[Physical properties of Strecker stents].

Strecker stent is a balloon-expandable metallic stent that is made of knitted tantalum wire mesh in order to Maintain flexibility. Therefore, the prosthesis is well suited to irregular and tortuous tube organs. We performed several physical experiments using 8 mm and 6 mm diameter stents made of 0.1 mm diameter wire filament. The bearing power of the 8 mm diameter stent against the circumferential compression pressure was divided into two groups, that is, 77-100% and under 66% of expansile rate. The capacity bearing the circumferential compression pressure of the latter group was greater than that of the former. Further, the bearing power of the 6 mm diameter stent was greater than that of the 56% expansile rate of the 8 mm diameter stent. The smaller the expansile rate of the stent, the smaller the minimum radius of curvature within the limits of the stent's plastic. To evaluate the suitability of the stent in clinical use, we made two projections on the inner surface of rubber tubes, and the stents were placed into the rubber tubes at different expansile rates. We evaluated the degree of contact of the stents against the rubber wall by taking soft X-ray photographs. The stents showed good suitability under the condition of incomplete expansion. For the above reasons, we concluded that, from the view-point of bearing power, the stent should be placed in the full expansile state. From the viewpoint of contact against the vessel wall, the stent should be placed in the incomplete expansile state.

[99mTc-pertechnetate scintigraphy in three cases with soft tissue tumors].

Three soft tissue tumors were studied with 99mTc-pertechnetate scintigraphy, 67Ga-citrate scintigraphy and MRI. These tumors included schwannoma, neurofibromatosis and malignant fibrous histiocytoma. On 99mTc-pertechnetate scintigram all patients showed more increased accumulation corresponding to the tumor than on 67Ga-citrate scintigram. In conclusion, 99mTc-pertechnetate scintigraphy may be useful in detection of soft tissue tumors.

[Experimental study of water jet angioplasty].

A newly invented angioplasty by using water jet energy was investigated for evaluating its safety and effectiveness in 3 dogs. The water jet was produced from a small tip nozzle (0.2 mm in diameter) of catheter by injecting 20 ml of diluted contrast medium. By using this method recanalization of femoral arterial occlusion produced by fresh thrombi was achieved in all 3 dogs. Post recanalization angiography showed no apparent small vessel occlusions. Injection apart more than 5 mm from the inner surface of human aorta provoked no apparent changes histopathologically. Water jet angioplasty may be useful in treating vascular occlusive disease.

[Hemodynamic responses to supine bicycle exercise in juvenile hypertensive subjects: an echocardiographic assessment (author's transl)].

Six juvenile hypertensive patients were studied by supine bicycle ergometer exercise during continuous echocardiographic recording. Thirteen normotensive young men were also studied for the control. Left ventricular end-diastolic dimensions (Dd) during exercise was significantly increased from 28.8 +/- 0.5 mm/m2 to 29.7 +/- 0.6 mm/m2 in normotensives, but the increase in Dd was not observed in hypertensives. Effects of propranolol on changes in Dd during exercise were almost equal in two groups. Left ventricular end-systolic dimensions (Ds) were decreased during exercise in both groups. After propranolol administration, Ds in hypertensives was significantly increased from 18.8 +/- 1.0 mm/m2 to 19.4 +/- 1.1 mm/m2 at rest, and during the following exercise it reached to 19.7 +/- 1.1 mm/m2, whereas Ds in normotensives was decreased during exercise even after propranolol. Peripheral vascular resistance at rest was almost equal between the two groups, but in hypertensives the reduction during exercise was restricted. These results suggest that sympathetic activities of cardiovascular system are accentuated in juvenile hypertensive subjects.