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62 Cards in this Set
- Front
- Back
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Coronary Arteries |
Two coronary arteries arise from the aorta -Right coronary artery -Left coronary artery (Left anterior descending and Circumflex) |
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Right Coronary Artery (RCA) |
-Travels in the right AV groove -Supplies blood to RV and inferior segment of LV -Posterior descending artery (arises) supplies inferior aspect of ventricle -supplies AV and SA node |
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Left Main Coronary Artery |
Initial trunk of the left coronary artery (short) -passes between the pulmonary artery and LA into AV groove -branches into the left anterior descending and circumflex |
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Left Anterior Descending |
-travels down the interventricular groove -septal branches supply the ventricular septum -diagonal branches supply anterior wall -Supplies the left ventricular apex and distal part of inferior wall |
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Left Circumflex Artery |
-travels through the left AV groove -supply lateral wall of the LV -posterior descending artery branches off |
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Myocardial Segments and Coronary Distribution |
RCA - RV and inferior wall of LV LM - branches into LAD and circumflex LAD - anterior wall and apex of LV Circumflex - lateral wall of LV |
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Wall segments supplied by the LAD |
Basal ant-septal, mid ant-sept, apical septal, apex, basal anterior, mid anterior, apical anterior |
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Wall segments supplied by the RCA |
Mid inf-septal, basal inferior septal, apical inferior, mid inferior, basal inferior |
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Wall segments supplied by the circumflex |
Basal anterior lateral, mid anterior lateral, mid inferior lateral, basal inferior lateral, apical lateral |
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Anatomy of a Vessel |
3 layers -Tunica Intima (internal) -Tunica Media (middle) -Tunica Adventitia (outer) |
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Tunica Intima |
Innermost layer 3 layers -Endothelial cells line lumen -Connective tissue -Internal elastic membrane *larger arteries have more extensive tissue and thicker intima |
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Tunica Media |
Middle layer -concentric sheets of smooth muscle within connective tissue -Change in diameter (vasoconstriction or vasodilation) -collagen fibers bind layer to intima and adventitia -arteries have an external elastic membrane |
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Tunica Adventitia |
Outermost layer -very thick connective tissue sheath -composed mostly of collagen fibers with some elastic fibers -blends in with surrounding tissue for stabilization and anchoring of vessel *veins layer is thicker than media |
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Endothelium |
Cells that line the surface of all vessels, heart, and valves -the barrier between blood and intima -prevents clotting -regulates vasoconstriction and vasodilation -immune response |
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Endothelial Dysfunction |
-Injury or inflammation of the endothelium -First step in getting atherosclerosis |
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Causes of Endothelium Dysfunction |
Dyslipidaemia, diabetes/insulin resistance, hypertension, low shear stress, smoking |
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Effects of Endothelium Dysfunction |
Vasoconstriction, Oxidative stress, Inflammatory cell adhesion and or infiltration, smooth muscle cell proliferation, and endothelial permeability |
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Stages of Atherosclerosis |
Fatty streak Plaque progression Plaque disruption |
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Fatty streak |
First visible signs of atherosclerosis |
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Plaque progression |
Endothelial dysfunction leads to intimal disruption that allows the smooth muscle cells of the media to proliferate into the intimal space and the vessel lumen |
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Plaque disruption |
The fibrous cap ruptures, potentially occluding flow in the vessel |
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Coronary Artery Disease (CAD) |
Refers specifically to the atherosclerotic process within the coronary arteries |
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Modifiable risk factors of atherosclerosis |
Nicotine use, diet, hypertension, diabetes, stress, sedentary life style |
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Non-modifiable risk factors of atherosclerosis |
Age, gender, and family history |
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Ischemia |
Imbalance between oxygen supply and demand (demand is > supply) |
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Myocardial Ischemia |
Occurs when myocardial oxygen demand exceeds myocardial oxygen supply |
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Myocardial oxygen supply |
-Diastolic perfusion pressure -Coronary vascular resistance -O2 carrying capacity |
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Myocardial oxygen demand |
-Wall tension -Heart rate -Contractility |
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Cardiac Output |
Resting CO = 5 L/min Exercise CO ~ 25 L/min |
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Cardiac Flow |
Resting cardiac flow = 4-5% of CO or ~ 250ml/min Exercise cardiac flow = 4-5% of CO or ~1250ml/min |
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Coronary artery flow |
Occurs during diastole |
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Coronary flow reserve |
-Arterioles dilate in response to local factors (decreased O2) -Stenosis in an artery leads to decreased blood flow downstream. Arterioles need to dilate to improve flow. -Stenosis progresses, arterioles must dilate chronically, and therefore cannot increase their diameter in response to exercise |
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How much higher is coronary flow during exercise compared to resting? |
5 times greater |
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Angina Pectoris |
An uncomfortable sensation in the chest and surrounding anatomy caused by myocardial ischemia. -coronary lesions are capable of producing angina once they obstruct the diameter of the vessel by about 70% or more -stable&unstable angina, variant angina, other causes |
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Clinical features of angina |
Described as pressure. Almost never referred to as pain. Lasts a few minutes, not second0s Discomfort is diffuse, not sharp or focal Typically precipitated by exertion or stress; resolves with rest |
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Angina Classifications |
Stable angina, unstable angina, variant angina |
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Stable angina |
Chronic pattern of transient angina pectoris precipitated by physical exertion or emotional upset, relieved by rest |
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Unstable angina |
Angina pectoris that is increasing in frequency and duration and produced by less exertion or even at rest |
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Variant angina |
Angina pectoris that is due to coronary artery spasm |
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Ischemia: ECG changes |
Normal T wave -ventricular repolarization -same direction as and smaller than QRS complex -upright, asymmetrical T wave changes -Deeply inverted, symmetrical |
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ST Depression |
Indicates ischemia -does not typically localize |
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Cardiac Enzymes |
Drawn in cases of chest pain or when cardiac ischemia is a consideration. -troponin is the main enzyme that is used in clinical medicine |
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Diagnosing Stable Coronary Stenosis (angina) |
-Exercise(stress) echo 1.Resting echo pictures of the LV 2.Patient exercises and then immediately upon stopping exercise pictures taken again -myocardial segments should be contracting more vigorously -segments supplied by diseased coronaries with significant disease will stop contracting (ischemia) |
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Another method to diagnose stable coronary stenosis |
Myocardial perfusion imaging (MPI) or nuclear stress test 1.injection of nuclear isotope 2. resting pictures 3. exercise or pharmacological agent that stimulates exercise 4. stress images -all segments should receive equal amounts of the isotope at rest and stress -segments that receive less of the isotope are infarcted (rest/stress) or ischemic (stress only) |
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Diagnosing Stable/unstable coronary stenosis |
Cardiac CTA (computed tomography angiography) -Fast CT scanners can take images during cardiac diastole -Contrast is injected and the patient is immediately imaged to see this contrast within the coronary arteries -diseased segments are directly visualized |
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Diagnosing Coronary stenosis |
Angiography -Catherization through femoral or radial artery -Wire advances to aortic root and into RCA and LCA -Contrast is injected into the arteries while fluoroscopic images show contrast |
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Variant Angina (coronary spasm) |
Intense spasms causes an acute blockage and ischemia -caused by endothelial dysfunction or sympathetic activation |
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Acute Coronary Syndromes (ACS) |
Unstable Angina NSTEMI STEMI |
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Unstable Angina |
Typically occurs when a stable coronary plaque becomes unstable, with rupture of the fibrous cap and clot formation. -non occlusive thrombus -non specific ECG -Normal cardiac enzymes |
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NSTEMI |
Occluding thrombus sufficient to cause tissue damage and mild myocardial necrosis -ST depression +/- T wave inversion on ECG -elevated cardiac enzymes |
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STEMI |
Complete thrombus occlusion -ST elevations on ECG or new LBBB -elevated cardiac enzymes -more severe symptoms |
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Pathophysiology of Myocardial Infarction |
-Plaque rupture is the typical precipitating event -Abnormal vessel wall cannot vasodilate and cannot release antithrombotic agents -Platelets adhere and thrombus forms narrowing the vessel lumen -Total vessel occlusion typically results in a ST elevation myocardial infarction -Partial vessel occulusion can result in a nonSTEMI or unstable angina |
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What can occur from Myocardial infarction if left untreated? |
A thinned wall that does not contract at all |
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What does MI mean |
Myocardial infarction - necrosis of tissue |
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What does an ST elevation indicate |
Myocardial infarction (heart attack) |
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What does stenting help with? |
Restoration of flow |
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STEMI treatment |
-Aspirin (antiplatelet) -Anticoagulant (heparin) -Oxygen -Nitrates -Morphine -Angiography is performed quickly |
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Coronary Stenting |
Stent placed opening the blockage and returning good flow to the rest of the coronary artery |
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Coronary Artery Bypass Grafting |
Surgical procedure |
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What is the most common artery used for bypassing the LAD |
Left internal mammary artery |
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What else can be harvested for bypass |
veins in legs or radial artery from arm |
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Complications of MI |
Arrhythmias Heart failure Cardiogenic shock Right ventricular infarction Papillary muscle rupture Ventricular free wall rupture Ventricular septal rupture Aneurysm formation |
