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Biomedical subjects

J C Daubert

Publications and source records attributed to J C Daubert.

At least 19 recordsLinked to original sources
PubMed1992

Is polyurethane lead insulation still controversial?

A controversy arose some 10 years ago over the reliability of polyurethane lead insulation. On the basis of one of the longest standing and largest databanks worldwide, the authors compare the cumulative survival of several thousand polyurethane, standard silastic, and high-performance silastic electrodes as it pertains to the failure criterion described as insulation degradation. With the possible exception of the Medtronic 6972 (Medtronic, Inc.) electrode, polyurethane electrodes have a 100% reliability at 84 months, which is similar to silastic electrodes.

Databases, Factual↗
PubMed1992

Failure of epinephrine to induce severe cardiac arrhythmia in rats with ventricular hypertrophy secondary to aortic pressure overload.

The arrhythmogenic action of epinephrine was studied in 3 groups of rats: 10 rats with mild constriction of the abdominal aorta (group H1), 10 rats with severe constriction (group H2), 10 sham-operated age-matched rats (group C). Blood pressure and ECG were recorded before, during and after 5 min. perfusion of increasing doses of epinephrine (1, 5, 10 and 25 micrograms.kg-1.min.-1). Ventricular arrhythmia was evaluated from the ECG using a modified Lown's grading system. The ventricular hypertrophy index was calculated from the heart/body weight ratio (mg/g). The mean arterial blood pressure was significantly higher in groups H1 and H2 than in the control group. The ventricular hypertrophy was significant in group H2, but not in group H1. There was no significant difference between the amplitudes of the epinephrine-induced hypertensive responses in the 3 groups but the extent of arrhythmia was significantly lower in the animals with high hypertrophy index.

Animals↗
PubMed1992

[Arrhythmogenic cardiomyopathies of the right ventricle].

Arrhythmogenic cardiomyopathies of the right ventricle (ACRV) are defined by an association of left delayed type ventricular arrhythmias, ranging from apparently uncomplicated extrasystoles to more severe or even potentially lethal arrhythmias such as polymorphous VT and ventricular fibrillation, with an anatomical substrate consisting of adipose or fibro-adipose degeneration of the myocytes of the free wall of the ventricle, which may be either focal (in particular: apex, anterior surface of the infundibulum and the sub-tricuspid region), or more diffuse. It is then accompanied by RV systolic dysfunction with dilatation of the cavity. This apparently well defined clinico-pathological entity is in fact more complex, if only because of the existence of associated lesions of the left ventricle in 1/3 of cases. The distinction from Uhl disease remains blurred, in particular in diffuse forms. It is most probable that more than one etiology is involved. A dysgenetic mechanism with probable autosomal dominant transmission has apparently been shown in familiar forms which are associated with a particularly severe risk of progression. The hypothesis of sequelae of multifocal myocarditis appears to be the most probable in sporadic forms. In the absence of histological criteria, which it is difficult to demand in view of the variability of results and potential dangers of endomyocardial biopsy involving such thin and fragile ventricular walls, the diagnosis of ACRV is based upon the concomitant existence of: (1) electrophysiological criteria: ventricular arrhythmias, in particular sustained monomorphous VT, with the particular feature of a very high degree of sensitivity to adrenergic stimulation (exercise), the existence of late potentials on the high amplification ECG, a highly specific sign, though unfortunately of poor sensitivity in localized froms, those which are most difficult to identify (2); segmentary morphological and kinetic RV abnormalities, most often resulting in localized akinetic or dyskinetic parietal vaulting, with stasis "in situ". Modern imaging methods (echocardiography, angioscintigraphy with phase analysis, nuclear magnetic resonance imaging, etc.) unfortunately do not yet offer an alternative to selective cineangiography of the RV which is the reference investigation when it is performed and interpreted under strict conditions. Several reports of sudden death or of ventricular fibrillation seen in confirmed cases of ACRV, as well as the publication of a number of autopsy registers indicating that this condition is one of the primary causes of sudden death in young individuals and in athletes, have cast doubt on the benign prognosis initially attributed to this condition.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

[Isolated myocardial infarction in the right ventricle: clinical and echocardiographic study].

The purpose of this study was, on the basis of 4 cases of isolated infarction of the right ventricle (RV), to describe the clinical profile of this disorder and compare the value of ultrasonography with other invasive methods of investigation (hemodynamic and kinetic angiocardiographic methods) in diagnosis and evaluation of the prognosis. In all cases the clinical situation was indicative: prolonged chest pain, slight enzymatic peak, downward shift of the ST segment in V3R and V4R. The diagnosis was rapidly confirmed by ultrasound in the face of the abnormal isolated segmental kinetics in the RV, associated with cavity dilatation and tricuspid incompetence. These data were consistent with those of RV kinetic angiography. Right cardiac catheterism showed the classical signs of adiastolism with no reduction in heart rate, except in one case. The outcome was generally simple. Ultrasound revealed the regression of the abnormalities of parietal kinetics. Thus, ultrasound examination is shown to be a method of exploration which is easy to perform and effective in the diagnosis of this disorder with a good prognosis.

Aged↗
PubMed1992

[Immediate and long-term results of 790 mitral valve replacements].

A total of 790 patients underwent isolated (N = 520) or mitral valve replacement associated with a tricuspid valve procedure for lesions excluding post-myocardial infarction mitral regurgitation. The mean age was 54 years: the sex ratio was 1.9 +/- 1.1, female/male. Three hundred and four patients (38.5%) were in the NYHA functional class II and 406 patients (61.5%) were in classes III or IV. The operative mortality was 9.7% (77 patients). The factors associated with a high operative risk were, on multifactorial analysis: double valve replacement, age over 70 years, NYHA class IV, aortic clamp time over 68 minutes and the presence of mitral regurgitation. Seven hundred and four of the 713 survivors were contacted (98.7% follow-up). The average follow-up period was 5.05 years (range 11 to 219 months) giving a total of 3,997 patient-years. The 5 and 10 year actuarial survival rates were 74.7% and 64.7% respectively. The presence of a tricuspid lesion requiring surgical correction, a high NYHA classification and the presence of mitral regurgitation were poor prognostic factors of long-term survival. Three hundred and sixteen of the 533 survivors at the time of the inquiry were in NYHA class I (59.3%), 188 in NYHA class II (35.3%) and 29 in NYHA class III or IV (5.4%). Mitral valve replacement should be considered early as the immediate and long-term results are closely related to the preoperative myocardial function.

Actuarial Analysis↗
PubMed1991

[New cardiac pacemakers].

Because of the extraordinary technological progress made over the past years in pulse generators, the objective and indications of definitive cardiac pacing have greatly changed. All the different advantages are aimed at mimicking the electrophysiological and mechanical conditions of normal heart function. We have seen the development of: DDD mode dual chamber pacemakers, which in cases of AV block recreate normal AV synchrony; single chamber rate-responsive units piloted by an external captor responding to the organism's metabolic needs (intra-corporal vibrations resulting from exercise, respiratory rate, minute ventilation, QT interval, central temperature, SV O2...); they provide effective correction of atrial (AAI-R mode) or ventricular (VVI-R mode) chronotopic incompetencies often associated with chronic conduction disorders which make it impossible for patients paced in VVI or AAI mode to adapt heart rate to exercise level; and finally, "universal" pacemakers capable of pacing in all the single or dual chamber modes with rate responsiveness to one or several captors. These new pacemakers offer adaptability to the paced patient's needs as they vary throughout his lifetime. These units will probably be the "standard" cardiac pacemakers of the future.

Arrhythmias, Cardiac↗
PubMed1991

[Aneurysm of a saphenous vein aortocoronary shunt caused by fissure syndrome].

The authors report a new case of an aneurysm of a saphenous vein aorto-coronary shunt. The aneurysm manifested itself by a fissure syndrome in a man 48 years of age, 9 years after myocardial revascularization surgery. A chest X-ray revealed a right paracardiac opacity, and two-dimensional ultrasound picked up an expansive, hypoechoic mass. The diagnosis was confirmed by coronary artery angiography. The aneurysm was opened up and the proximal anastomosis sutured. After a follow-up period of 30 months, the patient is asymptomatic.

Aneurysm↗
PubMed1990

[Myocardial infarction and massive biventricular thrombosis during thrombocytopenia induced by pentosan polysulfate and heparin].

Many cases of immuno-allergic thrombocytopenia complicated by serious thromboembolism induced by heparin or other heparinoids such as pentosan polysulphate have been reported. This case is of interest for two reasons: first of all, it was induced by pentosan polysulphate and then reactivated by secondary administration of heparin; secondly, it was complicated successively by an infero-apical myocardial infarction with probable spontaneous lysis of a coronary thrombosis because coronary arteriography performed one month later was normal, and then by massive biventricular thrombosis requiring surgical thrombectomy under cardiopulmonary bypass. Tests of platelet aggregation were positive to standard heparin and to several low molecular weight fractions. The outcome was favorable when the responsible substances were withdrawn.

Blood Coagulation Tests↗
PubMed1990

[Benefits and limits of single chamber atrial pacing with adaptive rate].

Twelve patients with isolated symptomatic sinus node dysfunction or bradycardia-tachycardia syndrome with atrial chronotropic incompetence during exercise testing were managed by single chamber rate responsive atrial pacing (AAIR) when AV conduction was normal, or by a dual chamber DDDR pacemaker programmed in the AAIR mode when AV conduction was abnormal, and followed up for 12.5 +/- 9.8 months. The patients were assessed clinically, by 3 monthly ECG and Holter recordings and comparative exercise tests in AAI and AAIR modes at the 6th month. One patient with an AAIR system was excluded at M21 because of symptomatic AV block requiring reimplantation of a DDD pacemaker. Ten of the 11 remaining patients are asymptomatic and have an excellent quality of life; one patient had invalidating symptoms on exercise attributed to the "AAIR pacemaker syndrome" which were corrected by reprogramming the pacemaker and modifying the medical therapy. The comparative exercise stress tests showed a significantly higher heart rate in the AAIR mode compared to AAI pacing at the initial and intermediate exercise levels (30 to 70 W); on the other hand, the heart rates were not significantly different at the highest exercise levels although in the AAI mode, the terminal acceleration sometimes occurred in junctional rhythm whereas it was usually an atrial paced rhythm in the AAIR mode. The total duration of exercise was longer in the AAIR mode (+22%; p less than 0.01) when the 8/11 patients with chronotropic incompetence during the baseline study were considered. The spike-R interval adapted normally to exercise in only one case: in the other patients, the interval remained constant or, in the worst of cases (N = 4), it increased paradoxically, to result in the "AAIR pacemaker syndrome": this phenomenon is observed mainly in patients treated by antiarrhythmics and/or betablockers. The AAIR mode would therefore seem to be a simple, effective and reliable method of treating patients with sinus node dysfunction and chronotropic incompetence; however, the failure of adaptation of the PR interval is a real limitation to its use and may constitute an argument in favour of the choice of a DDR pacemaker in these patients.

Adult↗
PubMed1990

[Auriculoventricular block disclosed in the exercise test].

Sixteen patients, 14 of whom described stress related symptoms, present a severe atrio-ventricular block (A-V B), identified during a stress test while the ECG at rest showed a 1/1 atrioventricular conduction (AV). The electrophysiological study (EPS) creates the A-B Block through atrial stimulation and specifies the location of the A-V B: intra-hissian in 8 patients (7 with small QRS an 1 with widened QRS) and infra-hissian in 8 patients (all with widened QRS). Non-invasive methods constitute the prime approach in the diagnostic work-up of stress symptoms. The ideal treatment consists of a dual-chamber cardiac stimulation.

Adult↗
PubMed1989

Clinical pharmacokinetics of levorotatory and racemic disopyramide, at steady state, following oral administration in patients with ventricular arrhythmias.

Electrophysiological effects, antiarrhythmic activity and kinetics of levorotatory disopyramide (R(-) DP) and racemic disopyramide (equimolar mixture of R(-) DP and S(+) DP) were compared in patients with ventricular arrhythmias. This double blind cross-over randomized trial was achieved, at steady-state, following oral administration of 200 mg three times a day. In comparison with baseline values, electrophysiological data indicated that R(-) DP and racemic DP prolonged, significantly and similarly, PR interval (+11.7% and +10%, respectively, P less than .01), and QTc interval (+9.2% and +7%, respectively, P less than .001), while QRS interval was not significantly affected. The antiarrhythmic activity, assessed by percent reduction in ventricular extrasystoles frequency, showed a similar efficiency of levorotatory and racemic DP: 80% and 74%, respectively (P = .24). Ventricular tachycardias disappeared with both treatments in the three patients concerned. During the racemic period, the mean total plasma clearance, expressed as CL/F, of S(+) DP (114.6 ml/min), was significantly lower than that of R(-) DP (157 ml/min), (P less than .001). The mean total plasma clearance of R(-) DP, during the levorotatory period (163 ml/min), did not differ from the respective value determined during the racemic period (P = .32). During the racemic period, the stereoselective difference in total plasma clearances, which is not observed when DP enantiomers are administered separately, may result from an increase in unbound fraction of R(-) DP, due to the presence of S(+) DP, which is known to be a potent displacer of R(-) DP.

Administration, Oral↗
PubMed1988

[Aortic valve replacement in persons over 75. 128 operated patients].

Aortic valve replacements are performed in ever older subjects. In the surgical cardiovascular clinic of Rennes, 128 patients aged 75 or over (up to 85 years) and presenting with solitary or predominant (126 cases) aortic stenosis underwent aortic valve replacement between 1976 and 1985 inclusive. Pre-operative evaluation consisted, on principle, of non-invasive explorations. Myocardial protection was ensured by hypothermic cardioplegia. We used a mechanical (Björk-Shiley) prosthesis in the 19 patients operated upon before 1980, and a bioprosthesis (Carpentier-Edwards porcine, supra-annular type since 1983), in the 109 patients operated upon since 1980. The operative mortality rate was 8.6% (11 deaths). The survival curve was similar to that of a control population of the same age-group (survivors 75% at 4 years, operative mortality included). The quality of survival was remarkable since 96% of survivors were in NYHA stages I or II, the poor results being due to early or late cerebral vascular accidents. Advances in surgery (notably myocardial protection), anaesthesia and intensive care make it possible reasonably to operate upon very old patients, provided they have remained in good general and cerebral vascular condition. Non-surgical alternatives, such as percutaneous valvuloplasty, now used in elderly patients can only be reliable if results of similar quality and durability can be expected from them.

Aged↗
PubMed1986

[Evaluation of coronary lesions in biventricular inferoposterior infarction].

Fifty-two patients with primary transmural infero-posterior infarcts underwent right heart catheterisation on admission to hospital and coronary angiography between the 7th day and 4th month after onset of symptoms. The patients were divided into two groups A (N = 34) with signs of right ventricular dysfunction on admission indicating biventricular infarction, and B (N = 18) without right ventricular dysfunction classified as isolated LV infarction. No significant differences were observed between the two groups with respect to: global and regional LV function; the incidence of single, double and triple vessel disease; the incidence and location of right coronary artery thrombosis; the incidence and location of lesions of the left coronary tree (LCA, LAD, Cx); the extent of coronary disease (Gensini score); the dominant artery (right coronary/circumflex), the frequency and quality of revascularisation of distal vessels. The only significant differences were the higher incidence of severe lesions (90 p. 100) of the right coronary and circumflex arteries and of stenosis of the first large septal branch of the LAD artery in Group A (p less than 0.05). These results show that the indications for coronary angiography in biventricular inferior infarction are no greater than those in mono LV inferior infarction. This supports experimental data on the physiopathology of RV infarction which demonstrates that except in cases of proximal thrombosis of the right coronary artery, the possibilities of revascularisation from the left coronary tree are limited.

Adult↗
PubMed1979

[Traumatic myocardial infarct].

Two cases of traumatic, closed chest, myocardial infarction in two young patients, aged 18 and 19 years respectively, are reported. They illustrate the two possible physiopathological mechanisms of this affection: in the first case, myocardial contusion after thoraco-abdominal trauma by crushing, probably complicated by a subendocardial tear of the inferior wall of the left ventricle, with a spontaneous favourable outcome; in the second case, a transmural myocardial infarction was observed secondary to a coronary lesion (? tearing of the adventitia of the left anterior descending artery) complicated by the early development of a large antero-apical aneurysm. Haemodynamic and arrhythmic complications necessitated infarctectomy and aorto coronary bypass surgery on the 35th day. The pathological lesions and their outcome are examined with respect to these two cases. The diagnostic, therapeutic and medieolegal problems associated with this condition are also discussed.

Adolescent↗