Joshua A. Beckman

Diabetes and Vascular Disease Pathophysiology, Clinical Consequences, and Medical Therapy: Part I

Diabetes mellitus affects approximately 100 million persons worldwide.1 Five to ten percent have type 1 (formerly known as insulin-dependent) and 90% to 95% have type 2 (non–insulin-dependent) diabetes mellitus. It is likely that the incidence of type 2 diabetes will rise as a consequence of lifestyle patterns contributing to obesity.2 Cardiovascular physicians are encountering many of these patients because vascular diseases are the principal causes of death and disability in people with diabetes. The macrovascular manifestations include atherosclerosis and medial calcification. The microvascular consequences, retinopathy and nephropathy, are major causes of blindness and end-stage renal failure. Physicians must be cognizant of the salient features of diabetic vascular disease in order to treat these patients most effectively. The present review will focus on the relationship of diabetes mellitus and atherosclerotic vascular disease, highlighting pathophysiology and molecular mechanisms (Part I) and clinical manifestations and management strategies (Part II). Abnormalities in endothelial and vascular smooth muscle cell function, as well as a propensity to thrombosis, contribute to atherosclerosis and its complications. Endothelial cells, because of their strategic anatomic position between the circulating blood and the vessel wall, regulate vascular function and structure. In normal endothelial cells, biologically active substances are synthesized and released to maintain vascular homeostasis, ensuring adequate blood flow and nutrient delivery while preventing thrombosis and leukocyte diapedesis.3 Among the important molecules synthesized by the endothelial cell is nitric oxide (NO), which is constitutively produced by endothelial NO synthase (eNOS) through a 5-electron oxidation of the guanidine-nitrogen terminal of l-arginine.4 The bioavailability of NO represents a key marker in vascular health. NO causes vasodilation by activating guanylyl cyclase on subjacent vascular smooth muscle cells.4 In addition, NO protects the blood vessel from endogenous injury—ie, atherosclerosis—by mediating molecular signals that prevent platelet and leukocyte interaction with …

ACC/AHA 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery: Executive summary - A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (writing committee to revise the 2002 guidelines on perioperative cardiovascular evaluation for noncardiac surgery)

WRITING COMMITTEE MEMBERS Lee A. Fleisher, MD, FACC, FAHA, Chair; Joshua A. Beckman, MD, FACC¶; Kenneth A. Brown, MD, FACC, FAHA†; Hugh Calkins, MD, FACC, FAHA‡; Elliot L. Chaikof, MD#; Kirsten E. Fleischmann, MD, MPH, FACC; William K. Freeman, MD, FACC*; James B. Froehlich, MD, MPH, FACC; Edward K. Kasper, MD, FACC; Judy R. Kersten, MD, FACC§; Barbara Riegel, DNSc, RN, FAHA; John F. Robb, MD, FACC

Advanced Glycation End Products Sparking the Development of Diabetic Vascular Injury

Advanced glycation end products (AGEs) are proteins or lipids that become glycated after exposure to sugars. AGEs are prevalent in the diabetic vasculature and contribute to the development of atherosclerosis. The presence and accumulation of AGEs in many different cell types affect extracellular and intracellular structure and function. AGEs contribute to a variety of microvascular and macrovascular complications through the formation of cross-links between molecules in the basement membrane of the extracellular matrix and by engaging the receptor for advanced glycation end products (RAGE). Activation of RAGE by AGEs causes upregulation of the transcription factor nuclear factor-kappaB and its target genes. Soluble AGEs activate monocytes, and AGEs in the basement membrane inhibit monocyte migration. AGE-bound RAGE increases endothelial permeability to macromolecules. AGEs block nitric oxide activity in the endothelium and cause the production of reactive oxygen species. Because of the emerging evidence about the adverse effects of AGEs on the vasculature of patients with diabetes, a number of different therapies to inhibit AGEs are under investigation.

2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for the diagnosis and management of patients with thoracic aortic disease: Executive summary: A report of the american college of cardiology foundation/american heart association task force on practice guidelines, american association for thoracic surgery, american college of radiology, american stroke association

2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM Guidelines for the Diagnosis and Management of Patients With Thoracic Aortic Disease A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, American Association for Thoracic Surgery, American College of Radiology, American Stroke Association, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, Society of Thoracic Surgeons, and Society for Vascular Medicine

2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM Guidelines for the Diagnosis and Management of Patients With Thoracic Aortic Disease

It is essential that the medical profession play a central role in critically evaluating the evidence related to drugs, devices, and procedures for the detection, management, or prevention of disease. Properly applied, rigorous, expert analysis of the available data documenting absolute and relative

2014 ACC/AHA Guideline on Perioperative Cardiovascular Evaluation and Management of Patients Undergoing Noncardiac Surgery A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines

Jeffrey L. Anderson, MD, FACC, FAHA, Chair Jonathan L. Halperin, MD, FACC, FAHA, Chair-Elect Nancy M. Albert, PhD, RN, FAHA Biykem Bozkurt, MD, PhD, FACC, FAHA Ralph G. Brindis, MD, MPH, MACC Lesley H. Curtis, PhD, FAHA David DeMets, PhD[¶¶][1] Lee A. Fleisher, MD, FACC, FAHA Samuel

2011 ACCF/AHA Focused Update of the Guideline for the Management of Patients With Peripheral Artery Disease (Updating the 2005 Guideline) A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines

Keeping pace with the stream of new data and evolving evidence on which guideline recommendations are based is an ongoing challenge to timely development of clinical practice guidelines. In an effort to respond promptly to new evidence, the American College of Cardiology Foundation/American Heart Association (ACCF/AHA) Task Force on Practice Guidelines (Task Force) has created a “focused update” process to revise the existing guideline recommendations that are affected by the evolving data or opinion. New evidence is reviewed in an ongoing fashion to more efficiently respond to important science and treatment trends that could have a major impact on patient outcomes and quality of care. Evidence is reviewed at least twice a year, and updates are initiated on an as-needed basis and completed as quickly as possible while maintaining the rigorous methodology that the ACCF and AHA have developed during their partnership of >20 years. These updated guideline recommendations reflect a consensus of expert opinion after a thorough review primarily of late-breaking clinical trials identified through a broad-based vetting process as being important to the relevant patient population, as well …

2011 ACCF/AHA focused update of the guideline for the management of patients with peripheral artery disease (Updating the 2005 Guideline)

Keeping pace with the stream of new data and evolving evidence on which guideline recommendations are based is an ongoing challenge to timely development of clinical practice guidelines. In an effort to respond promptly to new evidence, the American College of Cardiology Foundation/American Heart Association (ACCF/AHA) Task Force on Practice Guidelines (Task Force) has created a “focused update” process to revise the existing guideline recommendations that are affected by the evolving data or opinion. New evidence is reviewed in an ongoing fashion to more efficiently respond to important science and treatment trends that could have a major impact on patient outcomes and quality of care. Evidence is reviewed at least twice a year, and updates are initiated on an as-needed basis and completed as quickly as possible while maintaining the rigorous methodology that the ACCF and AHA have developed during their partnership of >20 years. These updated guideline recommendations reflect a consensus of expert opinion after a thorough review primarily of late-breaking clinical trials identified through a broad-based vetting process as being important to the relevant patient population, as well …

Diabetes and vascular disease: pathophysiology, clinical consequences, and medical therapy: part I

Hyperglycemia and insulin resistance are key players in the development of atherosclerosis and its complications. A large body of evidence suggest that metabolic abnormalities cause overproduction of reactive oxygen species (ROS). In turn, ROS, via endothelial dysfunction and inflammation, play a major role in precipitating diabetic vascular disease. A better understanding of ROS-generating pathways may provide the basis to develop novel therapeutic strategies against vascular complications in this setting. Part I of this review will focus on the most current advances in the pathophysiological mechanisms of vascular disease: (i) emerging role of endothelium in obesity-induced insulin resistance; (ii) hyperglycemia-dependent microRNAs deregulation and impairment of vascular repair capacities; (iii) alterations of coagulation, platelet reactivity, and microparticle release; (iv) epigenetic-driven transcription of ROS-generating and proinflammatory genes. Taken together these novel insights point to the development of mechanism-based therapeutic strategies as a promising option to prevent cardiovascular complications in diabetes.

ASCORBATE RESTORES ENDOTHELIUM-DEPENDENT VASODILATION IMPAIRED BY ACUTE HYPERGLYCEMIA IN HUMANS

BackgroundEndothelium-dependent vasodilation is impaired in patients with insulin-dependent and non-insulin-dependent diabetes mellitus and restored by vitamin C administration, implicating a causative role for oxidant stress. Hyperglycemia per se attenuates endothelium-dependent vasodilation in healthy subjects. Accordingly, this study investigated whether impaired endothelium-dependent vasodilation caused by hyperglycemia in nondiabetic humans is restored by administration of the antioxidant vitamin C. Methods and ResultsEndothelium-dependent vasodilation was measured by incremental brachial artery administration of methacholine chloride (0.3 to 10 &mgr;g/min) during euglycemia, after 6 hours of hyperglycemia (300 mg/dL) created by dextrose (50%) intra-arterial infusion, and with coadministration of vitamin C (24 mg/min) during hyperglycemia. Endothelium-dependent vasodilation was significantly diminished by hyperglycemia (P =0.02 by ANOVA) and restored by vitamin C (P =0.04). In contrast, endothelium-dependent vasodilation was not affected by equimolar infusions of mannitol, with and without vitamin C coinfusion (P =NS). Endothelium-independent vasodilation was measured by incremental infusion of verapamil chloride (10 to 300 &mgr;g/min) without and with coadministration of NG-monomethyl-l-arginine (L-NMMA). In the absence of L-NMMA, endothelium-independent vasodilation was not significantly altered during hyperglycemia (P =NS) but was augmented by vitamin C (P =0.04). The coadministration of L-NMMA eliminated the vitamin C-related augmentation in verapamil-mediated vasodilation. ConclusionsVitamin C administration restores endothelium-dependent vasodilation impaired by acute hyperglycemia in healthy humans in vivo. These findings suggest that hyperglycemia may contribute in part to impaired vascular function through production of superoxide anion.