral amiodarone (Am), either after loading (1.2 g for 7 days, n: 5) or reloading (1.2 g for 4 days, n: 15) of Am. All patients proved refractory to Am alone. Seven VT were also refractory to endocardial catheter fulguration in six patients. Thirteen patients had coronary artery disease, three had arrhythmogenic right ventricular dysplasia, two had dilated cardiomyopathy, one had valvular disease, and one had no structural heart disease. Ten patients had an EF less than 30%. Ten patients were in NYHA functional class three. VT was permanent in three patients, daily in three, weekly in seven, paroxysmal in seven. In 11 patients, VT occurred both at day and night. In 11 patients, decrease of the sinus cycle preceeded VT. Oral administration of a daily low dose of a beta blocker agent (acebutolol 100 mg, betaxolol 5-10 mg, metoprolol 50 mg, nadolol 20-40 mg, pindolol 2.5 mg, propanolol 30 mg, sotalol 80-160 mg, terta-tolol 2.5 mg) combined with 400 mg/day of Am suppressed VT episodes in all patients. None presented heart failure or collapse. The mean reduction of the heart rate was 15% (65 to 55/min). At discharge, exercise ECG (n: 14) induced non sustained VT in two patients. At programmed electrical stimulation (PES) (n: 15), VT was no longer inducible in 4 patients, was slower, well-tolerated in nine patients, and remained inducible at the same rate in only two patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1988

Transvenous and subcutaneous electrode system for an implantable defibrillator, improved on large pigs.

The currently required surgical procedure for implantable defibrillator implantation is a limiting factor and several groups are therefore investigating transvenous approaches. Our electrode system consists of a nondistal right ventricular catheter electrode and two or three subcutaneously (SC) placed electrodes. An optimal location for these SC electrodes is important to obtain the lowest possible defibrillation threshold (DFT) by allowing a more homogeneous current distribution within the thorax. An empirical approach consists of placing randomly the SC electrodes to find out the lowest possible DFT. A mathematical approach is to calculate the SC electrode locations for an optimal electric field distribution by using magnetic resonance images of thorax cross-sections and a specially designed computer program. Our recent experimental results are based on a series of 15 pigs weighing between 60 and 102 Kg. DFT ranged between 10 and 26 joules. We conclude that an electrode system with a right ventricular electrode and two or three subcutaneous electrodes can be optimized to reach a DFT for pigs with human-near body weights which is compatible with the energy capabilities of our implantable device.

Animals↗
PubMed1988

[Invasive and non-invasive methods for the diagnosis of tachycardia].

Surface ECG permits, in most cases, to determine the ventricular or supraventricular origin of a tachycardia with wide complexes, to individualize VTs with aspects of Left Buble Branch and left axis, to visualize epsilon waves in some chronic VTs. The late potentials detected by the sum-mean method seem to be well correlated with the occurrence of ventricular tachycardia, especially after myocardial infarction. The area of origin of a VT may be determined quite precisely by cartography and topographic stimulation. The predictive value of the provocation methods (stress test, transesophageal stimulation, endocardiac stimulation) is discussed. Some arrhythmias may be discovered on ultrasonic cardiography and the exact mechanism of some reciprocal permanent junctional tachycardias is well demonstrated with endocardiac stimulation and fulguration. Nuclear magnetic resonance offers a new possibility of etiological diagnosis in ventricular tachycardias with left delay.

Arrhythmias, Cardiac↗
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

[Rhythm and conduction disorders immediately after ventricular fulguration].

UNLABELLED: Forty-four patients with ventricular tachycardias (VT) refractory to medical treatment underwent 73 sessions of endocavitary electrode catheter ablation. The clinical series included 16 cases of post-infarction VT, 14 cases of arrhythmogenic right ventricular dysplasia, 6 cases of dilated cardiomyopathy, 6 cases of idiopathic VT, 1 case of sequela of myocarditis and 1 case of VT consecutive to surgical repair of a congenital cardiopathy. Cardiomegaly was present in 30 patients, and 16 patients had an ejection fraction of less than 30 p. 100. None of the patients were receiving digitalis or class I antiarrhythmic drugs when ablation was performed. A total of 235 shocks of 100 to 320 J (mean 221 +/- 42 J) were delivered. 115 shocks (49 p. 100) were complicated by dysrhythmia and/or disorders of conduction; 29 shocks (12 p. 100) induced 13 ventricular fibrillations and 16 ventricular tachycardias. No relation was found between energy delivered, shock synchronization, haemodynamic status, heart cavity treated, underlying heart disease, CK MB levels and these arrhythmias. On the other hand, ablations performed while the patients were experiencing VT increased the risk of arrhythmia (p less than 0.02). 36 AV blocks, 21 left bundle branch blocks, 12 right bundle branch blocks and 11 sinus bradycardia were observed. With the exception of one right bundle branch block and one left posterior hemi-block, all blocks were transient. IN PRACTICE: (1) electrode catheter ablation may be complicated by disorders of cardiac rhythm or conduction in 50 p. 100 of the cases; (2) these disorders can easily be corrected by stimulation or defibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗