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Biomedical subjects

M Dahan

Publications and source records attributed to M Dahan.

At least 109 records · Page 6Linked to original sources
PubMed1988

[Physical properties of the aorta and left ventricular geometry evaluated by Doppler echocardiography in normal subjects].

UNLABELLED: In 45 normotensive subjects (21-84 years) we simultaneously measured: 1) arterial pressure (AP) according to guidelines of the World-health-organization; 2) left ventricular (LV) wall thickness (WT) and antero-posterior radius (r), aortic diameter (AD) by M-mode echo with 2D echo control; 3) isthmus--diaphragm pulse wave delay (PWD) by measurement of time, between the foot of aortic velocity curves, respectively in the isthmus and near the diaphragm; 4) sternal length (L). We derived WT/r ratio, pulse wave velocity (PWV) as the ratio L/PWD, the product AD X PWD and the PWD/AD. RESULTS: AP, WT/r, PWD, PWV, AD, AD X CFD, PWD/AD are significantly correlated with age (respective r = 0.30, p = 0.05; r = 0.61, p less than 0.001; r = -0.67, p less than 0.001; r = 0.73, p less than 0.001; r = 0.61, p less than 0.001; r = -0.49, p less than 0.001; r = 0.52, p less than 0.001. WT/r is significantly correlated with PWD (r = -0.52, p less than 0.001); PWV (r = 0.50, p less than 0.001); AD (r = 0.44, p less than 0.03); AD X PWD (r = -0.38, p = 0.01) and PWD/AD (r = 0.35, p less than 0.02) but not systolic AP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[Long-term survival of surgically treated lympho-epithelial thymomas].

The authors report the results of a multi-centre trial on 500 cases of lymph-epithelial thymoma (TLE) treated by 14 surgical teams. Most typically a tumour of the adult in the fifth decade, occurring most commonly in women (60%), one in every two cases of TLE occurs in auto-immune disease: usually myasthenia. Most often (3 times out of 4) the disease is latent and occupies the middle (40%) or superior mediastinum (30%). In 15% of cases the pulmonary radiograph is normal. Radical surgery is possible in 75% of cases, otherwise it is incomplete or even reduced to a simple biopsy. The 15 year prognosis obtained using actuarial survival curves is based on the surgical-anatomical classification of the study group of thymic tumours (GETT) giving: for stage I: a survival of 80% for stage II to IVA of 40% and for stages III to IVB of around 10%. Finally it should be noted that existence of a recurrence after a complete surgical excision (stage I) poses the problem of post-operative radiotherapy and the associated total thymectomy. Also, the identical prognosis after biopsy or incomplete surgery (IIIA and IIIB) with an increased morbidity for incomplete surgery. Finally the confirmation that pleural involvement (IVA) is not as adverse a factor as one would have supposed.

Adolescent↗
PubMed1987

[Left ventricular hypertrophy. Advantages and disadvantages].

The increase in left ventricular myocardial mass is a mechanism of adjustment of the ventricular pump to a normal process, such as growth or sports, or a pathological process (mechanical overload or cardiomyopathy). The associated geometrical changes tend to normalize systolic performance and/or strain--one of the main determinants of myocardial metabolic requirements. When left ventricular hypertrophy is inadequate quantitatively, geometrically and functionally, and when contractility and preload reserves are exhausted, the systolic performance of the ventricular pump becomes narrowly dependent upon the increased systolic strain. some types of "pathological" hypertrophy may ultimately result in alteration of myocardial intrinsic properties during contraction, relaxation and/or extension, and this in turn may induce or aggravate ventricular failure. The causes of left ventricular hypertrophy are imperfectly known, the views most commonly held being metabolic imbalance of the myocardium due to increased demands, and reduction of coronary reserve and exchange capacities.

Cardiomegaly↗
PubMed1987

[Total pericardectomy. Exceptional treatment for recurrent idiopathic cortico-dependent pericarditis].

The authors report a case of definitive treatment of idiopathic relapsing pericarditis by total pericardectomy in the absence of signs of constrictive pericarditis after a 15 month period marked by multiple invalidating recurrences and the development of dependence on corticosteroid therapy. The indications of total pericardectomy must be discussed in these exceptional cases of failure of medical therapy in idiopathic relapsing pericarditis.

Humans↗
PubMed1987

[Evaluation of bidimensional echography in the etiological orientation of pericardial disease. Apropos of 39 anatomo-echographic comparisons].

Echocardiography provides a firm diagnosis of pericardial effusion and evaluates its repercussions on the cardiac cavities. The images obtained with two-dimensional echocardiography are of such quality that the anatomical lesions can be analyzed, but the predictive value of this examination for the aetiological diagnosis has not yet been established. To investigate this point we have compared the images recorded in 39 episodes of pericardial disease with the corresponding anatomical data provided by surgery (n = 38)) or necropsy (n = 1) less than 48 hours after the ultrasonic examination. In one case, the purely solid nature of the pericardial content, suspected on the presence of an echo-filled cavity with adherent membranes, was confirmed at surgery. Conversely, the totally or partly liquid nature of the effusion was ascertained whenever the two pericardial membranes were separated by an echo-free cavity in at least one portion of the region examined, and there was no false-positive result (n = 38). The images obtained could be compared with the anatomical lesions in 28 out of 38 cases of partly or totally liquid pericarditis. The pericardial cavity was entirely echo-free in 12 of these cases, and this was confirmed by the anatomical examination, except in one case where epicardial nodules were found at surgery. Abnormal intrapericardial images were detected in the other 16 echocardiographic examinations, viz.: round masses in 2 cases, linear echoes in 2 cases and mattress-like deposits in 12 cases. In 9 of these 16 cases corresponding intrapericardial formations were discovered at surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

[Reduction of auricular fibrillation and tachycardia using intravenous flecainide].

Fifty-one consecutive patients with atrial tachycardia [atrial fibrillation (FA) 37, atrial flutter (Fl) 10, tachycardia (TSA) 4] received a single 2 mg/kg dose of flecainide injected intravenously over 5 to 10 minutes. Patients over 75 years of age or presenting with heart failure or disorders of conduction were excluded from the study. Sinus rhythm was restored during the injection or within the following 5 minutes in 15 patients (FA 12, Fl 1, TSA 2). The most frequent side-effects were visual disorders (5 cases) and moderate prolongation of QRS (all cases). Five patients had more pronounced disorders of conduction, but none developed heart failure. Reduction was obtained in 12 of the 18 patients whose arrhythmia had lasted for less than 8 days, against only 3 of the patients whose arrhythmia was more than 8 days old. Drug-induced reduction always failed in patients with left atrial dilatation (greater than 45 mm at echocardiography). An increase in the ventricular rate of unreduced flutter was observed in only one patient. Plasma flecainide levels were high (1.5 and 5.5 mg/l) at the end of the injection, but they fell to the therapeutic range within less than 10 minutes. Flecainide therefore appears to be effective in reducing recent atrial fibrillation on a non-dilated atrium. In cases with disorders of conduction, altered ventricular function or flutter, the therapeutic risk is such that another method of conversion should be used.

Adult↗
PubMed1987

[Drug treatment of left ventricular insufficiency. Current aspects].

The medical treatment of left ventricular failure classically relies upon the use of diuretics with or without digitalis. The recent arrival of vasodilators allows for both an improvement in the quality of life as well as a prolongation of survival for people in heart failure. The "new" positive inotropic agents which can be used orally in the longterm have not yet given the results which were anticipated. The prognosis of left ventricular failure remains poor, underlining the importance of preventive treatment and in the last resort the possibility of cardiac transplantation.

Cardiotonic Agents↗
PubMed1986

[Left ventricular hypertrophy. Advantages and drawbacks].

The increase of the muscular mass of the left ventricle represents, for the ventricular pump, a mechanism of adaptation to a normal process (growth, sport, etc.) or a pathological process (mechanical overload or cardiomyopathy). The geometrical variations which are associated, tend to normalize the performances and/or the systolic constraints, determining elements of the metabolic needs of the myocardium. If left ventricular hypertrophy is not quantitatively, geometrically and functionally adequate and if the contractility and precharge reserves become exhausted, the systolic performance of the ventricular pump is altered and becomes extremely dependent upon the systolic constraints which are then increased. It may be difficult to take into consideration an insufficiency of the contractility of the ventricular muscle in front of clinical signs of cardiac insufficiency which is conditioned by abnormalities in the filling of the ventricular pump. In addition, some "pathological" hyperthophies may secondarily induce an alteration of the intrinsic properties of the muscle (during its contraction, relaxation an/or extension), susceptible to induce or aggravate a ventricular insufficiency. The causes remain uncertain, since a metabolic imbalance of the myocardium by increase of the needs as well as a decrease of the coronary reserve and the exchange capabilities are commonly accepted. What are the mediators of these mechanisms of quantitative, geometric adaptation and also--at least in some animals--structural adaptation (isoenzymes of myosin)? Why do they seem, at times, strangely absent or quickly out-of-date, or sometimes excessive, with all the drawbacks specific to hypertrophy? The answer to these questions would perhaps represent a new therapeutic approach to left ventricular insufficiency.

Adaptation, Physiological↗
PubMed1985

[Coronary and renal circulation in patients with cardiac failure after converting enzyme inhibitors].

The cardiac output and its peripheral distribution must fulfill the metabolic and/or functional requirements of the different organs. The various techniques used to measure blood flow rates in the coronary and renal arteries provide much information on this point, but they do not tell us all we would like to know about the distribution and "utilization" of these flows in tissues. In normal subjects the myocardial oxygen consumption is not markedly different from the renal oxygen consumption, but the mechanisms that regulate the coronary and renal circulations are not the same. The flow rate in the coronary vessels is about 10% of the cardiac output, the arteriovenous oxygen gradient is superior to 10 vol % and regulation is metabolic. In the renal vessels, which are primarily "functional", the flow rate is about 25% of the cardiac output and the arteriovenous oxygen gradient is inferior to 2 vol %. In heart failure patients, despite reduced cardiac output the blood pressure is kept normal for a long time by vasoconstriction of the arterioles, a process which involves, at least partly, the renin-angiotensin system. The vasoconstriction predominates in some circuits (the renal flow rate is less than 15% of the cardiac output) and spares the "privileged" circuits (the coronary flow rate is more than 15% of the cardiac output). Under the influence of angiotensin converting enzyme inhibitors, the cardiac output increases and its distribution is modified. The coronary flow rate remains stable or is reduced in proportion to the decrease in myocardial oxygen consumption, the metabolic regulation is preserved and there is no "coronary steal". The percent increase in renal flow rate is usually superior to that of the cardiac output. This peripheral redistribution of coronary and renal blood flow rates in heart failure patients after treatment with converting enzyme inhibitors seems to correspond to the physiological purposes of the two regional blood flows.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1985

Hemodynamic and coronary effects of molsidomine at basal state, during atrial pacing, and during cold pressor test in patients with stable angina pectoris.

Heart rate (HR), cardiac output (CO), coronary sinus blood flow (CSF), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), mean arterial (MAP), and coronary arteriovenous difference for oxygen (AVDcO2) were measured in patients with stable angina pectoris without cardiac failure before and 40 to 60 minutes after administration of 2 or 3 mg of molsidomine. In 20 patients these measurements were made in basal state during spontaneous rhythm. In eight of these patients (including three receiving beta blockers) the measurements were made during atrial pacing. In eight other patients, all receiving long-term beta-blocker therapy, the measurements were made during cold pressor test. At the basal state in spontaneous rhythm, a gradual reduction in the LVSP to 70% or less of its initial value was observed in four patients receiving 3 mg of molsidomine (two of whom received beta-blocker treatment). The LVSP was immediately restored by vascular filling. In the 16 other patients molsidomine decreased LVSP, LVEDP, MAP, CO, and double product (DP = LVSP X HR). The AVDcO2 was unchanged. CSF and myocardial oxygen uptake index (MVO2 = CSF X AVDcO2) were decreased. During atrial pacing, hemodynamic and coronary effects were similar to those seen in the basal state. During the cold pressor test, the increases in LVSP, MAP, and LVEDP were significantly reduced by molsidomine. The variations in CSF and coronary resistance (MAP/CSF) were also significantly different after administration of molsidomine, with better metabolic regulation of the coronary circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Changes in left ventricular performance during chronic pressure or volume overload: importance of physical properties of the arterial system.

The present study was aimed at evaluation of changes in systolic and diastolic left ventricular function during chronic pressure of volume overload, in comparison with normal subjects. Sixty-two patients were included: group 1 was composed of 25 normal subjects, group 2 was composed of 20 subjects with essential hypertension, and group 3 was composed of 17 subjects with aortic regurgitation without congestive heart failure. Cardiac output, aortic and left ventricular pressures (micromanometers), ventricular volume and ascending aortic radius (cineangiography), ejection fraction (EF), mean velocity of fiber shortening (VCF), ventricular mass (m), and the ratio m/EDV (EDV, end diastolic volume) were determined. Also measured were maxima for end systolic pressure (ESP), end systolic stress (ESS), and end systolic volume (ESV) and radius (ESR), as well as the modulus of left ventricular chamber and muscle stiffness (method of Gaash et al.) (1) and characteristic impedance of the ascending aorta (Zc). In hypertensive patients, m and m/EDV were increased, as was the ESP/ESV ratio, whereas EF and VCF were not modified and the ESS/ESR was normal or sometimes decreased. The systolic "pump" function thus appeared to be increased, whereas the muscle function appeared normal or decreased. The moduli of left ventricular chamber stiffness and muscle stiffness were increased. Zc was increased because of a greater pulse wave velocity, although aortic radius was larger. A close relationship was found between Zc and the ratio m/EDV. In patients with aortic regurgitation, the increased left ventricular mass was closely related to the regurgitant fraction (RF). The m/EDV ratio was normal. EF was unmodified and VCF and the ESP/ESV ratio were decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

[Non-invasive measurement of cardiac output by Doppler echography].

In this review paper the theoretical and technical bases of cardiac output measurement in the thoracic extracted from the literature and obtained by the authors themselves are summarized. The main physiological assumptions required for calculations (flat velocity profile in the aorta) and the main technical options (pulsed or continuous emission of ultrasounds, spectral or simplified Doppler signal analysis, evaluation or non-evaluation of the angle of incidence by two-dimensional imaging, echographic mode of measurement of the aortic diameter) are discussed. The need for controlled studies of each equipment and method on large populations of patients is emphasized.

Adult↗
PubMed1984

[Castleman's tumor with thoracic localization. Apropos of a case].

Castleman tumor usually presents as a mediastinal tumor which is never accurately diagnosed before surgery. Pathological findings and postoperative course establish the benign nature of this tumor. However, plasmocytic forms with prominent hematologic manifestations may be difficult to distinguish from a malignant lymphoma or thymoma. Differential diagnosis is all the more important that no complementary postoperative treatment is indicated in benign lymphoid tumors.

Adult↗