Rheological properties and function of blood cells in stored bank blood and salvaged blood

The technique involving filtration of diluted blood enables the separate analysis of the flow properties of different cell subpopulations. This study was designed to assess the changes occurring in the flow properties and function of blood cells in stored bank blood and salvaged blood compared to patient blood in a given clinical situation. We measured hydrogen peroxide production by neutrophils and the filterability, through 5 microm Nucleopore filters, of isolated red blood cells and of diluted blood. Samples were obtained from patients undergoing aortic surgery and blood intended for transfusion: either salvaged during surgery or stored bank blood. Both salvaged and bank blood were much less filterable than patient blood, with reduced deformability of both red and white blood cells. However, salvaged blood contained highly activated neutrophils with a prolonged transit time of the 'fast-flowing' cells in the analysis compared to bank blood. Bank blood contained significantly more particles which acted as pore-blockers. Cells in bank and salvaged blood therefore have markedly abnormal flow and biochemical properties compared to patient blood.

Circulating ICAM-1 and VCAM-1 in peripheral artery disease and hypercholesterolaemia: relationship to the location of atherosclerotic disease, smoking, and in the prediction of adverse events

We examined the relationship of soluble intercellular adhesion molecule-1 (sICAM-1) and vascular cell adhesion molecule-1 (sVCAM-1) with smoking and hypercholesterolaemia in peripheral artery disease (PAD). Serum samples were obtained from 119 patients with objectively-proven PAD, 39 patients with hypercholesterolaemia but asymptomatic for PAD, and 132 age and sex matched asymptomatic controls. Using ELISAs, we found increased sICAM-1 and sVCAM-1 (both p <0.01) in the patients with PAD relative to the controls, but no significant change in patients with hypercholesterolaemia. However, the effect for sVCAM-1 was lost when smoking was entered as a covariate. Only sICAM-1 was higher in patients with PAD in the femoral/iliac arteries compared to the carotid arteries (p <0.05). In a 39-month follow-up of 112 patients with PAD, increased ICAM-1 weakly (univariate p <0.05) predicted those 57 whose disease progressed (i.e. to end points such as myocardial infarction and arterial surgery). However, high fibrinogen was a much better (univariate p = 0.001, multivariate p <0.05) predictor of disease progression. We suggest (i) that increased levels of sVCAM-1 in atherosclerosis are due to smoking, (ii) that increased sICAM-1 is independent of this risk factor, (iii) that both these changes are independent of hypercholesterolaemia, and (iv) that increased sICAM-1 is a weak predictor of disease progression in peripheral atherosclerosis.

Shortening and reimplantation for tortuous internal carotid arteries

PURPOSE

The purpose of this study was to assess the outcome after the shortening and reimplantation of tortuous internal carotid arteries to prevent kinking after endarterectomy.

METHODS

Through a review of prospective records, we studied patients who underwent carotid endarterectomy (CEA) (n = 233) between 1993 and 1996 who had symptomatic stenosis of the internal carotid artery (ICA) of more than 70%. An elongated proximal ICA was excised, and the ICA was reimplanted into the bifurcation in 30 (13%) patients, with additional patch angioplasty in 5 patients. Of the remaining 203 patients, 50 (21%) had Dacron patch angioplasty, and the rest had conventional CEA with simple closure.

RESULTS

In the reimplanted group, one patient had a minor stroke with complete recovery on discharge. Three patients (10%) had neck hematomas requiring reexploration, but in none of these was the bleeding from the artery. At mean follow-up of 15 months, 93% of the arteries were widely patent. Significant stenosis secondary to neointimal hyperplasia was detected in only two patients, for a restenosis rate of 6.7%, which is in line with other published reports. In the control group, 8 (3.9%) patients had perioperative transient ischemic attacks, 5 (2.5%) had strokes, and 13 (6.4%) had hematomas requiring evacuation. At follow-up, 14 (6.9%) of the arteries had restenosed.

CONCLUSION

In carotid surgery, reconstructive techniques must be tailored to operative findings. Excision of a tortuous elongated proximal ICA with reimplantation is not associated with additional mortality or morbidity rates over those of conventional CEA alone and has the advantage of removing disease at the bifurcation. This procedure was carried out in 13% of our patients and should be a procedure with which the vascular surgeon is familiar.

Rheological properties and function of blood cells in stored bank blood and salvaged blood

The technique involving filtration of diluted blood enables the separate analysis of the flow properties of different cell subpopulations. This study was designed to assess the changes occurring in the flow properties and function of blood cells in stored bank blood and salvaged blood compared to patient blood in a given clinical situation. We measured hydrogen peroxide production by neutrophils and the filterability, through 5 microm Nucleopore filters, of isolated red blood cells and of diluted blood. Samples were obtained from patients undergoing aortic surgery and blood intended for transfusion: either salvaged during surgery or stored bank blood. Both salvaged and bank blood were much less filterable than patient blood, with reduced deformability of both red and white blood cells. However, salvaged blood contained highly activated neutrophils with a prolonged transit time of the 'fast-flowing' cells in the analysis compared to bank blood. Bank blood contained significantly more particles which acted as pore-blockers. Cells in bank and salvaged blood therefore have markedly abnormal flow and biochemical properties compared to patient blood.

Management practice at leg ulcer clinics

These three papers, presented at a Journal of Wound Care master class, describe procedures used at specialist clinics for the care of patients with leg ulcers.

Evaluation of the HemoCue for measuring intra-operative haemoglobin concentrations: a comparison with the Coulter Max-M

We compared haemoglobin concentration values obtained using a portable haemoglobinometer, the HemoCue, in the operating theatre with the results obtained by the Coulter Max-M in the laboratory. Haemoglobin concentrations were measured on 52 arterial blood samples obtained from 13 patients during aortic surgery, in theatre with the HemoCue and again by the Coulter Max-M. Twenty routine samples from the laboratory were also analysed by both methods. There was no significant difference between results, with a mean of 10.94 g.dl-1 and 10.90 g.dl-1 for the HemoCue and Coulter, respectively (p = 0.12, t = -1.99, df = 70). The limits of agreement of the two methods (mean difference +/- 2 SD) were -0.37 and +0.45 g.dl-1. The coefficients of repeatability of the 20 samples analysed in duplicate on each device were 0.26 g.dl-1 and 0.33 g.dl-1, respectively. The coefficients of variance were 0.74% (HemoCue) and 0.93% (Coulter). With adequate training and monitoring, the HemoCue provides comparable haemoglobin results for near-patient testing in theatre.

Circulating von Willebrand factor antigen II in atherosclerosis: a comparison with von Willebrand factor and soluble thrombomodulin

von Willebrand factor antigen II (vWFAgII) is the 100 kDa propolypeptide of endothelial cell marker von Willebrand factor (vWF). Our aim was to determine the relationship between vWFAgII and mature vWF and an additional endothelial cell marker, soluble thrombomodulin, in atherosclerosis. To do this, we measured levels of all three by enzyme-linked immunosorbent assay in plasma obtained from 24 patients with peripheral vascular disease (PVD), from 25 patients who survived a myocardial infarction [i.e. had ischaemic heart disease (IHD)], and from 47 age- and sex-matched controls. We found raised levels of vWFAgII in PVD (57.3 +/- 15.3 microg/dl; mean +/- standard deviation) and in IHD (53.4 +/- 19.2 microg/dl) compared with the controls (35.7 +/- 12.0 microg/dl; analysis of variance P < 0.001). Raised levels of vWf were found in both groups of patients but raised soluble thrombomodulin was found only in patients with PVD. Levels of vWFAgII correlated with those of vWf (r = 0.45, P < 0.001) but not with soluble thrombomodulin (r = 0.14, P = 0.17), nor any of the major risk factors for atherosclerosis. Our brief study reports raised levels of vWFAgII in atherosclerosis. This may, like that of vWf, be related to endothelial cell damage, although the incomplete correlation between the two implies different metabolic and/or release mechanisms.

Soluble platelet endothelial cell adhesion molecule-1 (sPECAM-1) in inflammatory vascular disease, atherosclerotic vascular disease, and in cancer

Cell surface adhesion molecule expression is likely to be important in inflammation, atherosclerosis and cancer, and soluble forms of many of these molecules are present in plasma. We measured levels of the soluble form of platelet endothelial cell adhesion molecule-1 (sPECAM) by ELISA in the serum of 77 patients with frank atherosclerosis, 69 patients with inflammatory connective tissue disease, and 39 patients with cancer. Each group of patients was controlled by an equal number of age- and sex-matched healthy subjects. There was no difference between sPECAM in patients with atherosclerosis and their matched controls or between patients with connective tissue disease and their controls. However, sPECAM levels were lower (16.6 +/- 5.0 ng/ml, mean +/- SD) in patients with cancer than in their controls (21.1 +/- 4.4 ng/ml, P < 0.001). No differences were found in sPECAM levels between the major subgroups of each type of disease, or as a result of factors such as age, sex or smoking in the controls. In contrast to levels of many other soluble adhesion molecules, levels of sPECAM are not altered in inflammatory or atherosclerotic vascular disease and therefore appear to have little relevance in these conditions. However, there may be significant differences in sPECAM levels in patients with low levels in cancer. Additional investigations are therefore justified.

Circulating endothelial cell markers in peripheral vascular disease: relationship to the location and extent of atherosclerotic disease

We examined the relationship between specific endothelial cell markers soluble E-selectin, von Willebrand factor and soluble thrombomodulin and the location or extent of atherosclerosis by analysing plasma samples from 200 patients with symptomatic peripheral vascular disease and 213 age- and sex-matched asymptomatic control subjects. Using ELISAS, we found increased von Willebrand factor and thrombomodulin (both P < 0.0001) in the patients relative to the control subjects, but no significant change in soluble E-selectin. Soluble thrombomodulin was increased in patients with disease at one locus (i.e. of the carotid or iliac/femoral arteries), with an additional significant increase in patients with disease at multiple loci (i.e. any combination of carotid, coronary or iliac/femoral artery disease). No marker differentiated carotid artery disease from iliac/femoral artery disease. We conclude that von Willebrand factor is a marker of generalized atherosclerosis, but that soluble thrombomodulin is related to the extent of disease. Further research into these endothelial cell products are warranted to explore their diagnostic and/or prognostic potential.

Repeated exercise induces release of soluble P-selectin in patients with intermittent claudication

Controversy exists as to whether exercise in patients with intermittent claudication causes a harmful biochemical effect associated with an ischaemia-reperfusion injury of skeletal muscle. We report on exercise-induced changes in neutrophil activation, soluble P-selectin and von Willebrand factor in 34 patients with intermittent claudication and 12 matched controls. Von Willebrand factor (vWF) showed a cyclical pattern of response to exercise in control subjects (rising from 103 +/- 8 to 119 +/- 7 U/dl); claudicants did not show this pattern but had higher levels of vWF throughout (p <0.03). There was no consistent pattern of response in neutrophil hydrogen peroxide production to exercise in either claudicants or control subjects. Soluble P-selectin levels increased after exercise, but this only reached statistical significance after repeated exercise in claudicants (rising from 320 +/- 28 to 357 +/- 28 ng/ml). This rise in soluble P-selectin after exercise may indicate progressive platelet activation which may contribute to the excess cardiovascular mortality that claudicants are prone to.

Increased soluble P-selectin following myocardial infarction: a new marker for the progression of atherosclerosis

Increased soluble P-selectin has been described in atherosclerosis, but the mechanisms for this and its clinical significance are unknown. In an attempt to clarify these points we measured soluble P-selectin and von Willebrand factor, an endothelial cell marker, by ELISA in 116 patients who had survived a myocardial infarction and in 116 matched controls. Raised levels of both soluble P-selectin (median 272 ng/ml, range 55-850 ng/ml vs 190 ng/ml, range 40-395 ng/ml) and von Willebrand factor (mean +/- SD 128 +/- 37 IU/dl vs 100 +/- 33 IU/dl; both P < 0.001) failed to correlate (r = 0.12), and soluble P-selectin failed to correlate with any of the major risk factors for atherosclerosis. A four-year follow-up of 68 of these patients revealed that soluble P-selectin was higher in the 33 (48%) who had suffered an additional cardiovascular event (e.g. subsequent myocardial infarction, arterial surgery; median 350 ng/ml, range 275-460 ng/ml) compared with those free of an end-point (270 ng/ml, range 140-400 ng/ml, P = 0.0012). We conclude that increased soluble P-selectin is unrelated to the risk factors for atherosclerosis but is a new marker of disease progression in patients who have survived a myocardial infarction.

The influence of smoking and of oral and transdermal nicotine on blood pressure, and haematology and coagulation indices

Nicotine is helpful in stopping smoking but its influence on cardiovascular risk factors is incomplete. Our aim was to determine its effect on blood pressure, routine haematology indices, and coagulation indices relevant to thrombosis. Eighteen subjects were seen whilst smoking (cotinine levels 1119 +/- 414 ng/ml), again after stopping smoking but while using nicotine chewing gum and/or skin patches (392 +/- 198 ng/ml), and again when not using nicotine (cotinine undetectable). There were no significant changes in blood pressures, platelet count, mean platelet volume, viscosity or anti-thrombin III. However, white blood cell count (p = 0.003), lymphocyte count (p = 0.016), red blood cell count (p = 0.02), haemoglobin (p <0.001), fibrinogen (p <0.001) and von Willebrand factor (p = 0.001) all fell between the first and second samples (when still using nicotine) but not between the second and third samples (when off nicotine). Oral and/or transdermal nicotine does not influence blood pressure or the haematology and coagulation indices we have measured.

Prognostic value of increased soluble thrombomodulin and increased soluble E-selectin in ischaemic heart disease

Endothelial cell dysfunction is likely to be important in the pathophysiology of ischaemic heart disease and increased levels of endothelial cell markers soluble E-selectin and soluble thrombomodulin may reflect this damage. To determine whether increased levels of these markers were predictive of disease progression, we obtained plasma from 54 patients who had survived a myocardial infarction. Soluble E-selectin and soluble thrombomodulin were measured by ELISA. After 49 months, 24 patients had suffered an additional cardiovascular event such as a second myocardial infarction or requirement for arterial surgery. Soluble E-selectin was 60+/-30 ng/mL in patients who suffered an end-point and was 54+/-23 ng/mL in those without an end-point (p=0.43). Soluble thrombomodulin was 65+/-24 ng/mL in patients who suffered an end-point and was 49+/-19 ng/mL in patients who were free of an end-point (p=0.009). The major risk factors for atherosclerosis (hypercholesterolaemia, hypertension, smoking) or peak creatinine kinase levels were unable to predict the development of an end-point. Using life tables, soluble thrombomodulin had a significant effect on survival free of an end-point (p=0.011). We conclude that the measurement of soluble E-selectin is of limited value in epidemiological studies, and that raised soluble thrombomodulin is a new marker for the progression of atherosclerosis in patients with ischaemic heart disease.

von Willebrand factor and soluble E-selectin in the prediction of cardiovascular disease progression in hyperlipidaemia

Two specific endothelial cell products, von Willebrand factor and soluble E-selectin, were measured together with serum lipids, lipoprotein(a), systolic and diastolic blood pressure (SHP, DBP) in a follow up study of 162 patients attending a dedicated lipid clinic. Patients were further classified by the presence or absence of symptomatic vascular disease and smoking. After a mean of 49 months, 45 patients experienced a cardiovascular event (fatal or nonfatal myocardial infarction, stroke, or arterial surgery) and 11 developed non-cardiovascular diseases, including cancer. In univariate analysis, existing vascular disease (P < 0.01), increased levels of von Willebrand factor (P < 0.0001) and low density lipoprotein cholesterol (P < 0.02), greater age (P < 0.01), and lower levels of soluble E-selectin (P < 0.03) were all predictive of future vascular events. However, in multivariate analysis, only increased von Willebrand factor was predictive (P < 0.001). von Willebrand factor was also higher in patients who developed non-cardiovascular disease relative to those free of disease (P < 0.05). Our data support the hypothesis that increased levels of von Willebrand factor are an indicator of poor prognosis in patients with atherosclerosis or its risk factors.

Pilot study of carotid surgery for acute stroke

BACKGROUND

Carotid endarterectomy is usually delayed for 2 months following an acute stroke, but the stroke may progress or a further stroke may occur. A randomized pilot study of urgent carotid surgery for acute stroke was undertaken to assess the feasibility of a definitive multicentre trial.

METHODS

Seven Manchester hospitals referred patients with acute stroke (less than 7 days previously), defined according to the Oxfordshire Community Stroke Project classification The carotid arteries were examined by portable continuous-wave Doppler ultrasonography. Patients with more than 50 per cent carotid stenosis on portable Doppler ultrasonography underwent colour duplex Doppler imaging. Patients with more than 70-99 per cent carotid stenosis were randomized to urgent carotid surgery or best medical care.

RESULTS

A total of 593 patients were assessed over 2 years. Of these, 414 had acute stroke, of whom 380 had probable cerebral infarction. Complete ipsilateral internal carotid artery occlusion was most common in patients with total anterior circulation infarcts (33 (28 per cent) of 117), whereas severe ipsilateral (70-99 per cent) stenosis was most common in partial anterior circulation infarcts (25 (20 per cent) of 128). Only 16 patients (one total and 15 partial anterior circulation infarcts) were fit enough for surgery and consented to randomization.

CONCLUSION

A definitive trial of urgent carotid surgery would need to screen large numbers of patients but could focus on patients with partial anterior circulation infarcts.

Soluble P-selectin in atherosclerosis: a comparison with endothelial cell and platelet markers

von Willebrand factor and soluble thrombomodulin are established plasma markers of endothelial cell dysfunction, whilst beta thromboglobulin is an established plasma marker of platelet activity. Soluble P-selectin may be the product of either or both types of cell and levels of all four molecules have been previously found to be increased in atherosclerosis. To determine the relationship of soluble P-selectin to the endothelial cell and platelet products, we measured the four indices in a case control study of 55 patients with peripheral vascular disease and 55 age and sex matched controls. von Willebrand factor (p < 0.0001), beta thromboglobulin (p = 0.0006), soluble P-selectin (p = 0.0021) and soluble thrombomodulin (p = 0.021) were all raised in the patients. Soluble P-selectin correlated with beta thromboglobulin (r = 0.34, p = 0.019) but failed to correlate with either endothelial cell marker. Co-culture of endothelial cells in vitro with bovine thrombin resulted in increased levels of von Willebrand factor in the supernatants but levels of soluble thrombomodulin and soluble P-selectin were not enhanced. Exposure of endothelial cell monolayers to elastase resulted in different patterns of release of von Willebrand factor, soluble thrombomodulin and soluble P-selectin. We suggest that soluble P-selectin is unlikely to arise from the endothelium and may be a new marker of platelet activation in atherosclerosis.

Monitoring wound healing by odour

A pilot study using electronic aroma detection was performed over a six-month period to assess the aroma of chronic non-healing venous leg ulcers and the effect of appropriate antibiotic therapy on modification of the aroma. Deep infection with pathogenic organisms was found on biopsy culture in 13 out of 15 patients. Odour analysis was performed at weekly intervals on the ulcer dressings using an AromaScan instrument. Data points on the aroma maps moved from their pre-treatment presentation. Alterations in aroma data correlated well with the progress of the ulcers. Aroma analysis is shown to be a potential tool in monitoring the progress towards healing of chronic venous ulcers.

Von Willebrand factor and soluble E-selectin in hyperlipidaemia: relationship to lipids and vascular disease

Our objective was to determine whether endothelial cell products von Willebrand factor and soluble E-selectin are related to serum lipids, lipoprotein (a), and vascular disease in patients with hyperlipidaemia. In order to achieve our aim, blood samples were obtained for four experiments from 1) 160 patients (49 with symptomatic vascular disease) with hypercholesterolaemia and an equal number of age and sex matched controls; 2) 31 patients who were studied serially before and after successful resolution of their hypercholesterolaemia; 3) 15 patients with hypertriglyceridaemia; and 4) 20 controls, half of whom consumed a lipid-rich breakfast. von Willebrand factor and soluble E-selectin were measured by enzyme linked immunosorbent assay (ELISA) using commercial reagents. In experiment (1) von Willebrand factor was increased in the patients with hypercholesterolaemia (P=0.0077) and was higher still in patients with vascular disease (P<0.0001). Soluble E-selectin was not influenced by hypercholesterolaemia or vascular disease. The correlation of von Willebrand factor with total and LDL cholesterol (both P<0.001) remained after both age and blood pressure were controlled. Experiment (2) showed that serial studies in patients over an average of 7 months a reduction in total cholesterol was associated with a reduction in von Willebrand factor (r=0.51, P=0.002). Experiment (3) demonstrated that von Willebrand factor was not increased in patients with hypertriglyceridaemia (median 8.9 mmol/L), and in experiment (4) a lipid-rich breakfast taken by fasted, healthy controls produced an increase in serum triglycerides (P<0.01) but did not influence von Willebrand factor over an 8 hour period. We conclude that von Willebrand factor, but not soluble E-selectin, is raised in hypercholesterolaemia and therefore may be a potential indicator of endothelial cell physiology in subjects with, or at risk of, atherosclerotic vascular disease.

Soluble P-selectin in hyperlipidaemia with and without symptomatic vascular disease: relationship with von Willebrand factor

Soluble P-selectin (CD62P) may arise from platelets, the endothelium, or both, and raised levels are found in those with thrombotic disease and atherosclerosis. To determine whether these increased levels in atherosclerosis are related to hypercholesterolaemia, blood samples were obtained from 86 patients (43 with symptomatic vascular disease) attending a hypercholesterolaemia clinic, and 86 age- and sex-matched controls. Parallel measurement of endothelial cell product von Willebrand factor helped define the origin of sP-selectin. Using ELISAs, soluble P-selectin was higher (median 290 ng/ml, range 80-735, P < 0.05) in patients with vascular disease than in both patients with uncomplicated hypercholesterolaemia (median 210 ng/ml, range 55-550), and controls (median 190 ng/ml, range 48-500). Von Willebrand factor was raised in both patients with uncomplicated hypercholesterolaemia (115 +/- 26 IU/dl, P < 0.05) and patients with hypercholesterolaemia and vascular disease (129 +/- 32 IU/dl, P < 0.02) compared with controls (102 +/- 30 IU/dl). Levels of soluble P-selectin did not correlate with von Willebrand factor, total low-density-lipoprotein (LDL) or high-density-lipoprotein (HDL) cholesterol or triglycerides levels, blood pressure or smoking, but von Willebrand factor correlated with LDL cholesterol (r = 0.42, P < 0.05). We conclude that plasma lipoproteins are not a major influence on levels of soluble P-selectin.

Should heparin be reversed after carotid endarterectomy? A randomised prospective trial

OBJECTIVE

To investigate whether heparin reversal after carotid endarterectomy reduces the incidence of haemorrhagic complications.

DESIGN

A randomised prospective trial.

METHODS

Sixty-four patients randomised to reversal of heparin or no reversal, of whom 31 received protamine titrated to the residual circulating heparin at closure of arteriotomy. Measurements included serial activated clotting times (ACTs), wound drainage, neck swelling using duplex Doppler imaging to measure the depth from skin to carotid bifurcation, and the recording of all complications.

RESULTS

Wound drainage volumes were significantly reduced by protamine reversal (68.5 ml compared to 35 ml, p < 0.001), but neck swelling was not (72 mm compared to 70 mm, p = 0.77). Two patients who were not reversed developed neck haematomas requiring evacuation. More importantly, two patients receiving protamine, thrombosed the operated internal carotid artery (ICA) postoperatively and died despite urgent thrombectomy. A further patient who was not randomised in this study but who received protamine also developed ICA thrombosis within the same 3 month period.

CONCLUSIONS

Reversing heparin with protamine reduces postoperative wound drainage after carotid surgery but may predispose to ICA thrombosis and stroke. This is in keeping with a previous retrospective study published during our trial.