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Biomedical subjects

D Bergqvist

Publications and source records attributed to D Bergqvist.

At least 217 records · Page 12Linked to original sources
PubMed1994

Heparin and protamine use in peripheral vascular surgery: a comparison between surgeons of the Society for Vascular Surgery and the European Society for Vascular Surgery.

It was the intent of this study to document, in general, the patterns and complications of heparin and protamine usage during carotid endarterectomy, aortic and femoral-popliteal-tibial reconstructions for occlusive disease, elective and emergent abdominal aortic aneurysmectomy, thromboembolectomy, and dialysis arteriovenous (AV) fistula placement by surgeons from North America and Europe. All vascular surgeons from the Society for Vascular Surgery (SVS) and the European Society for Vascular Surgery (ESVS) were surveyed by a voluntary, self-reported questionnaire. Six hundred and forty-six completed questionnaires (284 from SVS and 362 from ESVS), representing a 62% response rate, were returned for evaluation. Systemic and regional administration of heparin was common during vascular procedures performed by both SVS and ESVS surgeons. Use of protamine to reverse heparin anticoagulation varied among SVS and ESVS surgeons, respectively, during: carotid endarterectomy (54% vs. 26%, p < 0.01), elective aortic reconstruction for occlusive disease (58% vs. 23%, p < 0.001), elective aortic reconstruction for abdominal aortic aneurysm (63% vs. 27%, p < 0.001), and femoral-popliteal-tibial reconstruction (44% vs. 15%, p < 0.001). Adverse reactions to protamine among the 25,219 and 12,902 cases reported from SVS and ESVS surgeons, respectively, included: hypotension (1209 and 495 cases), pulmonary artery hypertension (65 and eight cases), anaphylaxis (52 and 10 cases), and death (seven and two cases). These adverse responses accounted for 5.3% and 4.0% of the SVS and ESVS cases, respectively. Although this study is subject to the known limitations of a retrospective survey, it is clear that heparin use is common. Protamine reversal of heparin anticoagulation is more common in North America.(ABSTRACT TRUNCATED AT 250 WORDS)

Data Collection↗
PubMed1994

Time-related anticoagulation after regional and systemic administration of heparin in patients undergoing aortoiliac surgery.

Heparin anticoagulation during cardiovascular surgical procedures remains poorly investigated and understood. The objective of this investigation was to assess the effectiveness of three methods of heparin administration. Heparin sulfate (75 IU/kg) administered to patients undergoing aortoiliac surgery was randomised to one of three methods: Group I (n = 9) heparin was injected into a central venous line 5 minutes before infrarenal aortic clamping; Group II (n = 9) heparin was injected into the distal aneurysm immediately after infrarenal aortic clamping; and Group III (n = 8) heparin was injected into a central venous line immediately after infrarenal aortic clamping. Blood samples were analysed for anticoagulant activity from both the upper and lower extremities at 5, 15, 30, 60, and 120 minutes after heparin administration. Anticoagulation, as measured by aPTT, antifactor Xa levels, and ACT, was achieved in all three groups by 5 minutes, but initially with lower heparin activity (measured as antifactor Xa) in the upper extremity (Group II) and lower extremity (Group III), respectively. These differences were also evident in ACT and aPTT determinations. Intravenous heparin administration prior to aortic cross-clamping achieves excellent anticoagulation (anti-factor Xa approximately 1 U/ml) in both upper and lower extremities after 5 minutes. With regional administration, rapid heparin redistribution occurs, but it takes longer to achieve the same level of anticoagulation distant from the site of administration. Nevertheless, from a practical perspective the method of administration does not appear to have a great influence on the eventual achievement of adequate anticoagulation.

Aortic Aneurysm, Abdominal↗
PubMed1994

Loss of seeded endothelial cells in vivo. A study of Dacron grafts under different flow conditions.

OBJECTIVES: To assess, in vivo, the loss of endothelial cells seeded in a Dacron graft at low, restricted arterial flow and at normal unrestricted flow. DESIGN AND SETTING: Laboratory animal study. MATERIALS: Indium-111-oxine labelled endothelial cells were seeded in externally supported, preclotted Dacron grafts, inserted as interposition grafts in the carotid arteries of nine sheep. Activity (radioactivity) was measured, flow established, on one side unrestricted 120-180 ml/minute, and on the other restricted to 50 ml/minute by a distal clamp. OUTCOME MEASURES: The reduction in activity over the grafts was measured for 2 hours. RESULTS: There was an immediate loss of activity to around 80% and thereafter a lower rate of cell loss to around 50%. No difference could be demonstrated in the loss from low flow compared to high flow grafts. All grafts were patent. There was no difference in thrombus weights. CONCLUSION: No difference could be demonstrated in seeded endothelial cell loss from a Dacron graft in vivo at low flow (50 ml/minute) compared with unrestricted flow (120-180 ml/minute).

Animals↗
PubMed1994

Vascular surgical audit during a 5-year period. Steering committee on behalf of the Swedish Vascular Registry (Swedvasc).

UNLABELLED: The objective was to explore possible time trends in the indications for peripheral vascular surgery in Sweden. DESIGN: Analysis of data from the Swedvasc vascular registry 1987-1991. SETTING: Routine vascular surgery in university, county and district hospitals within the Swedish public hospital system. The registry is independent of local administration, run by the surgeons themselves and financed by national authorities. MATERIALS: 4950 procedures registered in the 17 original centres 1987-91 and 1892 procedures registered in 16 new centres 1991. CHIEF OUTCOME MEASURES: Distribution of indications, mortality within 30 days and clinical outcome at one year. MAIN RESULTS: During the first 5 years of the registry (1987 to 1991) the proportion of procedures performed for acute ischaemia significantly decreased from 20% to 14.3%. Simultaneously procedures for critical leg ischaemia significantly increased from 24.8 to 30.3%. Changes in the proportions treated for aortic aneurysms, carotid artery stenosis, claudication, vascular access or other indications were less striking or nonsignificant. The 30-day mortality decreased in patients operated on for acute ischaemia but did not change in other groups. The proportion of elective/emergency operation for aortic aneurysm changed from 1.2 to 2.0 leading to a minimal decrease in overall aneurysm mortality. The proportion of patients treated for claudication who were alive and improved at one year changed from 77.2% to 72.9% which was not statistically significant, while the proportion of patients treated for critical ischaemia who were alive with an intact leg after one year increased from 65.2% to 80.2% which was a significant improvement. CONCLUSIONS: Decision making among vascular surgeons in Sweden appears to have improved as proportionally fewer patients are operated on for acute ischaemia, more for critical ischaemia with possibly an improved outcome.

Humans↗
PubMed1994

Protamine neutralization of intravenous and subcutaneous low-molecular-weight heparin (tinzaparin, Logiparin). An experimental investigation in healthy volunteers.

The aim of the present study was to investigate whether tinzaparin sodium (a low-molecular-weight heparin (LMWH)) was fully and permanently neutralized in vivo in man by protamine sulphate (PS) after intravenous (i.v.) or subcutaneous (s.c.) injection. Fifty healthy adults equally divided in five age- and sex-matched groups were included. The groups received 50 IU unfractionated heparin (UH)/kg body weight (b.w.) i.v., 50 anti-factor Xa (anti-Xa) IU tinzaparin/kg b.w. i.v., 75 anti-Xa IU tinzaparin/kg b.w. s.c., 175 anti-Xa IU tinzaparin/kg b.w. s.c., or 1 ml of saline s.c. PS was given as a 10 min infusion in a dose of 1 mg/100 IU of heparin in the four first groups while 0.5 mg PS/kg b.w. was given in the placebo group. In the i.v. groups PS was administered 45 min after the heparin injection, and in the s.c. groups 180 min post-heparin injection. In the UH group PS fully and permanently neutralized all three activities. In the i.v. tinzaparin group PS reversed 80% of the anti-Xa activity, while the anti-IIa and aPTT activities were fully reversed. A slight, but statistically significant, increase in anti-Xa and anti-IIa activities were seen following i.v. tinzaparin. In the s.c. groups 60-65% of the observed peak anti-Xa activity was neutralized, anti-IIa was almost completely reversed, and aPTT returned nearly to baseline values. A gradual return of the anti-Xa activity (65-75%), anti-IIa activity (55%) and aPTT activity (35-45%) was seen in the s.c. groups 3 h after reversal compared with the observed peak values.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Platelet accumulation and thrombus formation after microarterial injury. An experimental study in rabbits.

Patency rats and accumulation of 32P-labelled platelets were studied in the central ear arteries of rabbits (which were not treated with antithrombotic agents) after three types of vascular injury: End to end anastomosis, arteriotomy and superficial injury to the vessel wall to expose the lamina elastica interna/juxtaluminal parts of the tunica media, arteriotomy and deep injury to the vessel wall to expose the deeper layers of the tunica media. The superficial and deep vessel injuries were 5 mm long. Patency rates were 100% after end to end anastomosis and superficial injury, and 48% after deep injury. In a separate group of vessels with deep injuries the time course of formation of occlusive thrombi was investigated: occlusion was already present 15 minutes after reperfusion in all but one of seven occluded vessels. Platelet accumulation ratios were significantly higher after deep injury than after end to end anastomosis or superficial injury. In deeply injured patent vessels, platelet accumulation reached a maximum after about 30 minutes, which was later followed by a gradual decrease. Platelet accumulation patterns indicating sustained thrombogenicity throughout the measurement interval (embolization/reaccumulation patterns or late increases in accumulation) were encountered in only three of 22 deeply injured vessels. We conclude that: to cause formation of occlusive thrombus in otherwise healthy arteries and animals, a deep injury to the tunica media is necessary, and following reperfusion after repair of damaged vessels the time course of the thrombotic challenge is short.

Anastomosis, Surgical↗
PubMed1994

Effects of streptokinase and urokinase on microarterial thrombosis and haemostasis. An experimental study in rabbits.

The effects of streptokinase and urokinase on haemostasis, accumulation of platelets radiolabelled with phosphorus (32P) and patency were studied after arteriotomy and deep vessel wall trauma of the central arteries of rabbits' ears. In one study, 12 rabbits were given 1700 IU/kg body weight of streptokinase or urokinase as intraaortic bolus injections five minutes before vascular reperfusion (opening of vascular clamps). A further six were given saline (controls). In the second, 12 further rabbits were each given 3,400 IU/kg of either substance, one fifth as a bolus before reperfusion and the remainder as a continuous infusion during the next two hours. A further six were given saline (controls). Irrespective of the dosage regimens, neither substance improved patency compared with saline-treated controls. Separate dose response studies with streptokinase showed that bolus or bolus+infusion doses larger than those given caused troublesome arteriotomy bleeding. Compared with controls, streptokinase increased, and urokinase decreased, accumulation of platelets. This was not reflected in differences in patency rates, which were similar in all groups. In conclusion, fibrinolytic stimulation with non-thrombolytic doses of streptokinase or urokinase did not prevent microarterial thrombosis in rabbits. The therapeutic index for these substances in clinical microvascular surgery is probably low, as haemorrhagic complications may be expected.

Animals↗
PubMed1994

Effect of low molecular weight heparin, dextran and their combinations on experimental venous thrombosis in rabbits.

An experimental model based on the combination of endothelial damage and flow reduction was used to induce jugular vein thrombosis in rabbits. The effect on thrombosis of a low molecular weight heparin (LMWH [Fragmin]), dextran 70, placebo and their combination was studied in a double-blind fashion with actual doses used in clinical thromboprophylaxis. Saline and polygeline were used as placebo in the control group. Four groups with 120 isolated vein segments in 60 animals were studied for presence of thrombus formation, occlusive thrombi and thrombus weights. Dextran reduced the thrombus weights (p = 0.048) and the formation of occlusive thrombi (p = 0.01), but not the formation of thrombi when compared with the placebo control group. Similarly, LMWH reduced the thrombus weights (p = 0.046), the formation of thrombi (p = 0.007) and occlusive thrombi (p = 0.0001). Compared with the LMWH group the group treated with the combination of LMWH and dextran was found to reduce the frequency of occlusive thrombi (p = 0.03) and numerically, but not significantly, further reduce the overall frequency of thrombosis (p = 0.18) and thrombus weights (p = 0.11). The results are consistent with an augmentation of the antithrombotic effect of LMWH by dextran 70. The need for further evaluation of the combined efficacy of LMWH and dextran is apparent from this study.

Animals↗
PubMed1994

Study of the interaction of dextran and enoxaparin on haemostasis in humans.

The effect on haemostatic variables by dextran 70, enoxaparin and their combinations, given in doses of 500 ml i.v. and 40 mg s.c. respectively, was studied in a randomised cross-over fashion in twelve healthy male volunteers. Antifactor-IIa activity, antifactor-Xa activity, APTT, factor VIII, vWF, bleeding time and blood counts were analysed over a 24-h period. Dextran alone did not affect antifactor-IIa activity and antifactor-Xa activity. No difference in antifactor-IIa and antifactor-Xa activity was found for Amax, tmax, AUC0-8 h and AUC0-24 h in the groups treated with enoxaparin or the combination of enoxaparin and dextran. Only minor changes in APTT were observed without statistical significance between the treatment groups. Factor VIII did not change significantly in the three treatment groups. However, vWF was significantly reduced in the dextran and the dextran/enoxaparin group (p = 0.046 and 0.01 respectively) but no difference was found between the two groups. Bleeding time was not significantly increased four hours after administration of the test substances and no difference was found between the individual treatment groups. Our findings indicate that dextran can be combined with enoxaparin, when used in thromboprophylactic doses, without increased risk for bleeding.

Adult↗
PubMed1994

Duplex ultrasound scanning for diagnosis of aortoiliac and femoropopliteal arterial disease.

Forty patients with symptomatic aortoiliac and/or femoropopliteal occlusive arterial disease subjected to angiography were studied with duplex ultrasonography. The duplex scanning of the aortic, iliac, femoral and popliteal segments had a sensitivity of 93% in detecting significant stenoses and a specificity of 91%. The positive and negative predictive values were 75% and 98%, respectively. The sensitivity was relatively low in low-flow segments distal to total occlusions especially in patients with severe iliac disease and multiple distal femoropopliteal lesions. The results demonstrate the reliability of duplex scanning in detecting aortoiliac and femoropopliteal lesions.

Aorta, Abdominal↗
PubMed1994

Fatal pulmonary embolism in an unselected series: the possible role of caval filters in prevention.

OBJECTIVE: To evaluate the possible benefit of inserting a caval filter for the prevention of pulmonary embolism (PE) in an unselected group of patients admitted to hospital. DESIGN: Analysis of clinical data collected prospectively. SETTING: University hospital, Sweden. SUBJECTS: 1391 patients who presented during 1987 435 with deep vein thrombosis (DVT), thrombus in the right atrium or the right ventricle or PE at necropsy; 366 patients shown to have DVT on phlebography; 44 shown to have PE on pulmonary scintigraphy; and 546 patients operated on for hip fractures. OUTCOME MEASURES: Clinical description of patients and groups of patients who died of PE who could possibly have benefitted from insertion of a filter. RESULTS: Of the 435 patients with DVT or PE or both, 141 had DVT in the femoral or iliac veins or in the inferior vena cava together with PE which contributed to the cause of death. Only 11 of these had been suspected clinically of having DVT in or below the inferior vena cava and only 1 of these was less than 80 years old and did not have malignant disease with distant metastases. Of the 366 patients with phlebographically confirmed DVT 8 died with PE that had contributed to the cause of death; 6 had incurable cancer and the remaining two were over 85 years. Of the 44 patients with scintigraphically confirmed PE 2 patients (aged 78 and 89) died of PE that had already been diagnosed clinically and none would have benefited from insertion of a filter after diagnosis. There were 9 PE deaths related to PE among 546 patients operated on for hip fractures, and all but one had potentially lethal coexisting disease or were over 80 years old. CONCLUSION: In this epidemiological survey only a few patients would have benefited from insertion of a caval filter. The results call for a restricted use of caval filters until benefit has been confirmed by prospective studies.

Adolescent↗
PubMed1994

Inhibition of microarterial thrombosis by activated protein C in a rabbit model.

Protein C is the key component in a natural anticoagulant pathway. After its activation by the thrombin-thrombomodulin complex, it degrades the activated forms of coagulation cofactors VIII and V, which leads to downregulation of the coagulation process. Due to its specific anticoagulant activity, activated protein C (APC) is potentially interesting as an antithrombotic agent. The effect of bovine activated protein C on thrombus formation and haemostasis was investigated in a rabbit model of microarterial thrombosis. Segments of both central ear arteries were prepared and blood-flow interrupted with double vascular clamps. Longitudinal arteriotomies (7 mm) and deep vessel wall trauma (5 mm) were performed, whereafter the arteriotomies were closed with running sutures. Five minutes prior to opening of the clamps (reperfusion), boluses of APC (0.8 mg/kg bodyweight) or vehicle alone were administered to two groups, each of 10 rabbits, in a blind random fashion. Vessel patency-rates were drastically improved by the administration of APC compared to vehicle. Correspondingly, thrombus weights were significantly lower in the APC group than in the control group. The activated partial thromboplastin time was prolonged to approximately twice the baseline throughout the 2 h observation interval in the APC group. Levels of circulating platelets were unaffected by the APC infusion, but the arteriotomy bleeding times were significantly longer in the APC group. In summary, activated protein C exerted powerful and long-acting antithrombotic effects in a microarterial model of thrombosis in rabbits.

Animals↗
PubMed1994

[Surgery for abdominal aortic aneurysm. What is an acceptable complications rate?].

At the annual meeting of the Vascular Section of the Scandinavian Surgical Society in 1993 it was decided to discuss standards for quality in vascular surgery. This article is discussing operations for abdominal aortic aneurysms with special reference to early mortality and complications like graft infection and aortoenteric fistula. The discussion is based on national vascular registers and investigations on vascular surgical activity in the Scandinavian countries. In addition, a survey of the literature is given. Although these data should be regarded as a guide-line only, we feel that one should try to keep the 30 day mortality following elective resection for asymptomatic abdominal aortic aneurysm below 5-7 per cent. A mortality less than 50-60 per cent following operation for ruptured aneurysm may be regarded as reasonable. Patient-selection regarding age, concomitant disease etc. could significantly influence these results, and should be taken into consideration when comparison between different series is made. Graft infection is a serious complication and if the frequency is higher than 2 per cent, or there is an accumulation of graft infections in a vascular centre, the hospital routines should be reviewed carefully. The occurrence of infection is higher following operations for ruptured aneurysms than following elective operations. Early operations for haemorrhage and early occlusion should be below 5-6 per cent. Some authors have shown a correlation between the volume of operation, postoperative mortality and the frequency of complications. We therefore think that it might be reasonable to suggest that at least patients who have concomitant diseases like serious coronary heart disease or renal insufficiency should be operated on in vascular centres.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Aneurysm, Abdominal↗
PubMed1994

Endothelial cell seeded dacron aortobifurcated grafts: platelet deposition and long-term follow-up.

OBJECTIVE: The prospect of seeding endothelial cells to a prosthetic graft has been successful in the experimental setting, but less convincing in clinical studies in humans. This study was performed with the objective of evaluating endothelial cell seeding of aorto-bi-iliofemoral reconstructions with cells harvested at the same procedure. EXPERIMENTAL DESIGN: Randomized study with one graft limb seeded and with at least 5 year follow-up. SETTING: University Hospital. PATIENTS: 15 patients undergoing aorto-bi-ilio-femoral reconstruction. INTERVENTIONS: One graft limb (randomly determined) was seeded with autologous endothelial cells (median 5.2 x 10(5)) enzymatically (Dispase II) harvested from the saphenous vein (length 8-15 cm, diameter 4-8 mm). The other graft limb served as a control. MEASURES: Two months after surgery platelets were labelled with 111In and platelet activity registered over the graft. Long-term outcome were followed (median 5 years and 10 months). RESULTS: No difference in platelet activity was noted between the seeded and non-seeded graft limb. Different techniques of calculating graft wall activity showed large interindividual variations in the results. Long-term outcome showed that three patients died, two from myocardial infarction on postoperative day three and 60, and one patient died four years after surgery from a lung cancer. Grafts functioned well. In one non-seeded graft limb the patient had severe microembolisation postoperatively that required amputation 10 days after surgery. Of seeded graft limbs one occluded 42 months after surgery, intimal hyperplasia at the distal anastomosis was seen and in one patient progress of arteriosclerosis required additional surgery 12 months after initial operation with profundaplasty (partly due to intimal hyperplasia) and later two additional femoro-distal reconstructions were needed. CONCLUSION: In summary with our single-staged technique for seeding of endothelial cells to a graft limb in a high flow situation no effect on platelet activity at two months was found and long-term outcome was not obviously influenced.

Aged↗
PubMed1994

Incidence and causes of adverse outcomes of operation for chronic ischaemia of the leg.

OBJECTIVE: To assess the incidence of adverse outcomes after operation for chronic leg ischemia, to identify risk factors for an adverse outcome at one year, and to evaluate survival after operation. DESIGN: Retrospective study. SETTING: University department. SUBJECTS: 1635 consecutive patients recorded on the Swedvasc registry, 1987-1989. INTERVENTIONS: Data were analysed by logic regression and Cox's proportional hazards model. MAIN OUTCOME MEASURES: Morbidity and mortality at 30 days, one year, and 1000 days. RESULTS: At 30 days 54 of the 609 patients with claudication (8.8%) had either not improved or got worse, and this had increased to 126 (20.7%) at one year. Among the 1026 patients with critical ischaemia 124 had either had their limbs amputated or were dead at 30 days (12.2%), and the corresponding figure for one year was 359 (35.0%). Main factors associated with adverse outcome were age, heart disease, previous vascular surgery, reoperation within 30 days, and the presence of complications. Experience of the surgeon and the type of hospital were less important. At 1000 days 528 of the 609 patients with claudication (86.6%) were alive, compared with 628 of the 1026 with critical ischaemia (61.2%).* CONCLUSIONS: Better selection of patients may improve the survival figures at one year. More aggressive treatment of coexistent diseases may improve the results in the group with claudication.

Adult↗
PubMed1994

Increased thrombogenicity after polymer coating: experiences with the first version of a new woven Dacron graft for aortic reconstruction.

OBJECTIVE: To assess the initial results of insertion of a new woven Dacron graft coated with a polymer for occlusive and aneurysmal aortoiliac disease. DESIGN: Open study. SETTING: Four Swedish vascular surgical units. SUBJECTS: 28 patients who required aortoiliac or aortofemoral reconstruction between September 1988 and June 1989. MAIN OUTCOME MEASURES: Incidence of, and time to, occlusion; type of intervention; whether the graft needed to be replaced; and mortality. RESULTS: Two patients died in the postoperative period, and five during follow-up, giving an overall mortality of 25%. None of the tube grafts occluded but 17 of 24 bifurcation grafts did (71%), the median time to occlusion being 126 days (range 10-820). Our results have led to this graft being removed from the market while modifications are made in the process of impregnation of polymer. CONCLUSIONS: Strict protocols for the assessment of new graft materials should be introduced and enforced.

Aged↗