Biomedical subjects

S H Duda

Publications and source records attributed to S H Duda.

At least 55 records · Page 3Linked to original sources

PubMed1999

[Diagnosis of renal artery stenosis in 1.0 T using 3D phase contrast magnetic resonance angiography and dynamic contrast medium perfusion].

PURPOSE: To assess renal artery stenosis (RAS) by 3D phase contrast (PC) MR angiography and dynamic perfusion imaging of the kidneys. METHODS: On a standard 1.0 T MR imaging system (Magnetom Expert, Siemens), 32 patients with angiographically proven unilateral RAS were examined using a 3D PC sequence (TR 40 ms/TE 9 ms/venc 30 cm/s). An ECG-gated Turbo-FLASH 2D sequence (TR 4.5 ms/TE 2.2 ms/TIeff. 400 ms) was applied to study the first pass of paramagnetic contrast agent (0.1 mmol Gd-DTPA/kg) through the kidneys. Signal intensity (SI) over time curves of the renal cortex were obtained and evaluated considering temporal relation and percentage of maximum SI compared to the aorta and normal kidneys. Analysis of the MRA was performed by two independent blinded readers. The gold-standard DSA was interpreted by consensus reading of two experienced radiologists. RESULTS: RAS was detected by 3D PC MRA with a sensitivity of 93% and specificity of 81% (ppv 82%, npv 93%, accuracy 87%, kappa = 0.61). Maximum SI in RAS was significantly decreased (p < 0.001-0.0001). A temporally delayed enhancement of 1.5 +/- 1.3 s was found for RAS > 75% (p < 0.002) but not for RAS < 75% (p > 0.1). CONCLUSIONS: 3D PC MRA is capable of detecting RAS in a high percentage of patients. Dynamic perfusion imaging of the kidneys, applied additionally, can confirm the diagnosis and give valuable information about the hemodynamic relevance of RAS in suspected unilateral disease.

Contrast Media↗

PubMed1999

[MR tomography of the bone marrow changes after high-dosage chemotherapy and autologous peripheral stem-cell transplantation].

PURPOSE: Evaluation of MR standard imaging and short time inversion recovery (STIR) imaging to assess changes in red bone marrow cellularity after high-dose chemotherapy (HDC) and peripheral blood stem cells transplantation (PBSCT). MATERIALS AND METHODS: Sixty-one magnetic resonance (MR) studies were performed in 15 patients (8 female and 7 male, average age 45 years) who received HDC and PBSCT for therapy of either a solid tumor or multiple myeloma. All patients underwent MR examinations of the lumbar region and both femora with T1- and T2-weighted turbo spin-echo (TSE) and STIR sequences at predefined time intervals. Qualitative analysis of the signal intensity was performed by consensus reading of four radiologists. MR results were correlated with results of blood smears and marrow histology. RESULTS: STIR sequences demonstrated marked changes in signal intensity not only until the aplasia occurred but also during bone marrow repopulation. An increased signal intensity was observed after HDC in 13/15 patients (87%), followed by a decrease in signal intensity immediately after aplasia in 14/15 patients (93%). Signal intensity further changed parallel to marrow engraftment in 11/15 patients (73%). T2-TSE only showed clear changes during repopulation in 8/15 patients (53%). The individual course of the signal in T1-TSE was markedly inhomogeneous. CONCLUSIONS: STIR sequences show bone marrow edema during aplasia and marrow cellularity during reconstitution and are suitable for characterisation of red bone marrow after HDC and autologous PBSCT.

Adult↗

PubMed1999

Prevention of radiocontrast-media-induced nephropathy in patients with pre-existing renal insufficiency by hydration in combination with the adenosine antagonist theophylline.

BACKGROUND: Radiographic contrast media (CM) application causes a decline in renal function, especially in patients with pre-existing renal dysfunction. In addition to hydration, several vasodilating substances have been evaluated for their ability to prevent renal damage after CM application. In a prospective, double-blind, placebo-controlled study we investigated the effect of the oral administration of theophylline, an adenosine receptor antagonist, on changes in renal haemodynamics and tubular injury induced by CM in well-hydrated patients with mild-to-moderate renal insufficiency. METHODS: We studied 80 patients with pre-existing chronic renal insufficiency (creatinine > 1.5 mg/dl) who received more than 100 ml iopromide. Hydration (either oral or intravenous) started at least 24 h before and lasted until 24 h after CM application. In addition, patients were randomly assigned to receive either theophylline (810 mg daily) or placebo. Serum creatinine and creatinine clearance were measured before and for 3 days after CM application. Urine was collected to measure N-acetyl-beta-glucosaminidase (NAG) enzymuria for the same period. Sixty-four patients completed the entire study protocol (theophylline, n = 35 and placebo, n = 29). RESULTS: During the study period serum creatinine concentration and creatinine clearance did not change significantly in either group. Acute renal failure (increase of serum creatinine of at least 0.5 mg/dl) could be observed in two patients from the theophylline group (5.7%) and one from the placebo group (3.4%). The increase in NAG excretion reached statistical significance (P < 0.05) in the placebo group on days 2 and 3 after CM application. CONCLUSIONS: Our results indicate a role for adenosine in CM-induced tubulotoxicity. However, the glomerular filtration rate is preserved by hydration alone in these patients. The application of theophylline did not bring an additional benefit. The use of adenosine antagonists may be beneficial in patients where sufficient hydration may be impossible or in patients with a concomitant decrease in renal blood flow (e.g. congestive heart failure).

Acetylglucosaminidase↗

PubMed1999

Suture-mediated percutaneous closure of antegrade femoral arterial access sites in patients who have received full anticoagulation therapy.

PURPOSE: To assess the feasibility and clinical usefulness of suture-mediated closure of femoral arterial access sites after antegrade puncture for peripheral arterial interventions. MATERIALS AND METHODS: Eighty consecutive patients (49 men, 31 women; mean age +/- SD, 65.4 years +/- 12.3) who had undergone femoropopliteal angioplasty underwent suture-mediated percutaneous closure with 6-, 7-, or 8-F devices. Patients received heparin intravenously and aspirin orally and were immobilized for 1 hour after the intervention. All patients underwent a physical examination the day after the procedure. Color-coded duplex ultrasonography was performed in those patients (n = 27 [33%]) who were obese, were experiencing pain, and had suspicious clinical findings. After 3 months, an identical clinical examination was performed in every third patient. RESULTS: Hemostasis was achieved in 77 (96%) patients; one of 80 patients required blood transfusions and surgery despite an initially successful closure. The closure devices could be deployed in 78 (98%) patients; two of 80 patients needed compression because of a steep angulation of the puncture track and suture entrapment. Adjunctive compression was necessary in two (3%) of the remaining 78 patients. Mean time to hemostasis in the 78 patients who had successful device deployment was 5.2 minutes (range, 3.0-21.0 minutes). Minor complications (i.e., three small hematomas, a pseudoaneurysm, and a small lymphatic fistula) occurred in five (6%) patients. CONCLUSION: Suture-mediated percutaneous closure of antegrade puncture sites in the groin is feasible. Problems may arise in antegrade punctures owing to steep device angulation.

Aged↗

PubMed1999

Platelet glycoprotein IIb/IIIa receptor antagonist used in conjunction with thrombolysis for peripheral arterial thrombosis.

OBJECTIVE: This feasibility study was designed to evaluate the therapeutic potential of intraarterial urokinase combined with abciximab, an IV platelet glycoprotein IIb/IIIa receptor antagonist, in peripheral arterial thrombosis. CONCLUSION: The administration of a highly potent glycoprotein IIb/IIIa inhibitor in conjunction with intraarterial fibrinolysis was safe in 14 patients. One distal embolization and no major bleeding occurred. The primary success rate was 100%. Treatment times ranged from 50 min to 8 hr. We found a reocclusion rate of 7% (1/14) at intermediate follow-up.

Abciximab↗

PubMed1999

MR angiography and flow quantification of the internal mammary artery graft after minimally invasive direct coronary artery bypass.

OBJECTIVE: Six patients who had undergone minimally invasive direct coronary artery bypass surgery were examined to evaluate an MR imaging protocol that provided information about cardiac function, bypass graft patency, and flow characteristics with a single examination. CONCLUSION: Preliminary results suggest that our imaging protocol allows accurate follow-up of patients after minimally invasive direct coronary artery bypass surgery. Bypass graft patency was correctly determined in all patients. In four patients, anastomoses were visualized by MR angiography, and flow measurements revealed a volume range of 28-84 ml/min (native and grafted internal mammary arteries) and a trend for the flow values of bypass grafts to be lower than those of native vessels. Interobserver reproducibility was good (r = .99; slope, .98).

Contrast Media↗

PubMed1998

Remote suturing for percutaneous closure of popliteal artery access.

We present a case of balloon angioplasty of the superficial femoral artery via a popliteal artery access with successful percutaneous vascular closure of the vascular access site (6-F Techstar). A femoral arterial approach had not been feasible due to previous aorto-femoral and femoro-femoral bypass operations. Clinical and ultrasound follow-up showed no complications up to 3 months after remote suturing.

Aged↗

PubMed1998

Percutaneous arterial closure in severely scarred groins: a technical note.

We present a new method to enable the insertion of percutaneous suturing devices in severely scarred groins, using a peel-away sheath. This sheath stabilizes the percutaneous tract for the suturing device. It may help to salvage closure procedures, which would otherwise have to be aborted due to insufficient stiffness of the device shaft.

Catheters, Indwelling↗

PubMed1998

[Yamakawa prosthesis with prolonged placement as a therapy concept exemplified by benign biliary stricture].

AIM: As an alternative method to the operative revision of benign bile duct strictures, we report the use of a large-bore bile duct prosthesis (Yamakawa prosthesis) in one patient. METHODS: Bilateral percutaneous transhepatic implantation of Yamakawa prostheses (14 F right side, 12 F left side) was performed without adjunctive balloon dilatation. The prostheses were exchanged every 8 weeks under continuous antibiotic treatment and were finally removed after 8 months. RESULTS: Control cholangiography showed a normal intrahepatic biliary system on the right side and a 50% stenosis at the orifice of the left hepatic duct. Follow-up over 18 months showed no signs of recurrent disease. CONCLUSIONS: In comparison to balloon dilatation and implantation of metallic stents, prolonged bilateral splinting with large-bore Yamakawa prostheses seems to be an alternative for the treatment of benign bile duct strictures.

Adult↗

PubMed1998

Gd-enhanced 3D phase-contrast MR angiography and dynamic perfusion imaging in the diagnosis of renal artery stenosis.

The objective of this study was to investigate the role of contrast enhancement using a three-dimensional (3D) phase-contrast (PC) magnetic resonance (MR) sequence (3D PC-MRA) and to assess the value of a dynamic MR perfusion study of the kidneys to determine the hemodynamic relevance of unilateral renal artery stenosis (RAS). Seventeen patients with unilateral RAS were examined on a standard 1.0 T imaging system using a phase shift and magnitude sensitive 3D PC sequence (TR=160 ms, TE=9 ms, venc. 30 cm/s). Following the initial pre-contrast 3D PC-MRA a dynamic first pass perfusion study was performed using a Turbo-FLASH 2D sequence (TR=4.5 ms, TE=2.2 ms, TI=400 ms) after bolus injection of 0.15 mmol gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)/kg body weight. The 3D PC-MRA was then repeated during infusion of 0.15 mmol Gd-DTPA/kg body weight. Evaluation by three independent readers was based on maximum intensity projection images. Source images were rendered on request. Signal intensity (SI) over time curves of the renal cortex were obtained from the dynamic perfusion study and analyzed for maximum signal enhancement as well as temporal relationship to the aortic SI curve. Results from 3D PC-MRA revealed a sensitivity (pre-/post-contrast) of 100%/89%, specificity of 76%/63%, positive predictive value of 80%/69 %, negative predictive value of 90%/78%, and accuracy of 85%/75% (p=0.07). Interobserver agreement was kappa=0.61/kappa=0.47 (pre/post Gd-DTPA), respectively. Increased signal-to-noise was present in all segments of the renal arteries post contrast (p=0.0003). This came along with image degradation due to aliasing and elevated SI of venous flow that partially obscured the renal arteries. Dynamic SI curves showed a significantly decreased maximum SI in RAS (p=0.01-0.001). A temporal delay of cortical signal intensity enhancement could not be confirmed in this setting. Gd-enhanced 3D PC-MRA did not yield a superior diagnostic value in the diagnosis of RAS compared to pre-contrast measurements. Dynamic perfusion imaging of the kidneys, in combination with 3D PC-MRA, can contribute additional information in suspected unilateral RAS.

Aged↗

PubMed1998

[Intra-arterial calcium stimulation for preoperative localization of insuloma].

PURPOSE: Objective is to evaluate the efficacy of the intraarterial calcium test in the preoperative localisation of insulinomas. MATERIAL AND METHOD: To stimulate the pathological release of insulin, calcium gluconate (0.015 meq Ca++/kg) was selectively injected into the arteries supplying the pancreas. Prior to calcium injection and 30, 60, 90 and 120 seconds later, 5 ml samples of blood were obtained from the right or from both right and left hepatic veins. Insulin levels were then determined by mean of immunoassays. A twofold increase in insulin level in the venous sample after 30 or 60 seconds localised the insulinoma to the region of the pancreas supplied by the selectively injected artery. Results of the calcium test were prospectively analysed in 6 patients and compared with operative findings. RESULTS: All 6 patients had a surgically proved solitary and benign insulinoma. Calcium stimulation with venous sampling provided true-positive localisation of insulinomas in all patients without suspicion of liver metastasis. All 6 patients currently have normal insulin levels after a mean period of 16 months (range 4-24 months) with no evidence of hypoglycaemia on fasting. CONCLUSION: Intraarterial stimulation with calcium and hepatic vein samplings for insulin gradients is a very sensitive minimally invasive functional method and may replace transhepatic portal venous samplings for the preoperative detection of insulinomas.

Adult↗

PubMed1998

[Plaque morphology after arterial interventions in the New Zealand white rabbit--which model of restenosis is most suitable?].

PURPOSE: For evaluation of therapy for possible reduction of restenosis after PTA a suitable animal model is needed. The influence of different interventions on arterial plaque composition was analysed in New Zealand White Rabbits. MATERIAL AND METHODS: The following interventions were performed in the infrarenal aorta of New Zealand White Rabbits (n = 42): a) Balloon denudation (BD) with and b) without 0.5% cholesterol diet (CD), c) application of a Wiktor stent, d) CF without BD, and e) control group, 6 weeks after intervention morphometry and histology were performed. RESULTS: After BD the stenosis rate measured 26 +/- 18%, additional CD after prior BD increased the stenoses rate by 2.5 times up to 61.1%. After stent implantation there was only a thin neointimal layer (89 +/- 68 microns) around the stent wires. CONCLUSIONS: Neither implantation of stents nor single CD are suitable as restenosis models. BD with and without CD was followed by a distinct neointima formation with different cellular composition. The New Zealand White Rabbit constitutes an acceptable model for contemporary research in arteriosclerosis.

Angioplasty, Balloon↗

PubMed1998

[Transjugular intrahepatic portosystemic shunt in children. Initial clinical experiences and literature review].

PURPOSE: To present special methodical and clinical findings of transjugular intrahepatic portosystemic shunts (TIPSS) in children and to discuss potential indications. PATIENTS AND METHODS: Between 1993 and 1996, 6 children aged 2-13 years were treated by TIPSS-insertion. In four cases, the underlying disease was extrahepatic biliary atresia (EHBA) and in two cases liver fibrosis secondary to treatment of neoplasms during early childhood. Indications for TIPSS insertion were variceal bleeding resistant to other treatment modalities in three patients, hypersplenism in one patient and both bleeding and hypersplenism in two. Portal vein punctures were performed using 16-gauge needles, because 19-gauge fine-needles showed insufficient stiffness. The mean follow-up was 24.5 months. RESULTS: Shunt insertion succeeded in all children with a mean procedure time of 5.2 hours. Periportal fibrosis associated with EHBA, atypical course of hepatic veins and small diameters and distances of vessels were conditions making the procedure difficult. Bleeding ceased in all patients, peripheral platelet counts rose by a mean value of 58%. Procedure-related complications were minor extrahepatic bleeding in one child and temporary haemolysis in another child. Restenosis resulted in three patients and were treated successfully by means of transjugular interventions. 5 children remain free of symptoms to this day, one child underwent successful orthotopic liver transplantation 8 months after TIPSS. CONCLUSIONS: TIPSS insertion is technically more difficult in children and has to consider child growth and possible subsequent liver transplantation. Potential indications are recurrent variceal bleeding, also of intestinal origin, resistant to standard treatment and clinically significant hypersplenism.

Adolescent↗

PubMed1998

[Intra-arterial application of the ACE inhibitor ramipril using a microperforated catheter for the prevention of neointimal proliferation after angioplasty in an animal model].

PURPOSE: To evaluate the safety and benefit of a high-dose local drug administration via a microporous balloon catheter to prevent neointimal formation after balloon angioplasty. MATERIALS AND METHODS: In New Zealand white rabbits (n = 29) neointima formation was induced by balloon denudation. Additionally, the animals were fed a 0.5% cholesterol diet for 6 weeks. Directly after the denudation, local application of 1.8 mg ramipril (n = 7) or saline (n = 7) via a microporous balloon catheter was performed. Other animals (n = 7) were treated with a systemic ramipril administration. One control group were exclusively fed with a cholesterol diet (n = 8). 6 weeks after intervention the animals were sacrificed and morphometry of the vessels was performed. RESULTS: Local administration of ramipril resulted in a non-significant reduction of 17%. The local administration mode was combined with a significant increase in neointima formation. Systemic ramipril administration resulted in a 66% reduction of plaque area. CONCLUSIONS: The benefit of the local ramipril administration was diminished by the inherent vessel trauma. Systemic ramipril administration resulted in a significant reduction of neointimal proliferation in New Zealand white rabbits.

Angioplasty, Balloon↗

PubMed1998

[Stability of iodinated contrast media in UV-laser irradiation and toxicity of the photoproducts].

PURPOSE: In XeCl-Excimer laser angioplasty, unintended and possibly harmful interaction of the UV-laser light and the contrast media may occur due to the high concentration of contrast medium proximal to the occlusion or subtotal stenosis. METHODS: One ml of three nonionic monomeric contrast agents (iopromide, iomeprol, iopamidol), one nonionic dimeric (jotrolane), and one ionic monomeric (amidotrizoate) X-ray contrast agent were irradiated with a XeCl excimer laser (lambda = 308 nm, pulse duration 120 ns, 50 Hz) using a 9 French multifiber catheter (12 sectors). Up to 20,000 pulses (106 J) were applied. Using high performance liquid chromatography the amount of liberated iodide as well as the fraction of unchanged contrast media were measured. Cytotoxicity of the photoproducts was tested in a colony formation assay of human skin fibroblasts. The contrast agents were irradiated with 2000 pulses/ml (5.3 mJ/pulse; 10.6 J) and then added to the cell cultures for a period of three hours in a concentration of 10%. RESULTS: Excimer laser irradiation induced iodide liberation of up to 3.3 mg iodide/ml. Up to 19% of the contrast agents changed their original molecular structure. Incubation of irradiated contrast agents resulted in a significantly decreased potential for colony formation (p values ranging from 0.0044 to 0.0102) with significantly higher toxicity of amidotrizoate and iomeprol in comparison to iopromide, iotrolan, and iopamidol. DISCUSSION: Due to the cytotoxic photoproducts and the high level of liberated iodide, it is recommended to flush the artery with physiological saline solution before applying a pulsed excimer laser in human arterial obstructions in order to reduce the contrast agent concentration at the site of irradiation.

Cells, Cultured↗

PubMed1998

Abdominal aortic aneurysms: treatment with juxtarenal placement of covered stent-grafts.

PURPOSE: To determine the technical feasibility and clinical outcome of juxtarenal placement of covered stent-grafts for endovascular treatment of abdominal aortic aneurysms with a proximal neck less than 15 mm long. MATERIALS AND METHODS: In seven patients, abdominal aortic aneurysms with infrarenal necks 3-14 mm long were excluded with juxtarenal implantation of polyester-nitinol coknit stent-grafts. The proximal uncovered portion of the stent-graft (length, 12 mm) was placed across one or both orifices of the renal arteries. Seven patients underwent standard infrarenal stent-graft placement. Clinical outcome in all 14 patients was determined with computed tomography (CT) and laboratory values and also with captopril renography in the patients who underwent juxtarenal placement. The mean follow-up was 10.1 months. RESULTS: Findings from serial follow-up CT and laboratory analysis performed in all patients and captopril renography performed in five of the patients who underwent juxtarenal stent-graft placement did not reveal impaired renal function or perfusion. CONCLUSION: Successful exclusion of abdominal aortic aneurysms located closer than 15 mm to the orifices of the renal arteries is possible with juxtarenal placement of the uncovered portion of the stent in the abdominal portion of the aorta.

Aged↗

PubMed1998

Insulinoma and islet cell hyperplasia: value of the calcium intraarterial stimulation test when findings of other preoperative studies are negative.

PURPOSE: To evaluate the efficacy of the intraarterial calcium test in localizing sources of hyperinsulinism that remain undetectable at preoperative morphologic studies. MATERIALS AND METHODS: Twenty-four patients with clinically proved endogenous hyperinsulinism due to tumorous insulin production were prospectively enrolled. They underwent ultrasound (US), computed tomography, magnetic resonance imaging, endoscopic US, abdominal arteriography, and a calcium test, in which insulin concentrations were measured in hepatic venous blood after selective intraarterial calcium stimulation. The results of the calcium test in seven patients (five women, two men; age range, 30-66 years; mean age, 47 years) with negative findings of morphologic studies are described. RESULTS: Six solitary insulinomas (mean diameter, 0.73 cm) and one nodular hyperplasia were diagnosed after surgery. In all seven cases, calcium test findings allowed accurate localization of the pathologic source of insulin secretion. In three of these seven cases, results of arterial calcium stimulation with hepatic venous sampling (ASVS) affected intraoperative management. An increase in insulin concentration after stimulation in the hepatic artery was not observed, making hepatic metastases unlikely. CONCLUSION: ASVS, which is procedurally simpler than transhepatic pancreatic venous sampling, is effective for localizing sources of hyperinsulinism not detected with preoperative morphologic studies.

Calcium Gluconate↗

PubMed1998

Intravascular ultrasound diagnosis of aortic graft infection.

BACKGROUND: To assess the value of intra-aortic ultrasound (US) for diagnosing intraprosthetic vegetations in atypical aortic graft infection. METHODS: A 66-year-old man presented with fever 12 months after emergency insertion of a straight infrarenal aortic graft because of rupture of an inflammatory abdominal aneurysm. Blood cultures, leukocyte scan, transabdominal US study, and digital angiography were negative. Spiral CT was equivocal. The patient was imaged with a mechanically rotating US transducer at 12.5-MHz from inside the graft. RESULTS: Intravascular catheter ultrasound showed mobile lesions at the graft wall in the absence of periprosthetic fluid. Immediately after the procedure the patient developed several small cutaneous septic infarctions on both feet. At operation the presence of graft infection was confirmed. CONCLUSIONS: This case report suggests that intra-aortic US may constitute a helpful adjunctive modality in suspected atypical infection of prosthetic aortic grafts.

Aged↗