Biomedical subjects

J C Charniot

Publications and source records attributed to J C Charniot.

27 records · Page 2Linked to original sources

PubMed1996

[Contact dermatitis following cardiac pacemaker implantation].

The authors report a case illustrating the causality between the appearance of contact eczema and the implantation of a cardiac pacemaker. To the authors' knowledge, only 11 cases of eczema secondary to the implantation of a pacemaker have been previously reported, all in dermatological journals. In 60% of caes, the lesions were observed over the pacemaker implantation and the appearance of the rash varied from 2 days to 24 months. The causal allergens were mainly the metallic and plastic components. The physiopathological mechanisms, though not completely understood, are related to cellular immunity and therefore, to delayed hypersensitivity reactions. From the therapeutic point of view, locak steroid applications to limited excema lesions have been suggested but recurrence is common. The only effective treatment is removal of the allergen.

Aged↗

PubMed1996

[A study of 36 cases of mitral valve prolapse by isotopic ventricular tomography].

Left and right ventricular wall motion was studied in mitral valve prolapse with or without ventricular arrhythmias. Regional and global ventricular wall motion was evaluated by isotopic methods, based in ejection fraction and Fourier phase analysis representing the progression of wall contraction. The synchronisation of the ventricles was characterized by the difference of the mean phase of each ventricle. The heterogeneity of contraction of each ventricle was defined by the dispersion around the mean (standard deviations of the phases). Fifteen of the 36 patients had complex ventricular arrhythmias (Lown grade > or = III). 12 had LVP and 16 had mitral regurgitation. In mitral valve prolapse, the RV EF was decreased compared with normal controls (30 +/- 9% vs 40 +/- 10% ; p < 0.001), especially in patients with mitral regurgitation (26 +/- 7% vs 30 +/- 10%; p = NS) and complex ventricular arrhythmias (26 +/- 7% vs 32 +/- 10%; p < 0.01). The SDP of the LV was greater than those of controls (18 +/- 11 degrees vs 11 +/- 5 degrees ; p = NS) whereas the SDP of the RV was greater (27 +/- 17 degrees vs 12 +/- 5 degrees ; p < 0.05) especially in those with complex ventricular arrhythmias (36 +/- 21 degrees vs 21 +/- 10 degrees : p < 0.01). The SDP of LV and RV were greater in patients with mitral regurgitation: 20 +/- 11 degrees versus 17 +/- 10 degrees (NS) and 35 +/- 21 degrees versus 20 +/- 8 degrees (p < 0.01). Heterogenous ventricular contraction, more marked in the right ventricle in mitral valve prolapse suggests severe myocardial disruption in this valvular disease, reflected by the high incidence of LVP and complex ventricular arrhythmias.

Adult↗

PubMed1995

[Anti-arrhythmic therapy and cardiac failure].

In cardiac failure, continuous ambulatory electrocardiographic recording for 24 hours (Holter system) enables detection of 60 to 80% of complex ventricular arrhythmias, 15 to 40% of atrial arrhythmias and sudden death accounts for about 40% of fatalities but its causes are multiple and sometimes unrelated to arrhythmias. Abnormalities of cardiac structure, metabolic and neuro-hormonal changes and some drug therapies are implicated in the genesis of these arrhythmias, the management of which is discussed in two different situations with respect to the functional incapacity: in paucisymptomatic ventricular arrhythmias in patients with cardiac failure, class I antiarrhythmics and d-sotalol should be avoided and betablockers prescribed with caution; the indications of amiodarone have not yet been determined. When the arrhythmia is symptomatic (sustained ventricular tachycardia or ventricular fibrillation), class I antiarrhythmics are not effective enough in the prevention of sudden death; betablockers and amiodarone may give good results but should be compared with implantable defibrillators in the future. The multiplicity and complexity of the mechanisms of arrhythmias in cardiac failure, and the inadequate results obtained with classical antiarrhythmics necessitate the development of new antiarrhythmics based on blockade of non-selective channels probably activated in cardiac failure by the stretching of myocardial fibres.

Adrenergic beta-Antagonists↗

PubMed1994

Ventricular arrhythmia factors in mitral valve prolapse.

To assess the prevalence of ventricular arrhythmias and late potentials (LPs) in mitral valve prolapse (MVP) and to identify clinical, ECG, and echocardiographic markers of spontaneous ventricular arrhythmias, we studied 58 consecutive patients (mean age 46.6 +/- 17.8 years; 29 males, 29 females) with MVP diagnosed by echocardiography. Patients underwent ambulatory ECG recording (n = 58), exercise stress test (n = 56), signal-averaged ECG (n = 58), and programmed ventricular stimulation (n = 52). Ten patients (17.2%) had spontaneous nonsustained ventricular tachycardia (NSVT), 26 patients (44.8%) had premature ventricular contractions (PVCs), Lown grade > or = 3 during 24-hour ECG, and 19 had Lown grade > or = 3 PVCs during exercise stress test; 13 patients had LPs (22.4%). We provoked sustained VT in one case and NSVT in ten cases. Patients with complex ventricular arrhythmias during 24-hour ECG and exercise stress test were older and more often had mitral regurgitation. There was a statistical correlation between the presence of LPs and spontaneous VT (46.1% vs 8.9%; P < 0.005) and induced ventricular arrhythmias (50% vs 12.8%; P < 0.005). No correlation was found between spontaneous ventricular arrhythmias and thickness or posterior displacement of the mitral valve. In conclusion, complex ventricular arrhythmia (especially VT) and LPs are frequent in MVP. Patient age and mitral regurgitation seem to be determinant factors of complex ventricular arrhythmias in MVP. On signal-averaged ECG, absence of LPs seems to be a good additional marker to identify MVP patients without spontaneous VT. On the other hand, programmed ventricular stimulation does not appear valuable in determining a MVP subgroup with a high risk of ventricular arrhythmias.

Adult↗

PubMed1994

[Late ventricular potentials and mitral valve prolapse].

In order to determine the predictive value for ventricular arrhythmias of ventricular late potentials (LP) in mitral valve prolapse (MVP) the authors performed high amplification signal-averaging ECG (SA) and 24 hours ambulatory ECG (Holter) monitoring in 68 consecutive patients (34 men, 34 women, average age 48 +/- 17.7 years) with echocardiographically diagnosed MVP. Patients with bundle branch block or associated cardiac disease were excluded. Echocardiography showed 26 patients to have floppy mitral valves (38.2%), 50 patients to have posterior deplacement > or = 5 mm of the mitral valves in systole (73.5%) and 35 patients to have mitral regurgitation (51.4%). Holter monitoring showed 17 patients without ventricular extrasystoles (VES), 15 had Lown Grade I, 6 had Lown Grade II, 3 had Lown Grade III, 15 had Lown Grade IV A and 12 had Lown Grade IV B ventricular arrhythmias. Therefore, 30 patients had complex ventricular arrhythmias (> or = Lown Grade III) and 13 patients had spontaneous non-sustained ventricular tachycardia (NSVT) (one patient had NSVT on resting ECG but not on Holter monitoring). Eighteen patients had LP (26.5%). The incidence of complex ventricular arrhythmias was higher in patients with mitral regurgitation (62.8% versus 27.7%; p < 0.005) whereas the incidence of NSVT was not significantly different (25.7% versus 17.1%; p = 0.15). On the other hand, the frequency of complex ventricular arrhythmias was not significantly different in the presence or absence of LP (61.1% versus 40%: NS) whereas the incidence of NSVT was higher in patients with LP (44.4% versus 10%; p < 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗

PubMed1993

[Course of unstable angina and therapeutic implications. Apropos of 74 cases].

The role of thrombosis in the pathogenesis of unstable angina has been demonstrated experimentally. This retrospective study was designed to identify the potential usefulness of fibrinolytic treatment in this situation. The following parameters were evaluated in 74 patients (62 men, 12 women; mean age: 60 +/- 10.2) with primary unstable angina: the course of unstable angina (Braunwald classification), risk factors, electrocardiographic changes, echocardiographic segmental kinetics, coronary arteriography findings, treatment used and outcome with a minimum follow-up of 3 months (mean: 6.3 months). Thirty nine per cent of class I patients and 18% of classes II and III were stabilised by medical treatment only. This accounted for 18 patients in our series (24%). The other patients (76%) required one or more reperfusion techniques (thrombolysis: 5 patients; angioplasty: 42; bypass: 19). Serious complications were seen in 3 patients: myocardial infarction: 2 postoperative (including one fatal) and 1 occurring 24 hours after angioplasty followed by cardiogenic shock and death. Five patients required thrombolytic treatment leading to clinical stabilisation enabling an additional procedure (angioplasty or bypass). No complications of thrombolytic treatment were seen. Thus thrombolytic treatment appears to be useful for the stabilisation of unstable angina and enables subsequent radical treatment under better conditions.

Adult↗

PubMed1993

[Antioxidative treatment in myocardial reperfusion ischemia].

Perfusion-induced myocardial ischaemia is observed in several situations: chronic coronary insufficiency, unstable angina, myocardial infarction, and during coronary angioplasty or bypass surgery. Oxygen-derived free radicals are liberated in large quantities during myocardial reperfusion ischaemia. Though very toxic in experimental studies, the responsibility of these free radicals in myocardial injury remains to be demonstrated clinically. Oxidant stress, characterised by an imbalance between the free radical attack and insufficient cellular defense seems partially responsible for reperfusion arrhythmias and post-ischemic stunning. On the other hand, its role is less evident in prolonged myocardial ischaemia causing irreversible myocardial lesions such as infarction. Antioxidant therapy is under evaluation in clinical trials. There are several options: some prevent the formation of free radicals by inhibiting the biochemical reactions which may produce them or by limiting the intervention of the neutrophils--the "fulcrum" of free radicals formations. Other antioxidant therapies inactivate free radicals as they are formed by promoting their degradation or their neutralisation. Experimental data is profuse and discordant. The models are very different. The first clinical trials are under way using either specific antioxidant molecules or molecules having other beneficial effects: in the latter case, the benefit of the antioxidant action is more difficult to demonstrate. Antioxidant therapy could play a role in surgical myocardial protection, especially of transplant organs, in very early forms of ischaemia. It could also prevent the pejorative hemodynamic consequences of myocardial stunning of the border zones of infarction, so enabling patients to survive a difficult period. The results of on-going studies should clarify the role of antioxidant therapy in reperfusion-induced myocardial ischaemia.

Antioxidants↗

PubMed1993

[Evaluation of a new cardiotonic agent on human isolated atrium].

The action of a phosphodiesterase inhibitor, RGW 29 38, was analysed experimentally. A preliminary study with guinea pig isolated heart, using Langhendorf's method, revealed a cardiotonic effect, though less than with isoprenaline and dobutamine, with which it was compared. The inotropic action of the compound was then studied using human isolated atrium. The model is described. It consisted of measurement by a strain gauge of the contractions obtained in a stimulated atrial fragment obtained during a surgical procedure. The following parameters were analysed, expressed as percentage increase in relation to baseline conditions: maximum tension developed, positive dP/dt and negative dP/dt. The effect of RGW (n = 6) was compared with that of isoprenaline (n = 7). RGW caused an increase in maximum tension of 195% +/- 91%, in positive dp/dt of 110% +/- 72% and in negative dp/dt of 168 +/- 54%. This increase was, however, less than that seen in the isoprenaline group. Thus RGW had a definite positive inotropic effect on guinea pig isolated heart and human isolated atrium, though less than that of the catecholamines with which it was compared. Isolated human atrium appears to be a useful study model, in particular for analysis of the inotropic action of drugs.

Animals↗

PubMed1992

[Prevalence of atrial arrhythmia in 48 hypertensive patients: research of predictive criteria].

UNLABELLED: We studied atrial arrhythmias during a continue prospective work in 48 hypertensive patients referred to the OMS criteria. Hypertension was confirmed by a blood pressure ambulatory monitoring and stress testing blood pressure trend. All cardiovascular drugs were stopped at admission. Patients with associated valvular or coronary artery disease were excluded from analysis. In all patients, we realized a twelve lead-ECG, stress testing, 24 hour Holter monitoring, a blood pressure ambulatory monitoring, two-dimensional echocardiography with Doppler study and cardiac radio-nuclide angiography with diastolic function study. Atrial arrhythmias were considered significant if more than 100 premature atrial beats (PAB) and/or more than three successive PAB were present during Holter monitoring. Significant atrial arrhythmias were found in 39.5% of patients (group II, n = 19), not significant in 60.5% of patients (group I, n = 29). The duration of hypertension was longer in group II (140 vs 66 months, p < 0.05). There was no difference between the two populations considering left atrial size or blood pressure level. Furthermore, we were surprised to find a normal E/A ratio on mitral Doppler recording in patients with atrial arrhythmias (1.23 vs 0.9; p < 0.05). Others diastolic parameters didn't significantly differ. Left ventricular mass index was similar in the two groups but patients with atrial arrhythmias had more asymmetric hypertrophy (1.23 vs 1.13 septum/posterior wall ratio: p < 0.05). CONCLUSION: atrial arrhythmias in our study seem to be more dependent from duration of HTA and left ventricular asymmetric structure than from left atrial size.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗