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Biomedical subjects

P Laurens

Publications and source records attributed to P Laurens.

At least 19 recordsLinked to original sources
PubMed1983

Suppression of renin secretion by insulin: dependence on extracellular calcium.

The isolated perfused rat kidney was used to examine the effect of insulin on renin release (RR). Insulin produced a dose-dependent reduction of RR when added to the perfusate at concentrations between 10 and 1,000 microU/ml. When kidneys were perfused with a calcium-free perfusate, RR increased nearly fivefold. Insulin (1,000 microU/ml) not only failed to suppress RR in calcium-free perfusions but stimulated it. The addition of verapamil (10(-5) M) to the perfusate likewise prevented the insulin inhibition of RR. Perfusion without potassium reduced RR to one-third of control values. The addition of insulin to kidneys perfused without potassium further suppresses RR. We conclude that at concentrations similar to those found in plasma, insulin modulates renin secretion. This process requires the influx of calcium possibly through insulin receptor-operated channels.

Animals↗
PubMed1983

[Severe postoperative heart blocks appearing late. 16 cases].

Sixteen patients, aged 4 to 42 years, operated for congenital heart disease, presented, months or years after surgery, complete atrioventricular (11 cases) or sinoatrial block (5 cases). Six patients had transient complete atrioventricular block in the immediate postoperative period, the maximum duration of which was less than 30 days. The late postoperative period was defined as at least 6 months after surgery. The period between surgery and the implantation of a pacemaker varied from 9 months to 19 years, average 6,3 years. Analysis of long term electrocardiographic studies distinguished three types of progression: --group I: alternation of sinus rhythm and conduction defect until definitive block, sometimes presenting with syncope; --group II: sudden, severe conduction defect after a long period of sinus rhythm; --group III: progressive lengthening of the PR interval. Seven patients developed syncope; 4 had dizziness, 2 were short of breath; only 3 were asymptomatic. All underwent permanent pacing. The incidence of late conduction defects appears to be 1 to 2% of operated patients. The causes include progressive fibrosis, slow sclerosis extending over conduction pathways which are congenitally fragile. Most late blocks are of an advanced degree. Some may be responsible for unexplained sudden death. It is therefore desirable to avoid this complication by the judicious and considered implantation of a cardiac pacemaker. Some authors mention the following factors in deciding on the indications for pacing: --complete, transient atrioventricular block during the operation or the immediate postoperative period; --ECG appearances of right bundle branch block and left anterior hemiblock, or trifascicular block; --His bundle studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

[Anatomic study of the right ventricular inferior wall. Search for the optimal site for implanting epicardial pacing electrodes].

The inferior wall of the right ventricle was studied to determine the optimal site of implantation of epicardial pacing electrodes. The hearts of 10 patients without cardiac disease, aged 57 to 84 years, who died in Broussais hospital, were studied. The hearts were washed, weighed (300 to 550 g) and placed in a formol solution to which was added half its volume of Larsen's solution. They were then examined and cut in sections about 0,8 cm thick, perpendicular to the long axis of the heart. Each section was drawn and the thickness of the inferior right ventricular wall measured. The inferior wall of the right ventricle is shaped like a right angled triangle limited medially by the inferior interventricular groove, posteriorly by the atrioventricular groove (containing the right coronary artery), and laterally by the right free border. The surface area of the triangle varies between 14 and 34 cm2, a fatty border is always observed, and, in 5 out of 10 cases, vessels (arteries and veins) run in a randomised fashion across its surface. The inferior wall is very irregular on section, appearing craggy and cavernous with sudden variations of 1 to 10 mm in thickness due to the many 2nd and 3rd order trabeculations. In the muscular zone near the interventricular septum, the thickness varies from 2 to 10 mm, but only 10 out of 70 measurements were less than 4 mm. In the middle and central zones, only 34 out of 182 measurements were less than 4 mm thick. On the other hand, at the apex and right border of the heart, the values fell to 7 mm and parts of the anterior right ventricular wall was as thin as 0,5 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1978

[Incidence of hyperuricemia in atrioventricular block. Systematic study of 158 cases which required implantation of an isotopic cardiac pacemaker].

This is a study of 158 patients in whom the placement of an isotopic cardiac pacemaker was indicated; this procedure was carried out Broussais Hospital between 1970 and 1975. These patients, whose mean age was 39 (84 males, 47 females, 12 young men and 15 young women) were examined for uricaemia, and the levels compared with the mean for control population. The results were as follows: 91% had uricaemia at a level higher than the controls. Of these, 61% had uricaemia above 70 mg/l in the men and youths of over 15 years of age, and above 60 mg/l in the women and 50 mg/l in the adolescents. The highest uric acid levels were found in adults with post-operative atrio-ventricular block following surgical correction of a congenital cardiac abnormality, and also in children and adolescence with block which appeared to be congenital.

Adolescent↗
PubMed1976

[Isotop cardiac pacemaker during pregnancy. 3 cases].

The authors report three cases of full term pregnancies, without complications, in women with isotopic pacemakers. The newborn infants were normal. In one case, pregnancy occurred in a patient who already had a pacemaker. In two cases, the pacemaker was inserted during pregnancy (at 1 and 1/2 and 5 months respectively), in the treatment of syncopal attacks due to paroxysmal atrioventricular block. This type of pacemaker using a radioactive source (Plutonium 238) is, by virtue of the low degree of radiation, harmless and may be used in women of childbearing age. Under the least favourable conditions (pacemaker box in abdominal situation), the dose delivered during pregnancy (57 mrem) is approximately 20 times less than the authorised dose (1125 mrem).

Abdomen↗
PubMed1976

[Occurrence of hyperuricemia in atrioventricular block. (Results of a study of 158 patients with isotopic pacemaker implantations)].

The frequency of hyperuricemia is high in these patients with heart block, whose mean age is 39. 91% have serum uric acid levels above the normal range and 61% present "hyperuricemia," according to "gouty risk" criteria. The mean uric acid level, before surgery, of the patients whose total heart block follows "open-heart" is the highest in our statistics.

Adolescent↗
PubMed1975

[Long-term survival in persons with cardiac pacemakers. Study based on 1,159 patients, 499 with regression at 4-10 years].

Analysis of the long-term survival of pacemaker carriers showed a parallelism between two curves: that of the survival in patients treated with a pacemaker as from the second month, and that of a control group with the same age and physical structure. Treatment in the first few years was made problematical by defects in surgical technique: while in 17% of reoperations, the reason was straightforward substitution of the pacemaker owing to wear on the battery, 83% were the consequences of complications. Of these, 23% consisted of shifts in the intracavitary probe, electrode failures, or increase in the threshold. The frequency of infections due to implantation or reoperation was 7,4%, in certain cases with fatal outcome. Bearing in mind that mortality from Adam-Stokes disease was 50% prior to the introduction of pacemakers, it can be maintained that this therapy represents a considerable step forward in cardiology. Mortality was 27% in all patients submitted to implantation.

Adams-Stokes Syndrome↗
PubMed1975

[Survival time of patients with cardiac pacemakers (author's transl)].

A comparison between the life expectancy of patients with pacemakers and that of a control population of similar structure shows a parallel course, although originally, after a postoperative phase of 2 months, the mortality rate of the patients with pacemakers was higher. Today the results are considerably better. Implantation of pacemakers is one of the greatest cardiological advances in the last 10 years for the effective treatment and prevention of cardiac arrest in atrioventricular block. The significance of this type of therapy becomes understandable if the fact that the mortality of Adams-Stokes attacks used to be about 50% is taken into consideration. In France, about 5000 persons each year have Adams-Stokes attacks.

Adams-Stokes Syndrome↗