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Biomedical subjects

G Montalescot

Publications and source records attributed to G Montalescot.

121 records · Page 7Linked to original sources
PubMed1989

Effect of platelet depletion on lung vasoconstriction in heparin-protamine reactions.

In six awake sheep the control heparin-protamine reaction was associated with a 150-fold rise in arterial plasma thromboxane B2 (TxB2) levels, a 4.5-fold increase in pulmonary vascular resistance, a 20% decrease in cardiac output, a 30% decrease in arterial PO2, and a 30% reduction in arterial white blood cell concentrations. Depletion of 99% of circulating platelets by antibodies did not prevent either acute and severe pulmonary hypertension or increased plasma TxB2 levels induced by heparin-protamine administration. We produced sheep platelet aggregation in vitro with bovine thrombin and measured marked TxB2 release (36.3 +/- 16.3 ng/10(9) platelets). In contrast, neither heparin, protamine, nor heparin-protamine complexes over a 10,000-fold range of concentrations induced platelet aggregation and release of thromboxane in vitro. Therefore sheep platelets are not the source of thromboxane production associated with acute pulmonary hypertension during the heparin-protamine reaction, and other cells must produce the thromboxane.

Animals↗
PubMed1989

Nafamstat mesilate attenuates pulmonary hypertension in heparin-protamine reactions.

Rapid protamine reversal of heparin anticoagulation in awake sheep caused, after 1 min, a approximately 15-fold increase of arterial plasma thromboxane B2 (TxB2) levels, a 4-fold rise of pulmonary vascular resistance (PVR), a 2-fold rise of pulmonary arterial pressure, and after 3 min, a 2-fold rise of ovine arterial plasma complement C3a levels (P less than 0.05). Infusion of nafamstat mesilate (FUT-175), a protease and complement pathway inhibitor, before protamine reduced these increases by approximately 60-90% (P less than 0.05). FUT-175 did not modify heparin + protamine-induced leukopenia, suggesting that FUT-175 incompletely blocked C5a production. We also learned that infusing protamine first and heparin 5 min later did not increase either plasma C3a or TxB2 levels or PVR while the activated clotting time increased only minimally. Thus, in awake sheep, the sequence of heparin and protamine infusion influences complement activation and pulmonary vasoconstriction. FUT-175 pretreatment reduces thromboxane release and pulmonary vasoconstriction probably by limiting complement activation.

Animals↗
PubMed1989

Sonomicrometric regional diaphragmatic shortening in awake sheep after thoracic surgery.

Through a right thoracotomy in seven sheep we chronically implanted sonomicrometry crystals and electromyographic electrodes in the costal and crural diaphragmatic regions. Awake sheep were studied during recovery for 4-6 wk, both during quiet breathing (QB) and during CO2 rebreathing. Tidal volume, respiratory frequency, and esophageal and gastric pressures were studied before and after surgery. Normalized resting length (LFRC) was significantly decreased for the costal segment on postoperative day 1 compared with postoperative day 28. Fractional costal shortening both during QB and at 10% end-tidal CO2 (ETCO2) increased significantly from postoperative days 1 to 28, whereas crural shortening did not change during QB but progressively increased at 10% ETCO2. Maximal costal shortening during electrophrenic stimulation was constant at 40% LFRC during recovery, although maximal crural shortening increased from 23 to 32% LFRC. Minute ventilation, tidal volume, and transdiaphragmatic pressure at 10% ETCO2 increased progressively after thoracotomy until postoperative day 28. Our results suggest there is profound diaphragmatic inhibition after thoracotomy and crystal implantation in sheep that requires at least 3-4 wk for stable recovery.

Animals↗
PubMed1989

[Development of an ultrasonic system for the recanalization of coronary arteries].

We have devised an electro-acoustic system for the production and propagation of ultrasounds. With this system, linear vibrations can be transmitted through guides that are routinely used for coronary dilatation. Experiments performed on anatomical specimens have shown that ultrasounds are effective in destroying atheromatous formations. In addition, we tested this effectiveness with a setting that modelled the use of this system on the coronary vessels in terms of prerequisites: presence of a carrying catheter, aqueous environment, attention to vascular sinuosities and protection of arterial walls. The biological safety of low-frequency ultrasounds was tested in vitro and in animals. In view of these preliminary results, the subsequent development of an electro-acoustic system to be used in man seems to be justified.

Animals↗
PubMed1988

Diagnosis of primary cardiac sarcoma. Report of 4 cases and review of the literature.

The authors report the most extensive series of malignant primitive cardiac tumours. The patients presented with pericarditis in three cases and with a ventricular rhythm disorder in one patient. The diagnosis was made by non-invasive imaging techniques in three of the four. Angiography was carried out in three cases and was the determining diagnostic procedure in one. Diagnosis of the cardiac tumour was made prior to death in all cases. A histological diagnosis was obtained surgically in two cases. From the therapeutic viewpoint, surgical excision followed by chemotherapy and/or radiotherapy may prolong life. The average survival period of our patients was 11 months. The prognosis appears to be better after early surgical intervention. In view of the variability of the clinical features of cardiac sarcomas, cardiac computed tomography scanning is a valuable complement to cross-sectional echocardiography and, in our opinion, essential for early diagnosis.

Adolescent↗
PubMed1988

[Remote results of aortic valve replacement with the St. Jude medical prosthesis].

The St Jude Medical prosthesis on the aortic valve was evaluated in a 7-year prospective study which involved 49 patients. Survivors were followed up for 2,577 patient-months, meaning a mean follow-up of 5 years per patient and a minimum follow-up of 4 years per patient. The overall survival rate at 6 years was 79.6 +/- 5.7 p. 100. All deaths occurred during the first two years, and none of them was ascribable to the prosthesis. The left ventricular systolic and diastolic echocardiographic diameters were significantly greater in the patients who died. The linear rate of thromboembolic accidents was 0.93 p. 100 per patient-year, and that of accidents due to anticoagulants was 3.26 p. 100 per patient-year. The probability of freedom from all complication at 6 years was 71 +/- 9 p. 100. In the totality of patients, 10.2 p. 100 required pacemaker implantation; these patients had aortic stenosis exclusively, and all were alive at 7 years. The quality of live, assessed during consultations, was altered in one-half of the survivors. The good results obtained with the St Jude Medical prosthesis are marred by a high initial mortality rate, notably in patients with left ventricular enlargement, by the frequency of accidents due to anticoagulants and by the mediocre quality of life of survivors.

Actuarial Analysis↗
PubMed1988

[Development of left ventricular function following aortic valve replacement].

Changes in left ventricular function were evaluated in twelve patients with aortic valve stenosis and in eleven patients with aortic valve regurgitation in order to find out whether the results obtained soon after aortic valve replacement persisted over a long period. All patients had been provided with a St-Jude Medical valve. Evaluation included electrocardiography, radiography of the chest, phonocarotidography and echocardiography and was performed preoperatively, then three months and five years on average in each patient after surgery. In patients with aortic valve stenosis, the left ventricular mass clearly regressed during the first three months (p less than 0.01) and continued to regress, albeit not significantly, over five years. In patients with aortic valve regurgitation, the left ventricular volume and mass regressed significantly during the first three months and remained normal for five years. No significant variation in systolic performance was observed in both groups. In spite of good overall results, 26 p. 100 of the patients had an unfavourable long-term outcome as they developed major left ventricular dilatation. Nos prosthesis dysfunction was observed, and the St Jude Medical valve caused little obstruction. Thus, with this little obstructive prosthesis the postoperative improvement obtained persisted for five years in most cases of aortic valve stenosis or regurgitation.

Aortic Valve Insufficiency↗
PubMed1985

[Sarcoma of the heart. Apropos of 2 cases].

Sarcoma of the heart is a very rare condition. We present here two cases with very different clinical expression. The first patient, a 15-year old girl, presented with extremely severe ventricular arrhythmia, whereas the second patient, a 63-year old woman, mainly had signs of congestive cardiac failure. A diagnosis of cardiac tumour was made in the first case on the basis of ultrasonographic results which clearly showed the tumour developed from the walls of the left ventricle. In the second case, the tumour involved the right ventricular wall, the deformation of which was undetected by ultrasounds and only suspected at angiography. Both patients died rapidly, and the diagnosis of sarcoma was confirmed at post-mortem examination.

Adolescent↗
PubMed1984

Lithium causing a serious sinus-node dysfunction at therapeutic doses.

The cardiovascular effects of lithium have been indexed in literature since 1900, most frequently in cases of intoxication. We recently studied the exceptional case of a patient showing a serious sinus node dysfunction during lithium treatment. The serum lithium levels were always within the therapeutic range. After two endocardial explorations and withdrawal of lithium, we found that the sinus node dysfunction was due to lithium and reversible after withdrawal of it. Some ignored dysfunctions could exist with a regularly controlled treatment.

Ajmaline↗
PubMed1984

Serious sinus node dysfunction caused by therapeutic doses of lithium.

We studied an exceptional case of a patient showing serious sinus node dysfunction during lithium treatment with levels constantly within the therapeutic range. After two endocardial explorations we found that the sinus node dysfunction was due to lithium and reversible after its withdrawal.

Bradycardia↗
PubMedDate not supplied

[Hemodynamic effects of quinacainol administered via an intravenous route. Study in patients with normal left ventricular function].

The haemodynamic effects of a new antiarrhythmic drug quinacainol (RP 54272) were evaluated in 12 untreated patients with normal left ventricular function referred for diagnostic cardiac catheterisation. The haemodynamic data were obtained before, 5 and 25 minutes after the injection of the drug (0.21 mg/kg/min during 6 minutes). A slight decrease of cardiac contractility indexes was constantly observed: dp/dtmax decreased (-15%) in all patients (p less than 0.05), with no concomitant change of left ventricular pressure or left ventricular end diastolic volume with respect to control values. Cardiac output and left ventricular ejection fraction did not change significantly. Heart rate increased in all patients from 74.3 +/- 9.8 to 79.9 +/- 8.6 beats per minute after 5 minutes (paired t test p less than 0.05), and was 79.8 +/- 9.0 beats per minute after 25 minutes. Systemic arterial resistance increased in 7 patients due to a reflex adrenergic discharge. The interpretation of the haemodynamic data was difficult in 3 cases due to systemic vasodilatation, which was poorly tolerated in one patient. The contribution of vagolytic reaction and adrenergic reaction to the negative inotropic effects of the drug must be evaluated before giving in to patients with impaired left ventricular function.

Adult↗