Smoking, Haemostatic Factors and the Severity of Aorto-lliac and Femoro-Popliteal Disease

Synergistic Impact of Nicotine and Shear Stress Induces Cytoskeleton Collapse and Apoptosis in Endothelial Cells

Nicotine is the major component in cigarette smoke and has been recognized as a risk factor for various cardiovascular diseases such as atherosclerosis. However, the definite pathogenesis of nicotine-mediated endothelial dysfunction remains unclear because hemodynamic factor in most of prior in vitro studies was excluded. To understand how nicotine affects endothelium in the dynamic environment, human umbilical vein endothelial cells were treated by different laminar shear stresses (LSS; 0, 6, 8, and 12 dynes cm(-2)) with and without 10(-4) M nicotine for 12 h in a parallel plate flow system, following detections of cellular morphology and apoptotic level. Our results showed that cells sheared by 12 dynes cm(-2) LSS with nicotine excessively elongated and aligned with the flow direction, and exhibited significant apoptosis as compared to the groups with nicotine or LSS alone. We reasoned that the irregular morphological rearrangement and elevated apoptosis were resulted from the interruption of mechanostasis due to cytoskeletal collapse. Furthermore, all the impaired responses can be rescued by treatment with free radical scavenger ascorbic acid (10(-4) M), indicating oxidative stress was likely mediated with the impairments. In summary, our findings demonstrated an essential role of LSS in nicotine-mediated endothelial injury occurring in the physiological environment.

Management of Atherosclerotic Aortoiliac Occlusive Disease

Development of aortoiliac occlusive disease (AIOD) is associated with classic risk factors for atherosclerotic disease such as hyperlipidemia, hypertension, diabetes, or smoking. Risk factor modification, smoking cessation, and prevention of cardiovascular events remain the cornerstones of AIOD management. Symptom improvement and limb loss prevention are considered secondary goals of therapy. Continuous technological advances, new devices, as well as new revascularization techniques are constantly changing the landscape of AIOD management. Surgical interventions, which were considered a gold standard therapy for nearly 50 years, currently give way to newer and less invasive endovascular techniques.

Large and Small Vessels Atherosclerosis: Similarities and Differences

Atherosclerosis is a systemic, multifocal disease leading to a various symptoms and clinical events. Beyond disparities related to the organs involved, some differences might exist according to whether the lesions occur in the large (proximal) or small (distal) arteries. Atherosclerotic lesions occur predominantly in the large vessels first, and more distal lesions occur with aging. Proximal lesions are usually more evolving, especially with higher rates of unstable plaques in the proximal segments of coronary arteries. Racial differences regarding lesion distribution exist, with higher rates of distal lesions observed in races other than caucaians. Despite conflicting results found in each vascular territory, there is a suggestion of a stronger association between large vessel disease and smoking and dyslipidemia, whereas diabetes appears more specific for small vessel disease. Hypertension is more frequently reported in intracranial than in extracranial cerebrovascular disease. Preliminary studies report inflammatory markers preferably associated to large-vessel atherosclerosis. Proximal lesions in 1 territory are more frequently associated with concomitant lesions in other territories. Geometric, hemodynamic, and histologic particularities in large and small vessels may at least partially explain these differences, and some recent data point out different biologic properties of the endothelium according to its location.

Endothelial cell activation, injury, damage and dysfunction: separate entities or mutual terms?

The loss of well-regulated endothelial cell functioning is followed by adverse changes in a variety of physiological systems, such as the expression of adhesion molecules, maintenance of adequate blood vessel tone and haemostasis. Therefore, a full understanding of endothelial cell biology is essential if the losses of normal function of these systems are to be avoided. The viewpoint presented in this paper suggests that a spectrum between endothelial cell health and disease can be drawn: midway between these two extremes is immunological activation (by, for example, cytokines), which is reversible. Endothelial cell damage or injury (which may be the result of chronic inflammatory activation, hypercholesterolaemia, and/or smoking) are invariably associated with clinical conditions such as hypertension and oedema (and, ultimately, thrombosis and infarction), and are more difficult to reverse. A better understanding of the events, including apoptosis, that lead to vascular dysfunction may be useful in developing our understanding of vascular biology.

Smoking, hemorheologic factors, and progression of peripheral arterial disease in patients with claudication

PURPOSE

The purpose of the current study was to determine whether hemostatic and rheologic factors are associated with the deterioration of peripheral arterial disease in patients with intermittent claudication and the influence of smoking and severity of underlying disease on these relationships.

METHODS

We conducted a prospective cohort study with a 6-year follow-up period of a consecutive series of 607 patients with uncomplicated intermittent claudication. The study setting was the Peripheral Vascular Clinic, Royal Infirmary of Edinburgh. The main outcome measures were peripheral vascular intervention or onset of severe chronic leg ischemia (rest pain, ulceration, gangrene).

RESULTS

A total of 210 patients died during follow-up. Two hundred three patients did not have a vascular event or deterioration of limb ischemia, 45 patients underwent a peripheral vascular intervention, and 64 progressed to severe chronic leg ischemia. Median levels (interquartile ranges) of whole blood viscosity were significantly higher in the vascular intervention group (3.75 mPa/sec; range, 3.38 to 4.13 mPa/sec) than in those who did not deteriorate 3.48 mPa/sec; range, 3.06 to 3.83 mPa/sec) (p < or = 0.05), and plasma von Willebrand factor was higher in those with severe chronic leg ischemia (154.0 IU/dl; range, 122.0 to 187.0 IU/dl) than in those who did not deteriorate (131.0 IU/dl; range, 106.0 to 165.0 IU/dl) (p < or = 0.01). After adjustment for age, sex, cigarette smoking, and ankle brachial pressure index, the levels of plasma fibrinogen and blood and plasma viscosities were each associated with an increased risk of vascular intervention (all p < or = 0.05). There were no significant associations between any of the hemorheologic factors and the risk of severe chronic leg ischemia on multivariate analyses.

CONCLUSION

Elevations in rheologic factors may have important effects on further reduction of blood flow in the legs of patients with claudication and promote worsening ischemia and clinical progression of symptoms.

Haemostatic and rheological factors as predictors of restenosis following percutaneous transluminal angioplasty

OBJECTIVES

To determine whether pre-angioplasty levels of haemostatic and rheological factors predicted restenosis of the dilated arterial segment following percutaneous transluminal angioplasty.

DESIGN AND SETTING

Prospective study, Two regional hospital centres for angioplasty in Edinburgh and Glasgow, Scotland, UK.

METHOD

Haemostatic and rheological factors were measured in 102 subjects with atherosclerotic disease of the lower limbs, immediately prior to percutaneous transluminal angioplasty. Subjects were followed up after 2-3 years for restenosis of the original angioplasty site using duplex scanning.

RESULTS

Baseline clinical characteristics were similar between subjects who restenosed (n = 27) and those with no restenosis (n = 39), except that occluded lesions were more likely to restenose than stenoses (p < or = 0.05). There was no significant difference in age- and sex-adjusted mean levels of whole blood viscosity, plasma viscosity, haematocrit, von Willebrand factor, fibrin D-dimer or plasminogen activator inhibitor-1 activity between the stenosed and no restenosis groups (p > 0.1), but mean plasma fibrinogen was lower in the restenosed group (3.31 g/l vs. 3.75 g/l; p < or = 0.05). These results persisted after multivariate adjustment for smoking habit and type of lesion dilated.

CONCLUSIONS

This study provides no evidence that raised, pre-angioplasty levels of haemostatic and rheological factors predict restenosis following percutaneous transluminal angioplasty of the arteries of the lower limbs.