Aortic valvular endocarditis visualised by 16-row detector multislice computed tomography.
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Aortic Valve Insufficiency↗
Biomedical subjects
L Christiaens
Publications and source records attributed to L Christiaens.
Aspirin resistance: definitions, mechanisms, prevalence, and clinical significance.
Aspirin is the most commonly used therapeutic agent in prevention of vascular ischemic events. Aspirin exerts its antithrombotic effect primarily by interfering with the biosynthesis of thromboxane A2 (TXA2) and inhibition of TXA2 -dependent platelet aggregation. A meta-analysis of secondary prevention trials indicated that aspirin reduced major cardiovascular or cerebral events by 25%. This led to the widespread use of aspirin for prevention of cardiovascular events. However, it appears that aspirin antiplatelet effect is not uniform in all patients and previous studies estimated that 8-45% of the population were aspirin resistant. Furthermore, (i) the optimal dosage of aspirin for complete inhibition of platelet aggregation by physiological agonists (i.e arachidonic acid) is subject to great interindividual variability, (ii) the tests to detect aspirin resistance in vitro are subject to debate and (iii) the mechanisms by which some patients are resistant to aspirin in vitro remain to be determined. Despite these unresolved questions, recent clinical studies provide the reliable evidence that aspirin resistance correlates with confirmed clinical unresponsiveness, highlighting the clinical interest of determining the aspirin inhibitory effects on patients' platelets. In conclusion, discovery of aspirin resistance in individuals might be important in order to devise better anti-platelet strategies and improve our ability to prevent acute thrombotic complication.
Animals↗
[Aspirin resistance 2003: a review of the literature].
Despite the development of new molecules, aspirin remains a mainstay of the antiplatelet therapy, indispensable for the secondary prevention of cardiovascular events. The therapeutic used is based on the platelet aggregation inhibition induced by aspirin. The concept of aspirin resistance corresponds to a total or almost total absence of the platelet aggregation inhibition generally observed in vitro under aspirin. The frequency of this resistance depends on the platelet aggregation test used and the population studied. In a population with stable coronary disease treated in the long term with 160 to 325 mg of aspirin daily, 8 to 35% of patients are non-responders. Many hypothesis on the mechanisms of the lack of antiplatelet effect of aspirin are under investigation. The clinical implication of the in vitro antiplatelet effect resistance of aspirin has recently been evidenced by a relative risk of cardiovascular events at two years at 3. This would support an individual adaptation of the anti-platelet therapy.
Aspirin↗
[Cardiac hamartomas in Bourneville's tuberous sclerosis. Perinatal echographic diagnosis and spontaneous evolution].
UNLABELLED: Cardiac hamartomas are frequently the earliest revelation of Bourneville's tuberous sclerosis. They sometimes allow to consider the diagnosis during the antenatal period, and to plan therefore genetic and CNS investigations. After the neonatal period, the evolution of hamartomas is frequently favourable, characterised with at least partial involution. OBSERVATION: Antenatal equivocal cardiac echographic images did not allow the diagnosis in a fetus whose father had Bourneville's disease. Other antenatal investigations (genetics, central nervous system MRI) were not helpful. The diagnosis was carried out at birth as cardiac ultrasound reliably showed two cardiac hamartomas. CONCLUSION: Even when suspected, the antenatal diagnosis of Bourneville's disease is difficult. The presence of cardiac hamartomas at birth is a reliable mean to make the diagnosis.
Diagnosis, Differential↗
Resistance to aspirin in vitro at rest and during exercise in patients with angiographically proven coronary artery disease.
BACKGROUND: Acetylsalicylic acid, or aspirin, is widely used in secondary prevention of coronary artery diseases, but the inhibition of platelet aggregation is not uniform in all individuals. OBJECTIVE: To investigate the prevalence of aspirin resistance at rest and during exercise in coronary artery disease patients. MATERIALS AND METHODS: Fifty patients with stable coronary artery disease were prospectively studied. All patients received aspirin (75-300 mg/day for >1 month) and no other antiplatelet therapy. Aspirin resistance was studied, at rest and immediately after a stress test, using the standardized platelet function analyzer (PFA-100(R), Dade-Behring). Aspirin resistance was defined as a normal collagen/epinephrine closure time (<186 s). RESULTS: Ten patients (20%) were aspirin-resistant at rest. Out of the 40 patients who were aspirin-sensitive at rest, 9 (22%) were aspirin-resistant immediately after the exercise stress test. There were no differences in aspirin sensitivity regarding gender, age, diabetes, hypertension, dyslipidemia, platelet count, medical treatment or number of the coronary arteries involved. CONCLUSIONS: Aspirin resistance is detected, at rest, in 20% of our patients with stable coronary artery disease. Aspirin treatment does not seem to protect against exercise-induced platelet activation in 22% of such patients, despite aspirin sensitivity at rest.
Aged↗
Resistance to aspirin in vitro is associated with increased platelet sensitivity to adenosine diphosphate.
BACKGROUND: Platelet activation plays an important role in arterial thrombosis and the widespread use of aspirin has reduced major events by 25% in the secondary prevention of cardiovascular diseases. However, it appears that aspirin antiplatelet effect is not uniform and 8-45% of the population are, in vitro, aspirin resistant, and it is well recognized that platelets can be activated by pathways that are not blocked by aspirin, such as adenosine diphosphate (ADP). OBJECTIVES: To investigate whether aspirin-resistant patients have a modified sensitivity to ADP-induced platelet activation MATERIALS AND METHODS: Seventy-two patients were enrolled. Platelet function was measured by the PFA-100(R) analyser; platelet GP IIb-IIIa activation by ADP 10 micro M was assessed by flow cytometry using PAC-1 MoAb. RESULTS: Using a collagen/epinephrine coated cartridge on the PFA-100(R), the prevalence of aspirin resistance was 29.2% (n=21). For aspirin-resistant patients, the collagen/ADP coated cartridge showed a closure time significantly shorter (p=0.004) compared to the sensitive and control groups. Platelets from aspirin-resistant patients bound PAC-1 significantly more (p=0.03) than the aspirin-sensitive patients and controls when activated with 10 micro M ADP. CONCLUSIONS: Platelets from aspirin-resistant patients appear to be more sensitive and activable by ADP. This hypersensitivity could provide a possible explanation for the so-called aspirin resistance, and this could justify therapeutic improvement with alternative antiplatelet agents.
Adenosine Diphosphate↗
Assessment of platelet activation after exercise using a standardized whole blood flow cytometry assay.
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Aged↗
[Platelet polymorphism and coronary artery disease].
Several publications over the last ten years have addressed the problem of genetic mutation coding platelet membrane glycoproteins and thrombotic arterial disease. The principal polymorphisms studied are those of glycoproteins GPIIIa, GPIb and the GPIa-IIa complex. The relationships of each of these polymorphisms and myocardial infarction or coronary artery disease are reported and are often subject to controversy. The polymorphism PLA2 of the GPIIIa has been shown to be a risk factor for infarction in young people, especially when associated with cigarette smoking. Its role in triggering myocardial infarction or in the severity of coronary artery disease is not so clear in the general population. Two types of polymorphism concerning the GPIb and that of the GPIa-IIa complex should also predispose to early coronary thrombotic complications. In addition, the study of these platelet polymorphisms gives a better insight into individual sensitivity to platelet antiaggregant therapy.
Adult↗
Relationship between C-5T Kozak, C807T genotypes and expression of glycoproteins Ib alpha and Ia-IIa at platelet surface: from genotype to phenotype.
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Adult↗
[Systemic markers of inflammation after coronary angioplasty].
UNLABELLED: THE RISK OF RESTENOSIS: Coronary angioplasty is an effective treatment of stable and instable coronary disease and its principle limitation, despite technical progress, remains restenosis. In instable angina, the physiopathologic and prognostic role of inflammation proteins is well documented. THE ROLE OF THE C-REACTIVE PROTEIN (CRP): Is a validated risk factor for patients presenting with heart failure, whether instable or stable angina and in the general population. This risk factor is distinct from tobacco abuse, hypercholesterolemia or diabetes. In all the series studied to date, the frequency of restenosis following coronary angioplasty increases when CRP values are high prior to surgery and continue to rise up to the 48th or 72nd hour. PERSPECTIVES: New therapeutic measures widen the possibilities of mechanical strategies (angioplasty with or without stent) and treatment of inflammatory mechanisms in the atheromatous plaques (statines, brachytherapy or "covered" stents).
Angioplasty, Balloon, Coronary↗
Normal coronary angiogram and dobutamine-induced left ventricular obstruction during stress echocardiography: a higher hemodynamic responsiveness to dobutamine.
UNLABELLED: This study assessed the clinical or echographic factors predisposing to dynamic left ventricular obstruction (LVO) during dobutamine echocardiography (DE) in patients with angina-like chest pain but without coronary artery disease (CAD). DE is an effective technique for the noninvasive diagnosis of underlying CAD. During DE, an LVO is not unusual in ischemic patients. METHODS: DE (5-40 microg/kg/min) was performed in 52 consecutive patients with angina-like chest pain and normal coronary angiogram. Mean (standard deviation) age was 61 +/- 10 years (27 men, 25 women). Dobutamine-induced LVO was defined as a new intracavitary flow acceleration of at least 3 msec in the left ventricle. RESULTS: Dynamic LVO was observed during DE in 20 (38%) of the 52 patients and was not related to clinical or baseline echocardiographic parameters. The chronotropic response and the systolic blood pressure during DE were higher in the group with LVO (P < 0.03 and P < 0.05, respectively). Appearance of chest pain during the test was also more frequent when LVO occurred (P < 0.02). CONCLUSION: Dynamic LVO is common during DE in a population of patients with angina-like chest pain without epicardial CAD and is associated with a higher hemodynamic responsiveness to dobutamine.
Adrenergic beta-Agonists↗
Dobutamine stress echocardiography response of asymptomatic patients with diabetes.
AIMS: This study investigated the role of dobutamine stress echocardiography for the silent diagnosis of myocardial ischemia in a diabetic population. Results from the stress test were compared between diabetic and nondiabetic groups. METHODS: Forty-nine diabetics and 63 consecutive nondiabetics underwent dobutamine stress echocardiography between April and December 1999, to check for new regional wall-motion abnormalities. A single operator, using the same echograph with tissue harmonic imaging in each case, performed all the examinations, using the same techniques. RESULTS: Significant coronary artery disease was detected in 9% of asymptomatic diabetics. Dynamic left ventricular obstruction was observed in 59% of the diabetic population and only 22% in the nondiabetic population. One patient suffered an adverse event (fast atrial fibrillation) during the stress test. Cardiac frequency at the beginning and end of the stress test differed significantly between the two populations. CONCLUSION: Dobutamine stress echocardiography allows for detection of silent myocardial ischemia. In the diabetic population, we describe, for the first time under dobutamine infusion, a great number of dynamic left ventricular obstructions.
Cardiotonic Agents↗
[Ultrasonic myocardial characterization. Application of an original method of acoustic quantification to analysis of healthy and hypertrophic interventricular septal myocardium].
Echocardiography does not provide objective tissue characterisation of sonified tissues. A recent advance has been the introduction of the radiofrequency signal. At present, its exploitation remains a research tool. The required material for quantification is still insufficiently robust and discriminative. The indices derived from histograms of grey scales are calculated by the majority of workers for regions of interest manually positioned in the image. This statistical method allows analysis of the average grey level but not of the architecture of the tissue examined. Tissue characterisation is, therefore, only a potential feature of echocardiography. The authors' approach consists in developing software applied to digital signal provided by the echograph and not directly by the transducer, as in the research based on the use of radiofrequency signals. This software allows characterisation of the texture by two statistical methods applied to signal processing: the histograms of the grey scales, the matrix of co-occurrence (assessing the make-up of the different grey scales in the region of interest). This tool of tissue characterisation is presented here in the studies of the interventricular septum in the parasternal long axis view. Two populations, one with healthy myocardium and the other with myocardial hypertrophy, have been studied. These two populations are differentiated in a significant manner by their respective values of parameters of myocardial texture characterisation in early diastole. Despite a number of methodological problems, this study confirms the hopes that it will be possible in the near future to obtain a quantitative "histological" definition of tissues by echocardiography.
Echocardiography↗
[Tissue characterization by study of myocardial response to ultrasound. Review of the literature and perspectives].
Echocardiography is a routine daily cardiological investigation. Recent technological developments suggest that it may become possible to quantify myocardial texture and thereby achieve histological and functional definitions of cardiac diseases. Two approaches are under evaluation: "videodensitometry" uses tools of statistical quantification from the echocardiographic image; more recently, analysis of the radiofrequency signal has been proposed. This is based on direct exploitation of a continuous signal at the transducer head of wide dynamic range containing all the information received by the piezo-electric crystals. These two approaches have given encouraging preliminary results in the recognition of different myocardial hypertrophic reactions, in diabetic cardiac disease and in the identification of myocardial viability. Despite the many remaining problems, the perspectives are promising and a new field of echocardiography should see the light of day.
Echocardiography↗
[Valvular tumor: diagnostic trap. Report of a case of marastic endocarditis].
Marastic endocarditis is a rare clinical condition described in cases of cancer or other severe inflammatory diseases. The authors report the case of a young patient in good general condition, admitted after a cerebro-vascular accident. Investigations showed an isolated mitral valvular mass on transoesophageal echocardiography which, after unsuccessful medical therapy, was operated. It was, in fact, a case of marastic endocarditis, and a pulmonary tumour was discovered one month after surgery. The bronchopulmonary adenocarcinoma had remained infraclinical beforehand. The advances in echocardiographic imaging will probably lead to an increase in such cases of early diagnosed thrombotic non-bacterial endocarditis (ETNB. This case suggests that it is justified to carry out an aetiological investigation of thrombotic non-bacterial endocarditis in all cases of isolated mitral valve masses.
Adenocarcinoma↗
[Normal coronary angiography. Survival and functional status at 6 years].
Despite the development of non-invasive diagnostic techniques, the absence of significant coronary stenosis is observed in 10 to 30% of coronary angiographic studies. The authors report the survival and functional status at 6 years of 172 consecutive patients with symptoms of angina without significant angiographic coronary stenosis. The average age was 60.8 years with a sex ratio of 1.1 and chest pain as the indication for coronary angiography in over 90% of cases. The global mortality after an average of 75.6 months follow-up was 11%, lower in women (8.5%) than in men (13.3%) with an annual mortality of 16.3 per thousand. Sudden death was observed in 4 patients and a third of deaths was of cardiac origin. The persistence of symptoms was reported by 58% of patients, mainly atypical chest pain. Despite the result of coronary angiography, nearly half of the patients were followed up annually by a cardiologist, two thirds remained on anti-anginal therapy, 20% were treated by psychotropic agents and hospital admission to the cardiology department was required in 22% of cases during follow-up. None of the patients had myocardial infarction. Survival and myocardial function after normal coronary angiography therefore appear to be good in contrast with the functional status of these patients.
Adult↗
[Comparison of tissue harmonic imaging and standard imaging in echocardiography based on 4 different emission frequencies].
Harmonic imaging is an innovative technique which is now available in most of the echographic equipment currently on the market. The use of echographic contrast agents led to the introduction of this particular technology, which has largely superseded the former method. In everyday medical practice, it seems to provide a better definition of endocardial contours. In this article, the authors have described a prospective study including 32 patients with an average age of 64 years (+/- 5 years). The aim was to compare imaging quality obtained by 2 acquisition frequencies for standard imaging with that procured by harmonic imaging (emission and reception frequency, 2.5 and 3.3 MHz respectively for the former technique; emission and reception frequency, 1.7 and 2.2 MHz respectively for the latter). The overall scores given by 2 different examiners for emission and reception frequency were as follows: 3.28 and 3.15 for 2.5 MHz, 2.84 and 2.56 for 3.3 MHz regarding the standard technique; 2.56 and 3.031 for 1.7 MHz and 2.56 and 2.063 for 2.2 MHz for the harmonic imaging technique. The superior performance of tissue harmonic imaging has been confirmed in the endocardial study of the left ventricular segments and in the analysis of the mitral valve. This study shows that harmonic imaging, a technique which was easy to use in the present study, provides a means of obtaining an average level of ultrasound imaging that facilitates the interpretation of the clinical picture.
Biophysical Phenomena↗
[Idiopathic aneurysm of the pulmonary artery trunk. Report of a case].
Aneurysms of the aorta are frequent and treatment is well known, correlated with a statistical risk of rupture. Pulmonary artery aneurysms are less frequent. They may occur in connection with other conditions (infection, cardiopathy, notably pulmonary artery hypertension, endovascular trauma) or much more exceptionally regarded as idiopathic. Chest x-ray, CT-scan and digitalized pulmonary angiography and echocardiography give the diagnosis and help evaluate extension and localization. We report the case of a 72-year-old woman who developed idiopathic aneurysm of the left pulmonary artery which was discovered fortuitously. Because of the stability of the lesion and the lack of any worsening factor, we decided not to operate this high-risk patient. After 3 years, no complication has been observed and the CT-scan shows no evolution. In case of proximal idiopathic aneurysm of the pulmonary artery, the indication of surgery should be discussed.
Aged↗