| 1. |
- Demirer, S., et al.
(author)
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Haemostasis in patients with Behcet's disease
- 2000
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In: European Journal of Vascular and Endovascular Surgery. - : Elsevier BV. - 1078-5884 .- 1532-2165. ; 19:6, s. 570-574
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Journal article (peer-reviewed)abstract
- AIM: to determine whether Behçet's disease affects haemostatic function. SETTING: University Hospital, Turkey. PATIENTS: one hundred and twenty-seven consecutive patients with Behçet's disease, 34 of whom with a history of vascular involvement. METHODS: prothrombin fragment 1+2 tissue plasminogen activator, protein S and C, antithrombin, fibrinogen, von Willebrand factor, thrombomodulin and prothrombin time (PT) were measured in patient plasma. RESULTS: soluble thrombomodulin was significantly lower and von Willebrand factor (vWF) and tissue plasminogen activator (tPA) significantly higher in Behçet's patients. Patients with vascular involvement showed the highest levels of vWF and tPA. There was no activation of coagulation, not even in patients with an active disease at the time of sampling. CONCLUSION: there were indirect signs of endothelial activity or damage, particularly in patients with vascular involvement. Coagulation was not activated.
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| 2. |
- Ljungman, Christer, et al.
(author)
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A multivariate analysis of factors affecting patency of femoropopliteal and femorodistal bypass grafting
- 2000
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In: VASA. - 0301-1526 .- 1664-2872. ; 29:3, s. 215-220
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Journal article (peer-reviewed)abstract
- BACKGROUND: The most important factors that determine the outcome after femoropopliteal and femorodistal arterial reconstruction are still controversial. This report analysis the factors that determine the early and late patency of distal arterial reconstruction. PATIENTS AND METHODS: A retrospective analysis of patency after femorodistal arterial reconstruction with a new method for evaluation of angiographic runoff was performed for 336 arterial reconstructions. The different pre-, per- and postoperative risk factors were analysed in a Cox proportional hazards model. RESULT: The patency was significantly better for vein grafts in comparison to composite grafts and prosthetic grafts. It was 74% for vein, 46% for composite and 43% for prosthetic reconstructions, respectively, at 12 months after arterial reconstruction. The cumulative life table patency rate in extremities with good, intermediate and poor runoff was 62, 30 and 10%, respectively at 36 months. The patency rates for extremities operated on for claudication was significantly better than for extremities operated on for critical ischaemia. The multivariate analysis of different factors in a Cox analysis revealed that only the status of distal runoff, the graft material and the site of the distal anastomosis independently and significantly influenced the patency rates. CONCLUSIONS: A new model for evaluation of distal runoff proved to predict the patency rate of femoropopliteal and femorodistal arterial reconstructions reasonably well in this retrospective analysis.
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| 3. |
- Ulus, A. Tulga, et al.
(author)
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Effect of central venous pressure on spinal cord oxygenation
- 2009
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In: Asian cardiovascular & thoracic annals. - : SAGE Publications. - 0218-4923 .- 1816-5370. ; 17:1, s. 46-53
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Journal article (peer-reviewed)abstract
- To analyze the effect of central venous pressure on cerebrospinal fluid oxygen tension and intrathecal pressure, multiparameter sensors were introduced into the intrathecal space for continuous monitoring of cerebrospinal fluid Po(2), Pco(2), and intrathecal pressure in 15 pigs. After 20 min of aortic clamping, hypervolemia was established for 20 min, followed by normovolemia. The animals were divided into 3 groups: in group 1, cerebrospinal fluid Po(2) = 0% at some time during crossclamping; in group 2, cerebrospinal fluid Po(2) was <50%; and in group 3, cerebrospinal fluid Po(2) remained > or = 50%. Mean decreases in cerebrospinal fluid Po(2) during the initial 20 min of crossclamping were 82%, 57%, and 15% in groups 1, 2, and 3, respectively. Following induction of hypervolemia, central venous and cerebrospinal fluid pressures increased simultaneously; this caused a significant decrease in cerebrospinal fluid Po(2) in group 2 only. In this model, aortic clamping did not increase cerebrospinal fluid pressure if central venous pressure was not elevated. The detrimental effect of elevated intrathecal pressure on cerebrospinal fluid oxygenation was seen only in animals with an intermediate degree of spinal cord ischemia. This might have important implications for the prevention of paraplegia during thoracoabdominal aortic replacement.
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| 4. |
- Ulus, Fatma, et al.
(author)
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Alterations in Cerebrospinal Fluid PO2, PCO2, and pH Measurements during and after Experimental Thoracic Aortic Cross-Clamping
- 2009
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In: Annals of Vascular Surgery. - : Elsevier BV. - 0890-5096 .- 1615-5947. ; 23:1, s. 122-127
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Journal article (peer-reviewed)abstract
- In a model of aortic cross-clamping, we studied the use of a multiparameter sensor for measurement of cerebrospinal. fluid (CSF) PO2, PCO2, and pH during and after aortic cross-clamping. The present study addressed the above-mentioned alterations and their relation according to time intervals. In 31 pigs, a sensor was introduced into the intrathecal space and epidural laser Doppler was used to measure spinal cord blood. flow (SCF). By placing the aortic clamp at different levels, three different spinal cord ischemia groups were obtained (mild, moderate, and severe). CSF variables with SCF were studied for 25%, 50%, and 100% changes according to baseline level. In the clamping period, SCF decreased 71.5%, 40.0%, and 33.3% in groups 1, 2, and 3, respectively. CSF O-2 tension reached 0 in group 1, decreased 74.8% in group 2, and was 12.7% in group 3. CSF CO2 tension increased 247.2% and 202.0% in groups 1 and 2, respectively, but slightly increased in group 3. The maximum reaction time of CSF O-2 tension was about 16.7-26.9 min, although this range was 34.5-49.8 min in CSF CO2 tension. We recognized that O-2 tension reacts faster than PCO2 and pH. It is possible for O-2 tension to be used faster than produced CO2 in the ischemic medium, although it is known that the diffusion rate of CO2 is much higher. Spinal cord O-2 tension monitoring is an important method to detect ischemic changes.
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| 5. |
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| 6. |
- Christiansson, Lennart, et al.
(author)
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Aspects of the spinal cord circulation as assessed by intrathecal oxygen tension monitoring during various arterial interruptions in the pig
- 2001
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In: Journal of Thoracic and Cardiovascular Surgery. - : Elsevier BV. - 0022-5223 .- 1097-685X. ; 121:4, s. 762-772
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Journal article (peer-reviewed)abstract
- OBJECTIVE: We sought to study the effect of various modes of interruption of the spinal cord blood supply on intrathecal oxygenation.METHODS: In 24 pigs intrathecal PO (2), PCO (2), and pH were continuously monitored with a multiparameter catheter (Paratrend 7, Biomedical Sensors; Diametrics Medical, Inc, St Paul, Minn) during and after aortic crossclamping or selective interruption of segmental arteries and proximal collateral circulation.RESULTS: Proximal aortic clamping (n = 6) produced complete ischemia, whereas a second clamp close to the celiac trunk (n = 4) partly protected against spinal cord ischemia. This is explained by prevention of the steal phenomenon in the excluded part of the aorta. Adding clamps to the subclavian arteries (n = 6) created complete spinal ischemia as the collateral circulation was interrupted. In another group (n = 4) all segmental arteries below T5 were occluded with no reaction in the intrathecal variables. Additional selective clamping of supreme intercostal arteries (n = 4) showed the relative importance of the subclavian and vertebral collateral pathways.CONCLUSIONS: Continuous intrathecal PO (2) was monitored during various modes of interruption of the spinal cord blood supply. This provided insight into the ischemia mechanisms and relative importance of the segmental contribution and proximal collateral pathways of the spinal cord circulation in pigs. A short literature review is given, and aspects of comparative anatomy are discussed.
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| 7. |
- Christiansson, Lennart, et al.
(author)
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Increased FiO2 improves intrathecal oxygenation during thoracic aortic cross-clamping in pigs
- 2001
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In: Scandinavian Cardiovascular Journal. - 1401-7431 .- 1651-2006. ; 35:2, s. 147-150
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Journal article (peer-reviewed)abstract
- OBJECTIVES: To investigate the effect of 100% oxygen ventilation on cerebrospinal fluid (CSF) oxygenation in 11 pigs during thoracic aortic cross-clamping.DESIGN: An aorto-aortic shunt was used for control of central hemodynamics and study of hypoperfusion by exsanguination. CSF PO2, PCO2 and pH were continuously monitored before and during clamping. The changes in hemodynamic parameters and intrathecal gas tensions in response to variations in proximal mean aortic pressure and fraction of inspired oxygen (FiO2) were recorded.RESULTS: Baseline CSF PO2 decreased from 4.8 +/- 1.9 to 2.6 +/- 2.2 kPa following aortic occlusion. Increasing FiO2 to 1.0 resulted in a significant increase in CSF PO2 to 4.1 +/- 3.0 with a return to 2.7 +/- 2.1 kPa after reducing FiO2 to 0.4 again. The same variations in FiO2 did not induce any significant changes in CSF PO2 during hypotension.CONCLUSION: Increased FiO2 during experimental thoracic aortic cross-clamping with stable proximal arterial pressure helps to maintain CSF PO2, whereas severe hypotension could not be compensated for by hyperoxemia.
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| 8. |
- Hellberg, Anders, et al.
(author)
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A prolonged spinal cord ischaemia model in pigs. Passive shunting offers stable central haemodynamics during aortic occlusion
- 2000
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In: European Journal of Vascular and Endovascular Surgery. - : Elsevier BV. - 1078-5884 .- 1532-2165. ; 19:3, s. 318-323
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Journal article (peer-reviewed)abstract
- OBJECTIVES: to evaluate the effect of a modified aortic shunt on central haemodynamic variables during experimental thoracic aortic occlusion in a prolonged spinal cord ischaemia model.MATERIAL AND METHODS: central haemodynamic variables were evaluated during aortic cross-clamping. In the shunt group (n=11), after the placement of proximal and distal aortic clamps, distal aortic perfusion was restored through an aortoiliac shunt via the left subclavian artery. In the no-shunt group (n=11), spinal cord ischaemia was achieved with only proximal aortic cross-clamping. The clamping time was 60 minutes in the shunt group and 30 minutes in the no-shunt group.RESULTS: in the no-shunt group, all animals needed inotropic support, vasodilators and buffers during the experiment. None of these drugs were needed in the shunt group. In the no-shunt group, cross-clamping caused a significant increase in mean arterial pressure and heart rate compared to baseline values. These variables were stable in the shunt group during aortic occlusion. In the reperfusion period cardiac output, heart rate and arterial pCO(2)were significantly higher in the no-shunt than in the shunt group.CONCLUSION: the present experimental spinal cord ischaemia model, using double aortic cross-clamping with shunt, offers improved central haemodynamics. This enables the study of prolonged selective spinal cord ischaemia without interaction from vasoactive drugs or systemic reperfusion.
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| 9. |
- Hellberg, Anders, et al.
(author)
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Influence of low proximal aortic pressure on spinal cord oxygenation in experimental thoracic aortic occlusion
- 2001
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In: Journal of Cardiovascular Surgery. - 0021-9509 .- 1827-191X. ; 42:2, s. 227-231
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Journal article (peer-reviewed)abstract
- BACKGROUND: To evaluate the effect of low proximal aortic pressure on cerebrospinal fluid (CSF) oxygenation in an experimental thoracic occlusion model. METHODS: In nine pigs, continuous intrathecal pO(2), pCO(2) and pH monitoring was used during double descending thoracic aortic clamping following insertion of an aorto-aortic shunt. In five pigs, the shunt was connected to a citrated bag adjusted at approximately 40-45 cm above the heart for partial exsanguination in order to decrease mean proximal aortic pressure (MPAP) to below 50 mmHg. In four animals, sodium nitroprusside infusion was used for this purpose. RESULTS: Intrathecal pO(2) demonstrated a significant decrease from 4.9+/-2.1 to 2.9+/-2.4 kPa after 10 minutes of aortic cross-clamping. Lowering proximal aortic pressure caused a further significant decrease to 1.2+/-1.7 kPa (p<0.05). In seven pigs (5 in the exsanguination and 2 in the vasodilator group), restoration of mean proximal aortic pressure to 94.0+/-27.7 caused a recovery of CSF pO(2) from 1.2+/-1.9 to 2.8+/-3.0 (p<0.05). CONCLUSIONS: The results of this study demonstrate that MPAP which provides spinal cord perfusion through subclavian-vertebral arteries are crucial for maintenance of spinal cord oxygenation during thoracic aortic occlusion in this pig model.
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| 10. |
- Hellberg, Anders, et al.
(author)
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Monitoring of intrathecal oxygen tension during experimental aortic occlusion predicts ultrastructural changes in the spinal cord
- 2001
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In: Journal of Thoracic and Cardiovascular Surgery. - : Elsevier BV. - 0022-5223 .- 1097-685X. ; 121:2, s. 316-323
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Journal article (peer-reviewed)abstract
- OBJECTIVE: To study the correlation between intrathecal PO2 and ultrastructural changes in the spinal cord during thoracic aortic occlusion in pigs. MATERIAL AND METHODS: In 18 pigs, online intrathecal oxygenation was monitored by a multiparameter Paratrend catheter (Biomedical Sensors, High Wycombe, United Kingdom) during 60 minutes' clamping of the proximal and distal descending thoracic aorta. The animals were randomly divided into 2 groups (A and B) depending on the level of distal aortic clamping. Distal aortic perfusion was restored through an aorto-iliac shunt, which also maintained low thoracic segmental perfusion of the spinal cord in group B. Perfusion-fixation technique was used before harvesting the spinal cord specimens, which later were evaluated with light and electron microscopy by an independent observer. Intrathecal parameters were interpreted as normal if PO2 was more than 0.8 kPa and PCO2 was less than 12 kPa, as intermediate ischemia if PO2 was 0.8 or less or PCO (2) was more than 12 kPa, and as absolute ischemia if PO2 was 0.8 or less and PCO2 was more than 12 kPa. RESULTS: Among 6 animals with ultrastructural changes of absolute spinal cord ischemia-reperfusion injury, 5 also had absolute ischemia according to variables derived by the Paratrend catheter. The 2 methods were in agreement in 3 of 5 animals with intermediate ischemia-reperfusion changes and in 5 of 6 animals with normal findings. The accuracy of cerebrospinal fluid PO2 and PCO2 to predict electron microscopy-verified intermediate or absolute ischemia-reperfusion injury was 94%. CONCLUSIONS: Monitoring of intrathecal PO2 after clamping of the descending aorta correlated with ultrastructural changes in the spinal cord in this pig model.
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| 11. |
- Logason, Karl, et al.
(author)
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The impact of different spectral Doppler criteria on the proportion of high-grade internal carotid artery stenosis in patients undergoing duplex scanning
- 2002
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In: Angiology. - : SAGE Publications. - 0003-3197 .- 1940-1574. ; 53:3, s. 297-301
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Journal article (peer-reviewed)abstract
- AIM: To investigate the impact of different spectral Doppler criteria on the proportion of high-grade ICA stenosis in patients undergoing carotid artery duplex scanning. MATERIAL AND METHODS: Duplex scans of 4,548 internal carotid arteries (ICA) in 2,349 patients were retrospectively analyzed. The following different criteria were applied for each scan for definition of ICA stenosis > or = 70%: Criteria I=ICA peak systolic velocity (PSV) > 130 cm/sec and ICA end-diastolic (EDV) > 100 cm/sec, Criteria II=PSV ICA/common carotid artery (CCA) ratio > 4, Criteria III=ICA PSV > or = 230 cm/sec, Criteria IV=ICA PSV > 230 cm/sec and/or ICA EDV > or = 100 cm/sec and/or PSV ICA/CCA ratio > or = 3.2. RESULTS: The frequency of detecting a > or = 70% ICA stenosis with criteria I, II, III, and IV were 5.5%, 6.8%, 8.4%, and 9.6%, respectively (p < 0.05). CONCLUSION: The use of various duplex criteria significantly affected the number of scans receiving a diagnosis of ICA stenosis of > or = 70%.
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| 12. |
- Löfberg, Anne-Marie, et al.
(author)
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Distal percutaneous transluminal angioplasty through infrainguinal bypass grafts
- 2002
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In: European Journal of Vascular and Endovascular Surgery. - : Elsevier BV. - 1078-5884 .- 1532-2165. ; 23:3, s. 212-219
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Journal article (peer-reviewed)abstract
- AIM: to evaluate the results of transluminal angioplasty (PTA) performed through infrainguinal bypass grafts for stenotic or occlusive lesions at the distal anastomosis and/or in the runoff arteries. Design: retrospective clinical study. MATERIAL AND METHODS: forty-one patients underwent 57 procedures at the distal anastomosis (n=13), in the runoff arteries (n=32) or at both locations (n=12) at a median of 9.6 months (range, 2-76 months) after infrainguinal bypass grafting. Nineteen procedures were on the popliteal artery, the rest on the crural arteries. Eleven procedures related to occlusions less than 5 cm in length. RESULTS: technical success was achieved in 91%. Primary and primary assisted graft patency rates at 3 years were 32% and 53%, respectively. There were no significant differences in patency rates with regard to the graft material, the type of lesion, the level of PTA, the status of runoff and the use of thrombolysis before PTA. No patients underwent amputation as a direct consequence of failed PTA or graft occlusion. One patient underwent acute surgical intervention due to graft occlusion at the time of attempted PTA. CONCLUSION: the results of PTA at the distal anastomosis and/or in the runoff arteries in limbs with infrainguinal bypass seemed to be inferior to the results of surgical revisions reported in literature. However, as failed PTA did not jeopardise vein-patch angioplasty or jump grafting, it is a reasonable alternative to surgical intervention in selected cases.
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| 13. |
- Ulus, A. Tulga, et al.
(author)
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Prevention of intimal hyperplasia by single-dose pre-insertion external radiation in canine-vein interposition grafts
- 2000
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In: European Journal of Vascular and Endovascular Surgery. - : Elsevier BV. - 1078-5884 .- 1532-2165. ; 19:5, s. 456-460
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Journal article (peer-reviewed)abstract
- OBJECTIVES: to evaluate the efficacy of single-dose pre-insertion gamma radiation of vein grafts in the prevention of intimal hyperplasia. METHODS: femoral artery interposition grafts with internal jugular vein were inserted in 12 mongrel dogs. The animals were randomly divided into two groups. Immediately before graft replacement, jugular veins were treated with a single dose of cobalt-60 radiation at 14 Gy or received no radiation (control group). Six weeks after graft insertion, the vein grafts were pressure-perfusion fixed and harvested for the histomorphometric analysis. Quantitative data on anastomotic stenosis were calculated from Gilman parameters after cross-sectional image analysis. RESULTS: vein grafts treated with radiation demonstrated significantly decreased neointima formation compared with grafts in the control group. The mean Gilman parameter for the control group was 1.09 S.E.M. 0.34 mm and for the radiotherapy group was 0.65 S.E. M. 0.23 mm (p<0.05). All vein grafts in the radiotherapy group had a decreased amount of intimal and cellular infiltration. CONCLUSION: single-dose external pre-insertion gamma radiation of vein grafts reduced the amount of intimal hyperplasia in this animal model.
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| 14. |
- Ulus, A. Tulga, et al.
(author)
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The influence of distal runoff on patency of infrainguinal vein bypass grafts
- 2001
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In: Vascular surgery. - 0042-2835. ; 35:1, s. 31-35
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Journal article (peer-reviewed)abstract
- This retrospective study was conducted to analyze a new concept of evaluation of the effect of distal runoff on patency in infrainguinal bypass surgery for arterial insufficiency. Distal runoff was evaluated on postreconstruction angiograms in 191 limbs undergoing femoropopliteal and femorodistal reconstruction. Runoff was characterized as good, fair, or poor. Determination of graft patency was made by clinical examination, ankle-brachial index measurement, or duplex scanning at 1 month and thereafter at 6-month intervals. Cumulative patency rates were calculated according to the actuarial life table method. Patency rates in limbs with good runoff were better than in limbs with fair and poor runoff; at 6 months, patency rates were 88.2%, 70.9%, and 21.8%, respectively (p < 0.01). Similar patency rates were found for good runoff in femoropopliteal and femorodistal reconstructions (84.7% in femoropopliteal and 75% in femorodistal reconstructions) at 6 months. The authors conclude that this method of angiographic evaluation accurately predicts patency in infrainguinal bypass reconstructions.
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