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Biomedical subjects

M Chauvin

Publications and source records attributed to M Chauvin.

At least 145 records · Page 8Linked to original sources
PubMed1987

[Flecainide by the intravenous route: a new method for decreasing auricular fibrillation].

The action of intravenous flecainide was studied in patients presenting a tachyarrhythmia secondary to a permanent atrial fibrillation of recent onset. We obtained 9 improvements in 15 patients included in the protocol which consisted in the intravenous injection of 2 mg/kg of flecainide in 10 minutes. The side effects were minimal: no sign of cardia insufficiency nor alteration of the arterial blood pressure was noted. Nevertheless, although interesting, this method to decrease atrial fibrillation is not, in our opinion, destined to replace external electrical shock, except in some special cases.

Adult↗
PubMed1987

[Embolic intracardiac thrombosis on a catheter for permanent stimulation. An echocardiographic finding].

If endovenous thromboses on permanent cardiac stimulation catheter are rather frequent, it is usual to note the absence of complications, especially embolic complications. On the contrary, intracardiac thromboses, occurring always on a permanent stimulation catheter, are rare but may generate embolisms: the authors report a new case discovered on bidimensional sonocardiography recorded following pulmonary embolisms.

Aged↗
PubMed1987

[Continuous electrocardiogram recording (Holter). Normality criteria].

The interpretation of a continuous electrocardiographic recording according to Holter's method is valid only in terms of well defined standard criteria. These criteria are beginning to become more specific, in spite of uncertainties linked especially to study protocols. Finally, if these criteria were established among healthy populations, their application to pathological situations comes up against the notion of physical condition which may modify all norms.

Arrhythmias, Cardiac↗
PubMed1987

Effects of a low dose of pancuronium on oxygen consumption during sustained muscular exercise.

The effects of a low dose of pancuronium on muscular performance were studied in six healthy volunteers. Three dynamic exercise tests at increasing levels of power were performed by each subject on two consecutive days using an ergometric bicycle. To assess muscular function, oxygen consumption was measured in a steady state at each level of power output. Pancuronium 6-8 micrograms kg-1 or placebo was administered i.v. in a double-blind fashion before the second test each day. Plasma pancuronium levels were measured 8 min after administration but even with pancuronium clearly detectable in the plasma no significant differences were found either in oxygen consumption or in the haemodynamic measurements made. The authors conclude that such doses of non-depolarizing neuromuscular blocking agents do not disturb oxygen consumption during dynamic muscular exercise and are therefore unlikely to have a significant effect on muscular function.

Adult↗
PubMed1986

Rate-limiting diffusion processes following intrathecal administration of morphine.

Morphine concentrations in plasma in five patients following intrathecal (i.t.) administration and in five other patients following intravenous (i.v.) administration were measured by a specific RIA sensitive to 0.1 ng/ml. Pharmacokinetic analysis showed a similar apparent total body clearance of morphine following both i.t. and i.v. administration, and complete bioavailability of i.t. morphine to the systemic circulation. This indicates that morphine is probably not metabolised in the CNS and that all of an i.t. dose diffuses from CSF to the plasma compartment. However a marked decrease in the i.t. terminal rate constants, involving a flip-flop phenomenon, contributed to the prolonged terminal half-life of i.t. morphine. The slow diffusion of morphine from the i.t. space to the plasma compartment can account for the prolonged analgesia following i.t. administration.

Aged↗
PubMed1986

Pharmacokinetics and pharmacodynamics of vecuronium in patients with cholestasis.

The pharmacokinetics and pharmacodynamics of vecuronium were studied in nine surgical patients with cholestasis, and in 14 patients without hepatic or renal disease. After the administration of vecuronium 0.2 mg kg-1 the plasma concentration of vecuronium and the degree of neuromuscular blockade were measured. The plasma clearance of vecuronium was decreased significantly (P less than 0.01) from 4.30 +/- 1.56 ml min-1 kg-1 (mean +/- SD) in normal patients to 2.36 +/- 0.80 ml min-1 kg-1 in patients with cholestasis. The elimination half-life was of 58 +/- 22 min in normal patients and was prolonged to 98 +/- 57 min (P less than 0.05) in patients with cholestasis. The total apparent volume of distribution was unchanged in patients with cholestasis. A prolonged neuromuscular blockade induced by vecuronium was observed in patients with cholestasis: the duration of effect from injection to 75% recovery of the twitch height was prolonged from 74 +/- 19 min in normal patients to 111 +/- 13 min in patients with cholestasis. The plasma concentration corresponding to 50% recovery from paralysis did not differ significantly between the two groups. Vecuronium has a prolonged effect in patients with cholestasis which is caused by a delay in its elimination.

Adult↗
PubMed1986

The influence of hepatic plasma flow on alfentanil plasma concentration plateaus achieved with an infusion model in humans: measurement of alfentanil hepatic extraction coefficient.

In a group of seven patients undergoing intracranial surgery under neurolept anesthesia, an alfentanil infusion was initiated with a loading dose of 235 micrograms/kg over 5 min, followed by a maintenance infusion rate of 1.8 microgram X kg-1 X min-1 in order to obtain a steady state plasma concentration (Css) of 400 ng/ml-1 according to an infusion model. The mean values of Css (446 +/- 209 ng/ml) were close to the predicted ones. Nevertheless, an important intersubject variability in Css values was observed. A positive linear correlation existed between alfentanil steady state clearance and indocyanine green clearance (r = 0.88) and between alfentanil steady state clearance and cardiac index (r = 0.93). In three patients, a catheter was inserted into an hepatic vein to determine the alfentanil hepatic extraction coefficient. Alfentanil plasma clearance did not differ from alfentanil hepatic clearance and alfentanil hepatic extraction coefficient values ranged from 0.32-0.53. We conclude that alfentanil is a drug with an intermediate hepatic extraction coefficient and that alfentanil plasma clearance depends on hepatic plasma flow, which is thus one of the factors accounting for individual variability in plasma concentration plateaus achieved with an infusion model.

Adult↗
PubMed1985

[Reduction of auricular fibrillation with fenoxedil: the probable role of the autonomic nervous system].

It is still very difficult to study the mechanisms of action of anti-arrhythmic drugs in human clinical studies. The use of continuous electrocardiographic monitoring offers a number of advantages in this field. In this study, the authors evaluate the mechanisms of action of fenoxedil hydrochloride on atrial fibrillation. Holter monitoring suggests that there is a probable synergy between fenoxedil and the autonomic nervous system.

Anti-Arrhythmia Agents↗
PubMed1985

Clinical assessment and plasma pharmacokinetics associated with intramuscular or extradural alfentanil.

Patients with postoperative pain received alfentanil in doses of 15 micrograms kg-1 (n = 6) or 30 micrograms kg-1 (n = 6) via the extradural route or 15 micrograms kg-1 (n = 6) i.m. Effective analgesia was obtained in all patients in the extradural groups and in none in the i.m. group. Maximum pain relief developed within 10-15 min and the average duration of adequate analgesia was 78 min with the lower dose and 45 min with the higher dose, but this difference was not statistically significant. The 15-micrograms kg-1 extradural and i.m. groups showed the same pharmacokinetic pattern. Plasma concentrations were greater in the 30-micrograms kg-1 extradural group and this was associated with unwanted systemic effects. We conclude that the extradural administration of alfentanil can produce effective spinal analgesia. Its lipophilic property reduces the onset time, but does not modify its duration of action or impair absorption.

Adult↗
PubMed1985

Hepatic plasma flow during sodium nitroprusside-induced hypotension in humans.

Changes in hepatic plasma flow (HPF) during sodium nitroprusside (SNP) induced hypotension were studied in 14 patients undergoing intracranial aneurysm surgery under neurolept anesthesia. Patients were monitored with the use of a radial artery catheter and a thermistor-tipped Swan-Ganz catheter. Hypotension was induced with incremental increases in the rate of SNP infusion until a stable mean arterial pressure (MAP) 35-55 mmHg had been achieved. In one group (Group A) of 10 patients, indocyanine green (ICG) clearance was determined simultaneously with hemodynamic variables, before and during SNP hypotension. In a second group (Group B) of four patients, a catheter was inserted into a hepatic vein to determine the ICG hepatic extraction (HE) coefficient. In Group A, MAP decreased from 73 +/- 10 (SD) to 41 +/- 9 mmHg, while cardiac index (CI) decreased in six patients and increased in four patients. However, the mean value of CI did not change significantly. The mean value of ICG clearance was not significantly affected by SNP hypotension. Nevertheless, a positive linear correlation existed between individual variation in CI and ICG clearance (r = 0.96). On the other hand, no correlation was noted between the change in MAP and ICG clearance. In Group B patients, the ICG HE coefficient remained unchanged during SNP hypotension, suggesting that ICG clearance varies only according to the variation in HPF. In conclusion, this study demonstrated that HPF did not decrease, despite a range of 20-60% decrease in blood pressure when CI is maintained during SNP hypotension.

Adult↗
PubMed1985

[Dispersion of auricular refractory periods. Role of the intensity of the stimulation current].

In a series of 12 patients, the right atrial effective and functional refractory periods (ERP and FRP) were determined at 3 different sites and at 3 different intensities (threshold intensity and double and triple the threshold intensity). The mean of the range of the ERP in the same atrium was 43.4 ms and that of the FRP was 53.5 ms. These ranges appear to be independent of the intensity of stimulation. However, the values of the refractory periods were strictly correlated with the intensity of the stimulation current used. This correlation appeared to be much more marked for the ERP than for the FRP.

Electric Stimulation↗
PubMed1983

The major heat-shock protein (hsp70) gene family: related sequences in mouse, Drosophila, and yeast.

Heat shock induces the synthesis of a 70-kdalton protein in Escherichia coli, Drosophila, yeast, and mouse. We show that the genes for this heat-shock protein in mouse, yeast, and Drosophila share extensive sequence homology as determined by heteroduplex formation at different stringencies. We calculate that the heat-shock gene homology is 74% between yeast and Drosophila and 85% between mouse and Drosophila. The organization of the six copies of the Drosophila gene for the 70-kdalton heat-shock protein at two separate loci is summarized and evidence is presented that the yeast and mouse genomes each contain multiple copies of sequences related to the Drosophila gene for the 70-kdalton heat-shock protein. These results demonstrate that not only the sequence but also the repetitive organization of the major heat-shock genes is conserved.

Animals↗
PubMed1983

[Application of endocavitary mapping to the study of auricular flutter].

Many in vitro and animal experimental studies seem to support the hypothesis of reentry as the physiopathological mechanism of atrial flutter. Clinically, these studies are much more difficult because of problems in determining the different sequences of atrial depolarisation. In this study, the authors attempted to improve the technique of endocavitary atrial mapping. Three or four multi-recording electrodes were positioned in the atria using biplane 30 degrees RAO and 60 degrees LAO incidences. Right atrial angiocardiography showed up the atrial borders and enabled the recording catheters to be more accurately positioned. Thirty to 47 recordings points were thereby determined within the atrial cavities, the left atrium being studied via the coronary sinus, right pulmonary artery, patent foramen ovale or by the endooesophageal approach. This method of spatial orientation of the catheters associated with recording of the endocavitary potentials allowed the construction of an isochronic map of atrial depolarisation, which was then analysed for each case of flutter. The study confirmed two hypotheses: the asynchronism of right and left atrial depolarisation, and the circus motion of depolarisation. Three types of flutter were observed: --The first two types were similar with cirus motion within the right atrium. The wave front ascended in part or all of the septum and descended in the external free wall of the right atrium. There was a transitional zone, possibly reentrant, in the groove located anterior to the inferior vena cava. --The third type of flutter was atypical and was associated with cirus motion in the left atrium. Two transitional zones, similar to those encountered in the right atrium, were detected in one patient between the orifices of the pulmonary veins, and, in another patient, on the anterior part of the roof of the left atrium. These transitional zones seem to be at the basis of the physiopathological mechanism of flutter. Unfortunately, their small size makes their analysis by endocavitary mapping difficult.

Atrial Flutter↗