Search

Introduction We evaluated the incidence of change in serial 12-lead electrocardiogram (ECG) diagnostic classifications in patients resuscitated from out-of-hospital (OH) cardiac arrest (OHCA) comparing OH to emergency department (ED) ECGs. Methods This retrospective case series included: 1) adults (≥ 18 years old), 2) resuscitated from OHCA, 3) ≥ 1 OH and 1 ED ECG/patient, and 4) emergency medical services (EMS) transport to the study hospital. OH and ED ECGs were classified as: 1) STEMI (ST-segment Elevation Myocardial Infarction), 2) Ischemic, and 3) Non-ischemic. Two ED physicians and one cardiologist independently classified all ECGs, then generated a consensus opinion classification for each ECG based on American Heart Association’s 2018 Expert Consensus criteria. The most ischemic OH ECG classification was compared with the last ED ECG classification. Results From 7/27/12 to 7/18/19, 176 patients were entered with a mean age of 61.2 ± 16.6 years; 102/176 (58%) were male. Overall, 504 OH and ED 12-lead ECGs were acquired (2.9 ECGs/patient). ECG classification inter-rater reliability kappa score was 0.63 ± 0.02 (substantial agreement). Overall, 86/176 (49%) changed ECG classification from the OH to ED setting; 69/86 (80%) of these ECGs changed from more to less ischemic classifications. Of 49 OH STEMI ECG classifications, 33/49 (67%) changed to a less ischemic (non-STEMI) ED ECG classification. Conclusions Change in 12-lead ECG classification from OH to ED setting in patients resuscitated from OHCA was common (49%). The OH STEMI classification changed to a less ischemic (non-STEMI) ED classification in 67% of cases.

Mitochondria contribute to key processes of cellular function, while mitochondrial dysfunction is implicated in metabolic disorders, neurodegenerative diseases, and cardiovascular diseases, in which angiogenesis - the formation of new blood capillaries - is dysregulated. The Hippo signaling transducer, Yes-associated protein (YAP1) binds to the TEA domain (TEAD1) transcription factor and controls angiogenesis. YAP1 also regulates glucose metabolism through peroxisome proliferator-activated receptor gamma co-activator 1-alpha (PGC1α), a major player controlling mitochondrial biogenesis. However, the role of YAP1-TEAD1-PGC1α signaling in mitochondrial structure, cellular metabolism, and angiogenesis in endothelial cells (ECs) remains unclear. We now find that knockdown of TEAD1 decreases the expression of PGC1α and suppresses mitochondrial biogenesis, glycolysis, and oxygen consumption in ECs. A YAP1 mutant construct, YAP1S127A, which stimulates binding of YAP1 to TEAD1, upregulates the expression of PGC1α, induces mitochondrial biogenesis, and increases oxygen consumption and glycolytic flux in ECs; in contrast, YAP1S94A, which fails to bind to TEAD1, attenuates these effects. PGC1α knockdown inhibits YAP1S127A-induced EC sprouting in vitro and vascular morphogenesis in the fibrin gel subcutaneously implanted on mice, while overexpression of PGC1α reverses vascular morphogenesis suppressed by YAP1S94A. These results suggest that YAP1-TEAD1 signaling induces mitochondrial biogenesis in ECs and stimulates angiogenesis through PGC1α. Modulation of YAP1-TEAD1-PGC1α signaling in ECs may provide a novel intervention for angiogenesis-related diseases.

The solitary pulmonary nodule (SPN) is frequently encountered on chest imaging and poses an important diagnostic challenge to clinicians. The differential diagnosis is broad, ranging from benign granulomata and infectious processes to malignancy. Important concepts in the evaluation of SPNs include the definition, morphologic characteristics via appropriate imaging modalities, and the calculation of pretest probability of malignancy. Morphologic differentiation of SPN into solid or subsolid types is important in the choice of follow-up and further management. In this first part of a two-part series, we describe the morphologic characteristics and various imaging modalities available to further characterize SPN. In Part 2, we will describe the determination of pretest probability of malignancy and an algorithmic approach to the diagnosis of SPN.

Atherosclerosis of conduit epicardial arteries is the principal culprit behind the complications of coronary heart disease, but a growing body of literature indicates that the coronary microcirculation also contributes substantially to the pathophysiology of cardiovascular disease. An understanding of mechanisms regulating microvascular function in humans is an essential foundation for understanding the role in disease, especially since these regulatory mechanisms vary substantially across species and vascular beds. In fact all subjects whose coronary tissue was used in the studies described have medical conditions that warrant cardiac surgery, thus relevance to the normal human must be inferential and is based on tissue from subjects without known arteriosclerotic disease. This review will focus on recent advances in the physiological and pathological mechanisms of coronary microcirculatory control, describing a robust plasticity in maintaining endothelial control over dilation, including mechanisms that are most relevant to the human heart. This article is part of a Special Issue entitled "Coronary Blood Flow".

The eighth iteration of the American College of Chest Physicians Antithrombotic Guidelines presented, in a paper version, a narrative evidence summary and rationale for the recommendations, a small number of evidence profiles summarizing bodies of evidence, and some articles with quite extensive summary tables of primary studies. In total, this represented 600 recommendations summarized in 968 pages of text. Many readers responded that the result was too voluminous for their liking or practical use. Cognizant of this feedback, we worked hard to minimize the length of the text for the ninth iteration of the guidelines Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (AT9) without sacrificing key content. A number of topic editors found our shortening edits draconian, but we were determined to produce the leanest product possible. There were, however, a number of obstacles. In what we believe is a key advance in AT9, we conducted a systematic review of what is known about patients’ values and preferences regarding antithrombotic therapy and included the results as an article in AT9. In another forward step, we recognized the problems with asymptomatic thrombosis as a surrogate outcome, and devised strategies to estimate reductions in symptomatic DVT and pulmonary embolism with antithrombotic prophylaxis. We felt it important to explain this innovation to users of AT9, and this meant another article. We included, for the first time, an article on diagnosis addressing patients with symptoms and signs suggesting DVT. We increased the range of interventions we have covered, resulting in additional recommendations. Finally, we produced many summary of findings tables, which offer extremely succinct and informative presentations of best estimates of effect and the confidence associated with those estimates. If published in the same fashion as the Antithrombotic and Thrombolytic Therapy, 8th ed: American College of Chest Physicians Antithrombotic Guidelines, this would have resulted in a document with > 850 pages of paper text, an unacceptable length. Given this and with the advice of the journal, we decided to adopt a highly focused print version that includes only this executive summary and the following articles: An introduction describing the major innovations in AT9 A methods article explaining how we developed the guidelines (a potential model for other guideline groups interested in optimal rigor) Recommendations and grading from each article embedded in the table of contents of each article Those seeking the rationale for the recommendations, including the supporting evidence, should access the online version of the guideline (http://http://chestjournal.chestpubs.org/content/141/2_suppl) that includes a narrative summaries and supporting summary of findings tables. The numbering indicated beside the recommendations in this summary is aligned with the sections and tables found in the full articles. Those interested in a deeper understanding of the evidence can turn to online data supplements for each of the articles that include recommendations. There, they will find evidence profiles (expanded versions of the summary of findings tables) and some tables summarizing the methods and results, and the risk of bias, associated with the individual studies that contributed to the evidence profiles and summary of findings tables. The world of medical information is rapidly becoming a world of electronic storage and presentation of primary studies, recommendations, and a wide variety of other information of interest to health care practitioners. Although our abbreviated paper copy presentation represents a necessary response to a challenging situation, it is also a harbinger of the increasingly electronic world of medical information into which future editions of guidelines are destined to move.

Background To develop the Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: ACCP Evidence-Based Clinical Practice Guidelines (AT9), the American College of Chest Physicians (ACCP) assembled a panel of clinical experts, information scientists, decision scientists, and systematic review and guideline methodologists. Methods Clinical areas were designated as articles, and a methodologist without important intellectual or financial conflicts of interest led a panel for each article. Only panel members without significant conflicts of interest participated in making recommendations. Panelists specified the population, intervention and alternative, and outcomes for each clinical question and defined criteria for eligible studies. Panelists and an independent evidence-based practice center executed systematic searches for relevant studies and evaluated the evidence, and where resources and evidence permitted, they created standardized tables that present the quality of the evidence and key results in a transparent fashion. Results One or more recommendations relate to each specific clinical question, and each recommendation is clearly linked to the underlying body of evidence. Judgments regarding the quality of evidence and strength of recommendations were based on approaches developed by the Grades of Recommendations, Assessment, Development, and Evaluation Working Group. Panel members constructed scenarios describing relevant health states and rated the disutility associated with these states based on an additional systematic review of evidence regarding patient values and preferences for antithrombotic therapy. These ratings guided value and preference decisions underlying the recommendations. Each topic panel identified questions in which resource allocation issues were particularly important and, for these issues, experts in economic analysis provided additional searches and guidance. Conclusions AT9 methodology reflects the current science of evidence-based clinical practice guideline development, with reliance on high-quality systematic reviews, a standardized process for quality assessment of individual studies and the body of evidence, an explicit process for translating the evidence into recommendations, disclosure of financial as well as intellectual conflicts of interest followed by management of disclosed conflicts, and extensive peer review.

The Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines differs substantially from the prior versions both in process and in content. In this introduction, we describe some of the differences and the rationale for the changes.

Epoxyeicosatrienoic acid(s) (EETs) have been shown to protect cardiovascular tissue against apoptosis dependent on activation of targets such as ATP-sensitive K+ (KATP) channels (sarcolemmal and mitochondrial), calcium-activated K+ channels, extracellular signal-regulated kinase or phosphoinositide 3-kinase (PI3K). We tested if EETs protect human atrial tissue ex vivo from hypoxia/reoxygenation (H/R) injury, and compared our results with myocardium from two rodent species, rats and mice. EETs reduced myocardial caspase 3 activity in all three species and protected against loss of mitochondrial membrane potential in primary cultures of neonatal rat ventricular myocytes submitted to H/R. In addition, EETs protected mouse pulmonary arteries ex vivo exposed to H/R. Myocardium and pulmonary arteries from genetically engineered mice having elevated plasma levels of EETs (Ephx2-/-) exhibited protection from H/R-induced injury over that of wild type controls, suggesting that endogenously produced EETs may have pro-survival effects. Electrophysiological studies in myocytes demonstrated that EETs can stimulate KATP currents even when PI3K is inhibited. Similarly, activation of PI3K/Akt occurred in the presence of the KATP channel blocker glibenclamide. Based upon loss of protection with EETs in the presence of either wortmannin (a PI3K inhibitor) or glibenclamide, simultaneous activation of at least 2 pathways, PI3K and KATP channels respectively, appears to be required for protection. In conclusion, we demonstrate that exogenous and endogenous EETs have powerful pro-survival effects in cardiovascular tissues including diseased human myocardium, mediated by activation of not only one but at least two pathways, PI3K and KATP channels.

This chapter about antithrombotic therapy for coronary artery disease is part of the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicans Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggestions are weaker as there is uncertainty regarding the benefits, risks and costs such that individual patients' values may lead to different choices (for a full understanding of the grading see the "Grades of Recommendation for Antithrombotic Agents" chapter by Guyatt et al, CHEST 2008; 133[suppl]:123S-131S). Among the key recommendations are the following: for all patients presenting with non-ST-segment elevation (NSTE) acute coronary syndrome (ACS), without a clear allergy to aspirin, we recommend immediate aspirin (162 to 325 mg po) and then daily oral aspirin (75 to 100 mg) [Grade 1A]. For NSTE ACS patients who are at at least moderate risk for an ischemic event and who will undergo an early invasive management strategy, we recommend "upstream" treatment either with clopidogrel (300 mg po bolus, followed by 75 mg/d) or a small-molecule IV glycoprotein (GP) IIb/IIIa inhibitor (eptifibatide or tirofiban) [Grade 1A]. For NSTE ACS patients who are at least moderate risk for an ischemic event and for whom an early conservative or a delayed invasive strategy of management is to be used, we recommend "upstream" treatment with clopidogrel (300 mg oral bolus, followed by 75 mg/d) [Grade 1A]. For NSTE ACS patients who undergo PCI, we recommend treatment with both clopidogrel and an IV GP IIb/IIIa inhibitor (Grade 1A). We recommend a loading dose of 600 mg of clopidogrel given at least 2 h prior to planned PCI followed by 75 mg/d (Grade 1B). For all patients presenting with NSTE ACS, we recommend anticoagulation with UFH or LMWH or bivalirudin or fondaparinux over no anticoagulation (Grade 1A). For NSTE ACS patients who will undergo an early invasive strategy of management, we recommend UFH (with a GP IIb/IIIa inhibitor) over either LMWH or fondaparinux (Grade 1B). For NSTE ACS patients in whom an early conservative or a delayed invasive strategy of management is to be used, we recommend fondaparinux over enoxaparin (Grade 1A) and LMWH over UFH (Grade 1B). We recommend continuing LMWH during PCI treatment of patients with NSTE ACS when it has been started as the "upstream" anticoagulant (Grade 1B). In low- to moderate-risk patients with NSTE ACS undergoing PCI, we recommend either bivalirudin with provisional ("bail-out") GP IIb/IIIa inhibitors or UFH plus a GP IIb/IIIa inhibitor over alternative antithrombotic regimens (Grade 1B).

Evidence-based clinical practice guidelines (EBGs) can provide an invaluable distillation of knowledge regarding best practices based on the available evidence. EBGs, providing accurate and useful guidance to best clinical practices, require a rigorous development process. The American College of Chest Physicians (ACCP) has developed a process that embodies transparency, thoroughness, and timeliness, and effective conflict-of-interest management, and it continues to evolve. This process employs a quantitative and rigorous grading of the strength of recommendations and of the quality of evidence that incorporates sensitivity to health-care resource utilization and patient values and preferences. A review of this process is provided to inform the ACCP membership and those wishing to embark on EBG development.

In the past 35 years, a significant increase has occurred in sports participation by women. An estimated 3 million girls and young women compete in American high school sports. Women who participate in sports and fitness programs are generally healthier and have higher self-esteem. However, an increase has also been seen in gender-specific injuries and medical problems. The female athlete triad is a syndrome of separate but interrelated conditions of disordered eating, amenorrhea, and osteoporosis. Athletic amenorrhea is known to have a hormonal profile similar to menopause characterized by decreased circulating estrogens. Menopause is known to be associated with osteoporosis and accelerated cardiovascular disease. Although enhanced risk for cardiovascular disease is theoretically possible, it has not been explored in the young athletic population. Premature cardiovascular disease first manifests as endothelial dysfunction, which can be examined noninvasively with ultrasound. This article discusses disordered eating, amenorrhea, osteoporosis, and the potential for heightened cardiovascular risk in young athletic women.

Epoxyeicosatrienoic acids (EETs), derived from arachidonic acid by cytochrome P450 epoxygenases, are potent vasodilators that function as endothelium-derived hyperpolarizing factors in some vascular beds. EETs are rapidly metabolized by soluble epoxide hydrolase to form dihydroxyeicosatrienoic acids (DHETs). Recent reports indicate that EETs have several important non-vasomotor regulatory roles in the cardiovascular system. EETs are potent anti-inflammatory agents and might function as endogenous anti-atherogenic compounds. In addition, EETs and DHETs might stimulate lipid metabolism and regulate insulin sensitivity. Thus, pharmacological inhibition of soluble epoxide hydrolase might be useful not only for hypertension but also for abating atherosclerosis, diabetes mellitus and the metabolic syndrome. Finally, although usually protective in the systemic circulation, EETs might adversely affect the pulmonary circulation.

Cardiovascular disease remains a paramount focus of basic science and clinical investigation throughout the developed world, although the demographics have changed considerably in the later half of the 20th century. Atherosclerotic cardiovascular disease, especially ischemic heart disease, has emerged as the major concern, while rheumatic fever and its cardiac sequelae have been superseded by congenital heart disease. Understanding these disease states and their perturbations requires clarification of mechanistic changes in organ phenotype over time, the influence of genetic variations, and the effects of pharmacologic, surgical, and interventional treatment. These requirements have been addressed, in part, by genetic, biochemical, and system approaches. It is clear, however, that knowledge of the DNA sequence, although essential, is not sufficient. A more meaningful understanding of gene expression can be achieved through characterization of the products of that expression, the proteins that are the essential biological determinants of disease phenotype. The ultimate phenotype of cell, organ, and organism is reflected in the instantaneous proteomic profile; similarly changes in human states of health are the result of changes in the proteomes of individual patients over time in response to endogenous and/or external stimuli. The advent of novel proteomic approaches to investigate the complexity of human illness promises to shed new light on the pathogenesis of a broad range of cardiovascular diseases. These inferences are multifaceted and include the commonly recognized role of proteomics in characterizing biomarkers and biosignatures for the prognosis and diagnosis of disease, the capability of these technologies of revealing information regarding functional subproteomes of organelles and networks in the heart and vasculature, and the importance of proteomics in defining changes in these functional subproteomes to guide future therapy. The central focus of this review is to discuss the importance of proteomics as a non-biased tool for protein discovery. We explore the role of proteomics for hypothesis-driven research into cellular organelle status, and we discuss how this approach facilitates an understanding of the function of the cell in normal and diseased states. Lastly we present a review of proteomics as a tool for biomarker development and lay out a vision for how this technology promises to facilitate distinct biomarker development.

Most panels that develop clinical practice guidelines are poorly equipped to address resource allocation or cost issues associated with management options. This risks neglect, arbitrariness, lack of transparency, and methodological flaws in consideration of resource allocation. We provide recommendations for guideline panels to promote greater transparency and rigor. We suggest focusing on resource allocation issues for only a limited number of recommendations and provide criteria for selecting those in which economic considerations are likely to influence the direction or strength of the recommendation. Panels should involve a health economist to assist with the systematic review and critical interpretation of relevant economic analyses. They should carefully define the intended audience and may consider issuing alternative recommendations when available resources vary widely across target clinical settings. Targeting a limited number of recommendations for the consideration of resource allocation issues, and ensuring methodologically high-quality review, will best serve guideline panels, and the health-care providers and patients they hope to assist.

While grading the strength of recommendations and the quality of underlying evidence enhances the usefulness of clinical guidelines, the profusion of guideline grading systems undermines the value of the grading exercise. An American College of Chest Physicians (ACCP) task force formulated the criteria for a grading system to be utilized in all ACCP guidelines that included simplicity and transparency, explicitness of methodology, and consistency with current methodological approaches to the grading process. The working group examined currently available systems, and ultimately modified an approach formulated by the international GRADE group. The grading scheme classifies recommendations as strong (grade 1) or weak (grade 2), according to the balance among benefits, risks, burdens, and possibly cost, and the degree of confidence in estimates of benefits, risks, and burdens. The system classifies quality of evidence as high (grade A), moderate (grade B), or low (grade C) according to factors that include the study design, the consistency of the results, and the directness of the evidence. For all future ACCP guidelines, The College has adopted a simple, transparent approach to grading recommendations that is consistent with current developments in the field. The trend toward uniformity of approaches to grading will enhance the usefulness of practice guidelines for clinicians.

Atrial fibrillation (AF) is one of the most frequent complications of cardiac surgery, affecting more than one third of patients. The mechanism of this arrhythmia is believed to be reentry. The electrophysiologic substrate may be preexisting or may develop due to heterogeneity of refractoriness after surgery. Multiple perioperative factors have been proposed to contribute to the latter, including operative trauma, inflammation, elevations in atrial pressure (including that due to left ventricular diastolic dysfunction), autonomic nervous system imbalance, metabolic and electrolyte imbalances, or myocardial ischemic damage incurred during the operation. Whether ectopic beats originating in the pulmonary veins explain at least some episodes of postoperative AF, as has been shown for nonsurgical patients with the arrhythmia, is of current interest as such sites could easily be isolated at the time of surgery. The development of postoperative AF is associated with a higher risk of operative morbidity, prolonged hospitalization, and increased hospital cost compared with that in patients remaining in sinus rhythm. Many factors have been identified as being associated with postoperative AF, but the most consistent variable across studies is increasing patient age. It is speculated that age-related pathologic changes in the atrium contribute to arrhythmia susceptibility. An important modifiable risk factor for postoperative AF is the failure to resume therapy with β-adrenergic receptor blockers after surgery. The stratification of patients who are at higher risk for AF would focus preventative strategies on patients who are most likely to benefit from such therapy. Nonetheless, since postoperative AF often develops in patients with comorbidities who are predisposed to other complications and prolonged hospitalization, it is presently unclear whether the prevention of postoperative AF will result in improved patient outcomes, particularly shorter hospitalizations.

Post-cardiac surgery atrial fibrillation (AF) places patients at risk for thromboembolism and stroke, while the surgery and cardiopulmonary bypass alter the multiple factors of coagulation and may increase the tendency to bleed. It is in the context of this complex clinical picture that the physician must make decisions regarding the risks and benefits of anticoagulation therapy to lower the risk for thromboembolism and stroke associated with postoperative AF. Physicians must also weigh the usually transient and self-limited duration of new-onset postoperative AF against the potential for postoperative bleeding if anticoagulation therapy is started. No randomized, controlled clinical trials are available that specifically address the problem of anticoagulation therapy for the postoperative AF. In that context, recommendations are based on the established therapy for nonsurgical situations modified by the potential risk of bleeding in the postoperative patient.

This chapter about prevention of coronary artery bypass occlusion is part of the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S–187S). Among the key recommendations in this chapter are the following: For patients undergoing coronary artery bypass grafting (CABG), we recommend aspirin, 75 to 162 mg/d, starting 6 h after operation over preoperative aspirin (Grade 1A). In patients in whom postoperative bleeding prevents the administration of aspirin at 6 h after CABG, we recommend starting aspirin as soon as possible thereafter (Grade 1C). For patients undergoing CABG, we recommend against addition of dipyridamole to aspirin therapy (Grade 1A). For patients with coronary artery disease undergoing CABG who are allergic to aspirin, we recommend clopidogrel, 300 mg, as a loading dose 6 h after operation followed by 75 mg/d po (Grade 1C+). In patients who undergo CABG for non–ST-segment elevation acute coronary syndrome (ACS), we recommend clopidogrel, 75 mg/d for 9 to 12 months following the procedure in addition to treatment with aspirin (Grade 1A). For patients who have received clopidogrel for ACS and are scheduled for CABG, we recommend discontinuing clopidogrel for 5 days prior to the scheduled surgery (Grade 2A). For patients undergoing CABG who have no other indication for vitamin K antagonists (VKAs), we suggest clinicians to not administer VKAs (Grade 2B). For patients undergoing CABG in whom oral anticoagulants are indicated, such as those with heart valve replacement, we suggest clinicians administer VKA in addition to aspirin (Grade 2C). For all patients with coronary artery disease who undergo internal mammary artery (IMA) bypass grafting, we recommend aspirin, 75 to 162 mg/d, indefinitely (Grade 1A). For all patients undergoing IMA bypass grafting without other indication for VKA, we suggest clinicians not use VKA (Grade 2C).

Pulmonary arterial hypertension (PAH) occurs as an idiopathic process or as a component of a variety of disease processes, including chronic thromboembolic disease, connective tissue diseases, congenital heart disease, and exposure to exogenous factors including appetite suppressants or infectious agents such as HIV. This article reviews evidence for screening in susceptible patient groups and the approach to diagnosing PAH when it is suspected, and provides specific recommendations for applying this evidence to clinical practice.

Under physiologic conditions, epicardial arteries contribute minimally to coronary vascular resistance. However, in the presence of endothelial dysfunction, stimuli that normally produce vasodilation may instead cause constriction. Examples include neural release of acetylcholine or norepinephrine, platelet activation and production of serotonin and thrombin, and release of local factors such as bradykinin. This shift from a primary endothelial-mediated vasodilator influence to one of endothelial dysfunction and unchecked vasoconstriction is precisely the milieu in which coronary vasospasm is observed. This condition, which typically occurs during periods of relatively sedentary activity, is associated with focal and transient obstruction of an epicardial arterial segment resulting in characteristic echocardiographic changes and symptoms of myocardial ischemia. This review highlights the current understanding of mechanisms regulating the coronary circulation during health and examines the pathophysiologic changes that occur with coronary spasm. Genetic and other predisposing conditions are addressed, as well as novel therapies based on recent mechanistic insights of the coronary contractile dysfunction associated with coronary spasm.

Inflammatory bowel disease (IBD; i.e., Crohn's disease, ulcerative colitis) is characterized by refractory inflammatory ulceration and damage to the intestine. Mechanisms underlying impaired healing are not defined. Because microvascular dysfunction resulting in diminished vasodilatory capacity and tissue hypoperfusion is associated with impaired wound healing, we hypothesized that microvascular dysfunction may also occur in chronic IBD.Intact submucosal arterioles from control, involved, and uninvolved IBD specimens were assessed using in vitro videomicroscopy to assess endothelium-dependent vasodilation in response to acetylcholine (Ach) and fluorescence microscopy to detect oxyradicals.Normal microvessels dilated in a dose-dependent and endothelium-dependent manner to Ach (maximum, 82% +/- 2%; n = 34). Inhibition of nitric oxide synthase with N(G)-nitro-L-arginine methyl ester (L-NAME) reduced maximal dilation to 54% +/- 6% (P0.05, n = 7), and further reduction was observed after inhibiting cyclooxygenase (indomethacin; 23% +/- 10%, n = 6). Chronically inflamed IBD microvessels showed significantly reduced Ach-induced vasodilation (maximum, 15% +/- 2%; n = 33), with no effect of L-NAME. Indomethacin eliminated the remaining Ach-induced vasodilation, resulting in frank vasoconstriction (-54% +/- 9%, n = 6). Uninvolved IBD gut vessels and non-IBD inflammatory controls responded in a fashion similar to normal vessels. IBD-involved microvessels generated significantly higher levels of reactive oxygen species compared with control and uninvolved IBD vessels (P0.01).Human intestinal microvessels from chronically inflamed IBD show microvascular endothelial dysfunction, characterized by loss of NO-dependent dilation that may contribute to reduced perfusion, poor wound healing, and maintenance of chronic inflammation.

Enhanced oxidative stress, particularly an excess production of superoxide, has been implicated in the altered vasomotor responsiveness observed in diabetes mellitus (DM). Recent evidence suggests that an altered regulation of K + channel activity by enhanced oxidative stress may participate in the abnormal vascular responses. This review examines the mechanism of hyperglycemia-induced superoxide production and describes the consequences on hyperpolarization-mediated vasodilation. Several pathways have been proposed as mechanisms for hyperglycemia-induced superoxide overproduction, including increased flux through the polyol pathway, depletion of nicotinamide adenine dinucleotide phosphate (NADPH), altered endogenous antioxidant enzymes, and reduced availability of tetrahydrobiopterin, an essential cofactor for nitric oxide synthase (NOS). The resulting excess production of superoxide has been implicated in the impaired dilator responses to ATP-sensitive K + (K ATP ) channel openers in aorta and in mesenteric and cerebral arteries of streptozotocin-induced diabetic rats. This may have important implications for ischemia-mediated vasodilation. Potential alterations in voltage-sensitive K + (K V ) channel regulation also have been implicated in the vascular pathogenesis of DM. For example, incubation of small rat coronary arteries in high glucose for 24 h greatly reduces K V channel activity and functional responses, both of which can be partially restored by antioxidant treatment. However, not all K + channels are adversely affected by reactive oxygen species (ROS). For example, high-conductance Ca 2+ -activated K + (BK Ca ) channels may compensate for the loss of other vasodilator mechanisms in disease states such as atherosclerosis where ROS generation is increased. Therefore, BK Ca channels may be refractory to superoxide, providing a compensatory mechanism for partially reversing the reduced dilator responses attributed to the dysfunction of other K + channel types. In summary, determining the effect of ROS on K + channel-mediated dilation will be important for understanding the pathophysiology of diabetic vascular dysfunction and for developing therapies to improve tissue perfusion in this disease.

Objective: We have previously shown that brief myocardial ischemia impairs neural conduction in cardiac sympathetic efferent fibers. However, attenuation of the activity of afferent sympathetic nerves, which may contribute to impaired ischemic nociception and reflex hemodynamic responses, is not well understood. Therefore, we studied the electrophysiological effects of brief myocardial ischemia on the mechano-, chemo- and ischemia-sensitive properties of cardiac sympathetic afferent fibers. Methods: Single unit activity of sympathetic afferent Aδ and C fibers innervating the left ventricle (LV) was recorded from the thoracic chain or rami communicantes in 16 anesthetized cats. We tested the response of impulse activity to (1) mechanical LV probing, (2) epicardial application of bradykinin (10 μg), H2O2 (1.5%) or adenosine (500 μg), and (3) 1 min of coronary occlusion. Repeat tests were performed in 11 of 16 fibers after 15 min of coronary occlusion and 15 min of reperfusion. Control responses were measured in five fibers before and after a 30-min interval without ischemia. Results: Afferent fibers responded with increased activity to LV probing (16/16 fibers), bradykinin (13/16 fibers), H2O2 (7/11 fibers), adenosine (1/11 fibers), and to a 60 s period of coronary occlusion (11/16 fibers). The unit impulse activity to 1 min of coronary occlusion was markedly attenuated after 15 min of myocardial ischemia and 15 min of reperfusion (P

Objectives. Our aim was to test the hypothesis that increased beat to beat morphologic variations in the body surface electrocardiogram (ECG) are associated with fragmented diastolic electrical activity that appears after coronary artery ligation and to correlate the appearance of spontaneous ventricular fibrillation after coronary ligation with the magnitude of the ECG beat to beat variability. Background. Unstable and variably delayed electrical activation precedes the development of ventricular fibrillation in dogs with acute ischemia. Detection of these highly variable low amplitude signals from the body surface is currently impossible. We have developed a system designed to measure the degree of beat to beat variability of the ECG. Methods. With high fidelity electrocardiography, subtle beat to beat ECG morphologic variations were detected in epicardial and body surface electrograms and quantified as the variance of the ECG voltage at specific points of the cardiac cycle. The ratio of the variance at the QRS offset to that of the QRS onset (beat to beat variability index) was then calculated. Results. Ventricular fibrillation developed in 12 of 27 dogs after left anterior descending coronary artery ligation. In 7 of the 12 dogs it occurred immediately (

Light chain amyloidosis (AL) is a plasma cell dyscrasia associated with production of amyloidogenic immunoglobulin light chains (LC). Despite its often fatal course, the mechanism of injury remains unknown. We tested the hypothesis that AL is associated with oxidative stress by comparing serum protein carbonyl (a marker of protein oxidation and oxidative stress) in AL subjects (n=23, 60 ± 11 years) vs. controls (n=9, 54 ± 2 years); we also measured superoxide production (n=11) and dilator response to sodium nitroprusside (SNP, n=6) in isolated non-AL human adipose arterioles exposed to LC (20 μg/mL) purified from AL subjects for 1 h vs. control. Protein carbonyl was higher in AL patients (0.19 ± 0.04 vs. 0.003 ± 0.003 nmol/mg control, p=0.002). Post-exposure to LC proteins, arteriole superoxide was higher (1.89 ± 0.36 times control, p=0.03) with impaired dilation to SNP (10(-4) M, 54 ± 6 vs. 86 ± 4%, p=0.01, logEC50 -3.7 ± 0.2 vs. -6.7 ± 0.6, p=0.002). AL is associated with systemic oxidative stress and brief acute exposure to AL light chain proteins induces oxidative stress and microvascular dysfunction in human adipose arterioles. This novel mechanism of injury may be important in AL pathophysiology.

Background This guideline focuses on long-term administration of antithrombotic drugs designed for primary and secondary prevention of cardiovascular disease, including two new antiplatelet therapies. Methods The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement. Results We present 23 recommendations for pertinent clinical questions. For primary prevention of cardiovascular disease, we suggest low-dose aspirin (75-100 mg/d) in patients aged > 50 years over no aspirin therapy (Grade 2B). For patients with established coronary artery disease, defined as patients 1-year post-acute coronary syndrome, with prior revascularization, coronary stenoses > 50% by coronary angiogram, and/or evidence for cardiac ischemia on diagnostic testing, we recommend long-term low-dose aspirin or clopidogrel (75 mg/d) (Grade 1A). For patients with acute coronary syndromes who undergo percutaneous coronary intervention (PCI) with stent placement, we recommend for the first year dual antiplatelet therapy with low-dose aspirin in combination with ticagrelor 90 mg bid, clopidogrel 75 mg/d, or prasugrel 10 mg/d over single antiplatelet therapy (Grade 1B). For patients undergoing elective PCI with stent placement, we recommend aspirin (75-325 mg/d) and clopidogrel for a minimum duration of 1 month (bare-metal stents) or 3 to 6 months (drug-eluting stents) (Grade 1A). We suggest continuing low-dose aspirin plus clopidogrel for 12 months for all stents (Grade 2C). Thereafter, we recommend single antiplatelet therapy over continuation of dual antiplatelet therapy (Grade 1B). Conclusions Recommendations continue to favor single antiplatelet therapy for patients with established coronary artery disease. For patients with acute coronary syndromes or undergoing elective PCI with stent placement, dual antiplatelet therapy for up to 1 year is warranted.