Upper arm venous compliance and fitness in stable coronary artery disease patients and healthy controls

Assessment of Phasic Changes of Vascular Size by Automated Edge Tracking-State of the Art and Clinical Perspectives

Assessment of vascular size and of its phasic changes by ultrasound is important for the management of many clinical conditions. For example, a dilated and stiff inferior vena cava reflects increased intravascular volume and identifies patients with heart failure at greater risk of an early death. However, lack of standardization and sub-optimal intra- and inter- operator reproducibility limit the use of these techniques. To overcome these limitations, we developed two image-processing algorithms that quantify phasic vascular deformation by tracking wall movements, either in long or in short axis. Prospective studies will verify the clinical applicability and utility of these methods in different settings, vessels and medical conditions.

Assessment of Upper Extremity Venous Compliance in Patients With Abdominal Aortic Aneurysms

OBJECTIVE

Abdominal aortic aneurysm (AAA) is associated with morphological and functional changes in both aneurysmal and non-aneurysmal arteries. However, it remains uncertain whether similar changes also exist in the venous vasculature. The aim of this study was to evaluate global venous function in patients with AAA and controls.

METHODS

This experimental study comprised 31 men with AAA (mean ± standard deviation age 70.0 ± 2.8 years) and 29 male controls (aged 70.6 ± 3.4 years). Venous occlusion plethysmography (VOP) was used to evaluate arm venous compliance at venous pressures between 10 and 60 mmHg in steps of 5 mmHg. Compensatory mobilisation of venous capacitance blood (capacitance response) was measured with a volumetric technique during experimental hypovolaemia induced by lower body negative pressure (LBNP).

RESULTS

The VOP induced pressure-volume curve was significantly less steep in patients with AAA (interaction, p < .001), indicating lower venous compliance. Accordingly, the corresponding pressure-compliance curves displayed reduced venous compliance at lower venous pressures in patients with AAA vs. controls (interaction, p < .001; AAA vs. control, p = .018). After adjusting for arterial hypertension, diabetes mellitus, hyperlipidaemia, chronic obstructive pulmonary disease, and smoking, VOP detected differences in venous compliance remained significant at low venous pressures, that is, at 10 mmHg (p = .008), 15 mmHg (p = .013), and 20 mmHg (p = .026). Mean venous compliance was negatively correlated with aortic diameter (r = -.332, p = .010). Mobilisation of venous capacitance response during LBNP was reduced by approximately 25% in patients with AAA (p = .030), and the redistribution of venous blood during LBNP was negatively correlated with aortic diameter (r = -.417, p = .007).

CONCLUSION

Men with AAA demonstrated reduced venous compliance and, as a result, a lesser capacity to mobilise peripheral venous blood to the central circulation during hypovolaemic stress. These findings imply that the AAA disease may be accompanied by functional changes in the venous vascular wall.

Compliance in the deep and superficial conduit veins of the nonexercising arm is unaffected by short-term exercise

The effects of short-term dynamic and static exercise on compliance (CPL) in a single conduit vein in the nonexercising limb are not fully understood, although prolonged cycling exercise was found to produce a significant reduction of CPL in the veins. In this study, we investigated the cross-sectional area (CSA) and CPL in the brachial (deep) and basilic (superficial) veins of the nonexercising arm in 14 participants who performed a 5-min cycling exercise at 35% and 70% of peak oxygen uptake (study 1) and in 11 participants who performed a 2-min static handgrip exercise at 30% of maximal voluntary contraction (study 2). The CSA in the deep and superficial veins at rest and during the final minute of exercise was measured by high-resolution ultrasonography during a short-duration cuff deflation protocol. The CPL in each vein was calculated as the numerical derivative of the cuff pressure and CSA curve. During short-term dynamic and static exercise, there was no change in CPL in either vein, but there was a decrease in CSA in both veins. The simultaneous findings of unchanged CPL and decreased CSA suggest that CPL during short-term exercise are independently controlled by the mechanisms responsible for exercise-induced sympathoexcitation in both single veins. Thus, short-term exercise does not alter CPL in both conduit superficial and deep veins in nonexercising upper arm.