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Thomas Pfammatter

Publications and source records attributed to Thomas Pfammatter.

At least 19 recordsLinked to original sources
PubMed2006

Peripheral arteries in diabetic patients: standard bolus-chase and time-resolved MR angiography.

PURPOSE: To prospectively determine the diagnostic performance of a combination of standard bolus-chase magnetic resonance (MR) angiography and MR angiography with time-resolved imaging of contrast kinetics (TRICKS) for depicting severity of peripheral vascular disease of the lower extremity, including the pedal arteries, in diabetic patients with digital subtraction angiography (DSA) as the reference standard. MATERIALS AND METHODS: An ethical committee approved this study; written informed consent was obtained from patients. Standard three-station and TRICKS MR angiography of the calf and foot were performed in 31 consecutive diabetic patients (23 men, eight women; mean age, 67 years; range, 43-81 years). Two readers separately assessed images of arterial segments as diagnostic or nondiagnostic and graded stenosis. Results were compared with those at DSA when the corresponding arterial segments were considered diagnostic at DSA. Wilcoxon signed rank test was used to determine if a significant difference between imaging techniques existed, and kappa statistics were used to determine interobserver agreement. RESULTS: The difference between standard MR angiography and DSA regarding the number of diagnostic segments in the thigh was not significant (P = .50). A significantly higher number of calf and foot segments was considered diagnostic at TRICKS MR angiography than at standard MR angiography (P < .025). Sixteen of 26 segments in the foot that were considered nondiagnostic at DSA were considered diagnostic at TRICKS MR angiography. Average sensitivity of standard MR angiography for depicting hemodynamically significant arterial stenosis was 84% (reader 1) and 83% (reader 2) in the thigh and 78% (reader 1) and 80% (reader 2) in the calf. For both readers, average specificity was 97% in the thigh and 90% in the calf. Sensitivity and specificity of TRICKS MR angiography in the calf and foot were improved compared with those at standard MR angiography. CONCLUSION: TRICKS MR angiography of the distal calf and pedal vessels is superior to standard MR angiography regarding the number of diagnostic segments and assessment of the degree of luminal narrowing.

Adult↗
PubMed2006

Acute gastrointestinal bleeding: detection of source and etiology with multi-detector-row CT.

This study was conducted to determine the ability of multi-detector-row computed tomography (CT) to identify the source and etiology of acute gastrointestinal bleeding. Eighteen patients with acute upper (n = 10) and lower (n = 8) gastrointestinal bleeding underwent 4-detector-row CT (n = 6), 16-detector-row CT (n = 11), and 64-slice CT (n = 1) with an arterial and portal venous phase of contrast enhancement. Unenhanced scans were performed in nine patients. CT scans were reviewed to determine conspicuity of bleeding source, underlying etiology, and for potential causes of false-negative prospective interpretations. Bleeding sources were prospectively identified with CT in 15 (83%) patients, and three (17%) bleeding sources were visualized in retrospect, allowing the characterization of all sources of bleeding with CT. Contrast extravasation was demonstrated with CT in all 11 patients with severe bleeding, but only in 1 of 7 patients with mild bleeding. The etiology could not be identified on unenhanced CT scans in any patient, whereas arterial-phase and portal venous-phase CT depicted etiology in 15 (83%) patients. Underlying etiology was correctly identified in all eight patients with mild GI bleeding. Multi-detector-row CT enables the identification of bleeding source and precise etiology in patients with acute gastrointestinal bleeding.

Acute Disease↗
PubMed2006

Low-molecular-weight heparin for prevention of restenosis after femoropopliteal percutaneous transluminal angioplasty: a randomized controlled trial.

BACKGROUND: Restenosis after angioplasty is essentially due to intimal hyperplasia. Low-molecular-weight heparins (LMWHs) have experimentally been shown to have antiproliferative effects in addition to their antithrombotic properties. Their potential in reducing restenosis remains to be established. Therefore, we wanted to test the hypothesis that LMWH plus aspirin is more effective than aspirin alone in reducing the incidence of restenosis/reocclusion in patients undergoing percutaneous transluminal angioplasty (PTA) of femoropopliteal arteries. Further, different effects of LMWH in patients treated for critical limb ischemia (CLI) or claudication only should be investigated. METHODS: After successful PTA, 275 patients with symptomatic peripheral arterial disease (claudication or critical limb ischemia) and femoropopliteal obstructions were randomized to receive either 2500 IU of dalteparin subcutaneously for 3 months plus 100 mg of aspirin daily (n = 137), or 100 mg aspirin daily alone (n = 138). The primary end point was restenosis or reocclusion documented by duplex ultrasonography imaging at 12 months. RESULTS: Restenosis/reocclusion occurred in 58 patients (44%) in the dalteparin group and in 62 patients (50%) in the control group (P = .30). In a subgroup analysis according to the severity of peripheral arterial disease, we found that in patients treated for claudication, restenosis/reocclusion developed in 43 (43%) in the dalteparin group, and in 35 (41%) in the control group (P = .70); in patients treated for CLI, restenosis/reocclusion was significantly lower in the dalteparin group (15, 45%) than in the control group (27, 72%; P = .01). No major bleeding events occurred in either group. CONCLUSIONS: Treatment with 2500 IU dalteparin subcutaneously given for 3 months after femoropopliteal PTA failed to reduce restenosis/reocclusion at 12 months. However, dalteparin may be beneficial in the subgroup of patients with CLI at 12 months follow-up.

Aged↗
PubMed2006

Contrast material-enhanced visualization of the ablation medium for magnetic resonance-monitored ethanol injection therapy: imaging and safety aspects.

PURPOSE: This study was performed to test whether the dissociation rate of free Gd3+ ions from gadoterate meglumine is significantly increased when the contrast agent is dissolved in ethanol and whether the magnetic resonance (MR) signal of gadolinium/ethanol solutions is enhanced to a degree that promises reliable detection during MR imaging-guided intralesional administration, such as for the treatment of low-flow venous malformations. MATERIALS AND METHODS: The apparent gadoterate meglumine-induced enhancement of the longitudinal proton relaxation rate of sterile ethanol/water solutions, stored at a temperature of 24 degrees C +/- 5 degrees C in the dark, was monitored for 2 weeks. The content of dissociated Gd3+ ions was determined after 6 and 8.5 months of storage. The signal difference between contrast agent/ethanol solutions and muscle tissue was assessed with imaging at 0.5 T and 1.5 T. RESULTS: Commercialized gadoterate meglumine diluted with 94% ethanol was not shown to have released toxic Gd3+ during storage times that exceed its physiologic circulation and excretion times after intravenous injection by a factor of more than 100. A maximum dissociation rate of 0.05% per month was estimated from the detection limit of the analysis. The apparent molar relaxivity of the contrast agent in the mixtures varied by less than 0.1 L/mmol per second with no temporal trend. Gradient-echo ethanol/muscle contrast increased with Gd concentrations to maximums of 15 mmol/L (at 0.5 T) and 25 mmol/L (at 1.5 T). CONCLUSIONS: Neither limited solubility nor release of Gd3+ ions could be identified as a general safety hazard associated with the application of gadoterate meglumine/ethanol solutions at Gd concentrations of 0.5-25 mmol/L, and such ablation mixtures could be efficiently and reliably visualized.

Arteriovenous Malformations↗
PubMed2006

Segmental arterial mediolysis: CTA findings at presentation and follow-up.

OBJECTIVE: Segmental arterial mediolysis is a rare noninflammatory vascular disease of the abdominal splanchnic arteries. The purpose of our study was to retrospectively describe the CT angiography (CTA) findings of this disease and the evolution of those findings over time in five patients. CONCLUSION: Comparison of CTA and digital subtraction angiography suggests that CTA is useful to diagnose symptomatic segmental arterial mediolysis. Midterm CTA follow-up (median, 3 years) indicates that segmental arterial mediolysis lesions may resolve or remain unchanged.

Aged↗
PubMed2005

Aortoiliac and lower extremity arteries assessed with 16-detector row CT angiography: prospective comparison with digital subtraction angiography.

PURPOSE: To prospectively compare the accuracy of 16-detector row computed tomographic (CT) angiography with conventional digital subtraction angiography (DSA) as the reference standard in the assessment of aortoiliac and lower extremity arteries in patients with peripheral arterial disease. MATERIALS AND METHODS: This study was approved by the institutional review board, and informed consent was obtained. A total of 39 consecutive patients (27 men [mean age, 66 years] and 12 women [mean age, 64 years]) with peripheral arterial disease underwent both conventional DSA and 16-detector row CT angiography. For data analysis, the arterial vascular system was divided into 35 segments. A total of 1365 arterial segments were analyzed for arterial stenosis by two independent blinded readers using a four-point grading system (grade 1, <10% luminal narrowing; grade 2, 10%-49% luminal narrowing; grade 3, 50%-99% luminal narrowing; grade 4, occlusion). Interobserver agreements were calculated by using kappa statistics. A third independent blinded reader assessed possible reasons for disagreements between 16-detector row CT angiographic findings and conventional DSA findings. Effective radiation dose was calculated for both imaging modalities. RESULTS: Sixteen-detector row CT angiographic and conventional DSA findings were diagnostic in all vascular segments. Compared with conventional DSA, the sensitivity and specificity of 16-detector row CT angiography with regard to detection of hemodynamically significant stenosis in all 35 arterial segments were 96% and 97%, respectively, for both readers. Readers 1 and 2 overestimated arterial stenosis in 42 (3%) and 34 (2%) arterial segments, respectively, and underestimated arterial stenosis in 13 (1%) and 10 (1%) arterial segments, respectively. Interobserver agreement was excellent (kappa = 0.84-1.00). Presence of anteroposteriorly located luminal narrowing and extensive vascular wall calcification were considered main reasons for disagreements between imaging modalities. Effective radiation dose was lower for 16-detector row CT angiography (1.6-3.9 mSv) than for conventional DSA (6.4-16.0 mSv). CONCLUSION: Sixteen-detector row CT angiography is an accurate and reliable noninvasive alternative to conventional DSA in the assessment of aortoiliac and lower extremity arteries in patients with peripheral arterial disease.

Adult↗
PubMed2005

Midterm outcome of endovascular repair of ruptured abdominal aortic aneurysms.

PURPOSE: We sought to analyze the clinical and morphologic outcomes of bifurcated stent grafts in patients with ruptured aortoiliac aneurysms at midterm follow-up. METHODS: Thirty-seven patients (4 women; mean age, 73 years; mean abdominal aortic aneurysm [AAA] diameter, 77 mm) underwent endovascular abdominal aneurysm repair between June 1997 and July 2003 for ruptured AAA. Devices inserted were as follows: Vanguard (Boston Scientific, Natick, Mass; n = 7), Excluder (W.L. Gore, Flagstaff, Ariz; n = 25), Talent (Medtronic Vascular, Santa Rosa, Calif; n = 2), and Zenith (Cook Inc, Bloomington, Ind; n = 3). Except for the adjunct postimplantation computed tomographic scanning, the imaging follow-up was the same as for nonruptured AAAs. RESULTS: The mean follow-up period was 24 months (range, 1-59) months. Thirty-day mortality was 10.8%. Three patients died during the follow-up of non-AAA-related causes. One patient was converted early for presumed renal overstenting. The late conversion rate was 9% because of stent graft migration (n = 2) or infection (n = 1). Freedom from endoleak was 57% +/- 8.5% and 48.8% +/- 9% at 2 and 4 years, respectively. Seventeen secondary interventions were performed during the follow-up period, 41% of these within 1 month of stent graft placement. Endoleaks, primary or secondary, were responsible for 58.8% of these interventions. The cumulative risk of a secondary intervention was 35.3% +/- 9% at 2 years and 44.6% +/- 11% at 3 years. Aneurysmal sac shrinkage was observed in 30.8% +/- 9.1% and sac enlargement was observed in 15.3% +/- 10.8% at 2 years. CONCLUSION: Endoluminal devices are able to convert the acute life-threatening situation of ruptured AAA to a controlled situation that results in good patient survival at midterm follow-up.

Aged↗
PubMed2005

Endovascular repair of inflammatory abdominal aneurysm: a retrospective analysis of CT follow-up.

Retrospective radiologic and clinical midterm follow-up is reported for 10 patients with inflammatory abdominal aortic aneurysm (IAAA) after endovascular aortic aneurysm repair (EVAR). At a mean follow-up of 33 months, regression of the thickness of the perianeurysmal fibrosis (PAF) and decrease of aneurysmal sac diameter was observed in nine patients. Four EVAR-associated complications were observed: periinterventional dissection of femoral artery (n = 1), blue toe syndrome (n = 1), and stent-graft disconnection (n = 2). EVAR is the less invasive method of aneurysm exclusion in patients with IAAA with a comparable evolution of the PAF as reported after open repair.

Aged↗
PubMed2004

Assessment of skeletal muscle perfusion by contrast medium first-pass magnetic resonance imaging: technical feasibility and preliminary experience in healthy volunteers.

PURPOSE: To probe the potential and pitfalls of contrast medium first-pass skeletal muscle perfusion imaging under reproducible stress conditions. MATERIALS AND METHODS: Magnetic resonance (MR) signal dynamics in calf muscle and lower-leg arteries of 20 healthy volunteers were analyzed under postarterial occlusion reactive hyperemia and concurrent contrast medium first pass, using a saturation recovery spoiled gradient-echo type sequence without heartbeat synchronization. The signal vs. time curves were analyzed descriptively and by two-compartment deconvolution analysis. RESULTS: Highly significant changes in calf muscle signal dynamics in the hyperemic leg vs. those in the contralateral leg at rest were found in phenomenological and deconvolution analysis. Although a distortion of the arterial signal derived input function by inflow effects was found to cause large variations of the deconvolution results, the magnitude of the observed effects suggested a potential for immediate visual detection of areas with reduced tissue perfusion. CONCLUSION: The first-pass approach appeared promising for visual evaluation. However, a disentanglement of inflow and contrast medium-induced effects on arterial signal intensity was deemed a prerequisite for input function-based numerical assessment.

Adult↗
PubMed2004

Emergency stent-graft placement for hemorrhage control in acute thoracic aortic rupture.

OBJECTIVE: To report mid-term results of stent-graft (SG) implantation in acute thoracic aortic rupture as alternative to conventional open surgery with its associated high morbidity and mortality rates. METHODS: Out of a series of 69 patients undergoing thoracic aortic SG implantation since 1998, 24 (mean age 57+/-19 years, range 20-85-years-old) patients were treated on an emergency basis for hemorrhage control. The indication for SG placement was acute traumatic aortic rupture in 15 patients, type B dissection with contained rupture in 3 patients, penetrating aortic ulcer with periaortic hematoma in 3 patients, and thoracic aortic aneurysm rupture in 3 patients. Preoperative assessment was done by computed tomography (CT) scanning and echography. Patients were treated in the angiography suite by implantation of Excluder (n = 18) Talent (n = 4) Corvita (n = 1) and Vanguard (n = 1) self-expanding grafts. Local anesthesia was the most frequently used anaesthesiologic technique. RESULTS: Technical success rate of SG deployment was 100%. The early postoperative mortality was 12.5% (3 of 24). One patient suffered temporary paraplegia (4%). There was no intervention-related mortality during the mean follow-up of 34.1 months. Two secondary endoleaks were successfully treated with additional SG placement at 2 and 12 months postoperative, respectively. CONCLUSIONS: Emergency SG repair to control hemorrhage in patients with an acute thoracic aortic rupture is a less-invasive attractive and rational treatment option, especially if associated lesions or co-morbidity may interfere with the surgical outcome. Long-term follow-up results will be helpful to clarify procedure durability bounded by material failure and postoperative aneurysm or aortic wall remodelling.

Acute Disease↗
PubMed2004

Selective arterial calcium stimulation and hepatic venous sampling in the evaluation of hyperinsulinemic hypoglycemia: potential and limitations.

PURPOSE: To describe the potential and limitations of selective arterial calcium stimulation and hepatic venous sampling (ASVS) in the evaluation of patients with hyperinsulinemic hypoglycemia. MATERIALS AND METHODS: Twenty-seven consecutive adult patients with documented hyperinsulinemic hypoglycemia undergoing an ASVS test and histologically confirmed diagnosis were included. RESULTS: By histology, 24 patients were found to have an insulinoma, two had islet cell hyperplasia, and one had insulin-secreting neuroendocrine carcinoma of the liver. ASVS correctly predicted the source of excessive insulin secretion in 26 of 27 (sensitivity, 96%) patients. In two patients with an insulinoma, ASVS had to be repeated for correct diagnosis; in one patient with a glucose-sensitive insulinoma, ASVS was falsely negative. In one patient, a falsely negative ASVS test was caused by diazoxide treatment; in another patient a falsely negative ASVS test occurred because of extraordinarily high baseline insulin levels when the calcium stimulation was performed. CT and/or MR imaging correctly predicted the source of excessive insulin secretion in 59% of patients, the sensitivity of the intraoperative exploration was 88%. CONCLUSIONS: In the authors' experience, the ASVS test is superior to CT/MR imaging and even the intraoperative exploration in identifying the source of excessive insulin secretion in patients with hyperinsulinemic hypoglycemia. To prevent false negative ASVS tests, medications with an influence on insulin secretion have to be discontinued prior to ASVS and two baseline blood samples should be obtained before the calcium stimulation is performed.

Adult↗
PubMed2004

Abnormalities of proinsulin processing in functioning insulinomas: clinical implications.

OBJECTIVE: Abnormal proinsulin processing in insulinomas may result in secretory granules containing both insulin and proinsulin, a finding not encountered in healthy beta-cells. The aim of this study was to test whether such abnormalities in the proinsulin to insulin conversion have clinical implications in patients with hypoglycaemic disorders. DESIGN: Case-series. PATIENTS AND METHODS: Fifteen patients with histologically confirmed insulinoma and two patients with islet cell hyperplasia were included. The immunohistochemical distribution pattern of proinsulin within the tumour cells was classified as Golgi pattern (predominantly perinuclear immunolabelling) or diffuse pattern (immunolabelling in the periphery of the cells, indicating the presence of proinsulin in secretory granules). Data obtained from the 72-h fast and arterial calcium stimulation and hepatic venous sampling (ASVS) test were related to the morphological classification. RESULTS: Six insulinomas exhibited a diffuse proinsulin distribution pattern, while nine insulinomas and two islet cell hyperplasias disclosed a Golgi pattern. Median proinsulin concentrations at the termination of the fast tended to be higher in patients with the diffuse proinsulin distribution pattern than in patients with the Golgi pattern (86.9 vs. 18.8 pmol/l, P = 0.07). Higher insulin (P < 0.005) and proinsulin (P < 0.05) concentrations were significantly correlated with earlier occurrence of hypoglycaemia during the prolonged fast. During the ASVS test, tumours with the diffuse proinsulin distribution pattern exhibited a higher increase in both insulin (median, 37.3- vs. 10.5-fold, P < 0.05) and proinsulin (6.3- vs. 1.6 fold, P < 0.005) concentrations following calcium stimulation than the tumours with the Golgi pattern. CONCLUSIONS: Abnormalities in the proinsulin to insulin conversion in patients with insulinomas and islet cell hyperplasia correlate with impaired regulation of both insulin and proinsulin secretion during the prolonged fast as well as the ASVS test.

Adult↗
PubMed2004

Successful simultaneous islet-kidney transplantation using a steroid-free immunosuppression: two-year follow-up.

We report on the feasibility of a glucocorticoid-free immunosuppression (sirolimus, low-dose tacrolimus, and daclizumab) in simultaneous islet-kidney transplantation in nine patients with type 1 diabetes. There was one renal primary nonfunction. Renal function (n = 8) as assessed by creatinine and creatinine clearance over time was 103 +/- 6 micromol/L and 64 +/- 6 mL/min/1.73 m(2), respectively. Five out of six patients with >or= 2 islet transplantations became insulin independent. The mean HbA(1c) during the follow-up period for all patients after transplantation is 6.2 +/- 0.9% as compared with 8.7 +/- 1.9% prior to transplant. These results in patients with a median follow-up of 2.3 years suggest that kidney transplantation under a glucocorticoid-free immunosuppression is feasible, and that the rate of insulin independence of 80% can be achieved not only in patients with no or minimal diabetes complications, but also in patients with more advanced late complications and in conjunction with kidney transplantation.

Adult↗
PubMed2004

Resolution of hoarseness after endovascular repair of thoracic aortic aneurysm: a case of Ortner's syndrome.

We report the case of a 75-year-old man with a 6-month history of hoarseness due to a left recurrent laryngeal nerve palsy. Investigations revealed a thoracic aortic aneurysm compressing the left recurrent nerve; thus, the diagnosis of Ortner's syndrome, ie, cardiovocal syndrome, could be established. The aortic aneurysm was repaired by implantation of an endovascular stent graft under local anesthesia. The patient was discharged 5 days later, and at the 1-year follow-up visit the hoarseness had resolved completely. This case demonstrates for the first time the reversal of Ortner's syndrome after endoluminal aneurysm repair.

Aged↗
PubMed2004

Insulin determination by specific and unspecific immunoassays in patients with insulinoma evaluated by the arterial stimulation and venous sampling test.

OBJECTIVE: The aim of this study was to compare insulin concentrations measured by a traditional radioimmunoassay (RIA) and a more specific enzyme-linked immunosorbent assay (ELISA) in blood samples obtained during the arterial stimulation and venous sampling (ASVS) test in patients with insulinoma. DESIGN: Prospective case series. METHODS: In 14 patients with an insulinoma undergoing an ASVS test, blood samples were obtained from the hepatic vein at baseline and 60 s after calcium injection into an artery supplying the tumour and a control artery (supplying pancreatic tissue without tumour). A selective arterial calcium stimulation was performed in five additional patients without evidence for an insulinoma. We measured insulin by a traditional RIA and a specific immunoassay. RESULTS: In patients with insulinoma, insulin concentrations increased between 2.3- and 24.2-fold (median 8.2-fold) when measured by RIA and between 7.3- and 59.4-fold (median 16) when measured by ELISA following calcium injection into the artery supplying the tumour. Following calcium injection into the control artery, insulin concentrations were 0.6 to 1.3 times (median 1.0) the baseline values by RIA and 0.5 to 2.5 times (median 1.1) the baseline values by ELISA. In patients without insulinoma, insulin concentrations increased following calcium stimulation between 0.7- and 2.1-fold (median 1.3-fold) when measured by RIA and between 0.6- and 4.7-fold (median 1.3-fold) when measured by ELISA. CONCLUSIONS: When insulin is measured by specific immunoassays, a higher cut-off (i.e. five- to sixfold increase) rather than the traditional criterion of a twofold increase should be used to localise an insulinoma during the ASVS test. The increase in insulin concentrations following calcium stimulation is significantly higher when insulin is measured by a specific assay compared with results obtained with traditional RIAs.

Adult↗
PubMed2003

Right living donor hepatectomy in the presence of celiac artery stenosis.

BACKGROUND: Incidental celiac artery stenosis has been cited as an exclusion criterion for adult donor right hepatectomy. METHODS: We report our experience involving right donor hepatectomy performed in the presence of isolated high-grade (greater than 80%) celiac trunk stenosis in two young healthy and asymptomatic adult living liver donors. RESULTS: The immediate postoperative course was complicated by a superficial wound infection in one patient and a transient median nerve palsy caused by intraoperative positioning, which spontaneously resolved, in the second patient. Both were discharged within 7 to 10 days postoperatively. They are doing well at 1 year follow-up without any complaints and have both returned to 100% full employment. CONCLUSIONS: Our results show that right donor hepatectomy can be safely performed in the presence of significant celiac artery stenosis. However, careful long-term follow-up will be required to monitor for any future progression of mesenteric vascular disease.

Adult↗