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Biomedical subjects

D Bergqvist

Publications and source records attributed to D Bergqvist.

At least 19 recordsLinked to original sources
PubMed1992

Effect on primary haemostasis of prophylactic regimens of low molecular weight heparin, unfractionated heparin, dextran and their combinations. An animal experimental study.

The aim of the study was to determine whether an impairment of the haemostasis could be observed experimentally when thromboprophylactic substances, which act differently on the haemostatic mechanism, were given single or in combination in prophylactic doses. In 36 rabbits we measured the primary haemostatic plug formation time (PHT), rebleedings and total haemostatic plug formation time (THT) after transection of venules and arterioles using an intravital microscope. We combined unfractionated heparin (UH) and low molecular weight heparin (LMWH) in low dose with either dextran 70 or polygeline (placebo volume expander) in a randomized double-dummy set up. In the placebo group (NaCl and polygeline) the median PHT was 55 and 101 seconds for arterioles and venules respectively, which are well-comparable to earlier results from our group. Most prolonged PHT and THT for arterioles were seen for dextran+NaCl, actually less prolongation was seen for UH+dextran. We did not observe any differences, except for a prolongation of THT for venules in rabbits given dextran+NaCl (p less than 0.05). Thus, in thromboprophylactic doses used, there does not seem to be an impaired or additive effect between heparins and dextran 70 in primary haemostasis in rabbits.

Animals↗
PubMed1992

Prevention of venous thromboembolism after surgery: a review of enoxaparin.

This review discusses the problem of deep vein thrombosis (DVT) after operation and identifies three levels of risk of DVT: low (less than 10 per cent), moderate (10-40 per cent) and high (40-80 per cent). Special emphasis is placed on the most recent prophylactic treatment, low molecular weight heparins (LMWHs), particularly enoxaparin. Several LMWHs are now available, but they differ slightly and each must be evaluated on its own merits. In general, however, LMWHs are both effective and safe in those patients at moderate or high risk of DVT. Thromboprophylaxis is cost effective when analysed using health-economic methodology.

Adult↗
PubMed1992

Prevalence of abdominal aortic aneurysm in the offspring of patients dying from aneurysm rupture.

The prevalence of abdominal aortic aneurysm (AAA) is high in the brothers of patients with aneurysm. A genetic component in the development of AAA has, therefore, been postulated. In this study the offspring of patients who had died from AAA rupture were invited to undergo ultrasonography of the abdominal aorta. The attendance rate was 69 per cent. Thirty-nine sons of median age 60 (range 45-75) years and 23 daughters of median age 62 (range 42-80) years were examined. Abdominal aortic dilatation was found in eight men and one woman. The presence of aortic dilatation in these nine cases was not related to age, hypertension, smoking or symptoms of occlusive arterial disease. It is concluded that the sons of those who have died from ruptured AAA constitute a high-risk group for the development of this condition and should be considered for further screening.

Aged↗
PubMed1992

Diminished contractile responses to neuropeptide Y of arteries from diabetic rabbits.

The vascular smooth muscle contractile response to neuropeptide Y (NPY), potassium, noradrenaline, histamine and serotonin was studied in circular segments of isolated vessels in vitro from rabbits with alloxan-induced diabetes mellitus. The injection of alloxan resulted in a marked and maintained increase in serum glucose as early as 1 week after treatment. Four vessel types were examined: abdominal aorta, and renal, left anterior descending coronary and middle cerebral arteries. There was no difference in the contractile response to histamine or serotonin between control and diabetic vessels. However, in the cerebral artery the contractile response to noradrenaline was reduced in the diabetic group, while in the aorta and the renal artery no significant differences were seen. Noradrenaline failed to evoke any contractile response in the coronary arteries in either group. NPY induced strong, concentration-dependent contractions of coronary and cerebral arteries, but did not have any contractile effect per se in aorta or renal arteries, either in control or in alloxan-treated rabbits. The maximal contractile effect and the sensitivity to NPY was significantly less in diabetic coronary and cerebral vessels as compared to control. There was no difference in dilator effect of acetylcholine and substance P between the diabetic animals and the control group in any of the vessel types, indicating that the changed vascular responses to NPY and noradrenaline were not endothelium-dependent. In conclusion, the present study has shown that the postjunctional effects of NPY and noradrenaline in the peripheral sympathetic nervous system are selectively attenuated in this model of chronic diabetes.

Animals↗
PubMed1992

Noninvasive measurement of diameter changes in the distal abdominal aorta in man.

An ultrasound phase-locked, echo-tracking system was used to determine the dynamic properties of the distal abdominal aorta in 10 Caucasian male subjects (mean age, 25 years). Recordings were made at rest and during the blood pressure increase resulting from isometric exercise. The pressure diameter curve was nonlinear with an inflection at about 90-110 mmHg. Above this pressure range, the vessel was stiffer (less compliant), but the pressure diameter relationship was roughly linear above as well as below the inflection. Individual pressure diameter curves showed hysteresis, i.e., the aorta had a smaller diameter during expansion than during retraction at corresponding pressures. The pressure strain elastic modulus (Ep) and stiffness (beta) were at rest [Mean Arterial Pressure (MAP), 81 mmHg] 0.70 10(5) N/m2 and 6.0, respectively. During isometric exercise (MAP, 122 mmHg), Ep increased significantly by 91% and stiffness (beta) nonsignificantly by 27%. The variability of the compliance determinations was 5% when the ultrasonic system was combined with intra-arterial blood pressure measurements and less than 7% when combined with auscultatory blood pressure measurements. It is concluded that the phase-locked, echo-tracking system fulfills clinical requirements for routine measurements of vascular compliance.

Adult↗
PubMed1992

Papaverine effects on PGI2 and TXA2 release from the canine vascular wall.

Operative manipulation of blood vessels might lead to spasm, thereby destroying the endothelial cell function: the spasm can be prevented by the vasodilator papaverine. To study if this was mediated via the prostanoid pathway the following investigation was undertaken: canine jugular veins and carotid arteries were dissected with or without papaverine. Vessel segments were then perfused with Hank's balanced salt solution for five times 15 min. Prostacyclin was measured as the stable degradation product 6-keto-PGF1 alpha and thromboxane as TXB2, by radioimmunoassay. Control arterial segments' 6-keto-PGF1 alpha release was initially 129.5 + 20.1 pg/mm2/15 min, and 29.7 + 10.4 after 60 min (p less than 0.05 vs initial value) and responded to arachidonic acid (AA) with an increase to 139.2 +/- 23.1 pg/mm2/15 min (p less than 0.05). Segments treated with papaverine had the same release as the controls. In venous segments there was a lower initial release (p less than 0.05) from segments given papaverine than from controls, but this was more likely an effect of papaverine on the assay. There was no difference in release of prostacyclin from segments given papaverine in the perfusate compared to controls when using 125I tracer. When using 3H tracer including absorption of free antigen to dextran coated charcoal, papaverine displaced the free tracer giving artificially low values. There was no effect of papaverine given intraoperatively on the TXB2 release, neither from arteries nor from veins. In another experiment the vessel wall tension was examined and the cyclooxygenase inhibitor diclofenac did not inhibit the vasodilating effect of papaverine.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Acute thrombogenicity of collagen coating of dacron grafts: an experimental study in sheep.

The early stages of platelet accumulation in two types of sealed interposition Dacron grafts implanted in the carotid arteries of sheep have been studied. One type was externally coated with collagen (Haemaguard) while the other experimental conduit had an additional inner lining of the same substance. 32P-labelled platelets were used to assess platelet accumulation and corrections for wall absorption were calculated. The activities in both types of grafts were highest proximally and decreased towards the distal anastomosis. The increases in the doubly-sealed grafts were larger than in those that had been single sealed, presumably reflecting activation of platelets in contact with collagen at the graft-wall and bloodstream interface. In addition, a significantly larger amount of thrombus was formed in the doubly-sealed grafts 4 h after reperfusion. It is reasonable to assume that increased acute thrombogenicity due to direct collagen-blood contact on graft surfaces is unfavourable to long term patency.

Animals↗
PubMed1992

Preoperative assessment of the risk for cardiac death following thrombo-embolectomy for acute lower limb ischaemia.

Cardiac monitoring and the selective use of initial non-operative management is reported to reduce the high mortality rate in patients with acute lower limb ischaemia. Early estimation, prior to selection of initial therapy, of the risk for intraoperative or postoperative cardiac death following thrombo-embolectomy is therefore important. The aim of this prospective multi-centre study was to develop a simple and clinically useful index for assessment of the risk of post-operative cardiac death. Patients judged to need thrombo-embolectomy for acute lower limb ischaemia were evaluated on admission for routine clinical, cardiac and limb ischaemia parameters that could be related to cardiac function and these parameters compared to postoperative cardiac outcome. Sixteen per cent of the 117 patients died from intraoperative or postoperative cardiac complications. Analysis revealed five admission parameters that significantly and independently predicted a high risk for cardiac death: mean arterial blood pressure below 90 mmHg, clinical sign(s) of cardiac decompensation, ischaemia affecting the thigh, haemoglobin concentration exceeding 140 gl-1, and a history of a myocardial infarction in the previous 4 weeks. Definition of risk points for each risk factor allowed a simple classification of each patient into one of three significantly different cardiac risk classes with cardiac death rates of 6 +/- 3%, 27 +/- 8% and 75 +/- 16%, respectively. More than two thirds of the patients belonged to the low risk group. The described risk index provides a tool for preoperative assessment of the cardiac death risk associated with early thrombo-embolectomy in patients with acute lower limb ischaemia.

Aged↗
PubMed1992

Diameter and compliance in the male human abdominal aorta: influence of age and aortic aneurysm.

In this study changes in the diameter and compliance of the distal abdominal aorta (76 healthy Caucasian males, 5-71 years old) were determined non-invasively and related to age by means of an ultrasound phase-locked echo-tracking system. The diameter of the aorta increased not only in the period between 5 and 25 years of age, but also by about 30% between the ages of 25 and 71. The pressure diameter curves at 25, 51 and 70 years were non-linear with flattening between 90 and 110 mmHg, and the slope of the curves declined with age. Thus, the pressure strain elastic modulus (Ep) and stiffness (beta) increased (i.e. compliance decreased) in an exponential manner according to age. A group of 37 males with aneurysmal widening of the distal abdominal aorta had a significant increase in Ep when compared to an age-matched control group. Furthermore, the ranges for both Ep and beta were much larger in the aneurysm group than in the control group, indicating diversity in the pathogenesis of the disease. The non-invasive ultrasonic method of phase-locked echo-tracking is an appropriate method for studying compliance in major arteries under a variety of pathophysiological conditions.

Adolescent↗
PubMed1992

Storage in sodium chloride does not impair arterial prostacyclin release.

Heparinised sodium chloride solution is often used for the storage of veins and to prevent clotting in the arterial tree during vascular surgery. Sodium chloride deranges the morphology of endothelial cells and has therefore been interpreted as "toxic" to the endothelial cell. Perfused human saphenous veins and rabbit aortas show the same pattern of prostanoid release even though veins have a lower release than arteries. Excised rabbit aortas were stored in either (a) 0.9% sodium chloride or (b) 0.9% sodium chloride with heparin 5 I.U. ml-1 prior to being mounted in a perfusion model. The vessels were perfused ex vivo for 5 x 15 min with either Hanks' balanced salt solution (HBSS), calcium- and magnesium-free HBSS or 0.9% sodium chloride. For the last period, arachidonic acid (AA) 4 micrograms ml-1 was added. The release of prostacyclin, measured as the stable degradation product 6-keto-PGF1 alpha by radioimmunoassay, was not altered by storage in sodium chloride, or 0.9% sodium chloride plus heparin when compared with control segments. Perfusion with 0.9% sodium chloride did, however, significantly (p greater than 0.05) decrease the prostacyclin production when AA was added. This is most likely to be due to the low pH of the sodium chloride solution. It is concluded that short-term storage of rabbit aorta in sodium chloride plus heparin or 0.9% sodium chloride does not impair the prostacyclin cascade from the vessel wall, which might be of importance when choosing storage medium for reversed veins and veins used for coronary bypass surgery.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

The acute thrombogenicity of an infection-resistant rifampicin-soaked Dacron graft: an experimental study in sheep.

Every effort to reduce synthetic graft infection is welcome and when designing antibiotic-bonded grafts it is important not to increase graft thrombogenicity. In order to study the acute thrombogenicity of rifampicin-soaked gelatin-sealed Dacron grafts compared with untreated gelatin-sealed Dacron grafts, an experimental carotid artery sheep model was used. Twenty sheep were anaesthetised and 7-cm-long 5-mm-wide externally supported gelatin-sealed knitted Dacron grafts were sutured end to end into each carotid artery after excising a portion of that vessel. Test grafts had previously been immersed for 15 min in a rifampicin solution (1 mg ml-1) while control grafts were immersed in physiological saline for 15 min. There were two groups with 10 sheep in each. In one group the blood flow through the grafts was unrestricted but in the second the flow was restricted to 25 ml min-1. Platelets from sheep labelled with 111In and sheep fibrinogen labelled with 125I were injected intravenously. The isotope activities were continuously measured proximally and distally over the grafts for 4 h. With unrestricted flow 4 out of 10 rifampicin-soaked grafts occluded compared with 2 out of 10 control grafts (N.S.). Time to occlusion, thrombus weight, platelet and fibrinogen activity did not differ. In the restricted flow group 9 out of 10 rifampicin-soaked grafts occluded compared with 6 out of 10 control grafts (N.S.). The time to occlusion did not differ. The thrombus weight in the rifampicin group was significantly higher compared with the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

The effect of a combined thromboxane receptor- and synthesis-antagonist on platelet, fibrinogen and leucocyte uptake in ePTFE grafts: an experimental study in sheep.

Arterial expanded polytetrafluoroethylene (ePTFE) grafts were interpositioned in the common carotid arteries of 20 adult sheep. This model was used to study the effect of a combined thromboxane receptor- and synthesis-antagonist, Ridogrel (R 68070), on acute graft patency and platelet, fibrinogen and leucocyte uptake. The animals were randomised to treatment (n = 10) or control groups (n = 10). Treatment was given as an intravenous injection with Ridogrel of 8 mg kg body weight-1. The flow in one of the two inserted grafts was restricted to 25 ml min-1. Autologous 111In-labelled platelets, 125I-labelled fibrinogen and 99m-Tc-labelled leucocytes were injected intravenously and the radioactivity over the vessels measured before and after graft insertion using the gamma scintillation technique. After graft insertion the measurements continued for 4 h at two separate points over the proximal and distal anastomosis areas. In the treatment group six out of 10 grafts with restricted flow remained patent compared with nine out of 10 grafts with flow reduction in the control group (N.S.). The median thrombus weights did not differ significantly. There was no difference in the platelet and fibrinogen activities at the proximal anastomosis but distally the animals receiving treatment had a significant reduction during the first 2 h of the experiment. The leucocyte activity in the treatment group compared to the control group did not differ proximally but distally the activity was significantly higher during the last 3 h of the experiment. In the group with unrestricted flow all grafts in both groups remained patent. The thrombus weight was significantly lower in the treatment group compared with the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗