Biomedical subjects
Publications and source records attributed to M Dahan.
The authors report a standardised comparison between MRI, CT and Tomography, in 30 cases of tracheal lesions (postintubation, tumors, external compressions and invasions). They conclude on the superiority of MRI because of its multiplanar visualisation, its soft-tissue contrast resolution and its capability to differentiate inflammatory granuloma.
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Hypertension is a condition which demonstrates the relationship between the properties of the left ventricle and arterial system. The spectrum of aortic impedence expresses the principal factors which oppose LV ejection into the initial aorta: 1) capacitive forces related to the viscoelastic properties of the arterial wall, directly proportional to its rigidity, 2) forces of inertia which increase with the acceleration of the blood and which are inversely proportional to the aortic cross sectional area, 3) reflection. With respect to a stroke volume which is usually normal, hypertension is characterised by: 1) an increase in mean aortic pressure (MAP), 2) with respect to the increase in MAP, an increase in systolic, late systolic and differential pressures. These changes in the level and morphology of aortic pressure are due to: a) the increase in systemic arterial resistances, a continuous expression of the spectrum of the module, b) an increase in the elastic forces (increased rigidity of the aorta related to increased pressure and structural wall changes) usually insufficiently compensated by a decrease in the inertial forces (aortic dilatation), c) an earlier return of the reflected pulse wave, well before the end of the anterograde wave. Overall, there is a relationship between the mass, the geometry (concentric hypertrophy) and pump function of the left ventricle and the properties of the arterial system expressed in terms of pulse wave velocity, characteristic impedence or the late systolic pressure/stroke volume ratio. The relationship is much closer than that of the properties of the LV and aortic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
We report a case of large tracheal (cervical thoracic) rupture after using an endotracheal tube, which needed to be repaired via a double surgical approach: cervicotomy and right thoracotomy. To our knowledge, no similar cases have been previously reported in the medial literature.
Abnormalities in the diastolic function of the left ventricular pump are the common determinant and, above all, the earliest manifestation of all forms of chronic left ventricular failure, whether or not the left ventricular systolic function is abnormal. Congestive signs, in particular, are directly related to abnormalities of ventricular filling. Primary diastolic dysfunction is the cause of left ventricular failure in about 40 p. 100 of the cases, but it may also be observed in almost all cardiopathies. In myocardial ischaemia the pressure-volume relation is displaced upwards owing to a slowed down, inhomogeneous and incomplete relaxation. Left ventricular hypertrophy, whether it is due to excessive pressure (arterial hypertension, aortic stenosis) or reflects a primary hypertrophic cardiomyopathy, is associated with a slowing down of ventricular relaxation and a reduction of left ventricular diastolic distensibility, even though the ventricular pump systolic function remains normal for a long time. Outside alterations in the distensibility of the ventricular muscle, ventricular dilatation alters ventricular filling by forcing the ventricle to function on the vertical part of its diastolic pressure-volume relation. Nowadays, the aged hearts is the most frequent cause of heart failure with normal systolic function. In all cases dysrhythmias and atrioventricular desynchronization act as aggravating factors. Treatment is often difficult since positively inotropic drugs or arterial vasodilators frequently have a modest or even deleterious effect.
The aims of the study were (1) to describe the consequences of aging and hypertension on left ventricular geometry and physical properties of the aorta, (2) to study interactions between some physical properties of the aorta and left ventricular geometry in normal (NT) and hypertensive patients (HT) using Doppler echocardiography. Forty-five healthy normotensive subjects (age range 21 to 84 years) and 20 untreated sustained hypertensive patients (age range 20 to 70 years) were studied. We measured (1) resting arterial blood pressure with a Dinamap, (2) left ventricular radius (r), thickness (th), mass (LVM), th/r ratio and aortic diameter (AD) by M-mode echocardiography with 2D control, and (3) pulse wave velocity (PWV) in the descending thoracic aorta from aortic velocity tracings recorded by pulsed wave Doppler in the isthmus and near the diaphragm. The PWV/AD ratio was derived. In hypertensive patients, blood pressure, PWV, AD, PWV/AD, th, th/r and LVM were significantly increased compared with normal subjects at a similar age. In normal subjects, PWV, AD, PWV/AD, th, r, th/r and LVM correlated significantly to age. In both groups, th/r ratio was significantly related to PWV and PWV/AD. The Doppler echocardiographic method of PWV measurement is feasible, reproducible and gives similar results to other methods, especially the invasive haemodynamic method. Doppler echocardiography is an adequate method to study left ventricular geometry and some physical properties of the aorta. It can be used to assess the consequences of aging and hypertension on both left ventricle (concentric hypertrophy) and aorta (increase of aortic stiffness).
Conservative techniques with insertion of a subcutaneous implant have the advantage of being simple to perform but the frequent disadvantage of a poor result. The authors present two more radical techniques used in chest surgery: modelling osteochondroplasty and resection of the deformed sternocostal plate and replacement by a prosthesis. The indications are described together with the very satisfactory results with no major complications obtained in a series of 13 cases.
Invasive cardiac catheterisation remains the reference technique for the evaluation of the effects of vasodilator drugs in cardiac failure. The arterial, venous or mixed site of action can be determined. Venous vasodilators induce a fall in left ventricular end diastolic volume (EVD), left ventricular end diastolic pressure (EDP), and stroke volume (SV). Arterial vasodilators decrease left ventricular end systolic pressure (ESP), end systolic volume (ESV) and increase the stroke volume. Mixed vasodilators associate the effects of both, leading to a fall in left ventricular filling pressures and an increase in SV. It is not always easy to determine the exact site of action of a given vasodilator drug. Arterial vasodilatation can only be confirmed when peripheral arterial resistances and systemic blood pressure decrease simultaneously. Venous vasodilatation can only be formally confirmed by using other techniques such as pethysmography. Hemodynamic investigations have other fundamental objectives in the evaluation of the effects of a vasodilator, especially the demonstration of possible associated positive inotropic effects. This would be relatively easy in the case of a venous vasodilator which induces an increase in SV but more difficult in the assessment of an arterial vasodilator. Studying the distribution of regional blood flow after the administration of a vasodilator is another important objective of cardiac catheterisation. Although coronary flow can be studied properly, the hemodynamics of other regions can only be assessed approximatively. The phenomenon of tolerance at an early or late stage of vasodilator therapy can also be demonstrated by hemodynamic monitoring.
Chronic cardiac failure with normal left ventricular systolic function is observed in conditions without ventricular failure (pericardial adiastole, obstruction to intracardiac blood flow) or with ventricular failure due to isolated abnormalities of left ventricular filling. These forms of cardiac failure are often subject to diagnostic error. However, it is essential that they be recognised because traditional therapy must be used with caution and because of the efficacy of treatment of the underlying pathology whenever this is possible.
In 16 insulin-dependent diabetic patients, 36 +/- 8 years old with no microangiopathy, hypertension or coronary artery disease, and 16 healthy control subjects matched for sex, age and body surface area, the following parameters were obtained by Doppler-echocardiography: (1) end-diastolic left ventricular thickness and radius; (2) aortic pulse wave velocity; (3) mitral flow with measurement of early and late (atrial) peak velocities (E and A), pressure half-time and the velocity time integrals of the entire mitral curve and of the atrial wave; and (4) isovolumic relaxation time (i.e., the time between aortic closure and the mitral opening signals recorded simultaneously by continuous-wave Doppler). Heart rate and systolic blood pressure were not different in the 2 groups. Aortic pulse wave velocity and the wall thickness to radius ratio were significantly increased in the diabetic patients compared to the controls. E was significantly reduced whereas A/E, pressure half-time, the atrial contribution to the left ventricular filling (i.e., the ratio of the atrial velocity time integral to the mitral velocity time integral) and the isovolumic relaxation time were significantly increased in the diabetic group versus the control subjects. Lastly, 11 of 16 diabetic patients (69%) had at least 2 of the following abnormalities: A/E greater than 0.71, an atrial contribution to the left ventricular filling greater than 0.25, a pressure half-time greater than 50 ms and an isovolumic relaxation time greater than 88 ms. No correlations were found between the wall thickness to radius ratio, aortic pulse wave velocity and the filling indexes.(ABSTRACT TRUNCATED AT 250 WORDS)
Nicorandil is a new compound that has shown potent vasodilator activities on venous and arterial beds in experimental pharmacology. This study was designed to evaluate the magnitude and the time course of hemodynamic effects of different doses of nicorandil in congestive heart failure. Eleven patients with severe congestive heart failure (New York Heart Association class III or IV), with a cardiac index less than 3 liters/min/m2 and a pulmonary wedge pressure greater than 15 mm Hg were enrolled in the study. Three patients had ischemic dilated cardiomyopathy and 8 had idiopathic dilated cardiomyopathy. Hemodynamic assessments were performed by right-sided cardiac catheterization (Swan-Ganz catheter) with cardiac output determination (thermodilution) at baseline and from 30 minutes to 12 hours after single oral administration of nicorandil; 3 patients were given 40 mg, 6 patients 60 mg, and 2 patients 80 mg. Maximal hemodynamic changes were observed 30 minutes after dosing and remained statistically significant at 3 hours. Thirty minutes after drug administration, pulmonary wedge pressure decreased 34 +/- 6%, cardiac index increased by 55 +/- 13% and diastolic and mean arterial pressures decreased by 15 +/- 3% and 9 +/- 2%, respectively, from baseline values. The decrease in systolic blood pressure was slight (5 +/- 2%) and not statistically significant. Calculated systemic vascular resistances decreased by 36 +/- 6% and heart rate did not significantly change. Nicorandil was well tolerated. Thus, the results of this first study of nicorandil in congestive heart failure demonstrated the unloading action of this compound on the failing heart, leading to an improvement in cardiac function; further investigation of nicorandil in this therapeutic area is needed.
UNLABELLED: We studied 16 normotensive insulin-dependent diabetic patients (D) (11 males + 5 females) aged of 25-51 years old (mean = 35 +/- 6) with a good glycemic control, without microangiopathy and previous heart disease and 16 healthy control of 25 subjects (C) matched for sex age and body area. We measured: Systolic blood pressure (SBP) with a mercury sphygmomanometer, aortic diameter (AD), end diastolic left ventricular radius (r) and wall thickness (Th) by Echocardiography TM with 2 D echo control, the pulse wave delay (PWD) by measurement of time between the feet of aortic velocity tracings, recorded in the isthmus and near the diaphragm, Sternal length (L). Parameters calculated were: the ratio th/r. The pulse wave velocity PWV = L/PWD and the ratio PWV/AD which represents an indirect index of aortic characteristic impedance. (table; see text) PWV and the radio Th/r are significantly increased in diabetic patients as compared to the control group. Th/r is not significantly correlated with PWV in the 2 groups. This lack of correlation could be explained in the control group by the small rang of values of PWV (5-7.3 ms-1) and Th/r (0.26-0.38). It is not the case in the diabetic group where values are widespread (PWD 5-10 ms-1 and Th/r 0.23-0.53). IN CONCLUSION: in normotensive young insulin-dependent diabetic patients studied by doppler echocardiography: aortic rigidity measured by the pulse wave velocity is increased. Th/r ratio is also increased but this change of left ventricular geometry is not related to aortic rigidity in this group of patients.
We have studied 12 sustained hypertensive patients (H) (9 men and 3 women) untreated and without other heart disease than a left ventricular hypertrophy, 37 to 70 years of age (mean 56 +/- 12) and 12 normotensive subjects (N) of the same sex and 35 to 77 years of age (mean 52 +/- 16 ans). We have measured 1) arterial pressure (AP) by a standard mercury sphygmomanometer, 2) diameter of ascending aorta (AD), end diastolic left ventricular radius (r) and thickness (Th) by M mode echocardiography with 2D echo control., 3) isthmus-diaphragm pulse wave delay (PWD) from aortic velocity curves recorded in the isthmus and diaphragm aortic crossing by pulsed doppler. We derived 1) the pulse wave velocity (PWV) as PW = SL/PWD where SL is the sternal length, 2) PWV/AD ratio as an indirect index of characteristic impedance, 3) Th/r and LV mass (m) according to Teichholz formula: (table; see text) In both groups 1) m is significantly correlated with SAP (r = 0.67 p less than 0.001), PP (r = 0.61 p less than 0.001), PWV (r = 0.52 p less than 0.01) but not with PWV/AD; 2) Th/r ratio is significantly correlated with SAP (r = 0.64 p less than 0.001), PP (r = 0.63 p less than 0.001), PWV (r = 0.53 p less than 0.001) and PWV/AD (r = 0.41 p less than 0.05). Relationship between PWV and age of H is linear (r = 0.75 p less than 0.001) and shifted at left of that of N which is also linear (r = 0.061 p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Thirty-eight cases of bronchioloalveolar carcinoma were selected on anatomico-pathological criteria and analysed both radioclinically and histologically. At histology, this type of carcinoma is characterized chiefly by the growth of malignant cells along the alveolar walls. Cytology, which determines the nature of these cells (pneumocyte II or Clara cell), is not specific but remains important as regards phylogenesis. The course of bronchioloalveolar carcinoma gives a better understanding of its mode of propagation. Actuarial curves show that all patients with a diffuse carcinoma die very rapidly, whereas the survival rate of those who have localized lesions is 60% at 5 years. Moreover, the time required for dissemination to take place is long in assessable cases. This means that the condition should be diagnosed at an early stage on the presence of crepitant rales, on their air bronchogram at CT and on transparietal needle biopsy under CT. The chances are that early excision will result in cure.
The authors present the results of a preliminary study designed to define the surgical indications in diffuse pulmonary emphysema based on the data of haemodynamic investigations. This series consists of 10 patients identified for disabling dyspnoea, diffuse emphysema and dynamic expiratory compression documented by the data of right micro-catheterisation by a DEP/DIP ratio greater than 2. The surgical operation consisted of reduction in the lung volume, the results of which were defined by pre- and postoperative examinations. In this way, it is possible to distinguish 3 groups of patients: one group was markedly improved, another was moderately improved and the third group continued to deteriorate analysis of the results suggests the determinant role of dynamic factors, in particular haemodynamic factors. The role of the diaphragm is demonstrated by modifications in its radius or curvature.
An analysis of 7 cases of thoracic actinomycoses were recorded over 25 years enabling a better appreciation of the radiological and clinical criteria: a low grade pneumonia with haemoptysis and an alteration in the general physical state, with pseudo-tuberculous radiological images or "pseudo-tumoral" with bronchograms and parietal wall disease. This clinical picture calls for endoscopic biopsies or biopsies under CT scanning for a study combining both histological and bacteriological diagnosis on appropriate culture media, enabling an exploratory thoracotomy to be avoided, the latter the classic method of diagnosis. This approach should reduce the number of pneumonias which are not confirmed bacteriologically which are sensitive to the usual antibiotics and determine better the true frequency of actinomycoses.
Throughout the course of chronic congestive heart failure cardiac and peripheral compensatory mechanisms are at play, most of them under the influence of the neuroendocrine system. The reserves of heart rate and contractility are regulated essentially by the noradrenergic system (NAS), but this mechanism is partial and transient owing to the gradual decrease in the density and sensitivity of myocardial beta-adrenergic receptors induced by overstimulation. Adaptation of the heart to exercise may be reduced. This escape phenomenon is also observed with almost all cardiotonic drugs which interfere with cyclic adenosine monophosphate (cAMP), in contrast with the paradoxically favourable effects of beta-blockers in small doses or of drugs that are both agonists and antagonists of beta-adrenergic receptors. The mechanisms which contribute to the induction of left ventricular hypertrophy are imperfectly known. The noradrenergic system and the renin-angiotensin-aldosterone system (RAAS) are probably not the only ones involved. The setting in action of Frank-Sterling heterometric regulation, at first during exercise then permanently, requires an increase in filling pressure obtained by venous constriction (predominantly controlled by the NAS) and, mostly, by an increase in circulating blood volume. NAS and RAAS intervene in the kidneys to produce water-and-salt retention.(ABSTRACT TRUNCATED AT 250 WORDS)
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