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Biomedical subjects

H O Myhre

Publications and source records attributed to H O Myhre.

At least 19 recordsLinked to original sources
PubMed2001

Endovascular treatment of type B aortic dissections.

The purpose is to describe our experience with endovascular treatment of type B aortic dissections. Five patients were treated for complications following type B dissections like, false channel aneurysm formation, rupture and arterial obstruction. They were treated in general anaesthesia using a 'homemade' endoprosthesis or a commercially available endoprosthesis (Excluder) deployed during fluoroscopy. The patients have been followed at regular intervals with a median observation time of 18 months (range 12--36). One patient needed a secondary intervention due to dislodgement of the proximal stentgraft with haemorrhage into both the false and the true lumen. Otherwise there have been no early or late mortality or major complications in this series. Even if our experience with endovascular treatment of type B dissections is rather limited, the results so far are promising. Open surgery in many of these cases is complicated with high morbidity and mortality rate and the endovascular technique offers great advantages. A longer follow-up period is necessary to define the place of endovascular treatment.

Aged↗
PubMed2001

Spinal cord metabolism during thoracic aortic cross-clamping in pigs with special reference to the effect of allopurinol.

OBJECTIVE: investigate the metabolic response of the spinal cord and the effect of allopurinol following cross clamping of the descending thoracic aorta in a porcine model. DESIGN: experimental animal study. MATERIALS: twelve domestic swine. Six pigs were pre-treated with allopurinol, while six pigs served as controls. METHODS: measurement of extracellular concentrations of glucose, pyruvate, lactate, glycerol and glutamate using microdialysis in the lumbar spinal cord. Measurement of lumbar spinal blood flow using laser Doppler technique. RESULTS: for all animals there was a significant decrease in concentrations of glucose and pyruvate together with a significant increase in the lactate-pyruvate ratio during aortic cross clamping. There was also a significant increase in glycerol concentrations 60 min after cross clamping, and a significant decrease in glutamate concentrations after 50 min. No differences in concentrations of glucose, pyruvate, lactate and glutamate or the glutamate-pyruvate ratio were observed between animals used as controls and those treated with allopurinol. The laser Doppler flux decreased to 40% of pre cross-clamp level, returning to normal values at declamping. CONCLUSION: the changes in energy-related metabolites reflect a considerable ischaemia in the spinal cord tissue but there was no convincing effect of allopurinol on the lumbar spinal cord metabolism during thoracic aortic cross clamping in this model.

Allopurinol↗
PubMed2000

[Is thrombolytic therapy effective in stroke?].

BACKGROUND: The Norwegian Centre for Health Technology Assessment was asked to assess the treatment of stroke by trombolytic medication. We were also asked to include an evaluation of potential consequences for the organisation of the health care system. MATERIAL AND METHODS: Relevant literature was identified on Medline, the Cochrane Library (Systematic Reviews), and INAHTA (Systematic Reviews). Of particular importance are one study from the USA and two studies originating in Europe. RESULTS: The conclusion of the working group is that the benefit of thrombolytic treatment in the studies assessed is uncertain; furthermore, intracranial haemorrhage can occur as a complication of the treatment. INTERPRETATION: Future thrombolytic treatment of stroke patients should be carried out according to a research protocol with thorough documentation of effects as well as side effects.

Controlled Clinical Trials as Topic↗
PubMed2000

Initial experience with stereoscopic visualization of three-dimensional ultrasound data in surgery.

Initial in vivo and in vitro experiments were performed to evaluate the feasibility of stereoscopically displaying three-dimensional (3D) ultrasound data from neurosurgery, laparoscopic surgery, and vascular surgery. Stereoscopic visualization was illustrated by four video sequences, which can be downloaded from http://www.us.unimed. sintef.no/. These sequences show a brain tumor, hepatic arteries in relation to the gallbladder, a model that mimics a neuroendoscope in a cyst, and a "flight" into model of an artery with an intima flap. The experiments indicate that stereoscopic display of ultrasound data is feasible when there is sufficient contrast between the objects of interest and the surrounding tissue. True 3D vision improves perception, thus enhancing the ability to understand complex anatomic structures such as irregular lesions and tortuous vessels.

Filtration↗
PubMed2000

Cardiac output measurements during cross-clamping of the descending thoracic aorta in pigs. A comparison between transit-time ultrasound, thermodilution and pulsed Doppler ultrasound.

BACKGROUND: Cross-clamping of the descending thoracic aorta (XC) induces an increase in cardiac output (CO). The intention of this study was to evaluate the high CO during XC by the use of clinically available methods (thermodilution and pulsed Doppler ultrasound) compared to transit-time ultrasound flowmetry of the ascending aorta as the gold standard. METHOD: Ten pigs were anaesthetised with ketamine and fentanyl. The descending thoracic aorta was cross-clamped for 30 min, and cardiac output was measured with pulmonary artery thermodilution technique, pulsed Doppler ultrasound on the aortic annulus and transit-time ultrasound flowmetry of the ascending aorta. RESULTS: At 15 min following XC, CO increased from 1.7 l/min to 4.6 l/min measured with transit-time ultrasound (P<0.05). With thermodilution technique, CO increased from 2.6ll/min to 5.7 l/min (P<0.05), and from 2.4 l/min to 6.0 l/min measured with Doppler ultrasound (P<0.05). There was an increase in mean arterial pressure of 81% and heart rate increased 76% (P<0.05). CONCLUSION: XC of the descending thoracic aorta induces an increase in CO of 171%. Thermodilution and pulsed Doppler ultrasound are reliable methods for detecting high cardiac output during thoracic aortic surgery.

Animals↗
PubMed2000

Microdialysis of the spinal cord during thoracic aortic cross-clamping in a porcine model.

OBJECTIVE: Utilising microdialysis to measure the changes of glucose, lactate, pyruvate and glutamate levels in the spinal cord after cross-clamping of the thoracic aorta in an established porcine model to monitor the degree of ischaemia. DESIGN: Experimental study with a porcine model. SETTING: University Hospital, Trondheim. SUBJECTS: Six pigs. MAIN OUTCOME MEASURE: Lactate, pyruvate and glutamate concentrations in the microdialysis perfusate from the spinal cord. RESULTS: A significant increase of the lactate-pyruvate ratio during the last 30 min of the 1 h clamping period, with a maximum increase of 169% from the basal value the last 10 min before declamping. No evident change in this ratio between the clamping and the reperfusion period. No significant change in glutamate levels during clamping or reperfusion period. CONCLUSION: Microdialysis reflects the ischaemic state of the spinal cord during cross-clamping of the thoracic aorta in pigs, and is well suited to study each phenomena.

Animals↗
PubMed2000

The inflammatory response following treatment of abdominal aortic aneurysms: a comparison between open surgery and endovascular repair.

OBJECTIVES: to compare the inflammatory response following endovascular and conventional AAA repair. DESIGN: prospective study. PATIENTS AND METHODS: ten patients were selected for open surgery (OPEN) and ten for endovascular (ENDO) AAA repair. Leukocytes, platelets, myeloperoxidase, lactoferrin, beta-thromboglobulin, C-reactive protein (CRP), interleukin 6 (IL-6), tumour necrosis factor alpha (TNF-alpha) and complement activation products were measured before, during and after surgery. RESULTS: in the OPEN group the median hospital stay was longer (6 vs. 12 days, p=0.001) and more patients required transfusion (p=0.02). IL-6 and CRP increased postoperatively, most in OPEN (p<0.01). Platelet counts decreased after the first angiography in ENDO (p<0.01) and before aortic cross-clamping in OPEN (p<0.05). The decrease was larger in OPEN (p=0.02). Leukocyte counts decreased after the first angiography in ENDO, and thereafter increased (p=0.001). An equivalent increase was observed in OPEN after declamping (p=0.001). Leukocyte and platelet degranulation products increased after the first angiography in ENDO and after declamping in OPEN. Changes in complement activation products were small. TNF-alpha did not change significantly. CONCLUSION: endovascular AAA repair caused significant leukocyte and platelet activation. Based on the timing of activation this could be caused by radiographic contrast media.

Acute-Phase Reaction↗
PubMed1999

Endovascular treatment of abdominal aortic aneurysms in Norway: the first 100 patients.

OBJECTIVES: to present the first 100 consecutive endograft implantations for abdominal aortic aneurysms (AAAs) in Norway. DESIGN: retrospective study of 100 consecutive graft implantations, performed at five University Hospitals during 1995 to 1997. MATERIAL: one hundred patients with a median age of 70 years were included. In all patients the Vanguard modular system (Boston Scientific Corp.) was used. Ninety-four of the 100 patients were treated under regional anaesthesia. A completion angiography was done to evaluate the position of the graft and whether endoleaks were present. RESULTS: two patients died within 30 days, one due to cardiac insufficiency and another due to haemorrhage during the procedure. There were four early conversions to open repair. At discharge eight patients had an endoleak, while retrograde flow into the aneurysmal sac was observed in four patients. During the follow-up period one conversion to open repair became necessary due to graft migration. Four late leaks were all repaired successfully using endovascular techniques. Five cases of retrograde filling were detected and embolisation with coils was performed in two cases, while three were observed. Seven graft-limb occlusions occurred during the follow-up period and four of these required treatment. CONCLUSIONS: endovascular AAA repair should be regarded as an experimental treatment, although the short term results are promising. Close follow-up of patients with CT scans or arteriography is necessary.

Aged↗
PubMed1998

[Endovascular treatment of thoracic aortic aneurysm].

Two patients with aneurysms of the descending thoracic aorta were treated by endovascular technique. One of the patients was also treated for an infrarenal aortic aneurysm by open surgery during the same procedure. The other patient had chest pain, probably caused by an impending rupture. The procedures were performed using fluoroscopy by a C-arm. The thoracic aneurysms were replaced by an implant made of polyester where Z-stents had been applied on the inside. The prosthesis was mounted on a pusher and advanced through an introducer. When a proper position was obtained, the introducer was withdrawn, and the prosthesis was deployed immediately below the left subclavian artery. Endovascular treatment seems to represent a less traumatic procedure than open surgery. Both operations were uncomplicated and both patients were followed up for more than six months. No complications were observed. A longer follow-up period is necessary to evaluate this treatment fully.

Aged↗
PubMed1998

Chylous complications after abdominal aortic surgery.

Two patients developed chylous complications following abdominal aortic aneurysm repair. One patient had chylous ascitis and was successfully treated by a peritoneo-caval shunt. The other patient developed a lymph cyst, which gradually resorbed after puncture. Chylous complications following aortic surgery are rare. Patients in bad a general condition should be treated by initial paracentesis and total parenteral nutrition, supplemented by medium-chain triglyceride and low-fat diet. If no improvement is observed on this regimen, the next step should be implementation of a peritoneo-venous shunt, whereas direct ligation of the leak should be reserved for those who are not responding to this treatment.

Aortic Aneurysm, Abdominal↗
PubMed1998

Critical self assessment--is it too much for a surgeon?

Self-assessment can be performed by each individual surgeon or by a group of surgeons covering a sub-specialty at a hospital. The individual self-assessment programme can be performed by using appropriate soft-ware and a personal computer. In some countries such self-evaluation is an excellent preparation for re-certification examinations. Other parts of the self-assessment programmes should include indications for vascular surgery perhaps in the form of so-called indication conferences. Also morbidity and mortality conferences are of great importance to minimise similar problems after a broad multi-disciplinary discussion of complications and deaths which have occurred in the vascular service. By using vascular registers each individual surgeon can compare his own results with a national average or with the results of his colleagues at the actual hospital. Self-assessment programmes in vascular surgery should also include the results of diagnostic work performed in vascular laboratories. in this way we can get an impression of the sensitivity, the specificity, and overall accuracy for the procedures performed by the laboratory. A self-assessment programme should in conclusion be an integrated part of the practice of every surgeon.

Certification↗
PubMed1997

The concentration of high molecular weight compounds in interstitial tissue fluid: a study in patients with post-reconstructive leg oedema.

OBJECTIVES: To study whether relative changes in the concentration of different proteins of the subcutaneous interstitial tissue fluid in patients with postreconstructive leg oedema could give information on the integrity of the capillary wall following vascular reconstruction. MATERIALS: Sixteen patients developed ipsilateral leg oedema following femoropopliteal (n = 14) or femorotibial (n = 2) bypass surgery for intermittent claudication (n = 10) or critical lower limb ischaemia (n = 6) caused by obliterating atherosclerosis. METHODS: The leg volume increase was measured according to the formula of a truncated cone. The blister suction method was used for sampling of subcutaneous interstitial tissue fluid. The concentration of albumin, transferrin, immunoglobulin G and alpha 2-macroglobulin of serum and blister fluid was measured with nephelometry. RESULTS: Seven days postoperatively the mean leg volume increase was 32% (19.8%) in the operated leg compared to the contralateral side (p < 0.01). In the blister fluid each of the proteins had a significantly higher concentration in the operated leg compared to the control leg. This concentration difference was relatively larger for the proteins with the highest molecular weight, immunoglobulin G (p = 0.006) and alpha 2-macroglobulin (p = 0.002). CONCLUSIONS: A relatively larger concentration difference of the bigger molecules in the subcutaneous interstitial tissue fluid in patients with post-reconstructive leg ocdema suggests increased capillary permeability to plasma proteins following vascular reconstruction.

Aged↗
PubMed1997

The need for clinical trials of endovascular abdominal aortic aneurysm stent-graft repair: The EUROSTAR Project. EUROpean collaborators on Stent-graft Techniques for abdominal aortic Aneurysm Repair.

EUROSTAR (EUROpean collaborators on Stent-graft Techniques for abdominal aortic Aneurysm Repair) was established for the purpose of combining and studying data on endovascular abdominal aortic aneurysm (AAA) repair, EUROSTAR is independent of any commercial interest and has as its ultimate goal an independent, scientifically reliable assessment of endovascular AAA grafting. A standardized case record form is used for data collection and transmission, and the database is maintained in a central registry office. A comprehensive set of clinical, imaging, technical, and laboratory data obtained at initial admission and follow-up are recorded; these data are analyzed periodically and reports generated on the collated experience. As a first priority, an observational study without controls was initiated in July 1996 to address the issues of procedural safety, device durability, and long-term effect upon the aneurysms. Several ancillary studies have been initiated, including a "Retrieval and Analysis Study" for the evaluation of explanted devices. While a randomized study does not seem feasible at present, this may be organized at the appropriate time when the devices and techniques become more standardized.

Angioplasty↗