Generating anatomical models of the heart and the aorta from medical images for personalized physiological simulations.

The anatomy and motion of the heart and the aorta are essential for patient-specific simulations of cardiac electrophysiology, wall mechanics and hemodynamics. Within the European integrated project euHeart, algorithms have been developed that allow to efficiently generate patient-specific anatomical models from medical images from multiple imaging modalities. These models, for instance, account for myocardial deformation, cardiac wall motion, and patient-specific tissue information like myocardial scar location. Furthermore, integration of algorithms for anatomy extraction and physiological simulations has been brought forward. Physiological simulations are linked closer to anatomical models by encoding tissue properties, like the muscle fibers, into segmentation meshes. Biophysical constraints are also utilized in combination with image analysis to assess tissue properties. Both examples show directions of how physiological simulations could provide new challenges and stimuli for image analysis research in the future.

Hypothalamo-pituitary-adrenal axis in acute myocardial infarction treated by percutaneous transluminal coronary angioplasty: effect of time of presentation.

Acute myocardial infarction (AMI) is associated with a stimulation of cortisol which lasts 24 hours in patients treated by thrombolysis. Percutaneous transluminal coronary angioplasty (PTCA) is an alternative treatment for AMI which reduces the length of myocardial ischemia. Our objective was the determination of the amplitude and duration of cortisol and other hormones of the hypothalamo-pituitary-adrenal (HPA) axis release in patients undergoing PTCA. These responses were also analyzed in relation with the time of onset of AMI. The effect of coronarography with or without angioplasty in patients without AMI was also studied. Plasma ACTH, cortisol, corticotropin-releasing hormone and arginine vasopressin levels were determined during the first 48 hours in 20 patients with first AMI, treated by PTCA and in 10 patients without AMI undergoing coronarography (and angioplasty in five of them). A strong stimulation of the HPA axis was observed in AMI patients, but the duration of cortisol secretion was significantly reduced (less than 8 hours) as compared with previous studies in patients treated with thrombolysis. A clear-cut ACTH-cortisol dissociation was also observed after the third hour. ACTH and cortisol stimulation was higher in patients admitted between 04:00 h and 16:00 h than in patients admitted between 16:00 h and 04:00 h In patients without AMI, coronarography induced a moderate, but significant short-lasting ACTH and cortisol stimulation. In conclusion, our data suggest that the degree of stimulation of the HPA axis may depend upon the type of treatment and the circadian rhythm of this axis.

[Cytomegalovirus and arterial disease. Current aspects]. / Cytomégalovirus et pathologies artérielles. Aspects actuels.

The cytomegalovirus (CMV) is the only microbial agent implicated in three particular types of arterial disease: coronary disease of the transplanted heart, post-angioplasty restenosis and atherosclerosis. The object of this article is to analyse the recent data on the role of CMV in these pathologies with an exhaustive review of the literature. The available data is mainly epidemiological but the interpretation is difficult because of the multiplicity and imperfections of the diagnostic techniques of the infection. However, the results are quite concordant in favour of a real association. Different physiopathological mechanisms are proposed. In coronary disease of the transplanted heart, the lesions could be initiated by an inflammatory process. In post-angioplasty restenosis, the virus seems able to trigger cellular proliferation by inhibiting the mechanisms of apoptosis. Finally, in atherosclerosis, CMV infection seems to promote atherothrombotic processes and accelerate the progression of atherosclerotic plaques by activating inflammatory cells. Direct methods of detection of viral DNA show the presence of the virus within these lesions. There is, therefore, epidemiological, anatomo-pathological and physiopathological evidence in favour of a relationship between CMV infection and these three forms of arterial disease.

[Role of endovascular treatments in the management of arteriopathies of the aged subject]. / Place des traitements endovasculaires dans la prise en charge des artériopathies du sujet âgé.

Endovascular procedures have deeply modified the treatment of patients with peripheral arterial diseases. However risks of transluminal angioplasty are increased with patient age. In patients with acute ischemia by distal embolism or in situ thrombosis percutaneous thromboaspiration is an alternative to the Fogarty catheter. In patients with chronic critical ischemia, revascularization is necessary. Risks of surgical treatment are rather in favour of endovascular procedures. In patients suffering of intermittent claudication, results of a series of 38 patients confirm the efficacy of angioplasty. Thus endovascular procedures can be proposed in alternative to medical treatment to patients over 70 years of age.

Value and limitations of the Duke criteria for the diagnosis of infective endocarditis.

OBJECTIVES: The purpose of this study was to assess the value and limitations of Duke criteria for the diagnosis of infective endocarditis (IE). BACKGROUND: Duke criteria have been shown to be more sensitive in diagnosing IE than the von Reyn criteria, but the diagnosis of IE remains difficult in some patients. METHODS: Both classifications were applied in 93 consecutive patients with pathologically proven IE. Blood cultures, and transthoracic and transesophageal echocardiography were performed in all patients. RESULTS: Sensitivities for the diagnosis of IE were 56% and 76% for von Reyn and Duke criteria, respectively. Fifty-two patients were correctly classified as "probable IE" by von Reyn and "definite IE" by Duke criteria (group 1). However, discrepancies were observed in 41 patients. Eleven patients (group 2) were misclassified as "rejected" by von Reyn, but were "definite IE" by Duke criteria; this difference could be explained by negative blood cultures and positive echocardiogram in all patients. In eight patients (group 3), the diagnosis of IE was "possible" by von Reyn but "definite" by Duke criteria. This difference was essentially explained by the failure of the von Reyn classification to consider echocardiographic abnormalities as major criteria. Twenty-two patients (group 4) were misclassified as possible IE using Duke criteria, being false negative of this classification. Echocardiographic major criteria were present in 19 patients, but blood cultures were negative in 21 patients. The cause of negative blood cultures was prior antibiotic therapy in 11 patients and Q-fever endocarditis diagnosed by positive serology in three cases. CONCLUSIONS: Twenty-four percent of patients with proved IE remain misclassified as "possible IE" despite the use of Duke criteria, especially in cases of culture-negative and Q-fever IE. Increasing the diagnostic value of echographic criteria in patients with prior antibiotic therapy and typical echocardiographic findings and considering the serologic diagnosis of Q fever as a major criterion would further improve the clinical diagnosis of IE.

[Immediate results and 2-year follow-up of percutaneous transluminal angioplasty in intermittent claudication in patients over 70 years of age]. / Résultats immédiats et à 2 ans de l'angioplastie transluminale percutanée dans la claudication intermittente du sujet âgé de plus de 70 ans.

PURPOSE: This retrospective study was aimed at assessing immediate and mid-term results of percutaneous transluminal angioplasty for intermittent claudication in patients over 70 years of age, and the overall morbidity and mortality during follow-up. METHODS: Fifty-one percutaneous transluminal angioplasties were performed between 1993 and 1997 in 30 men and eight women (mean age: 78 +/- 5.2; range 71-91) for intermittent claudication (walking distance < 250 m). RESULTS: Angioplasties were supra-inguinal in 24 cases (47%) and infra-inguinal in 27 cases (53%). Clinical success (walking distance > 500 m) was obtained in 92% of the patients. Significant complications (5.9%) were inguinal hematoma requiring subsequent surgery in one patient and common femoral false aneurysms in two patients. Mean duration of hospitalization was 3 days and a half. After a mean follow-up of 25 months (range: 4-51 months), improvement in the walking distance was still present in 31 patients (82%). The condition of seven (18%) patients did not improve. No patient presented with critical ischemia. As well, no patient underwent surgical revascularization or amputation. However, the condition of eight (21%) patients required subsequent percutaneous transluminal angioplasty. Four (10.5%) patients died. Following percutaneous transluminal angioplasty, six (18%) patients presented with a major non-fatal clinical event. All the patients lived at home. CONCLUSION: Percutaneous transluminal angioplasty has little immediate risk when lesions are accessible and leads to positive mid-term clinical results in the treatment of intermittent claudication in patients over 70 years of age.

Combined hypervolemia and hypoosmolality alter hypothalamic-pituitary-adrenal axis response to endotoxin stimulation.

Changes in corticotropin (ACTH) and glucocorticoid secretion have been described during disturbances of body fluid homeostasis and attributed to alterations in arginine vasopressin (AVP) secretion from magnocellular hypothalamic neurons. In order to further characterize the mechanisms involved in the interactions between body fluid alterations and pituitary adrenal function, we manipulated osmolality and volemia in sheep under stimulation of the pituitary-adrenal axis by acute injection of endotoxin. We have recently shown that endotoxin injection induces a long-lasting release of both corticotropin releasing hormone (CRH) and AVP into hypophysial portal blood, and an early stimulation of AVP secretion into peripheral vessels, thus suggesting a joint activation of magnocellular and parvocellular neurons of the PVN. We used the same experimental model to investigate the effect of combined volume loading and plasma dilution (achieved by 1-deamino-8-D-arginine (dDAVP) administration together with infusion of 2 liters of 2.5% glucose solution) on CRH, AVP, ACTH and cortisol responses to endotoxin stimulation. In volume-loaded animals, ACTH and cortisol responses to endotoxin were significantly blunted and we observed a parallel decrease in portal CRH and jugular and portal AVP levels. These data show that hypoosmolality and/or hypervolemia reduce(s) ACTH and cortisol response to stress in sheep as in other species. They strongly suggest that this reduction in ACTH and cortisol responses to endotoxin involve not only magnocellular hypothalamic neurons secreting AVP, as usually assumed, but also PVN parvocellular neurons secreting both CRH and AVP.

On the meaning of low-dose ACTH(1-24) tests to assess functionality of the hypothalamic-pituitary-adrenal axis.

To analyse further the ACTH(1-24) low-dose test, which is of clinical interest, we have examined the dose-response relationship between plasma ACTH(1-24) and cortisol concentrations after i.v. administration of increasing doses (1, 5 or 250 microg) of ACTH(1-24) as a bolus. In addition, we have measured plasma ACTH(1-39) and cortisol levels after an insulin tolerance test (ITT). Although there was a dose response relationship between plasma ACTH(1-24) immunoreactivity and the dose injected, cortisol peaks were comparable, but lower than those reached after an ITT. Under these experimental conditions, an increase in plasma ACTH as low as 13 pmol/l (i.e. the increase obtained with the 1 microg dose) induced a near maximal cortisol response. Following injection of 1 microg ACTH(1-24), peak ACTH values were short lasting, similar to physiological daily bursts. After injection of 5 microg ACTH(1-24), plasma ACTH concentrations were higher than those reached during an ITT, but clearly shorter lasting. Injection of 250 microg ACTH(1-24) induced strikingly supraphysiological levels of plasma ACTH. We conclude that neither regular nor low-dose ACTH tests can fully reproduce the ITT. Our observations strongly suggest that the low-dose ACTH(1-24) test (1 microg) can be useful to estimate the adrenal sensitivity under basal, physiological conditions.

Effect of endotoxin on the hypothalamic-pituitary-adrenal axis in sheep.

Endotoxin has been shown to stimulate ACTH and cortisol secretion through an action at the hypothalamic level. However, the nature of hypothalamic neurohormones, corticotropin-releasing hormone (CRH) and especially arginine vasopressin (AVP), involved in that regulation is still controversial. The purpose of this study was to determine the effects of an acute i.v. endotoxin administration on CRH and AVP secretion into hypophysial portal blood (HPB). The experiment has been performed in sheep since it is possible to collect HPB and quantify CRH and AVP secretion in this animal under physiological conditions. The release of both peptides into HPB was stimulated by endotoxin injection, the increase in portal AVP being more pronounced than that of CRH. An initial, transient, increase in jugular AVP concentrations was observed, probably due to the activation of magnocellular AVP neurons. In conclusion, our data indicate that the activation of the pituitary-adrenal axis after endotoxin injection is associated with an increased release of both CRH and AVP into HPB. Magnocellular AVP neurons are initially stimulated while parvocellular CRH and AVP neurons are stimulated throughout the experiment.