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Biomedical subjects

P Louis

Publications and source records attributed to P Louis.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Comparison of gas exchange and hemodynamic variables during 2 types of exercise tests. Cycle-ergometry and the ergometric table].

The development of stress echocardiography on an ergometric table has increased the number of stress tests in the decubitus position, whereas most of the information currently available concerns stress tests in the sitting position or on the treadmill. In order to study the influence of this position of stress testing, the authors compared the results obtained in a series of 15 patients without cardiac disease (Group I) and another series of 15 coronary patients (Group II) undergoing the two types of stress testing, in the vertical position on a bicycle ergometer and in the lateral decubitus position on the ergometric table. Effort tolerance on the bicycle ergometer was significantly greater in terms of work load (202 +/- 35 vs 180 +/- 36 watts (p < 0.001) in the controls, and 120 +/- 32 vs 106 +/- 22 watts (p < 0.05) in the coronary group), of duration of effort (19 +/- 3 vs 16 +/- 3 minutes (p < 0.001) in the controls and 10 +/- 3 vs 8 +/- 2 minutes (p < 0.05) in the coronary patients), of heart rate (190 +/- 10 vs 172 +/- 21 beats/min (p < 0.005) in controls and 118 +/- 19 vs 111 +/- 14 beats/min (p < 0.05) in the coronary patients). On the other hand, blood pressure and O2 saturation tended to be greater during exercise in the decubitus position: SBP 200 +/- 23 vs 196 +/- 27 mmHg (NS) in the controls and 158 +/- 21 vs 166 +/- 23 mmHg (NS) in the coronary patients; DBP 97 +/- 10 vs 102 +/- 27 mmHg (NS) in the controls and 85 +/- 6 vs 90 +/- 10 mmHg (NS) in the coronary patients; O2 sat 96.8 +/- 1 vs 97.6 +/- 0.8% (p < 0.05) in the coronary patients. The anaerobic threshold and peak VO2 were much higher during exercise in the sitting position: oxygen consumption at the threshold 14.8 +/- 3.8 vs 12.6 +/- 2.3 ml.kg-1.min-1 (p < 0.01), peak VO2 22.2 +/- 5.9 vs 18.8 +/- 4.7 ml.kg-1.min-1 (p < 0.01) in the coronary patients. The results of this study show that the cardiovascular stimulation obtained in the decubitus position is not identical to that obtained by traditional exercise stress testing, particularly in coronary patients.

Adult↗
PubMed1998

[Result and outcome of prenatal detection of congenital cardiopathies at the Côte-d'Or over a period of 9 years].

Antenatal echocardiographic diagnosis of congenital heart disease in 699 women living in the department of the Côte d'Or between 1988 and 1996 revealed 39 cardiac abnormalities which were later confirmed by anatomical examination or echocardiography. During the same period, 157 cardiac malformations which could have been detected in the antenatal period were diagnosed after birth. The detection rate of congenital heart disease was 19.8% over the whole study period, and 33.3% in the last three years. The malformations which were most easily diagnosed were hypoplastic left ventricle, single ventricle, atriventricular canal and severe obstruction of the ventricular outflow tracts. Twenty-one abortions (53.8%) were undertaken because of the severity of the cardiac lesion or of a genetic abnormality. Seventeen children were live born (43.5%) but, globally, they had severe malformations and the mortality rate was 84.5% whereas in the children diagnosed post-partum, the lesions were generally less severe and the mortality was 19.7%. The detection rate of congenital heart disease depends on the screening of first intention. Thus, 90% of the lesions diagnosed in this series were referred because of a foetal heart abnormality and, in this indication, echographic expertise was by far the most accurate with 33% of confirmation. As other workers have reported, teaching programmes and regional collaboration between physicians implicated in antenatal care are essential.

Echocardiography↗
PubMed1998

[Influence of time (4 years) on the results of programmed ventricular stimulation].

The reproducibility of programmed ventricular stimulation has been previously demonstrated for periods of a few hours to several months. It has not been studied over longer intervals. The aim of this study was to assess the reproducibility of the method at long-term (> 2 years). Forty-six patients with underlying cardiac disease underwent two programmed ventricular stimulations in the absence of antiarrhythmic treatment at intervals of 2 to 6 years (mean 4 years). None of the patients had myocardial infarction or cardiac surgery during this period. The protocol was identical: up to 3 extra-stimuli were delivered in the two right ventricular sites over 3 cycles. Twenty-eight patients had inducible sustained monomorphic ventricular tachycardia during the first investigation (Group I): the investigation was negative in the remaining 18 patients (Group II). During the second investigation, 26 of the 28 patients in Group I had inducible ventricular tachycardia, the rate of which decreased from 206 +/- 50 bpm to 196 +/- 54 bpm. The induced ventricular tachycardia was slower in 15 patients and faster in 5 patients. The mode of induction was different in 12 cases. In Group II, 4 patients (22%) had inducible sustained ventricular tachycardia at the second investigation. The authors conclude that the reproducibility of programmed ventricular stimulation remains good in the long-term in subjects within inducible tachycardia, demonstrating the stability of the arrhythmogenic substrate; the frequency of this tachycardia is generally slower. In subjects with an abnormal initial investigation who became symptomatic, it may be useful to repeat programmed ventricular stimulation.

Adult↗
PubMed1997

Identification of plasmids in the genus Marinococcus and complete nucleotide sequence of plasmid pPL1 from Marinococcus halophilus.

Several plasmids were detected in the Gram-positive halophilic eubacterium Marinococcus halophilus and in the related strain M52. The complete nucleotide sequence (3874 bp) of one of these plasmids, pPL1, was determined. Four major open reading frames were identified. Whereas orf3 and orf4 showed no sequence similarities to known proteins, rep displayed a high sequence similarity to replication proteins of rolling circle plasmids. Upstream of this ORF, a sequence resembling the double-strand origin was detected. A region probably constituting the single-strand origin was identified. The ORF mob showed sequence similarity with Mob proteins of rolling circle plasmids. The observed characteristics suggest that pPL1 replicates according to the rolling circle mechanism.

Amino Acid Sequence↗
PubMed1997

[Intrabronchial migration and extraction of a fragment of an Accufix J-shaped atrial pacing catheter].

The authors report a case of exteriorisation and migration of a fragment of a J-shaped atrial Accufix Telectronix (Stimarec Class IV) responsible for a bronchial penetration without clinical repercussion. A systematic control chest X-ray detected this complication. The position of the metallic fragment was determined by chest CT scan and bronchial fibroscopy between the inferior right lobar bronches and artery confirming bronchial perforation. Rigid bronchoscopy with direct visualisation enabled extraction of the foreign body without complications.

Bronchi↗
PubMed1997

[Study of myocardial viability after myocardial infarction. Value and limits of magnetic resonance imaging compared with myocardial scintigraphy].

The aim of this study was to compare myocardial thickness measured by magnetic resonance imaging and quantified fixation of thallium. Twenty-one patients 61.2 +/- 11 years were investigated after myocardial infarction of the anterior wall in 8 cases, inferior in 10 cases, lateral in 2 cases and apical in one case. The mean angiographic ejection fraction was 46.5 +/- 19%. Myocardial scintigraphy was performed after an exercise or pharmacological stress test and followed by a study of redistribution. The data was analysed by a quantitative method. Magnetic resonance imaging was performed with vertical and horizontal long axis views in systole and diastole with division of the left ventricle into the same 12 regions. Three groups were defined according to fixation during redistribution. Group I: regions with fixation > 80% (n = 155); group II: 60 to 80% (n = 78); group III: fixation < 60% (n = 19). All measurement of myocardial thickness were correlated (p < 0.01) with the fixation of thallium during redistribution. Systolic thickening, was significantly greater in group I (3.80 +/- 3.1 mm) than in groups II (2.20 +/- 3.8 mm) and III (1.56 +/- 2.4 mm) in which it was comparable. Regions in group III had systolic (8.61 +/- 3.53) and diastolic (6.89 +/- 3.3 mm) thicknesses significantly inferior to those in groups I (13.79 +/- 4.4 mm: 9.95 +/- 2.8 mm) and II (11.59 +/- 5.5 mm: 9.38 +/- 2.9 mm). Ninety per cent of regions with a systolic thickness of over 10 mm had fixation during redistribution of more than 60%. This study shows that myocardial thickness is correlated to scintigraphic data. The systolic thickness over 10 mm would confirm the viability of a given region.

Adult↗
PubMed1997

[Can 1/1 atrial flutter be foreseen by class I anti-arrhythmics?].

1/1 atrial tachycardia or "quinidine" flutter under class I antiarrhythmic drugs is a serious complication of these agents which, unfortunately, cannot be anticipated. The aim of this study was to review the cases of 11 patients who had suffered this complication of class I antiarrhythmic therapy to see if it could have been prevented. All drugs of this class were included. The 11 subjects were aged 57 to 78: 7 had no apparent underlying cardiac disease and the others had valvular (n = 1), hypertensive (n = 1) and ischaemic (n = 2) heart disease. They were treated for episodes of paroxysmal atrial fibrillation or tachycardia. In the absence of treatment, 7 patients had a short PR interval on the ECG (PR between 0.11 and 0.14 s). In the other 4, the PR interval was normal (0.16 to 0.20 s), but the P wave was widened with appearances of left atrial hypertrophy or an intra-atrial conduction defect. High amplification ECG performed in 3 patients showed continuity of atrial and ventricular depolarisation. Atrial stimulation showed excellent nodal conduction with a Wenckebach point of 200/min. The authors conclude that a short PR interval is predisposing factor to 1/1 atrial tachycardia with class I antiarrhythmics. High amplification ECG which allows identification of the end of the P wave with respect to the QRS complex could help identify subjects at risk when the P wave is widened and that, consequently, the PR interval appears to be normal.

Aged↗
PubMed1997

[Long-term reproducibility of programmed atrial stimulation].

Programmed atrial stimulation is a technique increasingly used to assess different pathologies but the reproducibility of the results is totally unknown. The aim of this study was to determine its reproducibility. Two electrophysiological studies were undertaken without antiarrhythmic therapy in an interval of one to three months (average 18 months) in 48 patients. The programmed atrial stimulation used 1 and 2 extrastimuli delivered in sinus rhythm and then three paced rhythms (sinus cycle -10%, 600 ms, 400 ms). Twenty-one patients had documented atrial arrhythmias (atrial fibrillation n = 13, flutter n = 3 or tachycardia n = 5) (group 1) and the 27 other patients had no spontaneous arrhythmias (group II). In group I, clinical tachycardial was reproduced in 18 patients during the initial stimulation procedure. During the second investigation, 17 remained inducible and in the 3 in whom stimulation was negative, it remained so in 2 of the cases. The reproducibility was therefore 90%. In group II, 12 patients had inducible sustained (for over 1 minute) tachycardia during the first procedure (44%) but this only remained inducible in 6 patients. In the other 15 subjects, stimulation was negative during the first procedure but 7 of them had inducible tachycardial during the second procedure. The reproducibility of the technique was therefore only of 52%. The authors conclude that the reproducibility of programmed atrial stimulation in patients with documented spontaneous paroxysmal arrhythmias is excellent. However, the reproducibility is mediocre in subjects without spontaneous arrhythmias and the induction of tachycardial in this group of patients should be interpreted with caution given the variability of the response to programmed atrial stimulation.

Adolescent↗
PubMed1996

Quantitative analysis of the expression of the HLA-DRB genes at the transcriptional level by competitive polymerase chain reaction.

In addition to polymorphism of the peptide-binding site, the density of the MHC class II molecules expressed on the membrane of APC could well play a significant role in the MHC-peptide-TCR interaction during the immune response. We therefore investigated the regulation of the expression of the HLA-DRB genes at the transcriptional level. A competitive PCR approach was used to estimate the quantities of the HLA-DRB transcripts in peripheral blood B cells. When comparing the amounts of steady-state mRNAs among the different DRB1 alleles, the DRB1 transcripts in the DR52 haplotype group were found to be 2.5 to 3.5 times more abundant than the DRB1*01 transcripts, 1.5 to 2 times more abundant than the DRB1*04 transcripts, and 7 times more abundant than the DRB1*08 transcripts. Within the DR52 haplotype group, the DRB1 and DRB3 transcripts had the same abundance. Taken together, these results are in good agreement with the previously reported transcriptional activities of the DRB promoters except for DRB1*04, thus suggesting a differential post-transcriptional regulation among the DRB1 mRNAs.

Alleles↗
PubMed1996

Diastolic or systolic left and right ventricular impairment at moderate doses of anthracycline? A 1-year follow-up study of women.

A prospective study was carried out to assess the early and later alterations in left and right ventricular diastolic and systolic function after the termination of anthracycline therapy. In 33 women without cardiac disease who were treated by anthracycline therapy, cardiac function was evaluated by radionuclide angiography before the treatment (T0) and 1 month (T1) and 12 months (T12) after the end of the treatment. Cardiac function was assessed by radionuclide measurement throughout treatment. Analysis of ejection fraction (EF), peak ejection rate (PER), time to PER (TPER), peak filling rate (PFR) and time to PFR (TPFR) was performed before and after treatment. To normalise radionuclide measurements of the ventricular diastolic function, the ratio of the PFR and the EF and the ratio of the PFR and the PER were calculated. No patient developed symptomatic congestive cardiac failure. One-way analysis of variance showed a significant decrease in the three parameters (EF, PER, PFR) over time only for the left ventricle (LV); no significant alterations appeared for the right ventricle (RV). The EF of the LV decreased from 59%+/-5% at T0 to 57%+/-6% at T1 and 56%+/-5% at T12. The PER of the LV fell from 3.03+/-0.40 end-diastolic volume per second (EDV/s) at T0 to 2.79+/-0.47 at T1 and 2.78+/-0.43 at T12. The PFR of the LV dropped from 2.99+/-0.43 EDV/s at T0 to 2.62+/-0.44 at T1 and 2.56+/-0.42 at T12. For the normalised ratios, no differences were observed. Significant differences were found for EF, PER and PFR between T0 and T1, and between T0 and T12, but no difference was found between T1 and T12. This report shows simultaneous impairment of the systolic and diastolic LV radionuclide parameters at 1 and 12 months after anthracycline therapy without alteration in the RV function.

Antibiotics, Antineoplastic↗
PubMed1996

Quantitative myocardial thallium single-photon emission computed tomography in normal women: demonstration of age-related differences.

The aim of this study is the development of a database of normal women for quantitative analysis of exercise and reinjection myocardial single-photon emission computed tomography (SPET). We studied 101 subjects (40 males and 61 females) with less than 5% likelihood of coronary artery disease. All patients underwent stress and rest thallium-201 myocardial SPET. Myocardial stress was induced by bicycle exercise test (n=51), dipyridamole infusion (n=27) or a combined test (n=23). Multivariate ANOVA showed that the type of stress did not influence the percentage of thallium uptake for each region. Significant differences between men and women were found for the percentage of uptake in the inferior and the anterior wall. The most original finding of this study is the correlation between age and thallium uptake in the three regions of the anterior wall, showing an increase in measured thallium uptake with age for women. Consequently, two groups of women, those under and those over 55 years old, were separated, with a significantly lower tracer uptake in the anterior wall in the younger age group. These results may suggest that the commonly described breast tissue attenuation is due not only to breast volume or morphology but also to breast density. This emphasizes the need for two different databases for myocardial SPET quantitative analysis in the female population. Awareness of this fact should allow avoidance of any underestimation of possible anterior wall ischaemia in women aged more than 55 years.

Adult↗
PubMed1996

Significance and prevalence of inducible atrial tachyarrhythmias in patients undergoing electrophysiologic study for presyncope or syncope.

The purpose of the study was to report the prevalence of inducible supraventricular tachyarrhythmias (SVTA) in 827 consecutive patients aged 17 to 90 years who did not have spontaneous documented SVTA and who had unexplained presyncope and/or syncope. The electrophysiologic study (EPS) included programmed atrial and ventricular stimulation up to two extrastimuli at three cycle lengths, and the study of sino-atrial and AV conduction. The results were as follows. EPS was normal in 386 patients. Inducible junctional tachycardia or atrial flutter and fibrillation was the only finding in 187 patients (23%). In the remaining patients we found ventricular tachycardia in 103 (12%), heart block in 67 (8%), sick sinus syndrome in 56 (7%) and increased vagal tone in 28 (3%). The presence of an underlying heart disease (47%) and salvos of atrial premature beats on Holter monitoring (39%) were significantly correlated with the induction of SVTA. However, the comparison with similar groups without syncope indicates that only the induction of SVTA in patients with hypertrophic cardiomyopathy and mitral valve prolapse was significantly correlated with the history of syncope. In patients without heart disease or with prior myocardial infarction or decreased left ventricular function, the induction of SVTA, which is not associated with hypotension in the supine position, could require an induction after head-up tilting, because of the lack of specificity of programmed stimulation in these patients. Programmed atrial stimulation should be systematically performed in patients with unexplained syncope, in particular in those with hypertropic cardiomyopathy and mitral valve prolapse, who require a specific treatment, if a SVTA is induced. In other patients the results of programmed atrial stimulation should be interpreted cautiously.

Adolescent↗
PubMed1996

[Emergency angioplasty for total thrombosis of the left main coronary artery. Apropos of a case].

Complete thrombosis of the left main coronary artery is a rare angiographic finding and usually gives rise to cardiogenic shock during unstable angina or myocardial infarction. The prognosis of this condition is very dependent on the collateral coronary circulation and the myocardial protection seems to depend on the rapidity of revascularisation. Two therapeutic approaches may be envisaged; emergency coronary bypass grafting or percutaneous angioplasty, the natural history being particularly disastrous. The authors report the case of a 42-year-old patient with complete occlusion of the left main stem responsible for unstable angina and acute pulmonary oedema. The outcome with angioplasty in the acute phase associated with surgical revascularisation four days later, was good.

Angina, Unstable↗
PubMed1996

[Syncopes associated with mitral valve prolapse. Mechanisms].

Prolapsed mitral valve prolapse (PMV) is classically associated with disorders of ventricular excitability whose significance is unclear. However, syncope can suggest the possibility of a serious ventricular arrhythmia. The objective of this study was to try to identify the mechanisms of dizziness and syncope associated with PMV. We report the results of programmed atrial and ventricular stimulation performed under baseline conditions and after administration of Isuprel in 56 patients with PMV: 27 patients had a history of presyncope or syncope (group I), 14 had spontaneous atrial or supraventricular tachycardias without dizziness or syncope (group II) and 15 were asymptomatic and investigated for VEBs or conduction disorders (group III). The following results were obtained: In group I, 6 patients experienced sustained inducible ventricular tachycardia (VT); an atrial tachycardia (atrial tachycardia and/or atrial fibrillation) (AT) was also induced in 5 of them. In another 19 patients, a supraventricular tachycardia (SVT) and/or AT was induced. A total of 24 atrial or junctional tachycardias were triggered in this group. In group II, AT and/or SVT were reproduced in 13 out of 14 cases (93%). In group III, AT was triggered in 3 patients (20%). SVT were induced by Isuprel while AT were triggered prior to administration of Isuprel, under baseline conditions, and 3 of them were reproduced during vagal manoeuvres. A ventricular arrhythmogenic effect was observed in two cases in group II while taking class I antiarrhythmics. In conclusion, spontaneous AT and SVT of PMV are easily inducible with a sensitivity of 93%, but are difficult to induce in asymptomatic subjects. The high incidence of TA and SVT in the case of unexplained presyncope in subjects without documented tachycardia therefore appears to be suggestive of a relationship between these presyncopes and AT or SVT. However, the search for VT should take precedence. SVT appear to be catecholaminergic while AT tend to be vagal.

Adolescent↗
PubMed1996

[Symptomatic myocardial bridges. Apropos of 6 cases].

Myocardial bridge is often considered to be a simple anatomical variation often observed during coronary angiography. The responsibility of this condition for myocardial ischaemia is however uncommon and the physiopathological mechanisms are not well understood. The authors report 6 cases of myocardial bridge associated with myocardial infarction of unstable angina. The main features of this condition are discussed with respect to a review of the literature. Patients are usually young and male; the left anterior descending artery is the most commonly affected vessel: factors triggering ischaemia are discussed: coronary spasm, tachycardia and thrombosis at the site of the myocardial bridge. The diagnosis can only be made by coronary angiography showing reduction of the systolic diameter of the artery which may be accentuated by certain pharmacological tests such as injection of glyceryl trinitrate as used in the series.

Adult↗
PubMed1995

Programmed ventricular stimulation in survivors of acute myocardial infarction: long-term follow-up.

The prognostic significance of ventricular tachyarrhythmias induced by programmed ventricular stimulation was evaluated in 492 consecutive survivors of acute myocardial infarction (AMI). Holter monitoring, signal-averaged electrocardiogram (ECG) and measurement of left ventricular ejection fraction (EF) were also performed. The protocol used up to 3 extrastimuli. Sustained monomorphic ventricular tachycardia (VT) < 270 beats/min, > 270 beats/min (ventricular flutter) (VFI), and ventricular fibrillation (VF) were induced in 99, 66 and 52 patients, respectively. Long term follow-up (mean 3.7 +/- 2.2 years) showed that most episodes of VT occurred during the first months following AMI (n = 14), but some patients (n = 6) could develop VT as late as 4 years after AMI. Sudden death (SD) (n = 22) always occurred during the first year following AMI. Multivariate analysis demonstrated that EF < 30% and induction of a VT < 270 beats/min were the only predictors for total cardiac death (P < 0.001). EF < 30%, induction of a VT < 270 beats/min and also of VFI (P < 0.05) were predictors for VT and SD: the risk was 4% in patients without inducible VT, 12% in those with inducible VF1, and 21% in those with inducible VT < 270 beats/min. In conclusion, induction of a sustained monomorphic VT < 270 beats/min or > 270 beats/min is a predictor of arrhythmic events during the first year as well as 4 years after myocardial infarction. However the risk of arrhythmic sudden death decreases after the first year, while the risk of VT persists. Because of the low positive predictive value of programmed stimulation (respectively 21% and 12% for the induction of a sustained VT and VFI), we recommended the indication of programmed stimulation in only the patients with one abnormal non-invasive investigation.

Actuarial Analysis↗