Left atrial volume assessed by ECG-gated computed tomography: Variations according to age, gender and time during the cardiac cycle.

PURPOSE: The purpose of this study was to retrospectively assess the accuracy of the maximal left atrial volume (LAVmax) measured at 75% of the cardiac cycle compared to the 40% measurements and to evaluate this volume according to age and gender. PATIENTS AND METHOD: A total of 150 patients with a mean age of 50±17 (SD) years (range: 21-79 years) were analyzed. There were 78 men and 72 women. LAVmax were measured from retrospective triphasic cardiac-gated multi-detector computed tomography (MDCT) data at the 40% (LAV40) and 75% (LAV75) of the RR cycle phases by a semi-automatic method. RESULTS: LAV40was 50.7±14mL/m2 and LAV75 was 42.5±13mL/m2. The difference was statistically significant. Considering the reference range of LAVmax reported in the literature, 33% of the patients had enlarged LA with LAV40 and only 17% with LAV75. These volumes were positively influenced by age but not by gender. The relationship between LAV75 and LAV40 was: LAV75=0.908 LAV40-3.486 (r2=0.92) or LAV40=1.1×LAV75+3.8 (r2=0.92). CONCLUSION: LAVmax measured at the 75% of the cardiac cycle phase significantly underestimates actual LAV leading to reconsider normal values. LAV40 can be computed from the measured value of LAV75 obtained on prospective ECG-gated MDCT.

Establishment of diagnostic reference levels in cardiac CT in France: a need for patient dose optimisation.

The objective of this study was to propose diagnostic reference levels (DRLs) for coronary computed tomography angiography (CCTA), in the context of a large variability in patient radiation dose, and the lack of European recommendations. Volume Computed Tomography Dose Index (CTDIvol) and dose-length product (DLP) were collected from 460 CCTAs performed over a 3-month period at eight French hospitals. CCTAs (∼50 per centre) were performed using the routine protocols of the centres, and 64- to 320-detector CT scanners. ECG gating was prospective (n = 199) or retrospective (n = 261). The large gap in dose between these two modes required to propose specific DRLs: 26 and 44 mGy for CTDIvol, and 370 and 970 mGy cm for DLP, respectively. This study confirms the large variability in patient doses during CCTA and underlines the need for the optimisation of cardiac acquisition protocols. Availability of national DRLs should be mandatory in this setting.

[Thrombotic thrombocytopenic purpura: do not ignore cardiac involvement]. / Purpura thrombotique thrombocytopénique: ne pas méconnaître l'atteinte cardiaque.

INTRODUCTION: Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy due to ADAMTS13 deficiency (a von Willebrand factor's metalloprotease) with multiple organs' involvement, one of which may be the heart. CASE REPORT: We report a 29-year-old woman who presented a TTP during her last trimester of pregnancy, under the features of a HELLP syndrome. After caesarean section, cardiac involvement was revealed by chest pain, ECG changes, antero-septal hypokinesia and troponin rise. Cardiac MRI found no large-vessel ischemic heart disease and confirmed hypokinesia. CONCLUSION: When TTP is diagnosed, cardiac involvement must be systematically investigated by ECG and troponin assay because of the risk of a cardiac arrest.

[Chronic pericarditis: CT and MR imaging features]. / Pourquoi réaliser un scanner et une IRM dans une péricardite chronique?

A diagnosis of constrictive pericarditis is suggested by the presence of pericardial thickening (>=4 mm in thickness) and abnormal motion of the interventricular septum. Additional findings have been reported: tubular appearance of the right or left ventricles, dilatation of the vena cava, atrial dilatation or abnormal diastolic expansion of one or both ventricles. In patients with suspected chronic pericarditis, CT can more easily demonstrate the presence of pericardial calcifications compared to US and MRI, as well as detect the presence of mediastinal adenopathy and lung lesions, suggesting tuberculosis. Septal motion analysis should be performed during protodiastole and systole using a cine technique with both CT and MR.

[Current indications for cardiac CT]. / Les indications actuelles du scanner cardiaque.

There is a need to define the current indications for coronary CT angiography (CCTA) even as technology continuously evolves. CCTA using 64 MDCT units has shown to be highly accurate for diagnosis of stenoses >or=50% on selected populations. It is currently used for its negative predictive value (96-98%). Stenosis quantification remains inferior to conventional coronary angiography with tendency to overestimate stenoses <70%. For diagnosis of coronary artery disease, CCTA is considered based on clinical findings (pre-test probability of coronary artery disease) and presence of myocardial ischemia on other functional studies. The main appropriate indications include: In the setting of acute coronary syndrome, CCTA excludes coronary artery disease with excellent NPV and good negative likelihood ratio (0.05) when ECG is non-contributory, 2 consecutive troponin levels at 6 hours are negative in a patient with low risk of coronary artery disease. In the setting of stable angina or atypical precordial chest pain, CCTA is indicated in patient with low to medium risk when functional test are non-contributory or unavailable, or ECG is non-interpretable. CCTA is a complement to coronary angiography for morphological evaluation of some lesions prior to angioplasty and stent placement (long segment occlusion, proximal lesions involving LAD and circumflex arteries). In selected patients, CCTA may replace coronary angiography prior to valvular surgery.

[Idiopathic venous thromboembolic disease. risk factors for recurrence in 2006]. / Maladie veineuse thromboembolique idiopathique. Facteurs de risque de récidive en 2006.

The duration of anticoagulant therapy after a first attack of venous thromboembolic disease (VTE) is related to the risk of recurrence and the iatrogenic complication of bleeding. Recent prospective trials have provided information concerning the clinical and biological profiles of those at greatest risk of recurrence of deep vein thrombosis. The value of ultrasonic investigations and of D-Dimer measurements have also been assessed. The risk of recurrence is not negligible, about 10% in the first year after stopping treatment and 2/3 of recurrences occurring in the first two years. There are several risk factors for recurrence: male gender, past history of renal transplant, presence of malignant disease, proximal site of the initial thrombosis, initial presentation with pulmonary embolism, previous deep vein thrombosis and the co-existence of two thrombophilic factors. On the other hand, age, single deep vein thrombosis and a family history of deep vein thrombosis are not significantly related to increased risk. The presence of a residual thrombus at the end of treatment remains a subject of controversy. The risk of recurrence when the D-Dimers are normal one month after stopping the anticoagulants seems to be low, especially in cases of an associated thrombophilia. Finally, the risk of haemorrhage is related to the duration of oral anticoagulant therapy and the age of the patient. These trials have provided information for the issue of recommendations by consensus conferences and allow better economic evaluation of the duration of treatment after a first episode of deep vein thrombosis with respect to differing clinical situations.

Non-invasive antenatal RHD typing.

The existence of cell free fetal DNA, derived from apoptotic syncytiotrophoblast, in the maternal circulation has opened new possibilities of non-invasive prenatal diagnosis. Although still some technical problems exists, especially the lack of a generic positive control on the presence of fetal DNA and the aspecific amplification of background maternal DNA, non-invasive prenatal RHD typing has been successfully introduced in several laboratories, especially in Europe. The diagnostic accuracy reaches>99%. In the Netherlands PCR guided administration of antenatal anti-D prophylaxis is cost-effective and nearby. In this review the main characteristics and applications of cell free fetal DNA are discussed, with an emphasis on prenatal RHD genotyping.

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.

[Aspirin resistance 2003: a review of the literature]. / Actualités sur la résistance à l'aspirine en 2003.

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.

[Cardiac hamartomas in Bourneville's tuberous sclerosis. Perinatal echographic diagnosis and spontaneous evolution]. / Hamartomes cardiaques de la sclérose tubéreuse de Bourneville: diagnostic échographique périnatal et évolution spontanée.

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.

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.

[Platelet polymorphism and coronary artery disease]. / Polymorphisme plaquettaire et coronaropathies.

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.

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.

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.