Anisotropy of dynamic acoustoelasticity in limestone, influence of conditioning, and comparison with nonlinear resonance spectroscopy.

Anisotropy of wave velocity and attenuation induced by a dynamic uniaxial strain is investigated by dynamic acoustoelastic testing in limestone. Nonlinear resonance spectroscopy is performed simultaneously for comparison. A compressional resonance of the sample at 6.8 kHz is excited to produce a dynamic strain with an amplitude varied from 10(-7) to 10(-5). A sequence of ultrasound pulses tracks variations in ultrasonic velocity and attenuation. Variations measured when the ultrasound pulses propagate in the direction of the uniaxial strain are 10 times larger than when the ultrasound propagation occurs perpendicularly. Variations consist of a "fast" variation at 6.8 kHz and an offset. Acoustically induced conditioning is found to reduce wave velocity and enhance attenuation (offset). It also modifies "fast" nonlinear elastodynamics, i.e., wave amplitude dependencies of ultrasonic velocity and attenuation. At the onset of conditioning and beyond, different excitation amplitudes bring the material to non-equilibrium states. After conversion of velocity-strain dynamic relations into elastic modulus-strain dynamic relations and integration with respect to strain, the dynamic stress-strain relation is obtained. Analysis of stress-strain hysteresis shows that hysteretic nonlinear elasticity is not a significant source of the amplitude-dependent dissipation measured by nonlinear resonance spectroscopy. Mechanisms causing conditioning are likely producing amplitude-dependent dissipation as well.

[Right aortic arch and "isolated" left brachiocephalic arterial trunk. Fortuitous discovery in angiologic practice]. / Arc aortique droit et tronc artériel brachiocéphalique gauche "isolé". Découverte fortuite en pratique angiologique.

An exceptional case of congenital malformation of the supra-aortic trunks was discovered fortuitously during an angiographic examination. The echo-Doppler and arteriography findings are reported together with an outline of the most frequent congenital malformations of the supra-aortic trunks.

[Intra-arterial thrombolytic therapy of lower limb ischemia]. / Traitement thrombolytique intra-artériel des ischémies des membres inférieurs.

Between 1984 and 1989, 35 patients with recent arterial or graft occlusions have been treated with intra-arterial infusion using sequential association of Urokinase (U.K.) and Lys-Plasminogen. Occlusion was thrombotic in 68.5% of the cases ans embolic in 31.5%, involving 28 native arteries and 7 bypass grafts. The mean duration was 16 days (2 to 90). Continuous infusion of U.K.: 84,000 U.I./H and bolus of Lys-Plasminogen 15 microKatals every 30 minutes were delivered through a catheter embedded into the clot. Intra-venous heparin was always associated. The mean duration of lytic drug infusion was 8 H. Complementary arterial reconstruction by vascular surgery of percutaneous transluminal angioplasty was performed in 23% of the patients. Patients with recent alimentary tract bleeding, hemorragic stroke in the last six months or severe high blood pressures were contra-indicated. Complete lysis was obtained in 23 cases (66%), partial lysis in 7 (20%) and no lysis in 5 (14%). The clinical result was excellent in 24 cases (68.5%), good in 3 (8.5%) and bad in 8 (23%) in which amputation was always necessary. 5 local hematoma (14%) treated by surgery or transfusion and one death (3%) due to neurological complication occurring 24 hours after the end of the procedure were observed. The literature survey has shown that the results of low doses of Streptokinase (S.K.) local infusions were not better, and that higher doses of S.K. or U.K. delivered during a shorter infusion time increased the efficacy of lysis and decreased the rate of hemorragic complications. We have proposed the local thrombolytic treatment to the limb threatening ischemic cases when the traditional medical or surgical techniques where thought to be associated to a high risk of failure or complication. The specific indications are the acute or sub-acute ischemic situation due to atheromatous artery thrombosis, distal or old embolism where the Fogarty catheter is inefficient, and graft thrombosis. Severe acute ischemia with neurologic involvement are not good indications. Local thrombolysis can be successful on arterial occlusion even after one month duration.

[Ureteral invagination caused by a fibroepithelial polyp of the ureter. Apropos of a case]. / Invagination urétérale due à un polype fibro-épithélial de l'uretère. A propos d'un cas.

This article reports a new case of intussusception due to a ureteral polyp. The diagnosis was based on the preoperative radiological aspects. The polyp was both invaginated and twisted, and was removed along with a segment of the ureter.

[Ureteral endometriosis. Apropos of a bilateral form]. / Endométriose urétérale. A propos d'une forme bilatérale.

A case of bilateral ureteral endometriosis is reported. The patient presented, on one side, with endometriosis externa, associated with slight renal injury, and, on the other, with adenomyosis leading to uretero-ureteral invagination, and an associated severe renal impairment. A review of the reported cases and pathogenic theories is followed by a discussion of the diagnostic and therapeutic problems raised by ureteral endometriosis. The difficulty of establishing a correct diagnosis and the risk of damage to renal function often lead to surgical removal of the ureteral lesion.