Biomedical subjects
Publications and source records attributed to F P Kuhn.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Knitted flexible tantalum stents proved to be a valuable adjunct to percutaneous transluminal angiplasty (PTA) in the case of insufficient PTA results, and their use was established in the distal aorta, the iliac, the femoro-popliteal, the renal, and the coronary arteries. Recently, long arterial occlusions were defined as new indications for primary stenting; stent indications were further extended to the subclavian, the carotid, and the splanchnic arteries. Due to higher incidence of acute and late complications after stent treatment of small diameter arteries, patients have to be selected thoroughly. Newly designed drug-releasing stents tested in animal experiments promised to be suitable to diminish the incidence of late restenosis due to intinal hyperplasia, thus providing better long-term patency.
Percutaneously implantable vascular prostheses used clinically (Strecker, Palmaz and Wall stents) were tested as realistically as possible with regard to their mechanical stability. The Palmaz stent showed the greatest pressure stability. Even at pressures above three atmospheres the stent remained within 20% of its nominal diameter. In contrast, the Wall and Strecker stents showed much less pressure stability. Depending on the diameter of the wire and of the stent, there was 20% reduction in diameter at pressures between 0.13 and 0.68 atmospheres. These results will contribute to an improved application of the vascular endoprostheses which have been tested.
Case report on a 53-year old male patient; after transthoracic resection of the oesophagus a unilateral percutaneous biopsy of a newly developed round focus of the lung led to a bilateral pneumothorax (as well as a pneumomediastinum and a pneumoperitoneum). After transthoracic surgery the described alterations have also to be taken into account as possible complications of a unilateral percutaneous lung-biopsy.
Use of the Strecker flexible balloon-expandable tantalum stent for treatment of renal artery stenosis after failed angioplasty or transaortic thrombendarterectomy was evaluated in 18 patients (17 hypertensive, 1 normotensive). Right (n = 10) and left (n = 6) renal arteries were involved; in 2 patients renal artery stenosis had developed after kidney transplantation. Indications for stent placement were inadequate immediate postangioplasty response (n = 16), and obstructing intimal flaps following transaortic endarterectomy (n = 2). Stent placement was technically successful (less than 20% residual stenosis) and patency was preserved in 14 patients. Mid-term results (mean, 12-13 months) of 11 patients showed restenoses (greater than 50%) in 2 patients, and improvement of hypertension in 8 patients. The Strecker stent may be helpful in treating residual stenosis after failed revascularization procedures of the renal arteries, although long-term efficacy of stent placement will not be known until trials with more subjects and longer follow-up periods are completed.
30 patients with an acute build-up of renal transplant were examined comparatively via antegrade pyelography (AP), computed tomography (CT) and sonography (SONO). In the proof of obstructions and compressions of the ureter of renal transplant, antegrade pyelography was superior to sonography and computed tomography. Perirenal collections of fluids were recognised correctly via sonography by 73% (11/15) and computed tomography by 87% (13/15). The computer tomogram is superior in the differentiation of perirenal collection of fluids. In establishing proof of the cause of an acute build-up of renal transplant it was evident that computed tomography with a sensitivity of 64% and a specificity of 94% was slightly superior.
Palliative treatment of recurrent rectal cancer remains to be a challenge. From 1989 to 1991 13 patients with recurrent rectal cancer were treated with intraarterial infusion of 5-Fluorouracil and simultaneous radiotherapy in a palliative intent. Seven patients had received postoperative adjuvant radiotherapy with 56 to 60 Gy. Three patients had been treated with systemic chemotherapy. Radiotherapy of the recurrence was performed with 19.8 to 30.6 Gy in the pre-irradiated patients and with 50.4 to 59.4 Gy in the others. One complete remission, three partial remissions and nine minor responses were observed. Three patients had complete pain relief after the treatment, in the remaining patients major pain reduction was achieved. Palliation lasted from three to twelve months (median: five months). Our results indicate that locoregional chemo- and radiotherapy are a effective modality in recurrent rectal cancer.
The clinical clues of sudden arterial hypertension, acute pain in the side, proteinuria, hematuria, abdominal bruits and renal failure are suspicious for spontaneous dissection of the renal arteries, even in the absence of one or more of the above-mentioned symptoms. To confirm the diagnosis and to provide appropriate therapy, immediate renal arteriography is mandatory, otherwise acute loss of renal tissue may occur. We report on one patient with spontaneous dissection of the renal arteries.
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Use of the Strecker flexible balloon-expandable tantalum stent for treatment of renal artery stenosis after failed angioplasty or transaortic thromboendarterectomy was evaluated in 10 patients (nine hypertensive, one normotensive). Left (n = 3) and right (n = 5) renal arteries were involved; renal artery stenosis in two patients had developed after kidney transplantation. Indications for stent placement were inadequate immediate postangioplasty response (n = 7), development of considerable restenosis after angioplasty (n = 1), and obstructing intimal flaps following transaortic endarterectomy (n = 2). Stent placement was technically successful (less than 20% residual stenosis) and patency was preserved in eight patients. Of the seven hypertensive patients with successful implantation, two were cured, three had improvement, and two had no change at latest follow-up evaluation (mean, 10.6 months; range, 6-12 months). The Strecker stent may be helpful in treating restenosis after failed revascularization procedures, although the precise indication, true safety, and long-term efficacy of stent placement in renal arteries will not be known until trials with more subjects and longer follow-up periods are completed.
Color coded duplex sonography has definitive advantages over conventional duplex sonography for investigation of lower limb vessels. It contributes significantly to the non-invasive evaluation of peripheral aneurysms and complications associated with arterial puncture. After arterial graft surgery it is an effective imaging method to check bypass patency and evaluate suspected complications. Furthermore, color coded duplex sonography is sufficiently accurate to definitely diagnose lower extremity DVT, when not technically compromised. Postthrombotic vascular changes and clot alteration under anticoagulant treatment can be demonstrated with high sensitivity.
The most important radiologically detectable effects of the primary and secondary hyperparathyroidism of the skeletal system and the periarticular soft tissue structures are presented. In the following sensitivity and specificity of radiological imaging--sonography, scintigraphy, computed tomography, magnetic resonance imaging, arteriography and selective venous sampling--in the preoperative diagnostic of the parathyroid adenomas are discussed. Therefore, radiological imaging can be omitted before primary surgery. It was only in secondary surgery that radiological process proved useful and a guide during surgical intervention.
A retroperitoneal myxoid liposarcoma of the renal capsule must be differentiated from renal cell carcinomas, angiomyolipomas, fibrogenous lipomas, fibrolipomas and mixed tumours containing fat tissue. Myxoid liposarcomas can lead to intracaval tumour thromboses, which is often the case with renal cell carcinomas and revealed clinical with Budd-Chiari syndrome. Computed tomography and magnetic resonance imaging give additional information in the diagnosis of intracaval tumour thromboses and show the exact expansion of the topographic-anatomical structure.
Color Coded Duplex-Sonography (CCD) is the latest development in ultrasound equipment for non-invasive evaluation of the vascular system. Compared to conventional Duplex-Sonography the advantage of CCD is the ease of handling and quicker diagnosis, although there in no significant increase in information with CCD. The main indications for CCD are superficially located circumscribed vascular lesions as in carotid artery stenosis, tumors in the neck, disturbed renal transplant perfusion, hemodialysis vascular access shunts, deep vein thrombosis, testicular torsion and complications following vascular surgery of the extremities. The abdominal applications are limited.
Colour coded Duplex sonography has definite advantages over duplex sonography for the investigation of neck and limb vessels. Diagnosis of arterial stenoses, occlusions and aneurysms can be readily made. The method also allows to follow the evolution after vascular surgery and percutaneous transluminal angioplasty. Deep venous thromboses can be reliably detected without the use of contrast media. Application for abdominal vascular diagnosis is still limited.