A finite element analysis of a T12 vertebra in two consecutive examinations to evaluate the progress of osteoporosis.

Osteoporosis is a metabolic disease that causes bones to become fragile and be more likely to break. As basic clinical examinations to detect osteoporosis, dual energy X-ray absorptiometry (DXA) and quantitative computer tomography (QCT) are used. In the framework of a typical clinical examination, QCT scans were obtained from the T12 vertebra of an elderly woman and osteoporosis was diagnosed. One year later, new QCT scans were obtained in order to evaluate her clinical condition. Using both sets as primary information, two patient-specific finite element (FE) models were created and analyzed under compressive load. Vertebral bone was treated as orthotropic material and its elastic modulus was set as an indirect function of Hounsfield Units (HU). Commercial software for medical image processing and FE analysis, along with in house codes, were used for the mechanical analysis of the FE models. Alterations in the geometry/shape of the vertebra as well as in the distributions of several mechanical quantities were detected between the two FE models. As far as the volume of the vertebra is concerned, it augmented by a percentage of 9.7% while the volume of the vertebral body alone increased by 5.6%. In all the maximum values of the mechanical quantities a measurable reduction was observed (axial compressive displacement: 37.9%, von Mises stress: 23.8%, von Mises strains: 15.1%) and all the investigated distributions in the second FE model became smoother. Finally, the percentage of volume with von Mises strains greater than 4500 microstrain dropped from 8.9%, in the first examination, to 4.9% in the second one. Clinically, the prescribed medication seems to have reinforced the structural stability of the vertebra as a whole and through external remodeling the shape of the vertebra changed in a way that the majority of its volume was relieved from stresses and strains of high magnitude.

Comparative efficacy of primary angioplasty with stent implantation and thrombolysis in restoring basal coronary artery flow in acute ST segment elevation myocardial infarction: quantitative assessment using the corrected TIMI frame count.

Following thrombolysis and primary percutaneous transluminal coronary angioplasty (PTCA) for acute ST segment elevation myocardial infarction, basal flow in the culprit artery is known to influence prognosis. The purpose of this study was to determine if differences exist in basal flow in culprit and nonculprit coronary arteries in patients with acute ST segment elevation myocardial infarction who were treated with thrombolysis or primary PTCA with stent implantation. Twenty patients were randomized to thrombolysis (with recombinant tissue plasminogen activator) and 24 to primary PTCA with stent implantation within 3 hours of onset of acute ST segment elevation myocardial infarction. Coronary angiography was performed 90-120 minutes after thrombolysis or immediately after PTCA with stent implantation and again at 18-36 hours after intervention in both groups. Patients who failed to achieve thrombolysis in myocardial infarction (TIMI) grade 2 or 3 flow were excluded. The corrected TIMI frame count was used as the index of basal coronary artery flow. Early after intervention the mean corrected TIMI frame count in the culprit coronary artery was significantly lower in the primary PTCA with stent group (27.4 +/- 7.7 frames) than in the thrombolysis group (39.8 +/- 10 frames, p < 0.001). Eight thrombolysis patients (40%) and 20 primary PTCA patients (83%, p < 0.01) achieved TIMI grade 3 flow early after intervention. By 18-36 hours after intervention there were no significant differences in the mean correct TIMI frame count between the thrombolysis and primary PTCA with stent groups. There were no significant differences in the mean corrected TIMI frame count between these two groups in the nonculprit coronary artery, either early after intervention or at 18-36 hours. In successfully reperfused coronary arteries following acute ST segment elevation myocardial infarction, primary angioplasty with stent implantation reestablished TIMI grade 2 or 3 flow faster and more effectively than thrombolysis did.

Apical hypokinesis in a patient with hypertrophic cardiomyopathy and myocardial bridging: reversal with beta-blockade--a case report.

A 42-year-old man presented with effort angina pectoris of 20 minutes' duration. Hypertrophic obstructive cardiomyopathy, severe myocardial bridging involving the midleft anterior descending coronary artery, and apical hypokinesis were identified. Regional wall motion normalized following the initiation of beta blockade.

Comparison of endothelin-1 levels at rest and during exercise between patients with cardiac syndrome-X and healthy people.

Several previous studies have shown that endothelin-1 (ET 1) plasma levels are raised in cases of endothelial abnormality and microvascular dysfunction. Syndrome-X constitutes an important clinical entity characterized by angina-like pain and normal coronary arteries which is believed to reflect microvascular dysfunction. The aim of the present study was to investigate the role of ET 1 in the pathophysiology of the above syndrome. For that purpose the plasma ET 1 concentrations, measured by radioimmunoassay, between 28 X-syndrome patients (group A) and 10 age-matched normal control subjects (group B) at rest and at the peak of the exercise testing were compared. We specify that all individuals of group A were referred to our Department for effort angina and were found to have normal coronary arteriograms, negative ergonovine and hyperventilation test and positive exercise test. Our results showed that while at rest ET 1 plasma concentrations did not differ significantly between the two groups, at the peak of the exercise test its levels were found to be significantly higher in syndrome-X patients as compared with those of normal subjects (p< 0.001). In addition, in healthy control subjects ET 1 levels decreased during exercise as compared with the baseline values and that difference was found to be statistically significant (p approximately 0.01). The above finding suggests opposite kinetics during exercise of ET 1 between the two groups studied, which could explain effort angina onset in patients with syndrome-X.