Influence of Platelet Count on Haemostatic Plug Formation and Plug Stability

The initial haemostatic process in thrombocytopenic animals after transection of arterioles and venules was investigated in a rabbit mesenteric preparation. Graded thrombocytopenia with a bone marrow suppressant (busulphan) and anti-platelet serum gave comparable results. With decreasing platelet counts there was progressive prolongation in haemostatic plug formation time, and a significant non-linear relation between platelet count and haemostatic plug formation time. Haemostatic plugs formed under thrombocytopenic conditions were more stable than normal. The difference in stability normally seen between plugs in arterioles and venules disappeared with decreasing platelet counts. The relationship between venular and arteriolar haemostatic plug formation time was also reduced with decreasing platelet counts.

The Effect of Serotonin Inhibition on Initial Microvessel Hemostasis and Platelet Aggregation In Vivo

The role of serotonin (5-HT) in initial microvascular hemostasis is not fully understood. This study was made to evaluate the effect on hemostatic plug formation and laser-induced arteriolar microembolism of different substances which counteract the effect of 5-HT. Hemostatic plug formation time and stability was measured in the rabbit mesenteric microcirculation and laserinduced embolism in the rabbit ear chamber. Ketanserine, a selective 5-HT2-receptor blocker shortened arteriolar hemostatic plug formation time. Dihydroergotamine, an unselective blocker (with 5-HT- and α-adrenergic receptor affinity) increased venular hemostatic plug formation time and also decreased the hemostatic plug stability. Laser-induced platelet embolism was unaltered after both ketanserine and dihydroergotamine administration. The magnitude of these changes seems to exclude an important effect of 5-HT in initial microvessel hemostasis or on platelet activity.

Haemostatic Platelet Plug Formation in the Isolated Rabbit Mesenteric Preparation - An Analysis of Red Blood Cell Participation

In a model using an isolated rabbit mesenteric preparation microvessels were transected and the time until haemostatic plugs formed was registered. Perfusion of platelet rich plasma gave no haemostasis whereas whole blood did. Addition of chlorpromazine or adenosine to the whole blood significantly prolonged the time for haemostasis, and addition of ADP to the platelet rich plasma significantly shortened it. It is concluded that red cells are necessary for a normal haemostasis in this model, probably by a combination of a haemodynamic and ADP releasing effect.

The fundamental role of platelets in haemostatic plug formation is unquestionable but there are still problems concerning the stimulus for this process to start. Three platelet aggregating substances have been discussed – thrombin, adenosine diphosphate (ADP) and collagen. Evidence speaking in favour of thrombin is, however, very minimal, and the discussion has to be focused on collagen and ADP. In an in vitro system using polyethylene tubings we have shown that "haemostasis" can be obtained without the presence of collagen but against these results can be argued that it is only another in vitro test for platelet aggregation (1).

To be able to induce haemostasis in this model, however, the presence of red blood cells is necessary. To further study this problem we have developed a model where haemostatic plug formation can be studied in the isolated rabbit mesentery and we have briefly reported on this (2).

Thus, it is possible to perfuse the vessels with whole blood as well as with platelet rich plasma (PRP) and different pharmacological agents of importance.

Female Gender and Resistance to Activated Protein C (FV:Q506) as Potential Risk Factors for Thrombosis after Elective Hip Arthroplasty

Resistance to activated protein C (APC) caused by the R506Q mutation in factor V is the most common inherited risk factor for venous thrombosis. To elucidate whether APC-resistance is a risk factor for venous thrombosis after elective total hip replacement, the association between APC-resistance (presence of FV:Q506 allele) and postoperative thrombosis was investigated in patients (n = 198) randomised to received short (during hospitalisation, n = 100) or prolonged prophylaxis (three weeks after hospitalisation, n = 98) with low molecular weight heparin (LMWH). Among APC-resistant individuals receiving short prophylaxis, 7/10 developed thrombosis as compared to 2/12 receiving long prophylaxis (p <0.0179). Odds ratio for association between APC-resistance and thrombosis in the short prophylaxis group was 4.2 (CI 95% 1.02-17.5) (p <0.0465). Among those receiving prolonged, prophylaxis, there was no increased incidence of thrombosis associated with APC-resistance. Two unexpected observations were made. One was that APC-resistance was much more common in women (19/109) than in men (3/89) (p <0.001). The other was that even women without APC-resistance were much more thrombosis-prone than men. Thus, 24/48 of women with normal FV genotype and short prophylaxis developed thrombosis vs 8/42 among men, p = 0.002. The increased risk of thrombosis associated with female gender and APC-resistance was neutralised by the prolonged treatment. In conclusion, among patients receiving short prophylaxis, female gender was found to be a strong risk factor for venous thrombosis. Even though APC-resistance appeared to be a risk factor for postoperative thrombosis, the uneven distribution of APC-resistance between men and women, taken together with the increased risk of thrombosis among women, precluded valid conclusions to be drawn about the association between APC-resistance and an increased risk of thrombosis. Our results suggest that prolonged prophylaxis with LMWH after hip surgery is more important for women than for men.

Microvascular Haemostasis and the Effect of Local Stimulation and inhibition of Platelet Function. An Experimental Study in Rabbits

The local stimulation and inhibition of haemostatic plug formation was studied by local infusion and superfusion of different agents – ADP, thrombin, adenosine, heparin, prostaglandin E1 (PGE1) and laser injury. ADP and laser injury shortened venular haemostatic plug formation time whereas adenosine in the superfusate and PGE1 prolonged it. Thrombin infusion had no effect but thrombin in the superfusate significantly stabilised the haemostatic plugs. It is suggested that ADP released from red cells is the most potent stimulator for haemostatic plug formation in the rabbit mesenteric microcirculation.

Effect of Dextran on Experimental Venous Thrombosis in Rabbits

An experimental model combining controlled stasis and endothelial destruction by sodium morrhuate has been used to investigate the effect of dextran on venous thrombus formation in rabbits. Dextran 70 (1 g/kg body weight in a 10% solution), given 3 hours before thrombosis induction, significantly reduced the incidence of venous thrombosis when compared to a saline control. Dextran 40 (1 g/kg body weight in a 10% solution) and dextran 70 (0.6 g/kg body weight in a 6% solution) had no significant effect under these conditions. When given 10 or 120 minutes before initiation of thrombosis none of the dosages of dextran had any preventive effect. The results indicate that the haemodynamic effects of dextran were not involved in its preventive effect in this study. The effect of dextran was probably due to a combination of an effect on platelet reactivity and a change of the structure of fibrin formed during growth of the thrombi.

Steal Syndrome after Brachiocephalic Fistula for Vascular Access: Correction with a New Simple Surgical Technique

Purpose

Steal syndrome is the condition of arterial insufficiency distal to a permanent haemodialysis fistula. Three treatment options have been recommended: ligation of the fistula, banding of the fistula, and distal revascularization. We report an alternative simple surgical technique for correction of steal syndrome.

Methods

Two patients were treated for steal syndrome after brachiocephalic fistula operation. The treatment of the steal syndrome was done by interponating an ePTFE graft loop tunnelated subcutaneously in the upper arm.

Results

At follow-up one year later both fistula were patent without any reoperation and with normal flow at haemodialysis. There were no symptoms of steal.

Conclusion

This new method for correction of steal syndrome seems to be an attractive alternative.

Steal Syndrome of the Hemodialysis Vascular Access: Diagnosis and Treatment

Purpose

Steal syndrome is an uncommon but serious condition of arterial insufficiency distal to a permanent hemodialysis fistula. The management of the condition is a great challenge to the surgeon because of the conflicting goals of preserving the fistula and treat the ischemia. In this review the purpose was to analyze the clinical problem and treatment possibilities.

Methods

Medline and Embase databases were searched for studies relevant to diagnosis and management of steal syndrome of the hemodialysis vascular access.

Results

The diagnosis of steal syndrome is largely based on clinical features and non-invasive studies. In same cases angiography may be necessary to find out the real causes of the steal syndrome. The cause is usually high fistula flow but other causes as steal phenomenon, inflow, outflow or anastomotic stenosis have to be considered and even combination of causes. The main treatment options are some form of flow reducing procedure or the distal revascularization interval ligation method. In some cases simple distal arterial ligation is the method of choice. Furthermore, in some patients a stenosis has to be treated as the first treatment option.

Conclusion

For an appropriate treatment of a steal syndrome a careful analysis of the cause is important.

Editor's Choice - Management of Secondary Aorto-enteric and Other Abdominal Arterio-enteric Fistulas: A Review and Pooled Data Analysis

OBJECTIVES

To compare management strategies for secondary abdominal arterio-enteric fistulas (AEFs).

METHODS

This study is a review and pooled data analysis. Medline and Scopus databases were searched for studies published between 1999 and 2015. Particular emphasis was given to short- and long-term outcomes in relation to AEF repair type.

RESULTS

Two hundred and sixteen publications were retrieved, reporting on 823 patients. In-hospital mortality was 30.7%. Open surgery had higher in-hospital mortality (246/725, 33.9%), than endovascular methods (7/98, 7.1%, p < .001, OR 6.7, 95% CI 3-14.7, including staged endovascular to open surgery, 0/13, 0%). In-hospital mortality after graft removal/extra-anatomical bypass grafting was 31.2% (66/226), graft removal/in situ repair 34% (137/403), primary closure of the arterial defect 62.5% (10/16), and for miscellaneous open procedures 41.3% (33/80), p = .019. Among the subgroups of in situ repair, homografts were associated with a higher mortality than impregnated prosthetic grafts (p = .047). There was no difference in recurrent AEF-free rates between open and endovascular procedures. Extra-anatomical bypass/graft removal and in situ repair had a lower AEF recurrence rate than primary closure and homografts. Late sepsis occurred more often after endovascular surgery (2-year rates 42% vs. 19% for open, p = .001). The early survival benefit of endovascular surgery was blunted during follow-up, although it remained significant (p < .001). Within the in situ repair group, impregnated prosthetic grafts were associated with the worst overall and AEF related mortality free rates and vein grafts with the best. No recurrence, sepsis, or mortality was reported following staged endograft placement to open repair after a mean follow-up of 16.8 months (p = .18, p = .22, and p = .006, respectively, compared with patients in other groups).

CONCLUSIONS

Endovascular surgery, where appropriate, is associated with better early survival than open surgery for secondary AEFs. Most of this benefit is lost during long-term follow-up, implying that a staged approach with early conversion to in situ vein grafting may achieve the best results in selected patients.

Acute Renal Failure in Rats

It was demonstrated in rats that renal injury which follows transient renal hypoxia is potentiated by the contrast media metrizoate, ioxaglate, iopamidol and iohexol. Intravenous injection of 1 g I/kg of all four media alone to 82 rats caused no significant increase in serum urea 1, 3 and 7 days later. The percentage increase of serum urea is given in median values and interquartile range (in parentheses). Bilateral renal arterial occlusion alone for 40 minutes in 42 rats increased serum urea one day later by 40 per cent (20–130). Intravenous injection of the media followed in one hour by bilateral renal arterial occlusion for 40 minutes in 104 rats caused serum urea to increase one day later by 130 per cent (70–350) after metrizoate, by 220 per cent (50–380) after ioxaglate, by 290 per cent (60–420) after iopamidol and by 160 per cent (50–330) after iohexol. There were no significant differences between the potentiating effects of the various media on ischemic renal failure.

Complications after Percutaneous Transluminal Angioplasty of Peripheral and Renal Arteries

This review deals with complications after percutaneous transluminal angioplasty (PTA). First some methodologic points are discussed. It seems important to standardize the way in which complications are reported. Our own complications in peripheral and renal PTA are summarized and taken as a basis for an analysis of various types of complications. Principally these may occur at different levels: at the puncture site, at the dilatation site as well as distant and general complications. To make comparisons with surgical series relevant it is suggested that all complications and mortality within 30 days are reported.

Does Cerebral Angiography of Cadaveric Kidney Donors Interfere with Graft Function?

Cerebral angiography is used to diagnose brain death of cadaver kidney donors. Clinical and animal data suggest that angiographic contrast media may potentiate the noxious effect of renal ischemia. In order to find out if cerebral angiography of cadaveric kidney donors prior to nephrectomy interferes with function or survival of the renal grafts, two groups of cadaveric donors were compared. One group had been exposed to contrast medium from cerebral angiography in median 18 hours before nephrectomy and the other had not. There was no difference in graft survival and function between the two groups. In a previous investigation angiography was performed two hours before explantation and in that investigation there was a shorter graft survival in the angiography group than in a control group. A delay of 12 hours is suggested between cerebral angiography and explantation, to decrease the combined harmful effects of contrast media and ischemia on renal grafts.

Prolonged prophylaxis against venous thromboembolism with enoxaparin in patients undergoing cancer surgery: long-term survival analysis

Objective: ENOXACAN II was a randomized, double-blind trial that showed prolonged (four-week) thromboprophylaxis with enoxaparin to be more effective than and as safe as standard (one-week) thromboprophylaxis in patients undergoing surgery with a curative intent for abdominopelvic cancer. This follow-up study compared long-term, all-cause mortality in both groups.

Methods: Survival rates were calculated on the randomized, treated population ( n = 501). The primary efficacy endpoint was survival at one year. An exploratory analysis including survival data up to 44 months was performed. Because some patients were deemed to have undergone palliative as opposed to curative surgery, and there was a significant difference between the treatment groups in the percentage of patients undergoing palliative surgery, the survival analyses were adjusted for the type of surgery performed.

Results: When adjusted for type of surgery, there was a trend towards reduced mortality among patients undergoing palliative surgery in the prolonged prophylaxis group (hazard ratio [HR] = 0.598, P = 0.3565) that became more pronounced beyond the pre-specified one year follow-up period (HR = 0.469, P = 0.078). This trend may reflect a beneficial effect of prolonged prophylaxis on survival in the palliative surgery group (one-year survival 65.4 versus 50% for standard prophylaxis). In patients undergoing curative surgery, one-year survival rates were equal in the standard and prolonged prophylaxis groups (93.8 and 93.2%, respectively).

Conclusion: Prolonged thromboprophylaxis with enoxaparin may affect long-term survival in palliative surgery for cancer, but further investigation is warranted.

Prevalence and Aetiology of Leg Ulcers in a Defined Population of Industrial Workers

Objective:

To assess leg ulcer prevalence and aetiology in people below retirement age.

Design:

A validated cross-sectional questionnaire survey. Respondents with a history of leg ulcers were examined.

Setting:

A defined population of industrial workers.

Subjects:

All 2785 employees, aged 30–65 years, at the Volvo motor engine factories in Skövde were included. Men predominated (81%) and the median age was 44 years in both men and women. A questionnaire was used to select people with a history of ulceration. A leg ulcer was defined as ‘any wound below the knee (foot ulcers included) that did not heal within a 6-week period after onset of ulceration’.

Main outcome measures:

Point prevalence of open leg ulcers, overall prevalence of leg ulcer history and aetiological classification.

Results:

The overall response rate was 87%, and 131 out of 153 subjects with a ‘history of leg ulcers’ were examined (86%). In 98% of positive responders the answers were validated. The overall false-positive response rate was 64%. Fifty-four had a true history of ulcers, of whom 16 had open ulcers. Of the latter, 12 were self-caring (75%). Overall venous causation dominated (41%). The ratio of open to healed ulcers was 1:2. The point prevalence for open ulcers was 0.6% and the overall prevalence of ulcer history was 1.6%, if excluding pure traumatic ulcers. The point prevalence was tenfold higher in people aged below 50 years and seven times higher in the age decade 50–59 years if compared with previous estimates based on patients known to health-care professionals.

Conclusion:

Leg ulcer prevalence has been underestimated in people of working age because they are often self-caring. Since many ulcers have curable causes it is necessary to inform the public of the importance of seeking professional help early.

Lower Limb Deep Venous Incompetence is Rare in Patients Undergoing Obesity Surgery

Objective:

To investigate the incidence of lower limb venous insufficiency in morbidly obese patients.

Patients and methods:

The study group comprised 125 patients (109 women, 16 men). The median (range) age and body mass index were 35 (19–59) years and 42 (32–68) kg/m2 respectively. Eleven patients had clinical signs of varicose veins or had previously undergone varicose vein surgery. Patients were investigated with duplex ultrasound scanning on the day before surgery. Iliac, femoral, popliteal, and long and short saphenous veins in both legs were studied.

Results:

A total of 33 patients had abnormal reflux in the superficial veins (>0.5 s). In the deep veins 2 patients had valvular incompetence in the common femoral vein with reflux times of 2 and 0.7 s respectively. At reinvestigation 18 and 24 months after surgery the reflux times were normalised.

Conclusion:

In this study the incidence of deep venous incompetence in the lower limb in morbidly obese patients is low.

Cost consequences of preoperative duplex examination before varicose vein surgery: a randomized clinical trial

Objectives: To investigate the cost consequences of the addition of a duplex scan to the routine clinical examination prior to surgery for varicose veins (VV).

Methods: Cost data are based on a prospective study, which randomized 293 VV patients for surgery either with or without a preoperative duplex scan. Costs are collected during a two-year follow-up time and include direct costs for primary surgery and reoperation.

Results: The mean cost for the primary operation was SEK 12,827 (€1410) in the duplex group and SEK 9856 (€1083) in the control group ( P<0.001). A significant part of this increase was due to more extensive primary surgery. Costs for redo surgery decreased by SEK 1131 (€124) ( P = 0.011). The mean net cost increase because of duplex is estimated to be SEK 1840 (€202) ( P<0.003).

Conclusion: The savings in costs for redo surgery did not offset the costs for preoperative duplex examination before VV surgery during a two-year follow-up period.

Treatment of venous thromboembolism in cancer patients with dalteparin for up to 12 months: the DALTECAN Study

BACKGROUND

Treatment of venous thromboembolism (VTE) in patients with cancer has a high rate of recurrence and bleeding complications. Guidelines recommend low-molecular-weight heparin (LMWH) for at least 3-6 months and possibly indefinitely for patients with active malignancy. There are, however, few data supporting treatment with LMWH beyond 6 months. The primary aim of the DALTECAN study (NCT00942968) was to determine the safety of dalteparin between 6 and 12 months in cancer-associated VTE.

METHODS

Patients with active cancer and newly diagnosed VTE were enrolled in a prospective, multicenter study and received subcutaneous dalteparin for 12 months. The rates of bleeding and recurrent VTE were evaluated at months 1, 2-6 and 7-12.

FINDINGS

Of 334 patients enrolled, 185 and 109 completed 6 and 12 months of therapy; 49.1% had deep vein thrombosis (DVT); 38.9% had pulmonary embolism (PE); and 12.0% had both on presentation. The overall frequency of major bleeding was 10.2% (34/334). Major bleeding occurred in 3.6% (12/334) in the first month, and 1.1% (14/1237) and 0.7% (8/1086) per patient-month during months 2-6 and 7-12, respectively. Recurrent VTE occurred in 11.1% (37/334); the incidence rate was 5.7% (19/334) for month 1, 3.4% (10/296) during months 2-6, and 4.1% (8/194) during months 7-12. One hundred and sixteen patients died, four due to recurrent VTE and two due to bleeding.

CONCLUSION

Major bleeding was less frequent during dalteparin therapy beyond 6 months. The risk of developing major bleeding complications or VTE recurrence was greatest in the first month of therapy and lower over the subsequent 11 months.

Iatrogenic vascular injuries with lethal outcome

BACKGROUND

The aim was to study the nature of iatrogenic vascular injuries (IVIs) associated with postoperative death within 30 days.

METHODS

Patients who had undergone vascular surgery for IVIs and were reported prospectively to the Swedish national vascular registry during 1987-2008 were identified. They were cross-checked with the national population registry. Those who died within 30 days of surgery were studied regarding case records and death certificates.

RESULTS

A total of 56 patients with postoperative death within 30 days after IVI were identified. Among them, 52 case records were retrieved (93 %). In 24 cases the IVIs were caused by puncture during endovascular procedures (13 hemorrhage, 11 occlusive thrombosis), 11 by penetrating trauma during open surgery, 6 by occlusion after external compression, 6 by percutaneous accidental arterial puncture. Main symptoms were peripheral ischemia (19/52, 37 %), external bleeding (14, 27 %), and hypovolemic shock without external bleeding (10, 19 %). Main specialties involved were interventional radiology (n = 18), general surgery (n = 9), and interventional cardiology (n = 8). Overall, 22 (42 %) were avoidable, and only 13 (25 %) underwent autopsy. Within 2 weeks, 36 patients (69 %) were dead. Also, there was a higher proportion with uncertain correlation between IVI and death.

CONCLUSIONS

Interventional radiology, general surgery, and cardiology are the main specialities involved in IVIs with lethal outcome. Not all fatalities after IVI are attributable to the injury itself, but almost half of the injuries were considered avoidable.

Prevention and treatment of venous thromboembolism--International Consensus Statement

The aim of this document is to provide a clear and concise account of the evidence regarding efficacy or harm for various methods available to prevent and manage venous thromboembolism (VTE).

Vascular injuries caused by acupuncture. A systematic review

AIM

The aim of the study was to systematically review the literature on vascular injuries caused by acupuncture.

METHODS

This was a systematic literature search in Medline and PubMed.

RESULTS

Thirty-one cases were identified and the majority developed symptoms in direct connection with the acupuncture treatment. Three patients died, two from pericardial tamponade and one from an aortoduodenal fistula. There were seven more tamponades, eight pseudoaneurysms, two with ischemia, two with venous thrombosis, one with compartment syndrome and seven with bleeding (five in the central nervous system). The two patients with ischemia had remaining sequeleae. Information on follow-up was suboptimal with no information in fourteen patients.

CONCLUSION

Vascular injuries are rare, bleeding and pseudoaneurysm dominating. Follow-up is insufficient in the hitherto published papers.

Abdominal aortic aneurysm and new WHO criteria for screening

Does screening of abdominal aortic aneurysm (AAA) fulfil the recently revised the World Health Organization WHO criteria for screening? Contemporary data from the literature are used to analyze whether the ten recent WHO criteria can be used to motivate AAA screening. Although the prevalence of AAA seems to decrease, at least screening of 65-year old males saves lives and is cost-effective. Ultrasonographic screening for AAA in risk populations fulfils the new WHO criteria for screening.

Health Technology Assessment in Surgery

This review focuses on how surgical methods should be assessed from a health technology perspective. The use of randomized controlled trials, population based registries, systematic literature research and the recently published IDEAL method are briefly discussed.

Late follow-up of a randomized trial of routine duplex imaging before varicose vein surgery

Background

Routine preoperative duplex examination led to an improvement in results 2 years after surgery for primary varicose veins. The aim of the present study was to evaluate the impact of preoperative duplex imaging after 7 years, in relation to other risk factors for varicose vein recurrence.

Methods

Patients with primary varicose veins were randomized to operation with (group 1), or without (group 2) preoperative duplex imaging. The same patients were invited to attend follow-up with interview, clinical examination and duplex imaging. Quality of life (QoL) was measured with the Short Form 36 questionnaire.

Results

Some 293 patients (343 legs) were included initially; after 7 years 227 were interviewed, or their records reviewed: 114 in group 1 and 113 in group 2. One hundred and ninety-four legs (95 in group 1 and 99 in group 2) were examined clinically and with duplex imaging. Incompetence was seen at the saphenofemoral junction and/or saphenopopliteal junction in 14 per cent of legs in group 1 and 46 per cent in group 2 (P &lt; 0·001). QoL was similar in both groups. After a mean follow-up of 7 years (and including patients who underwent surgery after the review), 15 legs in group 1 needed reoperation and 38 in group 2 (P = 0·001).

Conclusion

Routine preoperative duplex imaging improved the results of surgery for primary varicose veins for at least 7 years. Registration number: NCT01195623 (http://www.clinicaltrials.gov).

A critical appraisal of bleeding events reported in venous thromboembolism prevention trials of patients undergoing hip and knee arthroplasty

BACKGROUND

Anticoagulants are effective for the prevention of venous thromboembolism (VTE) but cause bleeding. Interpretation of the risks and benefits of new anticoagulant regimens for VTE prevention is complicated by a lack of standardized definitions and reporting of bleeding. We reviewed the reporting of bleeding in randomized controlled trials of new anticoagulants compared with standard doses of enoxaparin in hip and knee arthroplasty, and examined the possible impact of differences in the definition of major bleeding on interpretation of the trial results.

METHODS

Electronic searches identified 16 phase III trials published between 2001 and 2010 involving 41,265 patients comparing one of five new anticoagulants with a common comparator, enoxaparin.

RESULTS

Major bleeding rates in patients treated with enoxaparin ranged from 0.1% to 3.1% in hip arthroplasty trials and from 0.2% to 1.4% in knee arthroplasty trials. In studies that excluded surgical-site bleeding from the definition, major bleeding rates were about 10-fold lower than in those which included surgical-site bleeding. Within the individual trials, the choice of bleeding definition and the methods of assessment of bleeding influenced the conclusions regarding the risk of bleeding with new anticoagulant regimens relative to enoxaparin. Eight of the 16 studies demonstrated a ≥ 40% relative risk differences in major bleeding between treatment groups but the difference was statistically significant in only two of these trials.

CONCLUSION

Randomized VTE prevention trials report markedly different rates of major bleeding despite similar patient populations and doses and durations of anticoagulant prophylaxis and were underpowered to detect modest differences in patient-important bleeding events. Standardization of bleeding definitions and reporting seems desirable.

Results of the randomized, placebo-controlled clopidogrel and acetylsalicylic acid in bypass surgery for peripheral arterial disease (CASPAR) trial

OBJECTIVE

Dual antiplatelet therapy with clopidogrel plus acetylsalicylic acid (ASA) is superior to ASA alone in patients with acute coronary syndromes and in those undergoing percutaneous coronary intervention. We sought to determine whether clopidogrel plus ASA conferred benefit on limb outcomes over ASA alone in patients undergoing below-knee bypass grafting.

METHODS

Patients undergoing unilateral, below-knee bypass graft for atherosclerotic peripheral arterial disease (PAD) were enrolled 2 to 4 days after surgery and were randomly assigned to clopidogrel 75 mg/day plus ASA 75 to 100 mg/day or placebo plus ASA 75 to 100 mg/day for 6 to 24 months. The primary efficacy endpoint was a composite of index-graft occlusion or revascularization, above-ankle amputation of the affected limb, or death. The primary safety endpoint was severe bleeding (Global Utilization of Streptokinase and Tissue plasminogen activator for Occluded coronary arteries [GUSTO] classification).

RESULTS

In the overall population, the primary endpoint occurred in 149 of 425 patients in the clopidogrel group vs 151 of 426 patients in the placebo (plus ASA) group (hazard ratio [HR], 0.98; 95% confidence interval [CI], 0.78-1.23). In a prespecified subgroup analysis, the primary endpoint was significantly reduced by clopidogrel in prosthetic graft patients (HR, 0.65; 95% CI, 0.45-0.95; P = .025) but not in venous graft patients (HR, 1.25; 95% CI, 0.94-1.67, not significant [NS]). A significant statistical interaction between treatment effect and graft type was observed (P(interaction) = .008). Although total bleeds were more frequent with clopidogrel, there was no significant difference between the rates of severe bleeding in the clopidogrel and placebo (plus ASA) groups (2.1% vs 1.2%).

CONCLUSION

The combination of clopidogrel plus ASA did not improve limb or systemic outcomes in the overall population of PAD patients requiring below-knee bypass grafting. Subgroup analysis suggests that clopidogrel plus ASA confers benefit in patients receiving prosthetic grafts without significantly increasing major bleeding risk.

Validation of the Simulator for Testing and Rating Endovascular SkillS (STRESS)-machine in a setting of competence testing

AIM

Endovascular skills are an integral part of modern-day vascular surgery. The STRESS machine has been developed to test these skills in vascular surgeons. This study aims to define an optimal pass/fail cutoff value for the STRESS test score.

METHODS

The STRESS machine consists of a dry glass model of the abdominal aorta and its tributaries with various stenotic lesions, elongations, and tortuosities. A camera and computer software are used to simulate plain fluoroscopy-mode. The test subjects are given two assignments after which two reviewers use a combination of the ICEPS and MRS to produce the final total score; 43 subjects were tested. According to previous endovascular experience, subjects were classified into four groups: novice-low (no experience, less than 11 performed procedures, less than 50 assisted procedures), novice-high (11-25 performed procedures, more than 50 assisted procedures), intermediate (1-10 performed and >11-25 assisted procedures, 11-25 performed and >1-10 assisted procedures or 25-50 performed procedures) and advanced (more than 50 performed procedures).

RESULTS

Test-score and noted experience showed a correlation of 0.794. All intermediate and advanced test subjects scored more than 50 points compared to 4 out of 15 novices.

CONCLUSION

We demonstrated that it is possible to determine an optimal cut-off value for competence testing with the STRESS machine.

Definition of major bleeding in clinical investigations of antihemostatic medicinal products in surgical patients

The definition of major bleeding varies between studies on surgical patients, particularly regarding the criteria for surgical wound-related bleeding. This diversity contributes to the difficulties in comparing data between trials. The Scientific and Standardization Committee (SSC), through its subcommittee on Control of Anticoagulation, of the International Society on Thrombosis and Haemostasis has previously published a recommendation for a harmonized definition of major bleeding in non-surgical studies. That definition has been adopted by the European Medicines Agency and is currently used in several non-surgical trials. A preliminary proposal for a parallel definition for surgical studies was presented at the 54(th) Annual Meeting of the SSC in Vienna, July 2008. Based on those discussions and further consultations with European and North American surgeons with experience from clinical trials a definition has been developed that should be applicable to all agents that interfere with hemostasis. The definition and the text that follows have been reviewed and approved by relevant co-chairs of the subcommittee and by the Executive Committee of the SSC. The intention is to seek approval of this definition from the regulatory authorities to enhance its incorporation into future clinical trial protocols.

Recommendations on biosimilar low-molecular-weight heparins

Based on the results of large clinical trials, several low-molecular-weight heparins (LMWHs) have been approved for prophylaxis and the treatment of venous and arterial thromboembolism. As a result of expiration or pending expiration of patent protection of the originator LMWHs, many generic or biosimilar LMWHs have been approved in some countries and more are likely to be approved elsewhere. Their greater availability may reduce the treatment costs. The Working Party on Requirements for Development of Biosimilar LMWHs of the Subcommittee on Control of Anticoagulation, Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis has reached a consensus on recommendations to ensure the quality of biosimilar LMWHs as compared with the originator LMWHs.

Introduction of new technology: the surgical point of view

Introduction of new non-pharmacological technology is challenging and the methodology for evaluating such technologies is much less standardized than when dealing with new pharmacological substances. It is, however, as important to use randomized design with blinded assessment and combine that with prospective population based registries to be able to analyze generalizability.

Juvenile diabetes mellitus--a risk factor for postoperative venous thromboembolism?

In a retrospective analysis of 125 patients and a prospective evaluation of 83 patients with terminal uremia undergoing kidney transplantation, juvenile diabetes mellitus was found to be a significant risk factor for the development of postoperative thromboembolism. We found a high frequency of objectively verified thromboembolism despite the relatively young age of the patients. Besides diabetes, no other clinical risk factor differed between patients with and without thrombosis.

Venous function five to eight years after clinically suspected deep venous thrombosis

One hundred and fifty-four patients, who had been subjected to phlebography 5-8 years previously because of clinical suspicion of deep venous thrombosis (DVT), were investigated to evaluate the frequency of deep venous insufficiency (DVI). The evaluation included clinical examination, registration of subjective complaints and objective measurements with plethysmography, venous pressure and Doppler ultrasound. DVT had been present in 75 legs. There were no statistically significant differences between legs with and without earlier DVT apart from more venous outflow obstruction in the former. DVI was as common after calf vein thrombosis as after more proximal DVT. DVI was more frequent in elderly patients and in patients with a history of previous DVI or DVT. The sufficiency of the popliteal vein seemed to be of great importance in the development of DVI. More than one third of legs without DVT had developed DVI at follow-up.

Coarctation of the abdominal aorta in elderly patients. Case report and review of the literature

Coarctation of the abdominal aorta as a congenital disease is infrequent, the diagnosis mostly being made at an early age because of renovascular hypertension. Patients who reach the age of 40 more often tend to have the problems located distally to the renal arteries. A 66-year-old female is described, who developed an aortic occlusion, renovascular hypertension and uremia. She was cured with a bifurcation graft and a patch angioplasty of a stenotic renal artery and nephrectomy of the contralateral kidney with an occluded artery without refilling. A literature survey is made of patients older than 40 years.

Low specificity of the 125I-fibrinogen uptake test for the diagnosis of deep vein thrombosis in patients with erysipelas of the leg

The 125I-fibrinogen test was evaluated as a diagnostic tool for deep vein thrombosis in patients with erysipelas. In the investigated group of 43 patients, several showed an increased uptake that could not be verified by subsequent phlebography. The false positive test may have been caused by the local inflammatory process. The 125I-fibrinogen test seems to be too unspecific to be used for diagnosing deep vein thrombosis in this patient group.