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Biomedical subjects

M Slama

Publications and source records attributed to M Slama.

At least 55 records · Page 3Linked to original sources
PubMed1994

[Pericardial constriction caused by epicardial patches of automatic implantable defibrillators. Apropos of 3 cases].

The authors report three cases of pericardial constriction secondary to implantation of an automatic defibrillator. In one case, the pericardial constriction occurred 1 year after implantation and was associated with ascending infection of the patch electrodes from the stimulator; the patient died when the patch electrodes were removed, the infection having eroded the left ventricular wall. In the other two cases, signs of constriction appeared 2 years after implantation. In one of these patients, surgery showed a fibrous pericardial reaction deforming the patch electrodes with a favourable outcome when the electrodes were removed. The other patient refused surgery. In the three cases, the diagnosis was confirmed by right heart catheterisation and ventriculography which showed signs of adiastole and severe deformation of the ventricular contours. Pericardial constriction due to patch electrodes is a potentially serious complication of implantable automatic defibrillators, the prevalence of which may be underestimated. The use of endocavitary or extra-pericardial electrodes should avoid this complication.

Defibrillators, Implantable↗
PubMed1994

[Electrophysiological mechanisms of ventricular arrhythmia in myocardial infarction].

In experimental models of coronary occlusion, the physiopathology of ventricular arrhythmias varies with its timing, there being three main phases: early, late and chronic. The early phase covers the first 30 minutes and is dominated by tachycardias and fibrillations resulting from multiple micro-reentry circuits which are the consequence of major changes in conduction and excitability created by acute ischaemia. These arrhythmias may be triggered by extrasystoles which have a different mechanism related to the injury current generated in the border zone between ischaemic and healthy cells. The late phase lasts about 72 hours: it is characterised by polymorphic ventricular extrasystoles and bursts of relatively slow ventricular tachycardia. Much more rapid tachycardia can be induced by stimulation. The origin of these arrhythmias is usually in the surviving Purkinje fibres of the subendocardium. The mechanisms are variable: abnormal automaticity, reentry or activity triggered by delayed after depolarisations. During the chronic phase, reentrant tachycardia is possible but only when induced by stimulation. Delayed conduction is the consequence of non-uniform antisotropism related to the disorientation of the myocardial fibres caused by fibrosis. In the clinical situation, most research has been centered on sustained monomorphic ventricular tachycardias of the chronic phase. Their mechanism is almost exclusively reentry (the circuits usually being located in the subendocardium) as suggested by the triggering and interruption of clinical tachycardias by stimulation, the recording of fragmented activation or prepotentials at the site of emergence of the tachycardia and the phenomena of pacing.

Arrhythmias, Cardiac↗
PubMed1993

Doppler echocardiographic evaluation of valve regurgitation in healthy volunteers.

OBJECTIVE: To study the prevalence and the characteristics of physiological valve regurgitation. DESIGN: Pulsed wave Doppler echocardiography, continuous wave Doppler echocardiography and Doppler colour flow mapping were performed prospectively in healthy volunteers. SETTING: Echocardiography laboratory in a city hospital. PATIENTS: 32 consecutive healthy volunteers (age 21-49 years, mean age 29.4). MAIN OUTCOME MEASURES: Identification of regurgitation with colour Doppler flow mapping and measurement of the jet area, jet length, and maximal velocity of the regurgitation. RESULTS: Regurgitation was recorded at the pulmonary (100%), tricuspid (100%), mitral (56%), and aortic valves (6%). The velocity of pulmonary and tricuspid regurgitation was similar to that predicted from the pressure gradient calculated from the Bernoulli equation. The jet area and jet length were generally small. CONCLUSION: Trivial regurgitation from the pulmonary, tricuspid, and mitral valves is common in healthy people. It is important to take such regurgitation into account when valve disease is diagnosed.

Adult↗
PubMed1993

[Role of coronary angiography in infarction without Q wave. Results of a prospective angiographic study].

Non-Q wave myocardial infarction is associated with a high recurrence rate of ischaemic events (angina and infarction). The artery responsible for the infarction is usually patent but stenosed and seems to be the cause of these complications. This prospective multicenter series of 66 patients treated by Heparin, Aspirin, Diltiazem and undergoing coronary angiography during the hospital period studied the artery responsible for the infarction and the value of coronary angiography in this setting. Several conclusions were drawn from the results: the precise diagnosis of the artery responsible for the infarct may be difficult (14%); the left circumflex artery or one of its branches is often implicated (47%); non-Q wave infarction is a various and heterogeneous group, including: infarctions located on small branch arteries, "warning" ischaemic episodes in the left anterior descending artery territory. definitive infarction of the left circumflex artery territory; nevertheless, this group is an intermediate state between Q wave infarction and unstable angina (low occlusion rate 26% and angiographic lesional appearances similar to those of unstable angina); early coronary angiography (48-72 h) seems to be useful to improve prevention of ischaemic recurrences by adequate revascularisation.

Adult↗
PubMed1993

[Mitral valvuloplasty during the acute phase of endocarditis].

Thirty-five patients were operated in the acute phase of mitral valve endocarditis between 1986 and 1991. The surgical indications were hemodynamic (22), echocardiographic (9), embolic (2) and infectious (2). There were pre-existing valve lesions in 45% of cases. The causal organism was identified in 90% of cases: streptococcus (19), staphylococcus (9) and Gram negative bacilli (4). Preoperative antibiotic therapy was prescribed for an average of 18 days. The aortic valve was infected in 9 patients and tricuspid valve in 1 patient. The mitral lesions were: abscess (11), vegetations (11), perforations (16), and ruptured chordae tendinae (22). All patients underwent Carpentier's mitral valvuloplasty. The operative mortality was 5.7% (2 patients). Early reoperation was required in 1 case. Follow-up was possible in 96% of cases for an average of 23 months. No recurrences of endocarditis were observed. One patient was reoperated and 3 died. All the others were in Classes I and II of the NYHA. None had significant mitral regurgitation or stenosis. These results show that mitral valvuloplasty is possible in the acute phase of endocarditis in 90% of cases. The mortality and morbidity are low and long-term results are stable.

Acute Disease↗
PubMed1993

Quantification of myocardial muscarinic receptors with PET in humans.

The potential for noninvasive quantification of myocardial muscarinic receptors using PET data, a mathematical model, multi-injection protocols and 11C-labeled methylquinuclidinyl benzilate (MQNB) as a radioligand was previously demonstrated in dogs. The present study examines the possibility of optimizing the experimental protocol to make this approach suitable for human studies. For six normal subjects, the protocol included three injections: a tracer injection, followed 30 min later by an injection of an excess of unlabeled MQNB (displacement) and then 30 min later by a simultaneous injection of unlabeled and labeled MQNB (coinjection). The model input function was estimated from the PET data corresponding to the left ventricular cavity. This protocol enables a separate evaluation of all parameters of a ligand-receptor model which includes three compartments and seven parameters. The complexity of this three-injection protocol, however, appears to be inconvenient for clinical use. A simplified two-injection protocol (tracer injection and coinjection) was evaluated in five other normal subjects and the results were compared to those obtained with the three-injection protocol. In regions of interest over the left ventricle, the mean value of the receptor concentration B'max and the equilibrium dissociation constant Kd were 26 +/- 7 pmole/ml tissue and 2.0 +/- 0.5 pmole/ml tissue, respectively. The possible existence of nonspecific binding was studied in two subjects using a double-displacement protocol. The corresponding rate constant was found to be very low (0.03 min-1).

Adult↗
PubMed1992

[Drug treatment of chronic ventricular arrhythmia].

The treatment of chronic ventricular arrhythmias depends on the severity and tolerance of the arrhythmia. Extrasystoles, even repetitive, in the healthy heart, are usually respected when asymptomatic or treated with betablockers in first intention when symptomatic. These drugs should also be proposed for patients with ischemic heart disease and non-sustained ventricular tachycardia, a situation in which Class I antiarrhythmics should be avoided. The prevention of sustained ventricular tachycardial may be empirical, with betablockers and/or amiodarone, or guided by the results of pharmacological tests during endocavitary electrophysiological studies.

Adrenergic beta-Antagonists↗
PubMed1992

[Value of early systematic postoperative transesophageal echocardiography in mitral valve replacements. A prospective study of 50 patients].

The aim of this study was to assess the value of routine transoesophageal echocardiography in the early postoperative period after mitral valve replacement. The authors report their experience in 50 consecutive operated patients (43 mechanical and 7 bioprostheses) investigated routinely by this method in the postoperative period in the surgical unit. Abnormal findings were observed in 36% of cases (18 patients): trans-prosthetic leaks (8 cases) and thrombosis (10 cases) in 2 bioprostheses and 8 mechanical prostheses; in 3 cases this led to haemodynamic dysfunction but in 7 cases the thrombus had no influence on the trans-prosthetic pressure gradient. No predisposing factor could be identified (spontaneous contrast, left atrial volume, left ventricular function, poor anticoagulation, blood clotting abnormalities). No abnormality of the mobile components of the prosthesis was observed at radioscopy. The outcome with heparin therapy was favourable with disappearance of the thrombi in 6 cases; the thrombi did not regress in 4 patients on heparin: 2 patients underwent thrombolytic therapy with a complete cure in 1 case and a severe embolic complication in the other; in 2 cases, the thrombus was so big that the patients were reoperated. Systematic early postoperative transoesophageal echocardiography before discharge from the surgical unit would seem to be necessary after early mitral valve replacement: it allows diagnosis of asymptomatic thrombosis which has an important emboligenic potential. The management of these thromboses remains controversial, but the poor natural outcome in cases of large thromboses should lead to referral for early reoperation.

Adolescent↗
PubMed1992

[How to evaluate the arrhythmogenic risk after myocardial infarction?].

The risk of sudden arrhythmic death after myocardial infarction is high, especially during the first months. The evaluation of this risk should be performed before hospital discharge in the same way as residual ischaemia and left ventricular function, which are independent risk factors for arrhythmia, are assessed. Holter monitoring provides information not only about ventricular hyperexcitability (especially the detection of unsustained ventricular tachycardia) but also about the activity of the autonomic nervous system by analysis of variations of the sinus rhythm, the decrease of which carries a poor prognosis. The search for an arrhythmogenic substrate requires signal averaged electrocardiography, but although the absence of late potentials carries a good prognosis, the positive predictive value of this investigation is very low. The association of non-invasive indices of poor prognosis greatly increases the probability of a major arrhythmic event; this may require consideration of programmed ventricular pacing, another method of substrate and risk assessment, which has the added advantage of sometimes indicating the most appropriate therapy.

Arrhythmias, Cardiac↗
PubMed1992

[Percutaneous ablation of atrioventricular junction by radiofrequency current in resistant atrial arrhythmia. Results of a series of 24 patients].

Catheter ablation of the atrioventricular junction may be proposed for the treatment of certain atrial arrhythmias resistant to antiarrhythmic therapy. One of the methods currently being evaluated uses radio-frequency energy which has certain advantages compared with direct current ablation because of the progressive and limited lesions it produces. This technique was used in 24 patients with atrial arrhythmias resistant to antiarrhythmic therapy. The radio-frequency energy was delivered without general anaesthesia with HAT 100 and 200 (OSYPKA) generators in the unipolar mode (average 17.4 watts) for an average period of 22.3 +/- 8 seconds. The catheter (8F USCI suction catheter in the first 18 patients and a 7F Polaris Mansfield, deflectable catheter with a large distal electrode in the remainder) was positioned at the nodo-hisian junction at a point where the two distal electrodes recorded a large atrial deflection and the smallest possible hisian potential. The conduction defects induced during the acute phase generally remain stable in cases of complete atrioventricular block and tend to regress in cases of incomplete atrioventricular block despite initial control of atrioventricular conduction. During follow-up (21 +/- 16 months), 14 patients (58%) remained in complete atrioventricular block, 4 patients (17%) had controlled atrioventricular conduction with an acceptable ventricular rate with associated previously ineffective antiarrhythmic therapy. Radio-frequency ablation was a failure in 6 patients (25%). There were no haemodynamic, rhythmic or ischaemic complications during the acute phase or during follow-up. These results suggest radio-frequency energy is a seductive alternative to direct current ablation for percutaneous modification of atrioventricular conduction in patients with refractory atrial arrhythmias. However, simple modulation of atrioventricular conduction gives aleatory results due to the tendency to regression during follow-up. On the other hand, complete atrioventricular blocks created by radio-frequency energy are generally definitive and are associated with a junctional escape rhythm which is usually stable.

Adult↗
PubMed1991

Determination of left ventricular inflow by pulsed Doppler echocardiography: influence of mitral orifice area and blood velocity measurements.

Pulsed Doppler echocardiography was performed in 30 patients to assess the influence of mitral orifice area and velocity on the determination of mitral stroke volume and inflow. Aortic forward stroke volume and outflow were measured at the centre of the aortic annulus, and compared with mitral flow measurements calculated by three methods. Both mitral stroke volume and inflow derived from an instantaneous velocity-area method showed an excellent correlation with aortic flow measurements. The other two methods, which determined mitral stroke volume and inflow based on a mean mitral valve area and diastolic velocity integral, significantly underestimated mitral flow measurements. This study indicates that the instantaneous velocity-area method offers a reliable means for quantitating left ventricular inflow.

Adult↗
PubMed1991

Assessment of severity of aortic regurgitation by M-mode colour Doppler flow imaging.

To assess the value of measuring the aortic regurgitant jet diameter at its origin by M-mode colour Doppler imaging, 82 patients with aortic regurgitation underwent, within 72 h of each other, colour Doppler examination and angiography. After excluding one patient without colour Doppler aortic regurgitation and five with a highly eccentric regurgitant jet, we found a close relationship between the jet diameter at its origin measured by M-mode colour Doppler and the angiographic grade of aortic regurgitation (r = 0.88). A jet diameter greater than or equal to 12 mm identified severe aortic regurgitation (grade III or IV) with a sensitivity of 86.4% and a specificity of 94.4%. In 38 patients, the jet diameter correlated well with the regurgitant fraction measured by a combined haemodynamic-angiographic method (r = 0.88). A jet diameter greater than or equal to 12 mm identified a regurgitant fraction greater than or equal to 40% with a sensitivity of 88.2% and a specificity of 95.2%. This study indicates that the size of the regurgitant jet diameter at its origin measured by M-mode colour Doppler provides a simple and useful measure of the severity of aortic regurgitation. It may allow differentiation between mild or moderate and severe aortic regurgitation and evaluation of regurgitant fraction.

Angiography↗
PubMed1991

End diastolic flow velocity just beneath the aortic isthmus assessed by pulsed Doppler echocardiography: a new predictor of the aortic regurgitant fraction.

End diastolic flow velocity just beneath the aortic isthmus was measured within 72 hours of cardiac catheterisation by pulsed Doppler echocardiography in 30 controls and 61 patients with aortic regurgitation. The end diastolic flow velocity was determined at the peak R wave on a simultaneously recorded electrocardiogram. In all controls there was no reverse flow at the end diastole beneath the aortic isthmus. In patients with aortic regurgitation the end diastolic flow velocity correlated well with the angiographic grade of regurgitation (r = 0.81) and regurgitant fraction (r = 0.82). The mean (SD) values were 6.3 (5.2), 12.2 (4.3), 22.1 (5.7), and 34.3 (9.3) cm/s for patients with regurgitant fraction of less than 20%, between 20% and 40%, between 41% and 60%, and greater than 60%, respectively. An end diastolic flow velocity of greater than 18 cm/s predicted a regurgitant fraction of greater than or equal to 40% with a sensitivity of 88.5% and a specificity of 96%. The study suggests that the pulsed Doppler derived end diastolic flow velocity is a useful index in the routine non-invasive assessment of the severity of aortic regurgitation.

Adult↗
PubMed1991

[Bone regeneration in implantology. The use of Gore-Tex membranes: GTAM].

The use of expanded polytetrafluorethylene membranes to attain bone regeneration around dental implants is described. Membranes discourage "non-desirable" cells form colonizing the healing site. These cells are essentially derived from gingival epithelium and gingival connective tissue. It is suggested that this procedure could be employed directly after tooth extraction.

Bone Regeneration↗
PubMed1990

[Treatment of arrhythmias in chronic cardiac insufficiency].

Arrhythmias are frequent and associated with a poor prognosis, especially when they arise from the ventricle. Although the correction of predisposing factors and improvement of hemodynamic conditions are essential, the use of antiarrhythmic drugs in this context poses problems. The treatment of even complex ventricular extrasystoles has not been shown to effectively prevent the serious arrhythmias responsible for sudden death. Depression of left ventricular function and: Or proarrhythmic effects of antiarrhythmic therapy in some patients, probably offset the benefits observed in others. The treatment of atrial arrhythmias remains traditional: reduction by drugs or electrotherapy and prevention of recurrences, or simply slowing the ventricular response. Sustained ventricular tachycardia and resuscitated ventricular fibrillation should be managed more aggressively, not by empirical antiarrhythmic treatment but by medical therapy guided by the results of electrophysiological studies, and, when this fails, by non-medical treatment: fulguration, implantable defibrillator, antiarrhythmic surgery, or even cardiac transplantation.

Adrenergic beta-Antagonists↗