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Biomedical subjects

Peter Waldenberger

Publications and source records attributed to Peter Waldenberger.

15 recordsLinked to original sources
PubMed2005

Language and arithmetic--a study using the intracarotid amobarbital procedure.

The intracarotid amobarbital procedure is used as a standard procedure in presurgical evaluation to assess hemispheric lateralization of language and memory, but has not been applied to investigate numerical processing. Patients with medically intractable epilepsy (n=20) were consecutively recruited during a presurgical evaluation programme. All 14 patients with left-lateralized language showed better arithmetic performance with the left hemisphere (intracarotid amobarbital procedure right), while five out of six patients with bilateral or right-hemispheric language representation showed better performance with the right hemisphere (intracarotid amobarbital procedure left). Furthermore, in patients with left-lateralized language, an interaction between intracarotid amobarbital procedure and type of arithmetic operation was found. The study suggests a close association between language lateralization and hemispheric specialization for arithmetic processing.

Adult↗
PubMed2005

An uncommon coronary artery fistula causing survived sudden cardiac death in a young woman.

Although most patients suffering from a coronary artery fistula remain asymptomatic during childhood and adolescence, many of them develop complications in adulthood due to volume overload, endocarditis or ischemia. Here we present a young woman surviving a sudden cardiac death due to myocardial ischemia with subsequent ventricular fibrillation caused by thrombosis of a coronary artery fistula deriving from the left main coronary artery. Parts of the thrombus had been embolized into the circumflex artery causing posterior myocardial infarction. The thrombosis might have been initiated by local compression from a round extracardiac mass of 3 cm with liquid and solid content located between the vena cava superior and the ascending aorta. This structure was suspected to be a hematoma which had been caused by a blunt thoracic trauma while playing soccer 2 weeks before.

Adult↗
PubMed2005

Does stent overlap influence the patency rate of aortoiliac kissing stents?

PURPOSE: To determine if the position of kissing stents in the distal aorta has any influence on the patency rate. METHODS: A retrospective review was conducted of 41 patients (22 men; median age 60.8 years, range 44-86) electively treated for atherosclerotic aortoiliac occlusive disease with angioplasty and kissing stents between January 1997 and January 2005. Two patient groups were defined by reviewing postinterventional anteroposterior radiograms: (1) patients in whom the proximal end of the kissing stents overlapped more than half of their angiographic width within the aorta ("crossing" group) and (2) patients in whom the proximal ends of the stents overlapped half of their width or less ("non-crossing" group). RESULTS: At 2 years, the primary and assisted primary patency rates by life-table analysis were 60.8% and 69.4%, respectively, for the 35 patients included in the life-table analysis. There was no significant difference between the 16-patient "crossing" group and the 19-patient "non-crossing" group in terms of the baseline demographic, morphological, and procedural variables. The primary and assisted primary patency rates at 2 years for the "non-crossing" group were significantly higher (94.1% and 100%, respectively) compared to 33.2% and 45.3%, respectively, for the "crossing" group (p=0.01). CONCLUSIONS: Failure of kissing stents in the aortic bifurcation may be significantly increased by the overlap of the free proximal stent ends in the distal aorta.

Adult↗
PubMed2004

Percutaneous management of a hepatic artery aneurysm: bleeding after liver transplantation.

In this article we present an unusual case of hepatic artery aneurysm bleeding due to a hepatic artery thrombosis after liver transplantation. The patient developed a recurrent hepatic artery thrombosis leading to severe graft failure in four consecutive liver transplantations. While being evaluated for a fifth transplant, stabilization of the clinical situation was attempted by interventional therapy. The first intervention was to place a stent into the hepatic artery to prevent further ischemic damage. This failed to improve graft function, but unfortunately led to the development of a pseudoaneurysm at the distal end with a subsequent rupture into the biliary tree. Bleeding was treated successfully by direct puncture and coil embolization of the aneurysm. In addition, the patient demonstrated a hemodynamically relevant portal vein stenosis on the CT scan. Stenting of the portal vein markedly improved graft function. After extensive investigations, a paroxysmal nocturnal hemoglobinuria was found to be the underlying cause of the recurrent hepatic artery thrombosis. Here we suggest that hepatic artery aneurysm bleeding is a rare but potentially fatal complication that can be successfully treated by percutaneous coil embolization. Additionally, we propose that stenting of the portal vein can lead to a significant improvement of the graft perfusion even though the hepatic artery remained occluded.

Adult↗
PubMed2004

Serial CT volume and thrombus length measurements after endovascular repair of Stanford type B aortic dissection.

PURPOSE: To evaluate the outcome of stent-graft placement in Stanford type B aortic dissection using contrast-enhanced spiral computed tomographic (CT) measurements of true and false lumen volumes and thrombus length. METHODS: Among 18 consecutive patients (13 men; mean age 60 years, range 44-79) who underwent endovascular repair of Stanford type B dissection, 12 completed at least a 12-month follow-up, which included CT measurements of true and false lumen volumes and thrombus lengths prior to discharge and at 6 and 12 months postimplantation. Volumes were assessed in 3 different aortic segments (A1, A2, A3) extending from the proximal attachment site of the prosthesis to the aortic bifurcation. In addition, thrombus length was measured to evaluate the influence of clot formation on outcome of the false lumen volume. RESULTS: Mean follow-up was 27 months (range 12-60). Within 12 months, mean true lumen volumes showed statistically significant increases in the A1 (p<0.001) and A2 (p=0.003) segments; false lumen volumes showed a significant decrease in the A1 segment (p=0.002) but an insignificant increase in the A2 segment. No substantial volume changes were observed in the A3 segment. Extension of clot formation in the false lumen varied among patients and over time. Length of stent-grafts, percentage of stented dissection length, or visceral arteries originating from the false lumen did not significantly influence thrombus development, nor did these parameters or thrombus formation distal to the prosthesis have a relationship to false lumen volumes. CONCLUSIONS: Volumetric analysis after endovascular repair of Stanford type B dissection shows optimal technical outcome in the stented segment, whereas the false lumen in the segment immediately adjacent to the stent-graft seems to be a vulnerable area. Extension of clot formation beyond the endograft seems to be no reliable predictor of outcome.

Adult↗
PubMed2003

Chemoembolization followed by liver transplantation for hepatocellular carcinoma impedes tumor progression while on the waiting list and leads to excellent outcome.

Orthotopic liver transplantation (OLT) has been considered the best treatment option for patients with hepatocellular carcinoma (HCC). Because of a steadily increasing waiting time, a noteworthy proportion of patients are excluded from OLT because of tumor progression. A 20% and more dropout rate from the waiting list has recently been reported. In this prospective study, we evaluated the effect of preoperative transarterial chemoembolization (TACE) on preventing tumor progression while on the waiting list in patients meeting current selection criteria (solitary lesion < or = 5 cm, three lesions < or = 3 cm). In addition, we analyzed the outcome of a separate group of patients with advanced-stage HCC outside the selection criteria but with at least 50% tumor reduction after TACE (downstaging) to expand current criteria. Forty-eight patients met the selection criteria and were eligible for this study. Seven patients are still on the waiting list; 41 underwent OLT. None of these patients had to be removed from the list because of tumor progression after a mean waiting time of 178 days (23 patients > or =180 days). The 1-, 2-, and 5-year intention-to-treat survival was 98%, 98%, and 94%. The outcome after OLT was also excellent with 1-, 2-, and 5-year survival rates of 98%, 98%, and 93%. Tumor recurrence occurred only in 1 patient (2.4%). Fifteen patients with advanced-stage HCC were included in this study. Three developed a tumor progression and had to be removed from the list (20% dropout rate). Despite tumor reduction before OLT, these patients had a significantly less favorable outcome in the intention-to-treat analysis as well as in the posttransplantation survival. Tumor recurrence was seen in 30% of patients after OLT. In conclusion, TACE followed by OLT is associated with an excellent outcome in selected patients. Furthermore, TACE is highly efficacious in preventing tumor progression while waiting for OLT. Although TACE reduced tumor preoperatively, it failed to show a beneficial effect on patient survival in advanced-stage HCCs.

Adult↗
PubMed2003

Emergency endovascular treatment of traumatic aortic arch rupture with multiple arch vessel involvement.

PURPOSE: To report successful endovascular stent-graft placement for emergency treatment of a complex traumatic injury involving the aortic arch and multiple arch vessels. CASE REPORT: An 81-year-old man underwent stent-graft placement for a complex traumatic vascular injury. Computed tomography on admission documented a dissection along the course of the aortic arch, intramural hematoma along the ascending aorta, dissection of the innominate artery, and a right subclavian artery pseudoaneurysm. The dissection of the aortic arch and the pseudoaneurysm of the right subclavian artery were treated immediately, the dissection of the innominate artery 7 days later. The patient did not develop any complications. Follow-up studies performed prior to discharge and at 6 and 12 months after the interventions showed successful repair of the complex vascular injuries. CONCLUSIONS: Traumatic injury of the aortic arch with multiple arch vessel involvement can be treated effectively by means of stent-graft placement.

Accidents, Traffic↗
PubMed2003

Detection and characterization of intracranial aneurysms with MR angiography: comparison of volume-rendering and maximum-intensity-projection algorithms.

OBJECTIVE: The purpose of this study was to compare volume rendering and maximum intensity projection as postprocessing techniques of MR angiography in the detection and characterization of intracranial aneurysms. MATERIALS AND METHODS: Three-dimensional time-of-flight MR angiography studies performed in 82 patients were retrospectively evaluated by two independent reviewers who were unaware of digital subtraction angiography findings, the standard of reference. Panoramic maximum-intensity-projection and volume-rendered angiograms were produced from each data set to investigate the presence of underlying aneurysms. Each detected aneurysm was then interactively evaluated with subvolume maximum-intensity-projection and targeted volume-rendering algorithms to evaluate aneurysm morphology and size. Aneurysm detection and characterization were evaluated by means of the receiver operating characteristic analysis, and aneurysm size was evaluated using the limits-of-agreement method. Image quality, aneurysm neck depiction, and vascular delineation were also compared between maximum-intensity-projection and volume-rendered images. The time required for the generation and interpretation of maximum-intensity-projection and volume-rendered images was assessed. RESULTS: Volume rendering tended to improve the diagnostic confidence (A(z) [area under the receiver operating characteristic curve] = 0.95 vs A(z) = 0.90 for maximum intensity projection) and yielded a considerable improvement in sensitivity (89% vs 71% for maximum intensity projection), particularly in the detection of small cerebral aneurysms. Regarding aneurysm morphology, volume rendering performed significantly better than maximum intensity projection in lobulation detection (p < 0.001) and slightly better in neck categorization (p > 0.238). Limits-of-agreement analysis showed a trend toward improved assessment of the aneurysm size by volume rendering (-0.31 +/- 1.62 mm vs -1.27 +/- 2.84 mm by maximum intensity projection). Overall image quality and vascular delineation of involved vessels on volume-rendered images were rated better than that obtained by maximum intensity projections (p < or = 0.007 and p < or = 0.001, respectively). Evaluation of time-of-flight MR angiography data sets was significantly facilitated with volume rendering (p < 0.001). CONCLUSION: The volume-rendering technique facilitates the evaluation of cerebral time-of-flight MR angiography data sets and allows better detection and more reliable characterization of intracranial aneurysms than does maximum intensity projection.

Adolescent↗
PubMed2003

Volume-rendered multidetector CT angiography: noninvasive follow-up of patients treated with renal artery stents.

OBJECTIVE: The purpose of our study was to evaluate the role of multidetector CT (MDCT) angiography with volume rendering for estimating the patency of renal artery stents. SUBJECTS AND METHODS: In 16 patients, 16 renal artery stents were evaluated with MDCT renal angiography and digital subtraction angiography (DSA). CT data were evaluated using multiplanar volume reformations and the volume-rendering algorithm with three different volume-rendered parameter settings (low-to-high, high-to-low, and high-low-high opacity transfer functions: VR(LH), VR(HL), and VR(VE), respectively). Targeted images of each stent were rendered in paraaxial and paracoronal planes and were interactively interpreted. The overall restenosis severity was measured on postprocessed paraaxial and paracoronal images and compared with that obtained on DSA using linear regression analysis. Image quality and lumen delineation on rendered images were also compared using Wilcoxon's signed rank test. RESULTS: Eight restenoses were identified on DSA. Correlations between restenosis severity measured with DSA and those measured with MDCT were significant (p < 0.001). Volume rendering with VR(HL) allowed the best correlation with DSA (reviewer 1, r(2) = 0.86; reviewer 2, r(2) = 0.94) and was significantly better than multiplanar volume reformations (p = 0.028). Overall image quality was high with all rendering techniques and with no significant differences (p > 0.59, for all comparisons). Stent lumen was well delineated with volume-rendering modalities; however, VR(HL) was significantly better than VR(LH) (p = 0.033). CONCLUSION: Volume-rendered MDCT angiography enabled high-quality three-dimensional reproducible evaluation of the patency of implanted renal artery stents. Volume rendering with VR(HL) achieved the best performance.

Aged↗
PubMed2003

Pretransplantation evaluation of the cirrhotic liver with explantation correlation: accuracy of CT arterioportography and digital subtraction hepatic angiography in revealing hepatocellular carcinoma.

OBJECTIVE: The aim of this study was to determine the accuracy of CT arterioportography and hepatic digital subtraction angiography, separately and combined, for the detection of hepatocellular carcinoma in the cirrhotic liver by using thin-section liver explant histopathologic findings. SUBJECTS AND METHODS: Fifty-nine patients with liver cirrhosis were examined with CT arterioportography and digital subtraction angiography as a part of preoperative diagnostic workup for liver transplantation. Before liver explantation, CT arterioportograms and digital subtraction angiograms were prospectively evaluated in a blinded manner, separately by two CT radiologists and two angiographers, respectively, and combined by two reviewer teams, each including a CT radiologist and an angiographer. In addition, each examination was retrospectively evaluated using direct comparison with the corresponding thin-section liver explant specimens RESULTS: There were 39 histologically confirmed hepatocellular carcinomas. In both prospective and retrospective assessments, the reviewers achieved the best performance with CT arterioportography and digital subtraction angiography combined (area under the curve [A(z)] 0.82). The diagnostic confidence in the detection of hepatocellular carcinoma was higher with digital subtraction angiography (A(z), 0.81) than that with CT arterioportography (A(z), 0.68). Prospectively, sensitivity and specificity were 75% and 60% for CT arterioportography, 77% and 80% for digital subtraction angiography, and 84% and 81% for CT arterioportography and digital subtraction angiography combined, respectively. Retrospectively, sensitivity and specificity were 80% and 62% for CT arterioportography; 82% and 79% for digital subtraction angiography; 87% and 81% for CT arterioportography and digital subtraction angiography combined, respectively. Five hepatocellular carcinomas, one poorly and four well differentiated, with a mean size of 1.4 cm were not detectable on the CT arterioportography and digital subtraction angiography combination. False-positive findings were 20, 11, and 10 on CT arterioportography, digital subtraction angiography, and the CT arterioportography and digital subtraction angiography combination. CONCLUSION: Combining CT arterioportography with digital subtraction angiography enabled reliable detectability of moderately and poorly differentiated hepatocellular carcinomas in cirrhotic livers but was less sensitive for the detection of well-differentiated hepatocellular carcinomas and resulted in a relatively high rate of false-positive findings.

Angiography, Digital Subtraction↗
PubMed2002

Investigation of cerebrovascular disease with MR angiography: comparison of volume rendering and maximum intensity projection algorithms--initial assessment.

We assessed the clinical utility of the volume-rendering (VR) algorithm as a postprocessing technique of intracranial magnetic resonance angiography (MRA) for the evaluation of cerebrovascular disease in comparison with the maximum intensity projection (MIP) algorithm. VR and MIP images were compared with digital subtraction angiography (DSA). Volume-rendered views improved the perceptibility of intracranial vasculature and consequently augmented diagnostic confidence, improved the characterization of underlying vascular pathologies, and facilitated image interpretation. Volume rendering has the potential to expand the role of cerebral MRA in the diagnostic investigation and treatment planning of cerebrovascular disease.

Adolescent↗
PubMed2002

Endotoxin and its binding proteins in chronic liver disease: the effect of transjugular intrahepatic portosystemic shunting.

BACKGROUND: Gut-derived endotoxin is insufficiently cleared by the diseased liver, and thus, is elevated in plasma of patients with chronic liver disease (CLD). Endotoxin action might be modified by binding to soluble CD14 (sCD14) and lipopolysaccharide-binding protein (LBP), both of which have not yet been sufficiently studied in CLD. METHODS: Endotoxin, sCD14 and LBP have been determined in peripheral blood of 72 patients and 39 control subjects, and in portal and hepatic venous blood of 12 patients during transjugular intrahepatic portosystemic shunt (TIPS) implantation. RESULTS: Peripheral endotoxin (average 3-fold increased compared to controls), LBP, and sCD14 plasma levels were elevated in chronic liver disease irrespective of Child stage m, preserve/absence of cirrhosis or aetiology. LBP, and sCD14. Furthermore, endotoxin levels in the portal vein (38.1 +/- 6.1 pg/ml) were only slightly elevated compared to the hepatic vein (29.2 +/- 4.4 pg/ml), and peripheral endotoxin levels did not increase after TIPS. CONCLUSIONS: Decreased hepatocellular function rather than hepatic blood shunting might be responsible for endotoxemia. The elevation in LBP and sCD14 levels may be a consequence of endotoxemia.

Acute-Phase Proteins↗
PubMed2002

3D MR angiography of renal arteries: comparison of volume rendering and maximum intensity projection algorithms.

PURPOSE: To compare volume rendering (VR) and maximum intensity projection (MIP) as postprocessing techniques of magnetic resonance (MR) angiography for detection and quantification of renal artery stenosis. MATERIALS AND METHODS: Twenty-seven patients underwent three-dimensional contrast material-enhanced MR angiography of the renal arteries with a 1.5-T imager. For each renal artery, targeted MIP and VR images were reconstructed in oblique coronal and transverse orientations. For each modality, image generation and evaluation were performed interactively by two independent radiologists blinded to angiographic results. In comparison with digital subtraction angiography (DSA) findings, stenosis quantification and detection by using MIP and VR were evaluated with the use of 50% and 70% cutoff points by using linear regression analysis and 2 x 2 tables. Overall image quality and vascular delineation on MIP and VR images were also compared. RESULTS: All main and accessory renal arteries depicted at DSA were also demonstrated on MIP and VR images. VR performed slightly better than MIP for quantification of stenoses greater than 50% (VR: r(2) = 0.84, P <.001; MIP: r(2) = 0.38, P =.001) and significantly better for severe stenoses (VR: r(2) = 0.83, P <.001; MIP: r(2) = 0.21, P =.1). For detection of stenosis, VR yielded a substantial improvement in positive predictive value (VR: 95% and 90%; MIP: 86% and 68% for stenoses greater than 50% and 70%, respectively). Image quality obtained with VR was not significantly better than that with MIP; however, vascular delineation on VR images was significantly better. CONCLUSION: The VR technique of renal MR angiography enabled more accurate detection and quantification of renal artery stenosis than did MIP, with significantly improved vascular delineation.

Adult↗
PubMed2002

Placement of endovascular stent-grafts for emergency treatment of acute disease of the descending thoracic aorta.

OBJECTIVE: The aim of this study was to evaluate the feasibility, safety, and effectiveness of endovascular stent-graft placement for the emergency treatment of acute descending thoracic aortic disease. MATERIALS AND METHODS: From January 1996 through November 2001, 18 patients underwent emergency endovascular stent-graft placement for various types of acute descending thoracic aortic disease. Five patients had Stanford type B aortic dissection, six had traumatic ruptures of the thoracic aorta, five had ruptured aortic aneurysms, and two had penetrating atherosclerotic aortic ulcers. All patients presented with life-threatening symptoms requiring treatment with stent-grafts from the emergency kit. All were at high surgical risk due to serious comorbidities. The efficacy of the procedure was assessed at follow-up studies before discharge and at 3, 6, and 12 months after intervention and yearly thereafter. RESULTS: The primary technical success rate was 78%. Four patients had primary perigraft leaks. The secondary technical success rate was 83%. One patient died 20 hr after intervention from stent-graft-related causes. Follow-up studies revealed stent-graft migration in one patient. Progression of disease was observed in one patient treated for dissection and in both patients treated for penetrating ulcers. One patient died 7 months after intervention of unknown reasons; all other patients are alive. The mean follow-up time was 17.4 months (range, 0-38 months). CONCLUSION: Emergency repair of acute descending thoracic aortic disease with stent-graft placement can be successfully accomplished and may be a promising alternative to open-chest surgery, especially in patients at high risk.

Acute Disease↗