Vascular disease in the lower limb in type 1 diabetes

The Effect of Revascularization on Lower Limb Circulation Parameters in Symptomatic Peripheral Arterial Disease

Background: The prevalence of peripheral arterial disease and the number of revascularization procedures performed in symptomatic patients are steadily increasing. However, uncertainties remain regarding hemodynamic monitoring after revascularization and the prediction of clinical outcomes. This study aimed to investigate hemodynamic parameters with a focus on the microvasculature. Methods: This prospective, single-center study included 29 patients (15 with intermittent claudication [IC] and 14 with chronic limb-threatening ischemia [CLTI]). Before and after the revascularization procedure, in addition to the ankle-brachial index (ABI), microperfusion parameters, including microvascular blood flow, capillary oxygen saturation (SO2), and relative hemoglobin content (rHb), were assessed with lightguide spectrophotometry combined with laser Doppler flowmetry using an oxygen-to-see (O2C) device in the horizontal and elevated leg positions. Results: At baseline, SO2 in the elevated leg position was significantly lower in patients with CLTI than in those with IC (p = 0.0189), whereas the other microcirculatory parameters and ABI values were not significantly different. Patients with diabetes mellitus had a higher flow rate than those without in the horizontal leg position (p = 0.0162) but not in the elevated leg position. After successful revascularization, the flow increased immediately and significantly in both positions, whereas SO2, rHb, and the ABI did not. Conclusions: Elevated leg SO2 was significantly lower in CLTI than in clinically compensated peripheral arterial disease, whereas microvascular flow was a suitable surrogate parameter indicating successful revascularization. In studies using surgical or interventional revascularization procedures, noninvasive hemodynamic monitoring of the microcirculation at the foot level might be beneficial.

Trends in diabetes-related foot disease hospitalizations and amputations in Australia, 2010 to 2019

AIM

To determine trends in the incidence of hospitalizations and amputations for diabetes-related foot disease (DFD) in Australia.

METHODS

We included 70,766 people with type 1, and 1,087,706 with type 2 diabetes from the Australian diabetes registry from 2010 to 2019, linked to hospital admissions databases. Trends in age-adjusted incidence were summarized as annual percent changes (APC).

RESULTS

In people with type 1 diabetes, total DFD hospitalizations increased from 20.8 to 30.5 per 1,000 person-years between 2010 and 2019 (APC: 5.1% (95% CI: 3.5, 6.8)), including increases for ulceration (13.3% (2.9, 24.7)), osteomyelitis (5.6% (2.7, 8.7)), peripheral arterial disease (7.7% (3.7, 11.9)), and neuropathy (8.7% (5.5, 12.0)). In people with type 2 diabetes, DFD hospitalizations changed from 18.6 to 24.8 per 1,000 person-years between 2010 and 2019 (APC: 4.5% (3.6, 5.4); 2012-2019), including increases for ulceration (8.7% (4.0, 13.7)), cellulitis (5.4% (3.7, 7.0)), osteomyelitis (6.7% (5.7, 7.7)), and neuropathy (6.9% (5.2, 8.5)). Amputations were stable in type 1, whereas in type 2, above knee amputations decreased (-6.0% (-9.1, -2.7). Adjustment for diabetes duration attenuated the magnitude of most increases, but many remained significant.

CONCLUSIONS

DFD hospitalizations increased markedly in Australia, mainly driven by ulceration and neuropathy, highlighting the importance of managing DFD to prevent hospitalizations.

A Tryptophan Metabolite of the Microbiota Improves Neovascularization in Diabetic Limb Ischemia

Diabetes mellitus (DM) is accompanied by a series of macrovascular and microvascular injuries. Critical limb ischemia is the most severe manifestation of peripheral artery disease (PAD) caused by DM and is almost incurable. Therapeutic modulation of angiogenesis holds promise for the prevention of limb ischemia in diabetic patients with PAD. However, no small-molecule drugs are capable of promoting diabetic angiogenesis. An endogenous tryptophan metabolite, indole-3-aldehyde (3-IAld), has been found to have proangiogenic activity in endothelial cells. Nevertheless, the role of 3-IAld in diabetic angiogenesis remains unknown. Here, we found that 3-IAld ameliorated high glucose-induced mitochondrial dysfunction, decreasing oxidative stress and apoptosis and thus improving neovascularization.

Risk Factors of Peripheral Vascular Disease in Diabetes Mellitus in Abbottabad, Pakistan: A Cross-Sectional Study

Introduction

Diabetes mellitus (DM) is a significant and common risk factor for the development of peripheral vascular disease (PVD). Peripheral vascular disease is the atherosclerotic narrowing of peripheral arteries and has a high prevalence among patients with diabetes.

Material and methods

A cross-sectional study was conducted in the Department of Medicine of Ayub Teaching Hospital, Abbottabad. A total of 271 diagnosed diabetic patients aged 40 years or above were included in the study. Ankle-brachial pressure index (ABPI) was measured using a hand-held Doppler device and sphygmomanometer. An ABPI < 0.9 was taken to be abnormal. The risk factors were noted through history taking, physical examination, and appropriate investigations. 

Results

Our study sample included 271 patients. A hundred and forty-five (53.5%) of them were males, and 126 (46.5%) were females. Fifty-three (19.9%) out of 271 patients had peripheral vascular disease. The prevalence of peripheral vascular disease was stratified among smoking (p=0.00), hypertension (p=0.00), obesity (p=0.004), and hypercholesterolemia (p=0.005) to determine if there was any association between these and peripheral vascular disease. A p-value less than 0.05 was taken to be significant.

Conclusion

This study showed a significant association between PVD and smoking, hypertension, hypercholesterolemia, and obesity.

Popliteal Entrapment Syndrome as a Cause of Chronic Lower Extremity Pain in a 16-Year Old

Popliteal entrapment syndrome is an uncommon cause of intermittent claudication in young patients lacking atherosclerotic risk factors. ZS is a 16-year-old cisgender female with type 1 diabetes complicated by microalbuminuria, obesity (body mass index (BMI) = 45.86 kg/m²), and a history of perinatal stroke with residual right-sided hemiparesis, who presented with six months of worsening bilateral, exertional lower extremity pain. Common causes of chronic bilateral lower extremity pain include peripheral vascular disease and diabetic neuropathy. Less common etiologies include trauma, infection, or juvenile idiopathic arthritis. Given her risk factors, the patient's pain was initially managed as a diabetic neuropathy with pregabalin. Symptoms failed to improve, and she re-presented with positional coolness of the right lower extremity, diminished pulses of the bilateral lower extremities, and weakness in her toes. CT angiography demonstrated occlusion of the right distal superficial femoral and popliteal arteries and diffused tibial disease. Ultimately, the patient was discovered to have right-sided femoral-popliteal occlusion, and she required urgent femoral-tibial bypass. Despite an initial improvement in symptoms postoperatively, she continued to have lower extremity pain and recurrent arterial thrombi, even with antiplatelet and anticoagulation therapy. Eventually, the patient required a right-sided below the knee amputation. This case highlights the high index of suspicion that clinicians must have in young patients with lower extremity pain, both with and without atherosclerotic risk factors, as early intervention facilitates better outcomes. Introduction.

Cutaneous and muscular afferents from the foot and sensory fusion processing: Physiology and pathology in neuropathies

The foot-sole cutaneous receptors (section 2), their function in stance control (sway minimisation, exploratory role) (2.1), and the modulation of their effects by gait pattern and intended behaviour (2.2) are reviewed. Experimental manipulations (anaesthesia, temperature) (2.3 and 2.4) have shown that information from foot sole has widespread influence on balance. Foot-sole stimulation (2.5) appears to be a promising approach for rehabilitation. Proprioceptive information (3) has a pre-eminent role in balance and gait. Reflex responses to balance perturbations are produced by both leg and foot muscle stretch (3.1) and show complex interactions with skin input at both spinal and supra-spinal levels (3.2), where sensory feedback is modulated by posture, locomotion and vision. Other muscles, notably of neck and trunk, contribute to kinaesthesia and sense of orientation in space (3.3). The effects of age-related decline of afferent input are variable under different foot-contact and visual conditions (3.4). Muscle force diminishes with age and sarcopenia, affecting intrinsic foot muscles relaying relevant feedback (3.5). In neuropathy (4), reduction in cutaneous sensation accompanies the diminished density of viable receptors (4.1). Loss of foot-sole input goes along with large-fibre dysfunction in intrinsic foot muscles. Diabetic patients have an elevated risk of falling, and vision and vestibular compensation strategies may be inadequate (4.2). From Charcot-Marie-Tooth 1A disease (4.3) we have become aware of the role of spindle group II fibres and of the anatomical feet conditions in balance control. Lastly (5) we touch on the effects of nerve stimulation onto cortical and spinal excitability, which may participate in plasticity processes, and on exercise interventions to reduce the impact of neuropathy.

Deep learning-based classification of lower extremity arterial stenosis in computed tomography angiography

PURPOSE

The purpose of this study is to develop and evaluate a deep learning model to assist radiologists in classifying lower extremity arteries based on the degree of arterial stenosis caused by plaque in lower extremity computed tomography angiography (CTA) of patients with peripheral artery disease.

METHODS

In this retrospective study, 265 patients who underwent lower-extremity CTA between January 1, 2016 and October 31, 2019 were selected. A total of 17050 axial images of iliac, femoropopliteal and infrapopliteal artery from these patients were used for the training and validation of the parallel efficient network (p-EffNet), a kind of supervised convolutional neural network, to classify the lower-extremity artery segments according to the degree of stenosis with digital subtraction angiography as reference standard. The classification results of the p-EffNet were then compared with those obtained from radiologists. Receiver operating characteristic curve (ROC) was used to evaluate the performance of the p-EffNet and accuracy, specificity, sensitivity and area under the curve (AUC) were used as measure metrics to compare the performance of the p-EffNet and that of radiologists.

RESULTS

The p-EffNet exhibited a good performance of 91.5 % accuracy, 0.987 AUC and 90.2 % sensitivity and 97.7 % specificity in classifying above-knee artery and 90.9 % accuracy, 0.981 AUC, 91.3 % sensitivity and 95.2 % specificity in classifying below-knee artery. When compared with human readers, for both above-knee and below-knee artery, the p-EffNet had comparable accuracy (p = 0.266 and p = 0.808, respectively) and specificity (p = 0.118 and p = 0.971, respectively) but lower sensitivity (p < 0.001 and p = 0.022, respectively).

CONCLUSIONS

The p-EffNet demonstrates promising diagnostic performance and has the potential to reduce the workload of radiologists and help to find the plaques that might otherwise have been missed or misjudged.

Influence of Changes in Sedentary Time on Outcomes of Supervised Exercise Therapy in Individuals with Comorbid Peripheral Artery Disease and Type 2 Diabetes

BACKGROUND

Although supervised exercise therapy (SET) is effective in improving walking distance among adults with symptomatic peripheral artery disease (PAD), some research suggests that individuals with comorbid PAD and type 2 diabetes mellitus (T2DM) may experience a blunted response to SET. It is unknown whether free-living sedentary time changes during SET, and if increases in sedentary time could, in part, explain poor response to SET. The purposes of this pilot study were to (1) determine if older adults with PAD (with and without T2DM) engaging in SET change their sedentary behavior and (2) examine the relationship between changes in sedentary behavior and SET outcomes. We hypothesized that decreased sedentary time during SET would be associated with greater improvements in six-minute walk test (6MWT) total distance and other key SET outcomes.

METHODS

Participants (n = 44) initiating a 12-week SET program completed the 6MWT, Short Physical Performance Battery, Walking Impairment Questionnaire, and accelerometer-assessed sedentary behavior at SET initiation, 6 weeks, and 12 weeks.

RESULTS

Participants' mean age was 72.3 (7.1) years, mean ankle-brachial index was 0.71 (0.25), and 47.7% were female. On average, sedentary time did not change after SET, although there was substantial variability (-40% to +38% change in minutes of sedentary time/day). Participants with T2DM experienced greater improvements in claudication onset distance than participants without T2DM (mean = 35 m, P = 0.044, 95% confidence interval = 1.6 to 115.4 m). Neither changes in sedentary time from baseline to 6 weeks (P = 0.419) nor T2DM (P = 0.154) predicted changes in 6MWT total distance from baseline to 12 weeks.

CONCLUSIONS

As SET availability increases, further examination of factors that may influence SET outcomes will help maximize benefits of this proven therapy.

Introduction to ion channels and calcium signaling in the microcirculation

The microcirculation is the network of feed arteries, arterioles, capillaries and venules that supply and drain blood from every tissue and organ in the body. It is here that exchange of heat, oxygen, carbon dioxide, nutrients, hormones, water, cytokines, and immune cells takes place; essential functions necessary to maintenance of homeostasis throughout the life span. This chapter will outline the structure and function of each microvascular segment highlighting the critical roles played by ion channels in the microcirculation. Feed arteries upstream from the true microcirculation and arterioles within the microcirculation contribute to systemic vascular resistance and blood pressure control. They also control total blood flow to the downstream microcirculation with arterioles being responsible for distribution of blood flow within a tissue or organ dependent on the metabolic needs of the tissue. Terminal arterioles control blood flow and blood pressure to capillary units, the primary site of diffusional exchange between blood and tissues due to their large surface area. Venules collect blood from capillaries and are important sites for fluid exchange and immune cell trafficking. Ion channels in microvascular smooth muscle cells, endothelial cells and pericytes importantly contribute to all of these functions through generation of intracellular Ca²⁺ and membrane potential signals in these cells.