Multifocal arterial disease: clinical implications and management.

PURPOSE OF REVIEW: Vascular disease often affects more than one territory. Atherosclerosis is a global disease affecting multiple organs/systems. Cardiovascular risk factors are associated with an increased risk for the development of arterial disease in all vascular beds but differ in their individual impacts for each vascular bed. We discuss the various options to identify and manage multifocal arterial disease. RECENT FINDINGS: Coronary artery disease may coexist with carotid artery stenosis, abdominal aortic aneurysms, and/or peripheral artery disease (PAD). Atherosclerotic renal artery stenosis and renal function impairment may complicate PAD. Recent studies have confirmed that patients with multivascular bed disease have higher risk than patients with monovascular disease. In addition to the specific surgical/endovascular therapeutic options available, aggressive medical treatment and vascular disease prevention strategies should be rigorously implemented to best manage the overall atherosclerotic burden. SUMMARY: A holistic approach is essential to reduce the cardiovascular morbidity and mortality rates of vascular patients. Preventive measures should complement surgical/endovascular procedures so as to improve outcomes.

Safety of urgent endarterectomy in acute non-disabling stroke patients with symptomatic carotid artery stenosis: an international multicenter study.

BACKGROUND AND PURPOSE: International recommendations advocate that carotid endarterectomy (CEA) should be performed within 2 weeks from the index event in symptomatic carotid artery stenosis (sCAS) patients. However, there are controversial data regarding the safety of CEA performed during the first 2 days of ictus. The aim of this international, multicenter study was to prospectively evaluate the safety of urgent (0-2 days) in comparison to early (3-14 days) CEA in patients with sCAS. METHODS: Consecutive patients with non-disabling (modified Rankin Scale scores ≤2) acute ischaemic stroke or transient ischaemic attack due to sCAS (≥70%) underwent urgent or early CEA at five tertiary-care stroke centers during a 6-year period. The primary outcome events included stroke, myocardial infarction or death during the 30-day follow-up period. RESULTS: A total of 311 patients with sCAS underwent urgent (n = 63) or early (n = 248) CEA. The two groups did not differ in baseline characteristics with the exception of crescendo transient ischaemic attacks (21% in urgent vs. 7% in early CEA; P = 0.001). The 30-day rates of stroke did not differ (P = 0.333) between patients with urgent (7.9%; 95% confidence interval 3.1%-17.7%) and early (4.4%; 95% confidence interval 2.4%-7.9%) CEA. The mortality and myocardial infarction rates were similar between the two groups. The median length of hospitalization was shorter in urgent CEA [6 days (interquartile range 4-6) vs. 10 days (interquartile range 7-14); P < 0.001]. CONCLUSIONS: Our findings highlight that urgent CEA performed within 2 days from the index event is related to a non-significant increase in the risk of peri-procedural stroke. The safety of urgent CEA requires further evaluation in larger datasets.

Cranial Nerve Injury After Carotid Endarterectomy: Incidence, Risk Factors, and Time Trends.

OBJECTIVE/BACKGROUND: To review the incidence of post-carotid endarterectomy (CEA) cranial nerve injury (CNI), and to evaluate the risk factors associated with increased CNI risk. METHODS: The study was a meta-analysis. Pooled rates with 95% confidence intervals (CIs) were calculated for CNIs after primary CEA. Odds ratios (ORs) were calculated for potential risk factors. A fixed-effects model or a random effects model (Mantel-Haenszel method) was used for non-heterogeneous and heterogeneous data, respectively. Meta-regression analysis was performed to examine the influence of publication year upon CNI rate. RESULTS: Twenty-six articles, published between 1970 and 2015, were included in the meta-analysis, corresponding to 20,860 CEAs. Meta-analysis revealed that the vagus nerve was the most frequently injured cranial nerve (pooled injury rate 3.99%, 95% CI 2.56-5.70), followed by the hypoglossal nerve (3.79%, 95% CI 2.73-4.99). Fewer than one seventh of these injuries are permanent (vagus nerve: 0.57% [95% CI 0.19-1.10]; hypoglossal nerve: 0.15% [95% CI 0.01-0.39]). A statistically significant influence of publication year on the vagus and hypoglossal nerve injury rate was found, with the injury rate having decreased from about 8% to 2% and 1%, respectively, over the last 35 years. Urgent procedures (OR 1.59, 95% CI 1.21-2.10; p = .001), as well as return to the operating room for a neurological event or bleeding (OR 2.21, 95% CI 1.35-3.61; p = .002) were associated with an increased risk of CNI, whereas no statistically significant association was found between CNIs and the type of anaesthesia, the use of a patch, redo operation, and the use of a shunt. CONCLUSION: The vagus nerve appears to be the most frequently injured cranial nerve after CEA, followed by the hypoglossal nerve, with only a small proportion of these injuries being permanent. The CNI rate has significantly decreased over the past 35 years to a point indicating that CNIs should not be considered a major influencing factor in the decision making process between CEA and stenting.

A Review of Open and Endovascular Treatment of Superior Vena Cava Syndrome of Benign Aetiology.

BACKGROUND: The widespread use of central venous catheters, ports, pacemakers, and defibrillators has increased the incidence of benign superior vena cava syndrome (SVCS). This study aimed at reviewing the results of open and endovascular treatment of SVCS. METHOD: Medical literature databases were searched for relevant studies. Studies with more than five adult patients, reporting separate results for the SVC were included. Nine studies reported the results of endovascular treatment of SVCS including 136 patients followed up for a mean of 11-48 months. Causes of SVCS were central venous catheters and pacemakers (80.6%), mediastinal fibrosis (13.7%), and other (5.6%). Percutaneous transluminal angioplasty (PTA) and stenting was performed in 73.6%, PTA only in 17.3%, and thrombolysis, PTA, and stenting in 9%. Four studies reported the results of open repair of SVCS including 87 patients followed up between 30 months and 10.9 years. The causes were mediastinal fibrosis (58.4%), catheters and pacemakers (28.5%), and other (13%). Operations performed included a spiral saphenous interposition graft, other vein graft, PTFE graft, and human allograft. Thirteen patients required re-operations (15%) before discharge mainly for graft thrombosis. RESULTS: In the endovascular group technical success was 95.6%. Thirty day mortality was 0%. Regression of symptoms was reported in 97.3%. Thirty-two patients (26.9%) underwent 58 secondary procedures. In the open group the 30 day mortality was 0%. Symptom regression was reported in 93.5%. Twenty-four patients (28.4%) underwent a total of 33 secondary procedures. CONCLUSIONS: Endovascular is the first line treatment for SVCS caused by intravenous devices, whereas surgery is most often performed for mediastinal fibrosis. Both treatments show good results regarding regression of the symptoms and mid-term primary patency, with a significant incidence of secondary interventions.

Haemodynamic Performance of Low Strength Below Knee Graduated Elastic Compression Stockings in Health, Venous Disease, and Lymphoedema.

OBJECTIVE: To test the in vivo haemodynamic performance of graduated elastic compression (GEC) stockings using air-plethysmography (APG) in healthy volunteers (controls) and patients with varicose veins (VVs), post-thrombotic syndrome (PTS), or lymphoedema. Responsiveness data were used to determine which group benefited the most from GEC. METHODS: There were 12 patients per group compared using no compression, knee-length Class 1 (18-21 mmHg) compression, and Class 2 (23-32 mmHg) compression. Stocking/leg interface pressures (mmHg) were measured supine in two places using an air-sensor transducer. Stocking performance parameters, investigated before and after GEC, included the standard APG tests (working venous volume [wVV], venous filling index [VFI], venous drainage index [VDI], ejection fraction [EF]) and the occlusion plethysmography tests (incremental pressure causing the maximal increase in calf volume [IPMIV], outflow fraction [OF]). Results were expressed as median and interquartile range. RESULTS: Significant graduated compression was achieved in all four groups with higher interface pressures at the ankle. Only the VVs patients had a significant reduction in their wVV (without: 133 [109-146] vs. class1: 93 [74-113] mL) and the VFI (without: 4.6 [3-7.1] vs. class1: 3.1 [1.9-5] mL/s), both at p <.05. The IPMIV improved significantly in all groups except in the PTS group (p <.05). The OF improved only in the controls (without: 43 [38-51] vs. class1: 50 [48-53] %) and the VVs patients (without: 47 [39-58] vs. class1: 56 [50-64] %), both at p <.05. There were no significant differences in the VDI or the EF with GEC. Compression dose-response relationships were not observed. CONCLUSION: Patients with varicose veins improved the most, whereas those with PTS improved the least. Performance seemed to depend more on disease pathophysiology than compression strength. However, the lack of responsiveness to compression strength may be related to the low external pressures used. Stocking performance tests may have value in selecting those patients who benefit most from compression.

Protamine Reduces Bleeding Complications without Increasing the Risk of Stroke after Carotid Endarterectomy: A Meta-analysis.

OBJECTIVES: The aim was to evaluate the safety and efficacy of heparin reversal with protamine after completion of carotid endarterectomy (CEA), summarising the available data from both randomised and non-randomised studies. METHODS: The study was a meta-analysis. Pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated for the outcomes of stroke and wound haematoma among patients receiving or not receiving protamine after CEA. Meta-regression analysis was performed to examine whether the documented differences were modified by potentially meaningful patient related or procedure related predictors, namely publication year, general anesthesia used, number of patients treated, mean age (years), males, neurological symptoms, use of patch, and use of shunt. RESULTS: Seven studies were included in the meta-analysis reporting on 3,817 patients receiving protamine after CEA and 6,070 patients not receiving protamine for heparin reversal. Only one study was randomised. A statistically significant reduction in wound haematoma requiring re-operation was recorded after heparin reversal with protamine in patients undergoing CEA (OR, 0.42, 95% CI, 0.22-0.80, p = .008). In contrast, no significant difference was observed in stroke rates between groups of patients that received and did not receive protamine (OR, 0.71, 95% CI, 0.49-1.03, p = .07). Meta-regression analysis did not reveal any significant effect mediated by the modifiers examined. CONCLUSION: On the basis of the available data, heparin reversal with protamine seems to reduce the risk of wound haematoma, without increasing the risk of procedural stroke. However, taking into account the limitations of the analysis, further studies are needed to increase the level of evidence provided by the current meta-analysis.

The May-Husni Procedure: A Reappraisal.

OBJECTIVES: The May-Husni procedure is a rarely used saphenofemoral venous bypass because of the small number of patients with post-thrombotic segmental femoral vein obstruction alone and the lack of validated selection criteria. There are only a few institutional series reporting the use of this technique. The purpose of this report is to present the author's experience and critically review the literature. METHODS: Within a 13 year period 12 patients with venous claudication, skin pigmentation, and severe pain and swelling of their legs underwent the May-Husni procedure. Their median age was 57 years (41-69 years). Imaging showed segmental venous obstruction of the femoral vein in all patients and poor or no inflow from the deep femoral vein. Two patients were lost to follow up and the remaining 10 patients were reviewed with a median follow up of 60 months (26-72 months). RESULTS: The saphenopopliteal bypass remained patent in all patients at follow up. The development of reflux of the saphenous conduit in four patients did not affect the clinical improvement. Venous claudication resolved, hyper-pigmentation improved, and pain was relieved in all patients. Recanalization of the femoral vein 3 years following thrombosis was followed by recurrence of the post-thrombotic symptoms in two patients. CONCLUSIONS: These results indicate that a highly selected subgroup of patients with severe symptomatic post-thrombotic syndrome secondary to chronic segmental obstruction of the femoral vein do well after the May-Husni procedure. In order to refine the criteria for the selection of patients who may benefit from this operation, there is a need for more studies that use a combination of hemodynamic and validated scales that diagnose and grade the severity of post-thrombotic syndrome.

Long-term Mortality in Patients with Asymptomatic Carotid Stenosis: Implications for Statin Therapy.

OBJECTIVE: Recent studies with asymptomatic carotid patients on best medical management have shown that the annual risk of stroke has decreased to approximately 1%. There is no evidence that a similar decrease in mortality has occurred. In addition, the intensity of statin therapy for these patients has not yet been determined. The aims of this review were to determine (a) the reported long-term all-cause and cardiac-related mortality in patients with asymptomatic carotid stenosis (ACS) > 50%, (b) whether there has been a decrease in mortality in recent years, (c) the available methods of mortality risk stratification, and (d) whether the latest ACC/AHA guidelines on the treatment of serum lipids can be applied to this group of patients. METHODS: Systematic review of PubMed, EuroPubMed, and Cochrane Library and meta-analysis using random effects for pooled proportions were performed regarding long-term all-cause and cardiac-related mortality and the associated risk factors in ACS patients. The last day for literature search was October 30, 2014. RESULTS: Seventeen studies were retrieved reporting 5-year all-cause mortality in 11,391 patients with ACS >50%. The 5-year cumulative all-cause mortality across all 17 studies was 23.6% (95% CI 20.50-26.80). Twelve additional studies, reporting both all-cause and cardiac mortality with a minimum of 2 year follow-up and involving 4,072 patients were identified. Of the 930 deaths reported, 589 (62.9%; 95% CI 58.81-66.89) were cardiac-related. This translates into an average cardiac-related mortality of 2.9% per year. CONCLUSIONS: All-cause and cardiac mortality in ACS patients are very high. Although risk stratification is possible, most patients are classified as high risk. In view of this high risk, aggressive statin therapy is indicated if the new ACC/AHA guidelines on serum lipids are to be adhered to.

Quantifying the degree graduated elastic compression stockings enhance venous emptying.

OBJECTIVES: Graduated elastic compression (GEC) stockings reduce reflux and venous volume but their performance on augmenting venous return is unproven. The aim of this study was to quantify the ability of stockings to increase venous outflow from the leg. DESIGN: A prospective study comparing venous emptying without compression, versus class 1 (18-21 mmHg) and class 2 (23-32 mmHg) compression, using air-plethysmography (APG). METHODS: The right legs of 20 healthy subjects were studied supine. A 12-cm thigh-cuff was inflated in 10 mmHg steps from 0 to 80 mmHg while the corresponding increase in calf volume was recorded using the APG sensor calf-cuff. At the 80 mmHg plateau, the thigh-cuff was released suddenly to measure the unrestricted venous emptying. Venous return was assessed by: (a) identifying the incremental thigh-cuff pressure causing the maximal incremental increase in calf volume (IPMIV); (b) measuring the percentage reduction in calf volume in 1 second following thigh-cuff release - outflow fraction (OF); (c) time to empty 90% of the venous volume - venous emptying time (VET90). RESULTS: Median and inter-quartile range (IQR) baseline values of IPMIV, OF, and VET90 without compression were 20 mmHg (range: 20-30 mmHg), 44% (39-50%) and 13 seconds (8.8-15.9 seconds), respectively. These improved significantly with all stockings. The application of any stocking raised the median IPMIV by 30 mmHg. The change from a class 2 stocking compared with no stocking versus the change from a class 1 stocking to no stocking had a more pronounced effect (p < .005). After sudden thigh-cuff deflation, the venous emptying was 41-45% greater and 9-10 seconds faster with all stockings (p < .005). CONCLUSIONS: This is the first study to quantify the venous return of below-knee GEC stockings. Assessments of stockings in augmenting venous return may be of use as a way of optimising compression for individual patients unresponsive to standard conservative treatment.

Validation of a new duplex derived haemodynamic effectiveness score, the saphenous treatment score, in quantifying varicose vein treatments.

OBJECTIVES: To evaluate a duplex-derived score for varicose vein treatments using numerical values of haemodynamic effectiveness. DESIGN: The saphenous treatment score (STS) was developed prospectively to compare the effect of endovenous treatments on reflux within saphenous segments. PATIENTS: Sixty-six patients were randomised to endovenous laser ablation (EVLA) or ultrasound-guided foam sclerotherapy (UGFS) to the great saphenous vein (GSV). METHODS: Assessments included the Aberdeen varicose vein severity score (AVVSS), the venous clinical severity score (VCSS), the venous filling index (VFI) and the STS. RESULTS: A mean STS of 5.70 decreased to 3.30, P < .0005, post-treatment. The median (IQR) AVVSS, VCSS and VFI (ml/sec) decreased from 21.52(15.48) to 18.86(11.27), P = .14, from 6(4) to 3(4), P < .0005 and from 7.1(6.9) to 1.9(.9) P < .0005, respectively. In 15 patients requiring additional UGFS the mean STS values decreased from 5.8 to 4.13 and then to 2.6 P < .0005, respectively. The individual above and below knee mean treatment differences in STS on 38 EVLA and 28 UGFS patients were 1.92 and .87 (EVLA) compared to 1.57 and .29 (UGFS) P = .001, respectively. CONCLUSIONS: The STS has been shown to grade the haemodynamic effects of different treatments as well as ongoing treatments on the GSV.

Availability of supervised exercise programs and the role of structured home-based exercise in peripheral arterial disease.

OBJECTIVES: The effectiveness of supervised exercise programs (SEPs) for the management of peripheral arterial disease (PAD) can be hampered by low accessibility and poor compliance. The current international availability and use of SEPs was evaluated and the evidence on alternative approaches such as structured, home-based exercise programs (HEPs) was reviewed. METHODS-MATERIALS: International survey on SEP availability among vascular surgeons using an online questionnaire. A systematic review on structured-HEPs effectiveness was also performed. RESULTS: A total of 378 responses were collected from 43 countries, with the majority (95%) from Europe. Only 30.4% of the participants had access to SEPs and within this group there was significant heterogeneity on the way SEPs were implemented. This systematic review identified 12 studies on the effectiveness of HEPs. In 3 studies SEPs were superior to HEPs in improving functional capacity or equivalent in improving quality of life (QoL). HEPs significantly improved most of the functional capacity and QoL markers when compared to the "go home and walk" advice and baseline measurements. CONCLUSIONS: SEPs remain an underutilized tool despite recommendations. Structured HEPs may be effective and can be useful alternatives when SEPs are not available. Further research is warranted to establish cost-effectiveness.

Cost and effectiveness of laser with phlebectomies compared with foam sclerotherapy in superficial venous insufficiency. Early results of a randomised controlled trial.

OBJECTIVES: Quantify endovenous laser ablation (EVLA) with concurrent phlebectomies and ultrasound-guided foam sclerotherapy (UGFS) in cost and effectiveness at 3 weeks and 3 months. DESIGN: Single-centre, prospective, randomised controlled trial. PATIENTS: One hundred patients (100 legs), C(2-6), age 21-78, M:F 42:58, with primary varicose veins received either EVLA under local anaesthetic or UGFS. METHODS: Assessments included duplex, Aberdeen varicose vein questionnaire (AVVQ), venous clinical severity score (VCSS), venous filling index (VFI), visual analogue 7-day pain score and analgesia requirements. Additional treatments with UGFS were performed, if required. Micro-costing, using individually timed treatments, was based on consumables, staff pay and overheads. RESULTS: Changes in AVVQ, VCSS and VFI values (3 months) did not demonstrate any significant difference between groups. At 3 months, the above-knee GSV occlusion rate (without co-existing reflux) was not significantly different between the groups (74% vs 69%; EVLA vs UGFS; P = .596). Of the 9 haemodynamic failures in each group, 7 EVLA patients and 4 UGFS patients had co-existing cross-sectional above-knee GSV occlusion at some point. However, UGFS significantly outperformed EVLA in cost, treatment duration, pain, analgesia requirements and recovery. CONCLUSIONS: UGFS is 3.15 times less expensive than EVLA (£230.24 vs £724.72) with comparable effectiveness but 56% (versus 6%) required additional foam (ISRCTN:03080206).

The efficacy of a new stimulation technology to increase venous flow and prevent venous stasis.

OBJECTIVES: Electrical stimulation of calf muscles has been shown to be effective in prevention of DVT. The aim was to determine: (a) dependence of venous blood velocity and ejected volume on the rates of stimulated calf contractions: (b) clinical factors affecting efficacy in healthy individuals. METHODS: The maximum intensity stimulus tolerated was applied to calves of 24 volunteers. In popliteal veins, peak systolic velocities (PSV), ejected volume per individual stimulus (stroke volume SV) and ejected total volume flow per minute (TVF) of expelled blood were determined using ultrasound. Stimulation rates from 2 to 120 beats per minute (bpm) were applied. RESULTS: Mean baseline popliteal PSV was 10 cm/s. For stimulation rates between 2 and 8 bpm, the PSV was 10 times higher and reached 96-105 cm/s. Stroke volume (SV) per individual stimulus decreased in a similar fashion. With increasing rates of stimulation the TVF increased by a factor of 12 times (from 20 ml/min to 240 ml/min). CONCLUSION: Electrical stimulation is an effective method of activating the calf muscle pump. Enhancements of popliteal blood velocity and volume flow are key factors in the prevention of venous stasis and DVT. Further studies are justified to determine the stimulation rates in those with a compromised venous system.

Combined intermittent pneumatic leg compression and pharmacological prophylaxis for prevention of venous thrombo-embolism in high-risk patients.

BACKGROUND: It has been suggested that combined modalities (methods of treatment) are more effective than single modalities in preventing venous thrombo-embolism (defined as deep vein thrombosis and pulmonary embolism, or both) in high-risk patients. OBJECTIVES: To assess the efficacy of intermittent pneumatic leg compression combined with pharmacological prophylaxis versus single modalities in preventing venous thrombo-embolism in high-risk patients. SEARCH STRATEGY: The Cochrane Peripheral Vascular Diseases (PVD) Group searched the reference lists of their Specialised Register (last searched 17 July 2007) and the Cochrane Central Register of Controlled Trials (CENTRAL) (last searched The Cochrane Library 2008, issue 3) for relevant articles to identify additional trials. SELECTION CRITERIA: Randomised controlled trials (RCTs) or controlled clinical trials (CCTs) of combined intermittent pneumatic leg compression and pharmacological interventions used to prevent venous thrombo-embolism in high-risk patients. DATA COLLECTION AND ANALYSIS: Data extraction was undertaken independently by two review authors using data extraction sheets.

Comparison of three intermittent pneumatic compression systems in patients with varicose veins: a hemodynamic study.

AIM: Previous studies have demonstrated the hemodynamic impact of sequential leg compression, compared to uniform compression. The aim of this study was to compare the hemodynamic effectiveness of three compression devices: 1) circumferential sequential gradient compression (CSG); 2) a posterior uniform compression device (PU) and a posterior sequential rapid gradient inflation device (PSR). DESIGN OF THE STUDY: open, controlled trial. Thigh length sleeves were tested in 12 patients with primary bilateral varicose veins. INTERVENTIONS: the three devices were tested in the semirecumbent position. MAIN OUTCOME MEASURES: augmented flow velocity and volume flow, including the total and peak volume of blood expelled per hour during compression, were measured using duplex scanning. Refilling time was determined from velocity recordings of the common femoral vein. All values were expressed as median and interquartile range with P values obtained using the Mann-Whitney U-test. RESULTS: Compared to the median baseline flow, all three devices increased flow during compression by 2.5-3 times (P<0.0001). The cycles per hour for the three devices CSG, PSR and PU were 78 (70-88), 60 and 60, respectively; the duplex effective compression time was 11, 12 and 6 s, respectively; single cycle volume expelled during compression was 105, 85 and 45 mL (P<0.005), respectively; the total volume expelled per hour was 7 800, 5 200 (P<0.028) and 3 300 (P<0.005) mL/hr, respectively; peak velocity increased (P<0.001) from baseline of 12 cm/s to 38 cm/s for the CSG, 33 cm/s for the PU and to 68 cm/s for the PSR. CONCLUSION: The highest volume expelled per hour during compression was observed with the CSG and the lowest with the PSR. This was due to increased volume per cycle and more compression cycles over time, because of the CSG device's sensing of refill time. Although the peak velocity with the PSR was high, it was associated with reduced expelled volume, because of its short compression period. The PU occupied an intermediate position. The relative effectiveness of the three devices in deep vein thrombosis prevention should be tested in future studies.

Comparison of two intermittent pneumatic compression systems. A hemodynamic study.

AIM: Sequential leg compression has been previously shown to be superior to uniform compression. The aim of our study was to compare the hemodynamic effectiveness of the portable sequential compression device (SCD Express Compression System, Tyco Healthcare Group LP, Mansfield, MA, USA) with a rapid inflation device (VenaFlow, Aircast, Inc, Summit, NJ, USA). The former, by sensing venous refill time, commences compression when the calf veins are refilled. METHODS: The two devices were tested in 12 normal volunteers in the semirecumbent position using duplex ultrasound. Baseline and augmented flow velocity and volume flow were measured at the level of the common femoral vein, above the saphenofemoral junction. Refilling time was determined from velocity recordings of the common femoral vein. Total and peak volume of blood expelled per hour during compression were calculated using flow data and the individual cycling rate. RESULTS: Both devices increased venous flow velocity, up to 3.8 times the baseline (all P<0.001). Refill time of the rapid inflation device was shorter in comparison with the sequential compression device (15+/-2.2 vs 25+/-4 s; P<0.001), suggesting incomplete vein evacuation. The sequential compression device, by augmenting flow throughout a significantly longer compression period per cycle (10.9 s vs 6.3 s), expelled significantly more venous blood (121+/-68 vs 81+/-63 mL; P<0.001). Similarly, the total volume of blood expelled per hour with the sequential compression device was 100% higher than the rapid inflation device (9685+/-5426 vs 4853+/-3658 mL; P<0.001). Although peak velocity enhancement was higher with the rapid inflation device, flow augmentation (a product of average blood flow velocity) was comparable (669+/-367 vs 771+/-574 cm/s; P=0.223) with the sequential compression device, mainly because the rapid inflation device failed to maintain flow enhancement beyond the initial flow surge. CONCLUSIONS: Sequential compression showed hemodynamic superiority compared to a rapid inflation device. This was enhanced further by the sensing of refill time, which resulted in more compression cycles over time. The relative efficacy of the two devices in deep vein thrombosis prevention should be tested in future studies.

Factors associated with mortality in patients with asymptomatic carotid stenosis: results from the ACSRS Study.

AIM: This study determines the factors associated with mortality in patients with asymptomatic carotid stenosis. METHODS: Patients (n=1,101) with asymptomatic internal carotid artery stenosis greater than 50% in relation to the bulb diameter were followed up for a period of 6 to 84 (median 38) months. Stenosis was graded using duplex scanning and expressed as a percentage of the carotid bulb diameter. Clinical and biochemical risk factors were recorded. The end-points were ipsilateral ischemic stroke, cardiovascular death and all cause mortality. RESULTS: In a Cox multivariate analysis 6 factors emerged as independent predictors of risk. Age, male gender, cardiac failure, left ventricular hypertrophy on electrocardiogram (ECG) and myocardial ischemia on ECG were associated with increased risk. Antiplatelet therapy was associated with decreased risk. Based on these risk factors a high-risk group consisting of one third of the population with a 40% cumulative cardiovascular death rate and a 66% all cause death rate at 7 years could be identified. The remaining 2/3 consisted of a low-risk group with a 10% cumulative cardiovascular death rate and a 21% all cause death rate at 7 years (P<0.0001 compared to the high risk group). There was not any significant difference in the cumulative ipsilateral stroke rate, which was 12% in the low and 13% in the high cardiovascular risk group (Log Rank P>0.05). CONCLUSIONS: The methodology and findings from the ACSRS natural history study need to be applied to randomized controlled trials on the value of carotid endarterectomy or stenting in patients with asymptomatic carotid stenosis. They may help refine the indications for intervention in patients with carotid endarterectomy.