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J R Allenberg

Publications and source records attributed to J R Allenberg.

At least 37 records · Page 2Linked to original sources
PubMed2001

Perfusion-weighted magnetic resonance imaging in patients with carotid artery disease before and after carotid endarterectomy.

OBJECTIVE: The purpose of this study was to investigate the potential of perfusion-weighted magnetic resonance imaging for preoperative and postoperative evaluation of cerebral hemodynamics in patients undergoing carotid endarterectomy for carotid artery stenosis. METHODS: We examined 26 patients with angiographically proven stenoses (60%-99%) of the internal carotid artery preoperatively. Perfusion imaging studies were performed by bolus-tracking of a dosage of 0.2 mmol/kg body weight of gadolinium diethylenetriaminepentaacetic acid on a 1.5-T scanner using a T2*-weighted fast low-angle shot sequence. The observed signal intensities were converted pixel by pixel into concentration-time curves. In each patient, the hemispheres were compared and the difference between the normalized first moments (NFMs) and the percentage changes of the regional cerebral blood volume (CBV) were calculated. Three months postoperatively, perfusion-weighted magnetic resonance imaging was performed in 13 patients. RESULTS: In patients with <80% stenosis (n = 10), there was no significant alteration of NFM and regional CBV compared with the contralateral hemisphere (-0.16 +/- 0.7 s, +5.9 +/- 24.6%). In patients with stenoses >or=80% (n = 16), we found an increase in NFM ipsilateral to the stenosis of 1.2 +/- 0.92 s (P < .001) and an increase of CBV of 16.8 +/- 15.2% (P < .005). Three months postoperatively, perfusion parameters were normal in all 13 patients examined. CONCLUSIONS: Perfusion-weighted magnetic resonance imaging is well suited to evaluate the preoperative and postoperative hemodynamic changes in patients with carotid artery stenosis. This noninvasive, semiquantitative magnetic resonance technique could prove to be a valuable adjunct in identification of patients who might benefit from carotid endarterectomy.

Adult↗
PubMed2000

[Carotid surgery in patients 80 years old or older].

BACKGROUND AND OBJECTIVE: Because of their high age and markedly increased co-morbidity, physicians and geriatricians are often cautious in their indications for carotid thromboendarterectomy (TEA) in patients 80 years or older. However, it is these very patients who are subject to an exponentially increased risk of ischaemic cerebral vascular accidents (CVA). This study examined the morbidity and mortality rates of TEA in patients of this age group at one institution. PATIENTS AND METHODS: Between 1994 and 1998, among a total of 912 TEAs, 46 had been performed in patients 80 years or older (15 women, 31 men): indications, diagnosis and associated diseases as well as perioperative complications were entered prospectively into a data-bank. RESULTS: Only one patient (2.2%) sustained a perioperative CVA and no patient died. Three patients (6.5%) developed transitory neurological deficits. One patient had to have an emergency reoperation because of a postoperative carotid artery thrombosis. One patient had an intraoperative asystole due to a hypersensitive carotid sinus. There were no other serious cardiovascular or pulmonary complications. One patient sustained some oral muscle weakness as a result of intraoperative retractor pull on a branch of the facial muscle. CONCLUSION: These results indicate that even in patients of this age group carotid TEA can be performed with great safety.

Aged↗
PubMed2000

[Urgent and emergency carotid TEA].

Restoration of blood flow to reperfuse ischemic but not infarcted areas of the brain (ischemic penumbra) and the removal of an ongoing embolic source are the therapeutic aims of emergency and urgent carotid endarterectomy (CEA), both in patients with an acute or progressive ischemic stroke and in patients in the early period after a carotid-related stroke. Based on poor results in the 60ies and 70ies, many centers traditionally perform CEA four to six weeks after a carotid-related stroke at the earliest interval. Since natural history is associated with a high risk of an disabling and/or recurrent stroke in several subgroups of patients, some reports were able to show that urgent and emergency CEA could be worthwhile in well-selected patients.

Acute Disease↗
PubMed1999

Results of surgery and multimodal therapy for patients with soft tissue sarcoma invading to vascular structures.

BACKGROUND: The aim of this study was to analyze the impact of resection and reconstruction of major vessels on the limb salvage rate, local disease free survival, and overall survival for patients with soft tissue sarcomas invading to neurovascular bundles. METHODS: Twenty patients were treated in a 7-year period by one surgical team. Preoperative therapy consisted of isolated limb perfusion (n = 6), systemic chemotherapy (n = 4), systemic chemotherapy combined with regional hyperthermia (n = 2), and external beam irradiation (n = 1). All patients underwent resection of the sarcoma monobloc together with the neurovascular bundle invaded. Vessels were replaced by an autologous vein transplant or an allograft, and, in six patients, a myocutaneous flap or skin graft had to be used for soft tissue coverage. RESULTS: Histologic examination revealed negative histologic margins (R0-resection) and infiltration of the neurovascular bundle in all patients. In four patients, a local recurrence was observed, and, in three of them, reresection with negative margins was achieved. The mean local recurrence free survival was 54 months (confidence interval [CI], 42-66 months), and the mean overall survival was 48 months (CI, 32-57 months). Limb salvage was achieved in 19 of 20 patients. Eleven patients developed distant metastases after a mean survival time of 30 months. CONCLUSIONS: Extended sarcoma resection, including vessel replacement after preoperative multimodal therapy, provides long term local control and limb salvage. Amputation of extremity sarcoma can hardly be justified, even in cases of tumor invasion to neurovascular bundles. However, efforts to achieve better control over systemic spread are required for long term disease free survival.

Adult↗
PubMed1999

[Carotid surgery for prophylaxis of ischemic stroke].

Every year more than 250,000 patients suffer from ischemic (80%) or hemorragic (20%) stroke. Some 40,000 of these strokes are induced by stenosis or occlusion of the extracranial carotid artery. Several randomized studies (NASCET, ECST, ACAS, etc.) have proved that operative removal of high-grade carotid stenoses is an effective method in the primary and secondary prophylaxis of ischemic stroke. Operative therapy is significantly better than medical therapy with thrombocyte aggregation inhibitors. The prerequisite for effective operative prophylaxis is a low perioperative stroke rate. Even though the prophylactic value of carotid thrombarterectomy (TEA) is obvious, only about 5% of all carotid-related strokes are prevented by this operation. Essential conditions for increased efficiency in carotid surgery are close cooperation with the neurologist and the internist, screening of patients with a high risk for ischemic stroke, sophisticated, mainly non-invasive diagnostics, and more operative capacity. Interventional methods (stent, PTA) have not yet been proved safe and effective. These methods should be employed only in special cases after interdisciplinary discussions or in randomized studies.

Cerebrovascular Disorders↗
PubMed1999

[Endovascular prostheses: evolution, state-of-the-art and perspectives of a new technology].

The treatment of infrarenal aortic aneurysms by means of transluminally placed endovascular prostheses reflects significant progress in the field of vascular surgery. In the case of infrarenal aortic aneurysm it is possible to achieve technically successful implantation of such a prosthesis in well over 90 % of cases. The rate of clinical success, meaning lasting effective exclusion of the aortic aneurysm, cannot (yet) be definitively determined, since no long-term results are so far available. Secondary leaks are observed in at least 10 % of all patients, making a further therapy necessary (endorepair, conversion, embolization). Further development of endovascular prostheses will include optimization of the aortal/iliac attachment of the prostheses, a better configuration and the development of long-lasting materials that can be used for endovascular prostheses.

Aortic Aneurysm, Abdominal↗
PubMed1999

Carotid endarterectomy and intracranial thrombolysis: simultaneous and staged procedures in ischemic stroke.

PURPOSE: The feasibility and safety of combining carotid surgery and thrombolysis for occlusions of the internal carotid artery (ICA) and the middle cerebral artery (MCA), either as a simultaneous or as a staged procedure in acute ischemic strokes, was studied. METHODS: A nonrandomized clinical pilot study, which included patients who had severe hemispheric carotid-related ischemic strokes and acute occlusions of the MCA, was performed between January 1994 and January 1998. Exclusion criteria were cerebral coma and major infarction established by means of cerebral computed tomography scan. Clinical outcome was assessed with the modified Rankin scale. RESULTS: Carotid reconstruction and thrombolysis was performed in 14 of 845 patients (1.7%). The ICA was occluded in 11 patients; occlusions of the MCA (mainstem/major branches/distal branch) or the anterior cerebral artery (ACA) were found in 14 patients. In three of the 14 patients, thrombolysis was performed first, followed by carotid enarterectomy (CEA) after clinical improvement (6 to 21 days). In 11 of 14 patients, 0.15 to 1 mIU urokinase was administered intraoperatively, ie, emergency CEA for acute ischemic stroke (n = 5) or surgical reexploration after elective CEA complicated by perioperative intracerebral embolism (n = 6). Thirteen of 14 intracranial embolic occlusions and 10 of 11 ICA occlusions were recanalized successfully (confirmed with angiography or transcranial Doppler studies). Four patients recovered completely (Rankin 0), six patients sustained a minor stroke (Rankin 2/3), two patients had a major stroke (Rankin 4/5), and two patients died. In one patient, hemorrhagic transformation of an ischemic infarction was detectable postoperatively. CONCLUSION: Combining carotid surgery with thrombolysis (simultaneous or staged procedure) offers a new therapeutic approach in the emergency management of an acute carotid-related stroke. Its efficacy should be evaluated in interdisciplinary studies.

Acute Disease↗
PubMed1999

[Adenosine-induced heart arrest for endovascular reconstruction of thoracic aneurysms of the aorta].

INTRODUCTION: Endovascular stent-graft repair is a less invasive technique than traditional open aortic reconstruction for strictly selected patients with descending thoracic aortic aneurysms. To prevent distal migration of the device as a result of the propulsive flow during systole, it is helpful to induce temporary asystole for > or = 20 s while the stent-graft is placed in the thoracic aorta. CASE STUDY: We report here a case study of a patient who was given a bolus dose of 60 mg of adenosine to induce temporary asystole. Placement of the stent-graft was successfully performed during the temporary asystole. After 45 s the patient returned to normal sinus rhythm. He was extubated 4 h after the conclusion of surgery and was discharged after 1 week. CONCLUSION: Induction of temporary asystole with bolus adenosine to facilitate placement of stent-grafts in the thoracic aorta is a simple, easy and effective method of avoiding distal device migration.

Adenosine↗
PubMed1999

Abdominal aortic aneurysm. Detection of multilevel vascular pathology by time-resolved multiphase 3D gadolinium MR angiography: initial report.

OBJECTIVE: To evaluate multiphasic 3D gadolinium-enhanced magnetic resonance angiography (3D-Gd-MRA) for detection of vascular pathology at multiple levels of the aorta and iliac arteries. METHODS: In 18 patients with abdominal aortic aneurysm (n = 13), dissection (n = 3), or both (n = 2), multiphase 3D-Gd-MRA was performed acquiring five consecutive (6.8 seconds) 3D data sets in a single breath-hold. In each of the five time-resolved phases, vessel visibility of the abdominal aortic branches and iliac arteries was assessed. The extent of vessel involvement by the aneurysm or dissection seen on multiphase 3D-Gd-MRA was compared with standard imaging and surgical findings. Digital subtraction angiography was available for comparison in 4 cases, CT angiography in 10 cases. RESULTS: Due to the delayed filling of the aortic aneurysm, the proximal aortic branches and the aneurysm neck demonstrated an inversely related enhancement compared with the distal abdominal and iliac vessels (P < 0.001). Review of all five phases of multiphase 3D-Gd-MRA allowed optimal visualization of each vessel segment without any artifacts due to parenchymal or venous overlay. In dissections, review of three phases was required (P < 0.001) for diagnostic evaluation of the true and false lumens. Substantially more vessel involvement was detected on multiphase 3D-Gd-MRA; this was surgically confirmed in 10 of 11 cases and affected therapy management in 11 of 18 cases. CONCLUSIONS: Multiphase 3D-Gd-MRA is a convenient, robust, and safe technique for presurgical anatomic mapping of complex aortic aneurysms and dissections.

Aortic Dissection↗
PubMed1998

Early carotid endarterectomy after non-disabling ischaemic stroke: adequate therapeutical option in selected patients.

OBJECTIVE: To evaluate neurological outcome and long-term results of early carotid endarterectomy (CEA) after non-disabling stroke. MATERIALS: Retrospective study between 1980 and 1995 of 56 patients undergoing CEA within 4 weeks of a transient (n = 15) or a permanent non-disabling (n = 41) ischaemic stroke. METHODS: Analyses of preoperative cerebral CT imaging, neurological outcome (mod. Rankin-scale) and long-term results (life-table analyses according to Kaplan-Meier). RESULTS: Incidence of early CEA increased from 1.7% (27 out of 1636) in the period 1980-1993 to 7.8% (29 out of 374) between 1994 and 1995. CEA was indicated after a neurological plateau phase was established (median interval 14 days). Fifty-seven per cent of the CEA patients had a minor ischaemic infarction (area < 2 cm), 18% showed a large territorial ischaemic infarction (area 2-5 cm) in cerebral CT imaging. Two patients deteriorated postoperatively (minor stroke rate 4%) but no major stroke or death occurred. Life-table probability of stroke-free survival (mean follow-up 42.7 months) was 94%, 90% and 84%, respectively, after 1, 2 and 5 years. Kaplan-Meier survival rates were 96%, 91% and 86% after 1, 2 and 5 years. CONCLUSIONS: Early CEA after non-disabling stroke is a safe procedure in selected patients.

Adult↗
PubMed1998

Renal MR angiography.

Three-dimensional gadolinium MR angiography (3D-Gd-MRA) accurately visualizes the renal arteries with almost no degradation from inplane saturation or motion artifacts. The diagnostic accuracy for detecting and grading of renal artery stenosis, as well as the assessment of other vascular pathology, approaches that of conventional x-ray angiography. For the renovascular system, this technique requires precise contrast media bolus timing since multiple successively enhancing structures are present. Details on performing renal MR angiography, strategies for image analysis, and examples of common renal vascular pathology are reviewed. The 3D-Gd-MRA protocol can be easily combined with other MR imaging techniques to provide a comprehensive assessment of the hemodynamic and functional significance of renal artery stenosis.

Aneurysm↗
PubMed1998

[Computer-assisted evaluation of aortic aneurysm morphology for choosing the method of therapy].

Computer aided surgery planning software for AAA is a industry-standard software development for viewing patient-specific data on a personal computer through a unique approach, which improve visualization, navigation, and decision support capabilities for both open and endovascular surgery. Raw scan data is extracted from CT scans, and rendered into a three-dimensional format. This 3D modeling technology and user interface provides a patient-specific model with a rapid visual access to the full range of information, including accurate 3D assessment of AAA morphology and pathology, interactive multiplanar reconstructions, measurements, and views to assist the surgeon in understanding of complex 3D relationships. It provides an optimal system for patient evaluation and selection for endovascular repair of AAA and in the post-operative evaluation of stent deployment and/or complications, such as endoleaks.

Aortic Aneurysm↗
PubMed1998

[Indications for urgent carotid reconstruction].

Diagnostic methods and indications for carotid surgery must be coordinated with the individual carotid-related stroke risk. The indication for urgent carotid reconstruction within a few days after the initial event should always be evaluated when a clinical and/or morphological unstable and therefore risky carotid lesion is present and the 30-day stroke risk without surgery is > 5%. Patients with high-grade symptomatic carotid stenoses fulfill these criteria as do patients with recurrent carotid-related TIA, patients with hemipheric TIA, patients with symptomatic carotid stenosis and contralateral carotid occlusion and patients after a non-disabling carotid-related stroke. The clinical significance of sonographic carotid plaque criteria and intracranial emboli detected by TCD must be further evaluated in prospective studies.

Carotid Stenosis↗
PubMed1998

[Computer-based training exemplified by the carotid artery].

The purpose of computer-based training (CBT) is interactive use of multimedia components, such as text, graphics, animation, sound, digital slide shows, and videos. This CD-ROM illuminates different aspects of carotid surgery: cerebrovascular insufficiency, sonographic and neuroradiological diagnostics, indications and results of carotid surgery in the literature, perioperative complications and new developments such as interventional procedures. Digital imaging (60 minutes of video sequences and 250 graphics) especially focus on operative standard procedures (conventional and eversion technique) and alternative methods. CBT is an evolving supplement to improve education programs in vascular surgery.

CD-ROM↗
PubMed1998

[Endovascular infrarenal surgery of abdominal aortic aneurysm in selected patients: 3-years outcome and complication management].

We report a over 3-year single center experience with five different self-expanding or ballon-expandable stent-graft devices used for aneurysm exclusion in the infrarental aorta. All devices appeared to offer a safe, efficacious, and minimally invasive means of excluding the aneurysms from circulation. Key to success is restrictive patient selection due to morphological criteria and improvements in surgical techniques and equipment to reduce the incidence of complications and endoleaks. At the moment, patients who opt for the endovascular method of repair should be aware that the minimally invasive technique carries the disadvantage of a higher failure rate compared to open surgery. Long-term results are required to establish selection criteria, especially for younger patients.

Aged↗