b.inside
| موضوع: Disorders of Cardiac Function 3/11/2009, 03:05 | |
| Definition and Functions of the Pericardium Definition A double-layered serous membrane Functions Isolates the heart from other thoracic structures Maintains its position in the thorax Prevents it from overfilling Contributes to coupling the distensibility between the two ventricles during diastole; they both fill equally Types of Pericardial Disorders Pericardial effusion The accumulation of fluid in the pericardial cavity Cardiac tamponade Slow or rapid compression of the heart due to accumulation of fluid, pus, or blood in pericardial sac Pericarditis An acute inflammatory process of the pericardium Can be acute, chronic or constrictive Coronary Heart Disease Impaired coronary blood flow that may cause: Angina Myocardial infarction or heart attack Cardiac arrhythmias Conduction defects Heart failure Sudden death The Evaluation of Coronary Blood Flow and Myocardial Perfusion ECG Echocardiogram M-mode, two-dimensional, Doppler, and esophageal Exercise stress testing Motorized treadmill and bicycle ergometer Nuclear cardiovascular imaging methods Myocardial perfusion imaging, infarct imaging, radionuclide angiocardiography, and positron emission tomography
Types of Artherosclerotic Lesions Fixed or stable plaque Obstructs blood flow Implicated in stable angina Unstable or vulnerable plaque Can rupture and cause platelet adhesion and thrombus formation. Implicated in unstable angina and myocardial infarction Major Determinants of Plaque Vulnerability to Rupture The size of the lipid-rich core and the stability and thickness of its fibrous cap The presence of inflammation with plaque degradation The lack of smooth muscle cells with impaired healing and plaque stabilization Plaques with a thin fibrous cap overlaying a large lipid core are at high risk for rupture
Antiplatelet and Anticoagulant Therapy Aspirin The preferred antiplatelet agent for preventing platelet aggregation in persons with CHD Inhibits synthesis of prostaglandin, thromboxane A2 Ticlopidine and clopidogrel May be used when aspirin is contraindicated Irreversibly inhibits the binding of ADP to its receptor on the platelets; no effect on prostaglandin synthesis
Antiplatelet and Anticoagulant Therapy (cont.) Platelet Receptor Antagonists Target a single step in the aggregation process Block the receptor involved in the final common pathway for platelet adhesion, activation, and aggregation Treat acute coronary syndrome Classification of Coronary Heart Disease Chronic ischemic heart disease Chronic stable angina, silent myocardial ischemia, and variant or vasospastic angina Acute coronary syndromes Represent the spectrum of ischemic coronary disease ranging from unstable angina through myocardial infarction
Types of Angina Chronic stable angina Associated with a fixed coronary obstruction that produces a disparity between coronary blood flow and metabolic demands of the myocardium Stable angina The initial manifestation of ischemic heart disease in approximately half of persons with CHD Populations Affected by Silent Myocardial Ischemia Persons who are asymptomatic without other evidence of CHD Persons who have had a myocardial infarct and continue to have episodes of silent ischemia Persons with angina who also have episodes of silent ischemia Non-pharmacologic Treatment of Angina Smoking cessation in persons who smoke Stress reduction Regular exercise program Limiting dietary intake of cholesterol and saturated fats Weight reduction if obesity is present Avoidance of cold or other stresses that produce vasoconstriction Determinants of ACS Status Persons with an ACS are routinely classified as low risk or high risk for infarction based on: Presenting characteristics ECG variables Serum cardiac markers The timing of presentation
Causes of Unstable Angina Atherosclerotic plaque disruption Platelet aggregation Secondary hemostasis Characteristics of Pain Associated with Unstable Angina The pain has a more persistent and severe course and is characterized by at least one of three features: It occurs at rest (or with minimal exertion) usually lasting more than 20 minutes (if not interrupted by nitroglycerin) It is severe and described as frank pain and of new onset It occurs with a pattern that is more severe, prolonged, or frequent than previously experienced
Basis for Diagnosis of Unstable Angina Pain severity and presenting symptoms Hemodynamic stability ECG findings Serum cardiac markers Manifestations of ST-segment Elevation AMI Abrupt onset Severe and crushing pain, usually substernal, radiating to the left arm, neck, or jaw Gastrointestinal complaints (nausea and vomiting) Complaints of fatigue and weakness Tachycardia, anxiety, restlessness, feelings of doom Pale, cool, and moist skin Factors Determining the Extent of an Infarct Location and extent of occlusion Amount of heart tissue supplied by the vessel Duration of the occlusion Metabolic needs of the affected tissue Extent of collateral circulation Heart rate, blood pressure, and cardiac rhythm Involvement of Heart Muscle in an Infarct Transmural infarcts Involve the full thickness of the ventricular wall Occur when there is obstruction of a single artery Subendocardial infarcts Involve the inner one third to one half of the ventricular wall Occur more frequently in the presence of severely narrowed but still patent arteries Medical Management Following Infarct Thrombolytic therapy Revascularization interventions Coronary artery bypass grafting (CABG) Percutaneous coronary intervention (PCI) Atherectomy Cardiac rehabilitation programs Myocardial Diseases Myocarditis Inflammation of the heart muscle and conduction system without evidence of myocardial infarction Primary cardiomyopathies Heart muscle diseases of unknown origin Secondary cardiomyopathies Conditions in which the cardiac abnormality results from another cardiovascular disease, such as myocardial infarction Types of Cardiomyopathies Dilated Hypertrophic Restrictive Arrhythmogenic Right Ventricular Peripartum
Predisposing Factors for Endocarditis A damaged endocardial surface A portal of entry by which the organism gains access to the circulatory system The presence of valvular disease, prosthetic heart valves, or congenital heart defects provides an environment conducive to bacterial growth In persons with preexisting valvular or endocardial defects, simple gum massage or an innocuous oral lesion may afford the pathogenic bacteria access to the bloodstream Manifestations of Rheumatic Fever Acute stage History of an initiating streptococcal infection Involves mesenchymal connective tissue of the heart, blood vessels, joints, and subcutaneous tissues Recurrent phase Extension of the cardiac effects of the disease Chronic phase Permanent deformity of the heart valves Function and Disorders of the Heart Valves Function: Promote directional flow of blood through the chambers of the heart Dysfunction results in disorders: Congenital defects Trauma Ischemic damage Degenerative changes Inflammation Disruptions Occurring with Valvular Heart Disease Narrowing of the valve opening so it does not open properly Stenosis Distortion of the valve so it does not close properly Incompetent or regurgitant valve: permits backward flow to occur when the valve should be closed Valve Disorders Mitral valve Disorders Mitral valve stenosis Mitral valve regurgitation Mitral valve prolapse Aortic Valve Disorders Aortic valve stenosis Aortic Valve Regurgitation
Factors Affecting Postnatal Pulmonary Vascular Development Prematurity Alveolar hypoxia Lung disease Congenital heart defects Signs and Symptoms of Childhood Congenital Heart Disease Symptoms associated with altered heart action Heart failure Pulmonary vascular disorders Difficulty in supplying the peripheral tissues with oxygen and other nutrients
Types of Congenital Heart Defects Patent Ductus Arteriosus Atrial Septal Defects Ventricular Septal Defects Endocardial Cushion Defects Pulmonary Stenosis Tetralogy of Fallot Transposition of the Great Vessels Coarctation of the Aorta Kawasaki Disease | |
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عدي الزعبي
| موضوع: رد: Disorders of Cardiac Function 3/11/2009, 17:24 | |
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theredrose
| موضوع: رد: Disorders of Cardiac Function 23/6/2011, 04:30 | |
| Disorders of Cardiac Function | |
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