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Biomedical subjects

P Merlet

Publications and source records attributed to P Merlet.

At least 19 recordsLinked to original sources
PubMed1992

Effects of calcitonin gene-related peptide on cardiac contractility, coronary hemodynamics and myocardial energetics in idiopathic dilated cardiomyopathy.

This study was performed to examine the effects of calcitonin gene-related peptide on cardiac function and coronary circulation in patients with heart failure. Synthetic human calcitonin gene-related peptide was infused in the left main coronary artery of 9 patients undergoing cardiac catheterization at different doses corresponding to incremental infusion rates of 15, 50, 150 and 600 pmol.min-1. No hemodynamic change was observed in response to administration of the 2 lowest doses. The 2 highest doses induced an increase in cardiac index and a decrease in systemic arterial pressure. The infusion of 600 pmol.min-1 resulted in a decrease of mean systemic arterial pressure (86.8 +/- 6.5 to 71.8 +/- 4.9 mm Hg; p less than 0.01), and an increase in both cardiac index (2.1 +/- 0.1 to 3.1 +/- 0.17 liters.min-1.m-2; p less than 0.01) and heart rate (87 +/- 3.7 to 101 +/- 6.1 beats.min-1; p less than 0.01). These hemodynamic changes were associated with a significant increase in plasma norepinephrine and epinephrine concentrations. Peak positive first derivative of left ventricular pressure did not change at any infusion rate. Left ventricular end-diastolic pressure decreased at the 2 highest doses associated with a decrease in plasma atrial natriuretic factor concentration (730 +/- 140 to 436 +/- 115 pg.ml-1; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Beta-adrenergic contractile reserve as a predictor of clinical outcome in patients with idiopathic dilated cardiomyopathy.

To examine the ability of beta-adrenergic contractile reserve assessment to predict the outcome of patients with heart failure, a prospective study was undertaken in 35 patients with idiopathic dilated cardiomyopathy and radionuclide ejection fraction below 40%. During right- and left-sided catheterization, right atrial and left ventricular (LV) pressures, peak positive LV dp/dt, cardiac index, and plasma norepinephrine and epinephrine concentrations were measured at baseline. After a left main intracoronary infusion of dobutamine (25 to 200 micrograms.min-1), beta-adrenergic contractile responsiveness was assessed as the net increase in peak positive LV dp/dt (delta LV dp/dt). After the initial examination, patients were treated with diuretics, digitalis, and angiotensin converting enzyme inhibitors and then followed-up. After a mean follow-up period of 13 +/- 7 months, two groups of patients were distinguished: those who responded to medical therapy (group A, n = 26) and those with clinical deterioration (group B, n = 9) leading to death (n = 4) or heart transplantation (n = 5). Initial peak positive LV dp/dt, LV end-diastolic pressure, cardiac index, and LV ejection fraction were better in group A than in group B (p less than 0.001). Initial plasma norepinephrine and epinephrine concentrations were significantly higher and delta LV dp/dt was lower in group B than in group A (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Relationship among neuropeptide Y, catecholamines and haemodynamics in congestive heart failure.

The relationship among neuropeptide Y (NPY), catecholamines and haemodynamics was assessed both at baseline and during inotropic intervention in patients with congestive heart failure. Eighteen patients with idiopathic dilated cardiomyopathy (left ventricular ejection fraction (LVEF) = 26 +/- 10%) underwent both right and left catheterization. Haemodynamic parameters were recorded at baseline and during dobutamine infusion. To measure norepinephrine (NE), epinephrine (E) (nmol.l-1: radioenzymatic assay) and NPY (pmol.l-1: immunoradiometric assay) plasma concentrations, blood samples were drawn from the femoral artery and from the coronary sinus, both at baseline and during dobutamine infusion. At baseline, NPY concentration were 2.15 +/- 0.97 pmol.l-1 in the femoral artery and 1.97 +/- 0.63 pmol.l-1 in the coronary sinus. Peripheral concentrations of NPY were, however, no different from those of patients without congestive heart failure: 2.4 +/- 2.7 pmol.l-1. Peripheral NE concentration was correlated to haemodynamic parameters: LVEF (r = -0.65; P less than 0.01), cardiac index (r = -0.54; P less than 0.05), LV end-diastolic pressure (r = +0.59; P less than 0.05), while peripheral NPY and E concentrations were not. Dobutamine improved haemodynamics, since cardiac index increased by 30% and LV end-diastolic pressure decreased by 40% (P less than 0.01). Peripheral NE concentration decreased from 6.48 +/- 4.5 to 4.82 +/- 2.69 nmol.l-1 (P less than 0.05) but there was no change in E (0.99 +/- 0.61 vs 1.04 +/- 0.74 nmol.l-1) or NPY concentrations (2.41 +/- 0.99 pmol.l-1). In the coronary sinus, neither NE nor NPY concentrations changed during dobutamine infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Myocardial beta-adrenergic desensitization and neuronal norepinephrine uptake function in idiopathic dilated cardiomyopathy.

Desensitization of myocardial beta-adrenergic receptors may result both from an impairment of the norepinephrine (NE) neuronal uptake function and from an increase in circulating NE concentrations. The respective role of these two mechanisms of desensitization was examined in 18 patients with congestive heart failure related to an idiopathic dilated cardiomyopathy. The neuronal NE uptake system was evaluated by [123I]metaiodobenzylguanidine (MIBG) scintigraphy. The desensitization level of beta-adrenoceptors was assessed as the net increase in peak positive left ventricular (LV) dP/dt during intracoronary dobutamine infusion. Arterial NE concentrations were determined at baseline. To obtain control values, we performed MIBG scintigraphy and determined baseline NE concentration in 12 normal subjects. Cardiac MIBG uptake was significantly decreased in patients as compared with controls. This decrease was related to the severity of the disease based on hemodynamic indexes. The inotropic response to intracoronary dobutamine infusion of heart failure patients correlated with both increased baseline NE concentration and diminished cardiac MIBG uptake (r = -0.63, p less than 0.01 and r = 0.73, p less than 0.001, respectively). These findings indicate that the desensitization process is related both to impaired neuronal NE uptake function and increased circulating NE concentrations. Moreover, a subset of 11 patients with moderate heart failure was identified who had diminished cardiac MIBG uptake but normal circulating NE concentrations. This suggests that impairment of the NE uptake function is an early mechanism of desensitization in idiopathic cardiomyopathy. Cardiac MIBG imaging may be a noninvasive means to assess severity of heart failure patients and may also be used to evaluate therapy effects on myocardial alterations of the adrenergic pathway.

3-Iodobenzylguanidine↗
PubMed1992

The value of pixel per pixel multiharmonic Fourier analysis to assess left ventricular function.

Left ventricular systolic and diastolic function can be assessed by peak ejection and filling rates and their time of occurrence. These parameters can be calculated using two different methods: from the global left ventricular time-activity curve analysed with a four harmonic Fourier fit and from each pixel time-activity curve analysed with two and three harmonics (the values being averaged over the left ventricular region of interest). In both cases, values were normalized for heart rate and end diastolic counts. A study was conducted in a series of 11 patients (six without and five with a previous myocardial infarction but a normal left ventricular function) examined at baseline and during an i.v. dobutamine infusion, at a dose known to increase both peak ejection and filling rates. During dobutamine infusion, analysis of global left ventricular time-activity curve demonstrated a statistically significant increase in both peak ejection and filling rates, but the local analysis showed a more significant increase of these parameters. To assess ventricular function, a local harmonic analysis can be used and appears to be a more sensitive approach than analysis of the global left ventricular time-activity curve. The local analysis provides spatial mapping and a histogram of the parameters which can be used as parametric images to describe systolic and diastolic function.

Dobutamine↗
PubMed1992

Prognostic value of cardiac metaiodobenzylguanidine imaging in patients with heart failure.

The prognostic value of 123I-metaiodobenzylguanidine (MIBG) imaging was compared with that of other noninvasive cardiac imaging indices in ninety patients (mean age = 52 +/- 7 yr) suffering from either ischemic (n = 24) or idiopathic (n = 66) cardiomyopathy. Patients had different measurements taken: cardiac MIBG uptake, radionuclide left ventricular ejection fraction, x-ray cardiothoracic ratio and echographic M-Mode data. Cardiac MIBG uptake was assessed as the heart-to-mediastinum activity ratio measured on the chest anterior view image obtained 4 hr after intravenous injection. The patients then had follow-up for 1-27 mo, at which time 10 patients had transplants, 22 had died and 58 were still alive. Data from patients with transplants were not used in the analysis, in which multivariate stepwise regression discriminant analysis showed that cardiac MIBG uptake was more potent to predict survival than other indices: H/M (p less than 0.0001), x-ray cardiothoracic ratio (p = 0.0017), echographic end-diastolic diameter (p = 0.0264) and radionuclide left ventricular ejection fraction (p = 0.0301). Moreover, multivariate life table analysis showed that cardiac MIBG uptake was also the best predictor for life duration: H/M (p = 0.0001), radionuclide left ventricular ejection fraction (p = 0.0098) and x-ray cardiothoracic ratio (p = 0.0139); echographic data were not useful. Thus, cardiac MIBG imaging may be helpful for heart transplantation decision making in patients with heart failure.

3-Iodobenzylguanidine↗
PubMed1991

[Neuroendocrine adaptations in chronic congestive heart failure].

Chronic congestive heart failure is typically accompanied by an abnormal production of vasoconstrictor antinatriuretic hormones and vasodilator natriuretic hormones. Decompensation occurs when the former prevail over the latter. These neuroendocrine abnormalities are increasingly taken into account to determine the prognosis and to decide on the best therapeutic approach in individual patients with chronic heart failure.

Adaptation, Physiological↗
PubMed1991

Ventricular function during the acute rejection of heterotopic transplanted heart: gated blood-pool studies.

Twenty patients who had undergone a heterotopic heart transplant were studied prospectively to determine the relationship between rejection and ventricular dysfunction assessed from gated blood-pool studies. A fully automated method for detecting ventricular edges was implemented; its success rate for the grafted left and right ventricles was 94% and 77%, respectively. The parameters, peak ejection and filling rates, were calculated pixel per pixel using a two-harmonic Fourier algorithm and then averaged over the ventricular region of interest. Peak filling and ejection rates were closely related with the severity of the rejection, while the left ventricular ejection fraction was not. Peak filling rates of both ventricles were the indices closely related to the presence of moderate rejection. Despite the low number of patients, these data suggested that gated blood-pool-derived indices of ventricular function are associated with ventricular dysfunction resulting from myocarditis rejection. Radionuclide ventriculography provides parametric data which are accurate and reliable for the diagnosis of rejection.

Algorithms↗
PubMed1991

Hemodynamic response to intracoronary infusion of atrial natriuretic factor in patients with normal or altered left ventricular function.

To assess the effects of atrial natriuretic factor (ANF) on cardiac function, synthetic human ANF was infused directly into the left main coronary artery of eight patients with congestive heart failure (CHF) and six subjects with normal left ventricular (LV) function (controls) who underwent cardiac catheterization. ANF infusion at the incremental rates of 60, 125, 400, and 800 ng/min induced a dose-related increase in plasma ANF concentrations in the coronary sinus, from 1,223 +/- 590 to 3,923 +/- 1,123 pg/ml in patients with CHF (p less than 0.01) and from 1,041 +/- 605 to 2,710 +/- 1,741 pg/ml in controls (p less than 0.01). Peripheral plasma ANF concentrations (femoral artery) increased from 538 +/- 278 to 752 +/- 262 pg/ml (p less than 0.01) in patients with CHF and from 193 +/- 63 to 401 +/- 147 pg/ml (p less than 0.01) in controls. The increase in peripheral or coronary sinus plasma ANF concentrations did not differ between patients with CHF and controls. At the three lowest ANF infusion rates, cardiac index (CI), systemic vascular resistance (SVR), and LV contractility assessed by peak positive dP/dt remained unchanged both in patients with CHF and in controls. At the highest ANF infusion rate, CI increased from 2.18 +/- 0.53 to 2.54 +/- 0.49 L/min/m2 (p less than 0.01) and SVR decreased from 14.6 +/- 3.6 to 12.8 +/- 4.5 mm Hg.min/L (p less than 0.01) in patients with CHF. There was no associated change in heart rate (HR), mean arterial blood pressure (MAP), cardiac filling pressures, or peak positive dP/dt.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Physiologic assessment of milrinone therapy in severe heart failure patients.

To assess the inotropic, vasodilator, and after-load-reducing effects of intravenous milrinone in patients with severe congestive heart failure, a simple noninvasive echocardiographic study coupled with a right catheterization was performed in 12 patients. Milrinone was administered intravenously as a 50 micrograms.kg-1 bolus followed by a 24-h milrinone infusion at a rate of 0.5 mg.kg-1.min-1 [corrected]. Echocardiographic left ventricular end-diastolic diameter (Ded), end-systolic diameter (Des), and wall thickness were measured at baseline and at 24 h of milrinone infusion, before and after a sublingual nitrate administration (0.8 mg of nitroglycerin) that induced load variations. Hemodynamic measurements were performed simultaneously. Left ventricular end-systolic meridional wall stress (Ses) was then calculated. The slopes of percent fractional shortening (percent FS)/Ses and Ses/Des, obtained during sublingual nitrate administration, were traced. Both end-systolic relations are an index of the contractile state. Milrinone therapy improved hemodynamics in all patients, resulting in stabilized hemodynamic conditions between 12 and 24 h of continuous milrinone infusion. At these times, the cardiac index increased to 30% while the capillary pulmonary wedge pressure and systemic vascular resistance decreased to 26 and 24%, respectively (all p less than 0.01). The average slope of Ses/Des shifted upward from 47.5 +/- 30 to 69.25 +/- 34 (p less than 0.05) and the average slope of (percent FS)/Ses shifted from -0.032 +/- 0.025 to -0.082 +/- 0.061 (p less than 0.01), both variations attesting the inotropic effect of milrinone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Percutaneous transluminal angioplasty of the common trunk during the acute phase of myocardial infarction].

The prognosis of cardiogenic shock in the acute phase of myocardial infarction has been transformed since the introduction of techniques of myocardial revascularisation. We report the case of a patient in cardiogenic shock after a large anterior myocardial infarct in whom failure of early thrombolytic therapy led to referral for emergency percutaneous transluminal coronary angioplasty. The success of the procedure on the patient's haemodynamic condition was life-saving. The originality of this case resides in the fact that revascularisation concerned the left main coronary stem.

Angioplasty, Balloon, Coronary↗
PubMed1990

[The role of isotope methods in evaluating the left ventricular function].

Cardiac angioscintigraphy is a non-invasive, reproducible and reliable technique used to obtain a number of cardiac function parameters, the most important of which is left ventricular ejection fraction. Methodologically, the examination is simple. Fourier's analysis (a mathematical decomposition of ventricular mechanics) provides additional information on some abnormalities and is particularly useful in segmental kinetics studies and in the topographical diagnosis of cardiac rhythm disorders. The technique is indicated mainly for prognostic evaluation and follow-up of patients with left ventricular dysfunction. Metaiodobenzylguanidine (MIBG) cardiac scintigraphy makes it possible to evaluate the reuptake of noradrenaline by neurons, which represents the inactivation pathway of adrenergic neurotransmission and is the principal factor of noradrenaline extraction. MIBG scintigraphy is an indirect way of evaluating left ventricular function in congestive heart failure, as suggested by the results of studies showing correlations between MIBG uptake, left ventricular function indices and disease severity as judged on the basis of evolutive parameters.

3-Iodobenzylguanidine↗
PubMed1990

[Cardiac transplantation: indications and results].

Although many problems remain, cardiac transplantation is now associated with a 5 year survival rate of about 70 per cent which is a very acceptable therapeutic result in patients with cardiac failure and no other medical or surgical alternative. Parallel improvement in the medical management of chronic cardiac failure has prolonged survival of many patients. Transplantation should only be considered if the benefits not only in terms of survival but also in terms of quality of life, are greater than of survival but also in terms of quality of life, are greater than those of medical treatment of the cardiac disease. The indications and timing of cardiac transplantation are therefore based on a complex prognostic evaluation adapted to each individual case which may eventually need reconsideration. Satisfactory results depend on strict patient selection with respect for the surgical indications and contra-indications.

Adult↗
PubMed1990

[Hypertrophic and/or obstructive primary cardiomyopathies: genetic, etiologic, physiopathologic aspects].

The morphological features, mode of presentation and physiopathology of hypertrophic cardiomyopathy (HCM) are variable. Autosomal dominant seems to be the usual mode of transmission but with variable presentation. From the anatomical point of view, the hypertrophy is asymmetrical with septal predominance. The main histological features are myocytic architectural disorganisation, fibrosis and abnormal coronary arteries of small diameter. Ventricular hyperkinesis is usually present and sometimes associated with outflow obstruction, the physiological role and mechanisms of which are still not fully understood. On the other hand, abnormal diastolic function is frequently observed, and, quite independently of disease of the epicardial coronary arteries, ischaemic phenomena may occur. Although the biological substrate of HCM is unknown, abnormalities of the adrenergic system and transmembrane calcium flux probably play a part in the expression of the disease.

Cardiomyopathy, Hypertrophic↗
PubMed1990

[The treatment of chronic left ventricular insufficiency].

Left ventricular failure is caused by a variety of myocardial diseases and its symptoms results from adjustments attempted by the left ventricle and the circulatory system to cope with the initial myocardial pathology. Treatment of heart failure has various objectives, depending on whether one tries to correct the initial myocardial disease, or its consequences on the myocardium, or its repercussions on blood circulation, or, more simply, to alleviate the symptoms experienced by the patient. The ideal treatment of heart failure would include a drug acting on its cause, another drug to restore a degree of contraction and relaxation adjusted to the amount of load, a third drug bringing back to normal a perturbed peripheral circulation and a fourth drug to relieve the symptoms due to sodium retention. Such a treatment does not exist, and the management of chronic left ventricular failure can only be composite. Should it be prescribed from the start? This, increasingly, is the current trend.

Cardiovascular Agents↗
PubMed1990

Filters and Fourier analysis of gated blood pool studies: a search for the optimal combination.

Fourier analysis of gated blood pool studies is performed after filtering the raw data by a spatial median 3 x 3, 9 x 9 or temporo-spatial 9 x 9 x 9 filter. 20 patients and a dynamic cardiac phantom were studied to determine the quantitative effects of these filters and of multiharmonic Fourier filtering (MHFF). The filtered MHFF data, with or without preprocessing, were compared with a 3 D or 2 D filter to the raw data using a chi 2 distribution. The MHFF (two or three harmonics) procedure applied to the raw data of patients without any preprocessing produced the smallest chi 2 value, thus demonstrating the very close relationship between filtered images and raw data. Preprocessing the raw data by the median filter also preserved the signal when two or three harmonics were applied, whereas the 3 D and 2 D (9 x 9) filters did not. The phantom study also demonstrated that MHFF preserved the signal better than any other preprocessing. The median filter introduced a smaller distortion than the 2 D (9 x 9) and 3 D filters. It is concluded that MHFF applied with two or three harmonics on the raw data or after preprocessing by a median (3 x 3) filter is the most successful way of preserving the real signal. It is believed that the other filters should be avoided. The clinical advantage of MHFF processing is to provide both very accurate filtering and parametric images.

Fourier Analysis↗