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Biomedical subjects

N Marienhoff

Publications and source records attributed to N Marienhoff.

11 recordsLinked to original sources
PubMed1999

[Digital subtraction angiography with carbon dioxide--basic principles, technique and clinical application].

Carbon dioxide digital subtraction angiography Carbon dioxide (CO2) digital subtraction angiography offers the possibility for diagnostic and interventional angiographic procedures in high risk patients for ionidated contrast material. As a gaseous contrast agent its physicochemical properties have special requirements concerning the radiologists knowledge, the X-ray equipment, the injector and the catheters. This article reviews the current literature concerning the history, physics and physiology, indications and contraindications, clinical use, adverse effects and possible complications of carbon dioxide digital subtraction angiography.

Angiography, Digital Subtraction↗
PubMed1997

[Angiography during interventional procedures with carbon dioxide (CO2) (carbo-angiography) in patients with increased contrast media risk].

Within the last 18 months we examined 130 patients with known complications or contraindications using iodinated contrast media for angiography by using carbon dioxide as contrast agent in digital subtraction angiography technique. These were diagnostic pelvis-leg angiographies (n = 106) with simultaneous consecutive interventional radiologic therapy in 68 cases. In 19 dialysis access fistulas 11 angioplasties were performed in the same session. In 5 cases of renal allografts no interventional radiologic therapy was necessary. For CO2 application an electronic controlled special injector was used. Carbon dioxide has a number of advantages: no adverse reactions, nonallergenic and can be used several times without increasing risks and is cost-saving. CO2 angiography is a sensitive method, for detection vessel wall processes below the diaphragm. It can replace conventional angiography.

Angiography, Digital Subtraction↗
PubMed1995

[The importance of sonography before laparoscopic cholecystectomy].

The increasing use of minimally invasive techniques for the treatment of symptomatic cholecystitis requires exact preoperative diagnosis. The significant sonographic findings are stones in the biliary system or indirect evidence of stones, consisting in dilatation of the bile duct to more than 10 mm, as well as free mobility of the abdominal wall to exclude peri-umbilical adhesions. Amongst 100 patients who had laparoscopic cholecystectomies there were 7 with bile ducts wider than 10 mm. In two of these cases calculi could also be demonstrated. ERCP was performed on the remaining five and in 3 of these stones were seen. Peri-umbilical adhesions were seen in 6 Patients, resulting in alternative placing of the incision. The sonographic findings which are of relevance to the surgeon were analysed in these 100 cases. A standardised examination protocol is an important feature for proper patient selection.

Adolescent↗
PubMed1995

[First experiences with temporary vena cava filters].

AIM: For prophylactic measures we used 3 different temporarily insertable vena cava filters. MATERIAL AND METHODS: In 49 patients we inserted 12 Cook-filters (6 transjugular, 6 transfemoral), 11 Angio-cor-filters (1 transjugular, 10 transbrachial), 26 Antheor-filters (1 transjugular, 1 transfemoral, 24 transbrachial). 35 patients underwent a lysis therapy, 11 a major operation of the pelvis, and 3 patients a Caesarean section. RESULTS: No patient suffered from a clinically significant pulmonary embolism after filter insertion, but complications occurred caused by the basic therapy (1 lethal abdominal aortic aneurysm operation, 1 cerebral bleeding, 2 retroperitoneal haematomas, 2 streptokinase fever reactions, 1 compartment syndrome, 1 macro-haematuria) or by therapy joined with the filters insertion (2 groin haematomas, 2 haematomas of the bend of the elbow, 2 subclavian vein thrombosis, 1 catheter dislocation, 1 infection, 1 air embolism, 1 break of a leg of the filter basket). CONCLUSION: Temporary vena cava filters are highly efficient in preventing pulmonary embolism, but the side-effects show that they should only be inserted in patients with known deep vein thrombosis and a high risk treatment of the underlying disease.

Evaluation Studies as Topic↗
PubMed1993

Diagnosis of renal transplant failure by real-time and duplex Doppler sonography.

A total of 419 real-time and duplex Doppler ultrasound examinations of renal allografts were carried out in 61 patients. Results were related to the clinical diagnoses based on histomorphological, clinical, and laboratory findings. The results of all sonographic examinations in terms of the diagnostic parameters of normal function, acute tubular necrosis, and interstitial and vascular rejection did not yield reliable criteria for distinguishing between the different forms of transplant dysfunction. The maximum difference was calculated for each ultrasound parameter between a time of normal transplant function and at a time of dysfunction. By means of this 'maximum parenchyma-pyelon index difference' it was possible to discriminate between acute tubular necrosis and vascular rejection (P < 0.05). Acute tubular necrosis could be distinguished from interstitial rejection using the maximum longitudinal renal diameter difference and the maximum parenchyma-pyelon index difference (P < 0.05). To discriminate between interstitial and vascular rejection the maximum pulsatility index difference was very useful (P < 0.05). Combined real-time and duplex Doppler sonography is most valuable in the diagnosis of transplant failure when it is performed not only in the case of dysfunction but also when transplant function appears to be normal.

Female↗
PubMed1993

[Diagnosis of thrombophlebitis of the leg using duplex sonography].

In a prospective study 113 extremities of 98 patients with suspected lower extremity deep venous thrombosis were examined by duplex sonography and phlebography. In 66 examinations phlebography demonstrated fresh thromboses which were limited to the calf in 14 cases. In all other cases thrombosis was partially or totally localized above the knee. Duplex sonography had a sensitivity in detection of thromboses of 91% (calf veins) up to 94% (proximal veins) and a specificity of 95% and 97%, respectively. Duplex sonography is a reliable method in diagnosis of thrombosis in the popliteal, superficial and common femoral und distal iliac vein. If phlebography is contraindicated, duplex sonography is the method of choice. It should also be performed additionally to phlebography to visualise surrounding tissue and detect the possible cause of thrombosis and clinical symptoms. Duplex sonography can also visualise veins that are not shown phlebographically.

Adolescent↗
PubMed1992

[Plain CT of venous thromboses of the leg].

In 41 patients with deep vein thrombosis which had been demonstrated by duplex sonography, non-enhanced CT was performed at various levels before phlebography was carried out. Clots judged clinically to be fresh (1-7 days) show predominantly hyperdense thrombus material (60-80 Hu). With longer histories, on the other hand, the majority of thrombi were hypodense (50 Hu or less). Non-enhanced CT provided a rough indication of the age of a thrombus and may aid in deciding whether to use fibrinolysis. Dilatation of veins was found in 80% of the hyperdense early thrombi, but also in the presence of loose and old thrombi. This phenomenon and the presence of perivascular and soft tissue oedema does not indicate the type or age of the thrombus. These findings may be expected to occur also in other vascular areas.

Dilatation, Pathologic↗
PubMed1988

Lowered plasma erythropoietin in hypoxic rats with kidney tubule lesions.

The role of the kidney tubules in the renal formation of erythropoietin is incompletely understood. Therefore, the capability to produce erythropoietin in response to hypoxia was studied in rats with tubular lesions. Nephron damage was induced in two different ways. First, rats were treated with the nephrotoxic aminoglycoside gentamicin (67.5 mg/kg and day) for 14 days. The animals were then subjected to simulated altitude (6,800 m) for 6 h. The resulting plasma erythropoietin concentration was significantly lower (0.5 IU/ml) than in saline treated control rats exposed to hypoxia (1.0 IU/ml). Second, unilateral hydronephrosis was induced by ureteral ligation. The contralateral kidney was removed immediately before the animals were exposed to simulated altitude for 6 h. The plasma erythropoietin concentration in the ureter-ligated rats did not increase above the value (0.3 IU/ml) in hypoxia exposed anephric rats. These results indicate that the production of erythropoietin is reduced following tubular injury. Tubule cells may directly produce the hormone or interfere with the O2-sensing mechanisms controlling its synthesis. The latter hypothesis would seem to be supported by our failure to demonstrate in vitro erythropoietin production by the two established kidney tubule cell lines, LLC-PK1 and PK-15.

Altitude↗
PubMedDate not supplied

Follow-up study of renal transplants by duplex Doppler and gray-scale ultrasound.

In the early postoperative period after renal transplantation 388 follow-up ultrasound examinations were performed in 77 patients. Over a period of 18 months standardized duplex indices (resistive index, pulsatility index) and gray-scale parameters (parenchyma/sinus index; medulla/cortex index) were sampled. These data were correlated retrospectively with clinical and pathological diagnoses. To delineate the individual course of duplex and gray-scale indices during different transplant diseases we created a new parameter: the MID (maximal index difference) which is a result of the difference between the highest index during the phase of renal dysfunction and the lowest index during the phase of normal renal function. This MID, calculated for duplex indices and for the parenchyma/sinus index, indicated significant differences in the behavior of renal transplants during the four main diseases: interstitial rejection, vascular rejection, acute tubular necrosis and Cyclosporine A nephrotoxicity. Using the MIDs, a table of cut-off values was established, which enables to differentiate retrospectively these four transplant complications with a sensitivity of 84% and specificity of 81%. In our opinion consequent follow-up examinations with duplex and gray-scale sonography should be performed, enabling sonography to become a helpful diagnostic instrument in the monitoring of renal transplants.

Cyclosporine↗