Large artery biomechanics and diastolic dysfunctionin patients with Type 2 diabetes

Inflammatory, Metabolic, and Coagulation Effects on Medial Arterial Calcification in Patients with Peripheral Arterial Disease

Calcium deposits in the vessel wall in the form of hydroxyapatite can accumulate in the intimal layer, as in atherosclerotic plaque, but also in the medial layer, as in medial arterial calcification (MAC) or medial Möenckeberg sclerosis. Once considered a passive, degenerative process, MAC has recently been shown to be an active process with a complex but tightly regulated pathophysiology. Atherosclerosis and MAC represent distinct clinical entities that correlate in different ways with conventional cardiovascular risk factors. As both entities coexist in the vast majority of patients, it is difficult to estimate the relative contribution of specific risk factors to their development. MAC is strongly associated with age, diabetes mellitus, and chronic kidney disease. Given the complexity of MAC pathophysiology, it is expected that a variety of different factors and signaling pathways may be involved in the development and progression of the disease. In this article, we focus on metabolic factors, primarily hyperphosphatemia and hyperglycemia, and a wide range of possible mechanisms by which they might contribute to the development and progression of MAC. In addition, we provide insight into possible mechanisms by which inflammatory and coagulation factors are involved in vascular calcification processes. A better understanding of the complexity of MAC and the mechanisms involved in its development is essential for the development of potential preventive and therapeutic strategies.

Medial artery calcification in peripheral artery disease

Medial artery calcification (MAC) is a distinct, highly regulated process that is often identified in small and mid-sized arteries of the lower extremities. It is associated with advanced age, diabetes, and chronic kidney disease. MAC often occurs in conjunction with atherosclerotic occlusive disease in lower extremity arteries, and when seen together or in isolation, long-term limb outcomes are negatively affected. In patients with peripheral artery disease (PAD), the extent of MAC independently correlates with major amputation and mortality rates, and it predicts poor outcomes after endovascular interventions. It is associated with increased arterial stiffness and decreased pedal perfusion. New endovascular methods aimed at treating calcified lower-extremity lesions may improve our ability to treat patients with limb-threatening ischemia. Although recent developments have increased our understanding of the mechanisms contributing to MAC, further investigations are needed to understand the role of medial calcification in PAD, and to develop strategies aimed at improving patient outcomes.

AMPK: Potential Therapeutic Target for Vascular Calcification

Vascular calcification (VC) is an urgent worldwide health issue with no available medical treatment. It is an active cell-driven process by osteogenic differentiation of vascular cells with complex mechanisms. The AMP-activated protein kinase (AMPK) serves as the master sensor of cellular energy status. Accumulating evidence reveals the vital role of AMPK in VC progression. AMPK is involved in VC in various ways, including inhibiting runt-related transcription factor 2 signaling pathways, triggering autophagy, attenuating endoplasmic reticulum stress and dynamic-related protein 1-mediated mitochondrial fission, and activating endothelial nitric oxide synthase. AMPK activators, like metformin, are associated with reduced calcification deposits in certain groups of patients, indicating that AMPK is a potential therapeutic target for VC.

Increased Arterial Stiffness Is Associated With Reduced Diastolic Function in Youth With Obesity and Type 2 Diabetes

Background: Increased arterial stiffness is associated with diastolic dysfunction in adults. Data in youth are lacking, so we examined the impact of arterial stiffness on diastolic function in youth. Methods: We obtained diastolic function and augmentation index, pulse wave velocity, brachial artery distensibility, and carotid stiffness on 612 youth [10-24 years, 65% female, 38% normal weight, 36% obese, and 26% with type 2 diabetes mellitus (T2DM)]. Participants were classified as compliant (C) vs. stiff (S) arteries based on seven arterial stiffness parameters [Global Stiffness Index (GSI), S = GSI > 4). Mean differences in covariates were evaluated by Student's t-tests. A stepwise regression analysis was performed to determine if GSI was an independent predictor of diastolic function. Results: Lower diastolic function and more adverse cardiovascular disease (CVD) risk factors were present in the S group (n = 67) than the C group (n = 545) (p < 0.001). Covariates that were associated with diastolic dysfunction were higher GSI, male sex, higher body mass index (BMI), and systolic blood pressure (SBP) z-score (R ² = 0.18 to 0.25; p ≤ 0.05). Conclusion: Adverse diastolic function is seen in youth with increased arterial stiffness independent of CVD risk factors. Interventions to improve arterial stiffness prior to clinical onset of diastolic dysfunction are needed to prevent development of heart failure.

Management of Atherosclerotic Cardiovascular Disease Risk Factors in the Older Adult Patient With Diabetes

: Older adults with diabetes are at higher risk for atherosclerotic cardiovascular disease (ASCVD) than younger adults with diabetes and older adults without diabetes. The rationale to implement ASCVD risk-lowering therapies in older adults with diabetes is compelling. Recommendations for lifestyle modification, lipid-lowering therapy, blood pressure management, blood glucose control, and aspirin therapy are often based on studies that show their efficacy in younger populations. However, the risks associated with each of these interventions increase with age, and favorable risk-to-benefit ratios demonstrated in younger adults with diabetes are less certain in older populations. The variability in health status among older adults is pertinent. Those with robust health are more likely to tolerate and derive benefit from many therapies when compared with those who have more complex health including frailty. Age- and/or frailty-stratified data to help clarify these relationships are sparse. In this Perspective, current recommendations for modifying ASCVD risk are described with a review of the pertinent literature that guides their application in older adults. A pragmatic approach to the treatment of ASCVD risk factors in older adults with diabetes is presented.

Medial vascular calcification revisited: review and perspectives

Vascular calcifications (VCs) are actively regulated biological processes associated with crystallization of hydroxyapatite in the extracellular matrix and in cells of the media (VCm) or intima (VCi) of the arterial wall. Both patterns of VC often coincide and occur in patients with type II diabetes, chronic kidney disease, and other less frequent disorders; VCs are also typical in senile degeneration. In this article, we review the current state of knowledge about the pathology, molecular biology, and nosology of VCm, expand on potential mechanisms responsible for poor prognosis, and expose some of the directions for future research in this area.

The vascular smooth muscle cell: a therapeutic target in Type 2 diabetes?

The rising epidemic of T2DM (Type 2 diabetes mellitus) worldwide is of significant concern. The inherently silent nature of the disease in its early stages precludes early detection; hence cardiovascular disease is often established by the time diabetes is diagnosed. This increased cardiovascular risk leads to significant morbidity and mortality in these individuals. Progressive development of complications as a result of previous exposure to metabolic disturbances appears to leave a long-lasting impression on cells of the vasculature that is not easily reversed and is termed 'metabolic memory'. SMCs (smooth muscle cells) of blood vessel walls, through their inherent ability to switch between a contractile quiescent phenotype and an active secretory state, maintain vascular homoeostasis in health and development. This plasticity also confers SMCs with the essential capacity to adapt and remodel in pathological states. Emerging clinical and experimental studies propose that SMCs in diabetes may be functionally impaired and thus contribute to the increased incidence of macrovascular complications. Although this idea has general support, the underlying molecular mechanisms are currently unknown and hence are the subject of intense research. The aim of the present review is to explore and evaluate the current literature relating to the problem of vascular disease in T2DM and to discuss the critical role of SMCs in vascular remodelling. Possibilities for therapeutic strategies specifically at the level of T2DM SMCs, including recent novel advances in the areas of microRNAs and epigenetics, will be evaluated. Since restoring glucose control in diabetic patients has limited effect in ameliorating their cardiovascular risk, discovering alternative strategies that restrict or reverse disease progression is vital. Current research in this area will be discussed.

Brachial-ankle pulse wave velocity is the only index of arterial stiffness that correlates with a mitral valve indices of diastolic dysfunction, but no index correlates with left atrial size

The objective of this study was to determine the optimal assessment of arterial stiffness that relates to diastolic dysfunction. Forty-one patients had measurements of brachial-ankle pulse wave velocity (baPWV), carotid-femoral pulse wave velocity (cfPWV), ankle brachial index (ABI), pulse pressure (PP), and augmentation index (AIx). Diastolic dysfunction was evaluated by echocardiographic indices of the ratio of the peak early diastolic mitral valve velocity and the peak late diastolic velocity (E/A ratio), left atrial diameter, and left atrial volume indexes. There was a significant (P < 0.05) correlation between baPWV and E/A ratio with an inverse relationship indicating that higher arterial stiffness was associated with greater diastolic dysfunction. In contrast, there was no significant correlation between E/A ratio and cfPWV, PP, ABI, or AIx. After multivariate analysis, the relationship between baPWV and E/A ratio remained significant (P < 0.05), independent of age and systolic blood pressure (BP). There were no correlations between any index of vascular stiffness and left atrial dimension or volume. In summary, baPWV correlates with diastolic dysfunction, independent of a patient's age and BP and is a better indicator of diastolic dysfunction than other indicators of arterial stiffness. baPWV has the utility of infering the presence of left ventricular diastolic dysfunction.

Mitigation of diabetes-related complications in implanted collagen and elastin scaffolds using matrix-binding polyphenol

There is a major need for scaffold-based tissue engineered vascular grafts and heart valves with long-term patency and durability to be used in diabetic cardiovascular patients. We hypothesized that diabetes, by virtue of glycoxidation reactions, can directly crosslink implanted scaffolds, drastically altering their properties. In order to investigate the fate of tissue engineered scaffolds in diabetic conditions, we prepared valvular collagen scaffolds and arterial elastin scaffolds by decellularization and implanted them subdermally in diabetic rats. Both types of scaffolds exhibited significant levels of advanced glycation end products (AGEs), chemical crosslinking and stiffening -alterations which are not favorable for cardiovascular tissue engineering. Pre-implantation treatment of collagen and elastin scaffolds with penta-galloyl glucose (PGG), an antioxidant and matrix-binding polyphenol, chemically stabilized the scaffolds, reduced their enzymatic degradation, and protected them from diabetes-related complications by reduction of scaffold-bound AGE levels. PGG-treated scaffolds resisted diabetes-induced crosslinking and stiffening, were protected from calcification, and exhibited controlled remodeling in vivo, thereby supporting future use of diabetes-resistant scaffolds for cardiovascular tissue engineering in patients with diabetes.

Diastolic dysfunction in asymptomatic type 2 diabetes mellitus with normal systolic function

BACKGROUND

The incidence of heart failure in diabetic subjects is high even in the absence of hypertension and coronary artery disease.

AIMS

The purpose of this study was to study the incidence of diastolic dysfunction in diabetic subjects and its relation to age, duration of diabetes mellitus (DM), Glycosylated hemoglobin (HbA1c) levels, obesity indices and diabetic microangiopathies.

SETTINGS AND DESIGN

This was a case control prospective study conducted at the teaching hospital during a one year period.

MATERIALS AND METHODS

A total of 127 subjects (case) with type 2 diabetes of more than five years duration were studied. Total 100 healthy subjects were included as the control group. Echocardiography was performed to assess left ventricular diastolic function.

RESULTS

Out of the total 127 subjects, 69 (54.33%) from the case group had diastolic dysfunction, and 11% amongst 100 in the control group population showed the diastolic dysfunction (P < 0.001). Patients with a longer duration of DM (of 11 to 15 years) had a higher prevalence of diastolic dysfunction (P < 0.02). Subjects with high waist circumference and high waist to hip ratio had statistically significant diastolic dysfunction with 'P' =0.001 and 'P' = < 0.02 respectively. Subjects with HbA1c > 7.5% had a higher prevalence of diastolic dysfunction than subjects with HbA1c < 7.5% (P < 0.02). Diastolic dysfunction was present in majority of the subjects with autonomic neuropathy and retinopathy.

CONCLUSIONS

Present study reveals high incidence of diastolic dysfunction in asymptomatic diabetic; subjects and, this finding was correlated with the duration of diabetes, HbA1c levels, obesity indices and diabetic microangiopathies. We conclude that early diagnosis and institution of treatment will reduce morbidity and improve the outcomes, and prevent future heart failure.