Natural history of stenosis in the iliac arteries in patients with intermittent claudication undergoing clinical treatment

Study of blood flow patterns in a stenosed artery through the combined effect of body acceleration and generalized womersley solution

Stenosis causes the narrowing of arteries due to plaque buildup, which impedes blood flow and affects flow dynamics. This work numerically analyzes flow fluctuations in stenosed arteries under realistic physiological conditions (resting and exercise) and external body acceleration. The artery is inclined at angle Θ , and blood rheology is modeled using a generalized power-law fluid. A modified two-dimensional SIMPLE pressure-correction-based numerical solver with orthogonal coordinate transformation simulates blood flow. A generalized Womersley solution is imposed at the inlet. We validate the solver and perform simulations to assess the influence of geometric and flow parameters, analyzing time-averaged and phase-averaged data. We investigate the correlation between hyperviscosity and physiological conditions, finding that exercise increases recirculation downstream of the stenosis. We also study the impact of transitioning between resting and exercise conditions, noting that the transition rate correlates with stenosis development, indicating potential complications.

The Impact of Diabetes in Intermittent Claudication: A Prospective Cohort Study

The aim of this study was to determine the lower-limb outcome in patients with intermittent claudication (IC) and to identify predictors for deterioration. This study employed a prospective observational cohort single-centre design. One hundred fifty patients with IC attending a vascular surgery unit for the first time were recruited. Lower limb perfusion was assessed utilising ankle brachial index (ABI) measures, toe-brachial index (TBI) measures, Doppler waveform analysis and the walking impairment questionnaire. Follow-up was conducted after 1 year and 2 years following recruitment to assess haemodynamic parameters, symptom severity and outcome. Recruited participants had a mean age of 69.7 (±9.3) years, BMI 27.8(±4.2) and 79.3% were men. Significant haemodynamic decline (decline in ABPI by ≥0.15 and/or decline in TBPI by ≥0.1) occurred in 50.6% of the cohort within 2 years of whom 23.3% developed chronic limb threatening ischaemia (CLTI) with rest pain and/or tissue loss. Baseline ABPI, ABPI ≤ 0.5, TBPI ≤ 0.39, infrapopliteal artery (IPA) disease and high Haemoglobin A1c were identified as significant predictors for deterioration to CLI. (P < .05, binomial logistic regression). Patients with IC are at a high risk of developing CLTI within 2 years. Risk of lower limb adverse events is tripled in patients with IPA disease, low ankle and toe pressures and poorly controlled diabetes. Early identification of those at high risk for early deterioration may justify a paradigm shift in the management of this subgroup.

Effect of stenosis shape on the sound emitted from a constricted blood vessel

Effect of stenosis shape on the post-stenotic pressure fluctuations and the sound emitted from a constricted blood vessel is studied numerically. Large eddy simulations are performed using OpenFOAM under pulsatile flow conditions with a non-Newtonian fluid model. Findings indicate that the high slope at the stenosis entrance and overlap of more than one stenosis shorten the length of the flow jet, trigger turbulence, and increase vortical activity, turbulent kinetic energy, and magnitude of pressure fluctuations at the post-stenotic region. Also, these morphological parameters strengthen the audible signal especially in the systolic phase of the pulsatile flow. On the other hand, asymmetry of the stenosis creates an opposite effect. Based on the wall pressure data, it is shown that the stenosis shape affects the intensity and the pattern of the murmurs generated. Stenosis shape is found to be an essential factor for the acoustic-based non-invasive diagnosis of stenosis. Graphical abstract Wall pressure content of the elliptic stenosis shape.

Carbon dioxide contrast medium for endovascular treatment of ilio-femoral occlusive disease

OBJECTIVES

Compare the use of carbon dioxide contrast medium with iodine contrast medium for the endovascular treatment of ilio-femoral occlusive disease in patients without contraindications to iodine.

MATERIALS AND METHODS

From August 2012 to August 2014, 21 consecutive patients with ilio-femoral occlusive disease who were eligible for endovascular treatment and lacked contraindications to either iodine contrast or carbon dioxide were randomized into the carbon dioxide or iodine groups and subjected to ilio-femoral angioplasty.We analyzed the feasibility of the procedures, the surgical and clinical outcomes, the procedure lengths, the endovascular material costs, the contrast costs and the quality of the angiographic images in each group.

RESULTS

No conversions to open surgery and no contrast media related complications were noted in either group. A post-operative femoral pulse was present in 88.9% of the iodine group and 80% of the carbon dioxide group. No differences in procedure length, endovascular material cost or renal function variation were noted between the groups. Four patients in the carbon dioxide group required iodine supplementation to complete the procedure. Contrast media expenses were reduced in the carbon dioxide group. Regarding angiographic image quality, 82% of the carbon dioxide images were graded as either good or fair by observers.

CONCLUSIONS

The use of carbon dioxide contrast medium is a good option for ilio-femoral angioplasty in patients without contraindications to iodine and is not characterized by differences in endovascular material costs, procedure duration and surgical outcomes. In addition, carbon dioxide has lower contrast expenses compared with iodine.

External aggression to the limb as a predictive factor in the evolution of patients undergoing arterial revascularization

PURPOSE

A variety of predictive factors for the evolution of arterial grafts in patients with critical ischemia have been well defined in clinical studies, including diabetes mellitus, dialytic renal insufficiency, smoking, and distal arterial runoff. The goal of this study was to determine whether patients with critical ischemia undergoing arterial reconstruction in which ischemic lesions appeared spontaneously, compared to those in which the ischemic lesion appeared following an external aggression to the limb present different patterns of evolution.

METHODS

From February 2002 to January 2004, 100 patients undergoing infra-inguinal arterial reconstruction were followed. They were divided into 2 groups: 1) the spontaneous group (n = 52), comprising individuals presenting with ischemic lesions of spontaneous origin and 2) the external aggression to the limb group (n = 48), comprising individuals for which an external causal mechanism for the appearance of the ischemic lesion was identified. The variables analyzed were limb salvage and graft functioning rates.

RESULTS

Patients with spontaneous lesions had rates of limb salvage and graft functioning significantly lower than those for patients with lesions that were secondary to external aggression (42.3% versus 87.5%, respectively for both outcomes; P <.001).

CONCLUSIONS

The absence of an external aggression as a contributing factor to a critical ischemic lesion in the lower limb may result in a poorer evolution of both graft function and limb salvage following arterial revascularization. However, this factor is not expected to directly influence the case conduct, since almost half of the patients without evident external aggression had good graft functioning and limb salvage. This prognostic factor should be used just as all others are, i.e., to give patients and doctors a better idea of the possible evolution in such cases.