Coronary Information and Courses from MediaLab, Inc.

These are the MediaLab courses that cover Coronary and links to relevant pages within the course.

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Emerging Cardiovascular Risk Markers
Introduction We are all aware of the clinical laboratory's role in assessing overall health and we are also aware that measuring a patient's serum lipids will provide some insight into their cardiovascular health. The traditional measurements of low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides are the 'classic' cardiovascular risk markers.Laboratorians, and even the general public are now well-aware that LDL-C ('bad' cholesterol) concentrations should be low while HDL-C ('good' cholesterol) concentrations should be high. Triglycerides should be kept in check as well. Optimal levels are shown in the table below. So what is the risk if these values are not within optimal ranges?Cardiovascular risk can be simply defined as increasing the odds of having a pathology which affects blood flow and/or the heart. The most common cardiovascular pathology is atherosclerosis. Other cardiovascular pathologies whose odds increase as serum lipids and other cardiovascular markers become suboptimal are myocardial infarction (heart attack), stroke, congestive heart disease and coronary artery disease. Other diseases such as diabetes and the metabolic syndrome are also strongly associated with the classic cardiovascular risk markers LDL-C, HDL-C and triglycerides.	View Page
Atherosclerosis Atherosclerosis is a clogging, narrowing and hardening of the body's large and medium-sized blood vessels. Atherosclerosis can lead to hypertension, stroke, myocardial infarction (heart attack), renal problems, etc. Not surprisingly, cardiovascular risk markers tend to reflect a person's degree of atherosclerosis.Atherosclerosis is actually a chronic inflammatory response within the walls of arteries. Small lipoproteins like LDL are able to diffuse through the endothelial wall of blood vessels and accumulate. The inflammatory component of atherosclerosis results from the migration of leukocytes (mainly macrophages) that enter the blood vessel walls. These macrophages seek to remove the deposited LDL as well as intermediate-density lipoproteins (IDL). As macrophages phagocytose these lipoproteins, they become foam cells that get trapped in the endothelial space. This eventually leads to "hardening" or "furring" of the arteries and plaque formation. Arteriosclerosis is a general term describing any hardening (loss of elasticity) of medium or large arteries whereas atherosclerosis is a hardening of an artery specifically due to plaque. The risk to patients with significant atherosclerosis is that eventually a narrowing of the artery (stenosis) can cause a reduction in oxygen delivery to tissues and plaque rupture can lead to an acute coronary event.	View Page
Patient Studies to Validate Risk Markers Risk markers are first hypothesized and then tested. Once a potential marker is identified, concentrations of the serum marker are correlated with patient outcomes. Cardiovascular risk marker studies are typically either retrospective or prospective epidemiology studies. A retrospective study looks backwards at a patient population. For example, we identify (through a hospital database perhaps) patients who have had myocardial infarcts or some other adverse outcome as well as similar subjects without that outcome to use as controls. We then go back and find archived patient serum samples and relate the concentrations of our new risk marker with patient outcomes. Retrospective studies can only be performed if you have archived samples from the patient. Prospective studies look forward in time. For example, we first select a group of subjects and measure our new risk marker in these patients over time. After a few years, we see how the serum concentrations relate to the patient outcomes. Obviously, prospective studies take much longer to perform than retrospective studies. Whatever study model is used, when assessing the value of a cardiovascular risk marker, we must correlate serum concentrations with a specific outcome. The outcome is determined by the study authors. Outcomes could be things like myocardial infarction, stroke, a diagnosis of coronary artery disease, death, or any cardiovascular 'event.'Concentrations of risk markers are divided into tertiles, quatriles or quintiles. This simply means that the top 33%, top 25% or top 20% of the serum concentration values are compared to the bottom 33%, 25% or 20%. For example, risk marker studies will often compare the outcomes of patients with serum concentrations in the upper tertile (those in the top third) with those in the bottom tertile (those in the bottom third) to see if the top 33% had significantly worse outcomes; if so, the risk marker has clinical value.	View Page
References Atherosclerosis. U.S. Department of Health & Human Services National Institutes of Health. Available at http://www.nhlbi.nih.gov/health/dci/Diseases/Atherosclerosis/Atherosclerosis_WhatIs.htmlAccessed June 23, 2009.Daniels LB, Barrett-Connor E, Sarno M, Laughlin GA,Bettencourt R, Wolfert RL. Lipoprotein-associated phospholipase A2 (Lp-PLA2) independently predicts incident coronary heart disease (CHD) in an apparently healthy older population: The Rancho Bernardo study. J Am Coll Cardiol. 2008;51:913-919.Executive Summary of the third report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). JAMA. 2001; 285:2486-2497. Frostegard, J, Wu R, Lemne C, Thulin T, Witztum JL and de Faire U. Circulating oxidized low-density lipoprotein is increased in hypertension, Clin Sci 2003; 105, 615.Garza CA, Montoir VM, McConnell JP, et al. Association between lipoprotein-associated phospholipase A2 and cardiovascular disease: a systematic review. Mayo Clin Proc. 2007;82(2):159-165.Interpretive Handbook, (MC0440rev0407) Mayo Clinic, Rochester MN;2007. Maksimowicz-McKinnon K, Bhatt DL, Calabrese LH: Recent advances in vascular inflammation: C-reactive protein and other inflammatory biomarkers. Curr Opin Rheumatol. 2004;16:18-24.Mora S, Szklo M, Otvos JD, et al. LDL particle subclasses, LDL particle size, and carotid atherosclerosis in the multi-ethnic study of atherosclerosis. Atherosclerosis. 2007;192:211-217.NACB Laboratory Medicine Practice Guidelines. Emerging biomarkers of cardiovascular disease and stroke. National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines. 2006.PLACtest animation, diaDexus. http://www.plactest.com/laboratorians/action.php Accessed June 23, 2009.Rifai N, Warnick GR. Lipids, lipoproteins, apolipoproteins, and other cardiovascular risk factors. In: Burtis CA, Ashwood ER. Bruns DE. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 4th ed. St. Louis, MO: Elsevier Saunders: 2006; chap. 26.Ridker PM, Rifai N, Rose L, et al. Comparison of C-reactive protein and low-density lipoprotein cholesterol levels in the prediction of first cardiovascular events. N Engl J Med. 2002;347:1557-1565.Sniderman AD. Differential response of cholesterol and particle measures of atherogenic lipoproteins to LDL-lowering therapy: Implications for clinical practice. J Clin Lipidol 2008;2:36-42.Tsimikas, S, Brilakis ES, Miller ER, et al. Oxidized phospholipids, Lp(a) lipoprotein, and coronary artery disease, N Engl J Med: 2005;353:46.Tsimikas S, Bergmark C, Beyer RW, et al. Temporal increases in plasma markers of oxidized low-density lipoprotein strongly reflect the presence of acute coronary syndromes. J Am Coll Cardiol. 2003; 41: 360.Tsimikas, S, Lau HK, Han KR, et al. Percutaneous coronary intervention results in acute increases in oxidized phospholipids and lipoprotein(a): Short-term and long-term immunologic responses to oxidized low-density lipoprotein. Circulation. 2004;109, 3164.Tsimikas S, Witztum JL, Miller ER, Sasiela WJ, et al. High-dose atorvastatin reduces total plasma levels of oxidized phospholipids and immune complexes present on apolipoprotein B-100 in patients with acute coronary syndromes in the MIRACL trial, Circulation: 2004;110, 1406. Walldius G, Jungner I, Holme I, et al. High apolipoprotein B, low apolipoprotein A-I, and improvement in the prediction of fatal myocardial infarction (AMORIS study): a prospective study. Lancet. 2001;358:2026-2033.Yusuf S, Hawken S, Ounpuu S, et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet. 2004;364:937-952.	View Page
Size and Number Although lipoproteins of a particular class are generally within a given size range, there are many biochemical processes that interact with lipoproteins to alter their size, density, and lipid composition. When low-density lipoprotein (LDL) becomes smaller and denser, it is more likely to interact with the arterial wall, leading to deposition of cholesterol and initiating or worsening atherosclerosis. Research has shown that high numbers of smaller, denser LDL are more atherogenic than larger, lighter LDL particles. Small, dense LDL particles are associated with more than a three-fold increase in the risk of coronary heart disease.	View Page

Fundamentals of Hemostasis

Anticoagulation Therapy

Anticoagulant therapy is employed in a number of clinical situations Some of these clinical situations include: After an episode of thrombosis, such as deep venous thrombosis (DVT) in the veins of the legs, to prevent reoccurrence. Prophylactically after some surgeries, especially those involving vascular repair such as coronary bypass surgery to prevent clots from blocking newly formed vasculature. In heart valve and chamber disorders where there is an increased risk of thrombosis occurring.

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Phlebotomy
Plasma lipids Lipids are fats dispersed in plasma. They include: Triglycerides Cholesterol Lipoproteins The amount and ratios of various lipids in the blood will determine a person’s risk of getting coronary artery disease.	View Page

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