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87 Cards in this Set
- Front
- Back
What is ischemia?
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-Loss of blood supply - either partial or complete.
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What are the 2 main physiologic dysfunctions that result from ischemia?
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-Loss of both aerobic and anaerobic metabolism due to loss of metabolic substrate supply.
-Accumulation of toxic products |
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When is ischemia reversible?
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Prior to cell membrane disruption
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What is the threshold beyond which ischemic changes are irreversible?
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Membrane injury
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What happens when the membrane is injured?
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Cell death
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What can we do to detect cell injury?
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Measure enzymes like CK, LDH, myoglobin, and troponin.
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What do we see on an EKG that reflects ischemic myocardium?
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ST elevation
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What is the immediate manifestation of ischemic myocardium?
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Contractility ceases
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How long does it take for contractility to cease?
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1 minute of ischemia
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Why do we care about ischemic heart disease?
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It is the leading cause of death in the U.S.
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What has happened to the death rate in the past 40 years due to ischemic heart disease?
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A significant decline in death rates
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What is the cause of ischemic heart disease?
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Atherosclerosis in the coronary arteries
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What is atherosclerosis in the oronary arteries called?
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CAD - coronary artery disease
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What occurs in CAD to cause ischemic heart disease?
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Plaque formation and disruption
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When in the course of CAD does ischemia occur?
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late
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How many patients with IHD have CAD?
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90%
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When does CAD begin?
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In childhood
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How does CAD progress to cause IHD?
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A fatty streak turns into an occlusive plaque.
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What are the 7 big risk factors for CAD?
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SDHHMAR
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What is SDHHMAR?
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-smoking
-diabetes -hypercholesterol -hypertension -male -age -race |
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At what age does CAD risk increase for
-males -females |
Males: 45 yo
Females: 55 yo |
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What race is at increased risk for hypertension as a risk factor for CAD?
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African americans
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What are the 5 features of Metabolic syndrome?
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Obesity
Hypertension Impaired glucose tolerance Dyslipidemia Microalbuminuria |
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How is metabolic syndrome related to IHD?
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Patients with it are at a 2-3x higher risk of developing cardiovascular disease than the rest of the population.
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What are 3 risk factors for women in developing CAD?
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-Elevated triglycerides
-Central obesity -Gestational diabetes |
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What are 4 ways to reduce the risk of getting CAD?
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-Diabetes management
-Lipid management (statins) -Smoking cessation -BP control |
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What is a female-specific way to reduce the risk of CAD?
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Hormone replacement therapy
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What is the problem with HRT?
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The risks seem to outweigh the benefits.
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What are the 4 risks of HRT?
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-Stroke
-CAD -Pulmonary embolism -Breast cancer |
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What is the best way to treat dyslipidemia?
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Statins
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How does Statin therapy work?
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-Increases HDL
-Decreases triglycerides and LDL |
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What is CRP?
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An inflammatory marker from expanded cores of atheromatous plaques.
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What are 4 types of patients in which increased CRP can be found?
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-Smokers
-Obese -Diabetics -Metabolic syndrome patients |
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What is the best inflammatory marker for CAD risk?
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CRP
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What level of CRP indicates:
-low risk of CAD -high risk of CAD |
low risk: < 1 mg/dl
high risk: >3 mg/dl |
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What molecule may cause endothelial dysfunction by interfering with NO functions?
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Homocysteine
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What are the functions of NO that are interfered with by homocysteine?
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-Vasodilation
-Antithrombogenicity |
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What is the process that starts of atherosclerosis?
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Fatty streak propagation
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How does a fatty streak develop?
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By the combination of activated smooth muscle + persistent hypercholesterolemia
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What are 3 stimulators of smooth muscle?
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-PDGF
-FGF -TGF-beta |
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What does activated smooth muscle produce?
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-Collagen
-Elastin -ECMatrix proteins |
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So what is the first step in forming an atherosclerotic plaque?
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Injury to the endothelial lining
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What happens in response to endothelial injury?
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-WBCs adhere to the endothelium and migrate into the intima
-WBCs secrete chemokines that stimulate macrophages and smooth muscle cells |
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What do stimulated macrophages do in generating a plaque?
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Secrete pro-inflammatory molecules to form a chewy center of the plaque.
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What do stimulated smooth muscle cells do in generating a plaque?
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Produce ECM proteins that form a covering around the plaque.
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What is determined by the balance between activated macrophages and smooth muscle cells?
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Whether the plaque will become stable or unstable.
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What is the result of an unstable plaque?
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Acute coronary syndrome
-Angina |
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What are the characteristics of a stable plaque?
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-Fairly sturdy fibrous cap covering the pro-inflammatory center - protecting it from platelets or thrombogenic sticky things.
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What happens if collagen and the proinflammatory center are revealed by an unstable fibrous cap of an unstable plaque?
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Activation of the clotting cascade and thrombogenesis - occlusion of the vessel.
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What is more stable; larger, more occlusive plaques, or smaller ones?
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LARGER >75% occlusive
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Why are larger plaques more stable?
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-Less bloodflow past the occlusion
-Less hemodynamic stress -More fibrin |
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What plaques are at greater risk of being unstable?
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50-75% occlusive plaques
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What protective mechanism is induced by stable plaques?
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Collateral circulation
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What does collateral circulation achieve?
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Myocardial conditioning
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So what plaques are at the greatest risk for acute plaque change and acute coronary syndrome?
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Medium sized
50-75% occlusions |
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What do we term these medium sized plaques?
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Vulnerable plaques
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What shape are the vulnerable plaques, and what is the implication of that shape?
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-Eccentric
-The long leading edges are stress points for fissure |
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What are 2 categories of causes of acute plaque change?
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-Mechanical stress
-Hemodynamic stress |
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What is the main form of mechanical stress inducing acute plaque change?
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Vasoconstriction due to sympathetic stimulation.
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At what time do most patients present clinically with angina due to adrenergic stimulation induced vasoconstriction?
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Early in the morning when they rise and shine
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What are 4 things that can happen in an acute plaque change?
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THER
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What is THER?
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-Thrombosis
-Hemorrhage -Erosion/ulceration -Rupture |
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How can a plaque HEMORRHAGE into itself?
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Blood vessels can develop inside them.
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So what are the 4 steps in acute plaque disruption?
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1. Loss of fibrous cap integrity
2. Thrombogenic collagen exposure 3. Capillary damage in the core 4. Fragmented plaque |
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And what are the 2 pathologic results of fragmented plaques?
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-Embolization
-Platelet activation and thrombus |
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What type of infarct results from a total occlusion caused by thrombosis on top of plaque disruption?
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Transmural
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What can result from a partial occlusion caused by thrombosis on top of plaque disruption?
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-Subendothelial infarct
-Unstable angina -Sudden death syndrome |
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What part of the ventricular wall is most at risk for developing ischemia?
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The subendocardial tissue just under the layer that recieves nourishment from the lumen of the ventricle itself.
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So the most common cause of ischemic heart disease is:
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CAD
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What are 3 other less common causes of IHD?
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-Hypotension
-Shock -Severe anemia |
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So what are 4 clinical presentations of ischemic heart disease?
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-Angina
-Myocardial infarct -Sudden death -Ischemic cardiomyopathy (chronic) |
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What are the symptoms of stable angina?
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-Transient
-Squeezing chest pain -Left arm/neck/jaw pain -Relieved with rest/nitroglyc |
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What does the EKG show in relation to angina?
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Cell membrane instability seen by ST segment elevations.
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In what sex is sudden cardiac death more common? Why?
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Women - they are less symptomatic and more likely to have silent MI
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What is the risk of MI in women over 60 yo?
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The same as for men
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In what race is IHD more common?
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Whites
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In what race is hypertensive heart disease more common?
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African americans
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What are 3 things that can cause vasoconstriction?
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-Adrenergic agonists (NE)
-Activated platelet products (txA2) -Decreased endothelial derived relaxing factors (NO) |
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What is vasospasm related to?
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Prinzmetal's Angina
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What is Prinzmetal's angina?
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Angina symptoms at rest
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Do patients with Prinzmetal's angina have CAD?
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They may or may not
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What is the general cause of sudden cardiac death?
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Lethal arrythmia due to irritable myocardium
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What happens when there are chronic ischemic disruptions?
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Fibrosis of the myocardium
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What happens as the fibrosis is replaced by scar tissue?
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Loss of myocardial compliance and contractility
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What is the early sign of chronic ischemia?
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Diastolic dysfunction (decreased filling)
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What is the later sign of chronic ischemia?
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Systolic dysfunction (inability to pump it out)
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What are the 4 main methods for detecting IHD?
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-Risk factor profiling
-Symptoms -Stress test -Coronary anatomy |