Lecture 9 Cardiovascular Disease PDF

Cardiovascular Diseases and Evaluation Tests Pixabay.com 1. Heart Structure Four chambers, two atria and two ventricles Tricuspid and bicuspid (mitral) valves Veins Arteries 2. Heart Blood Flow Hopkinsmedicine.org 3. Electrocardiogram (ECG/EKG)...

Cardiovascular Diseases and Evaluation Tests Pixabay.com 1. Heart Structure Four chambers, two atria and two ventricles Tricuspid and bicuspid (mitral) valves Veins Arteries 2. Heart Blood Flow Hopkinsmedicine.org 3. Electrocardiogram (ECG/EKG) Recording of electrical changes in the myocardium during a cardiac cycle Changes are detectable on the surface of the body Electrodes placed on skin The instrument responds to small electrical changes Deflections – electrical changes in myocardium Distance between deflections – time between phases of cardiac cycle Baseline – time between heart beats https://www.mayoclinic.org/tests-procedures/ekg/about/pac-20384983 4. Electrocardiogram Cells remain polarized between cycles Resting state Triggered impulse: atrial cells depolarize First deflection – P wave Ventricular cells depolarize Greater deflection (QRS complex) Ventricular cells repolarize – T wave 5. The Impact of Electrolytes Changes on ECG ❖Potassium: Hypokalemia Hyperkalemia ❖Calcium: Hypocalcemia (prolonged S-T segment) Hypercalcemia 6. Cardiac Risk Assessment Risk’s factors and medical history Age, sex, blood pressure, smoking, family history Lipid Profile Total cholesterol, LDL-C, HDL-C, triglycerides Fasting blood glucose (or hemoglobin A1c) Natriuretic peptides Control blood pressure, fluid balance and electrolyte homeostasis Troponin levels Troponin I and troponin T Used to diagnose MI 7. Myocardial Infarction (MI) Also known as heart attack Necrosis caused by ischemia Responsible for the signs and symptoms Chest pain, shortness of breath, dizziness, nausea Main cause Wikimedia Commons, 2024 Blockage of vessels supplying O2 to cardiac muscle Coronary arteries Common cause of morbidity and mortality  8. Pathology of MI Most common cause: blockage of coronary arteries Atherosclerosis (inflammatory process) Progressive narrowing of the arterial Wikimedia Commons, 2024 lumen Reduced coronary perfusion Chest pain Unstable plaques may rupture Clot formation (thrombosis) Sudden occlusion of the artery Myocardial infarction  9. Cardiac Biomarkers Useful to detect myocardial cell death ❖Troponins – proteins involved in muscle contraction Rise within a few hours Highly sensitive troponin assays are available (3 hours) Remain elevated for over a week Troponin I for about 7-10 days Troponin T for even longer Elevation is associated with potential cardiac event in the next 30 to 60 days Troponin I or T reference is < 0.0 1 ng/mL 9. Cardiac Biomarkers ❖Troponins I and T Two of the most specific biomarkers for myocardial injury Part of troponin complex in myocardial cells Released when cells die Troponin I is the most specific ❖Troponin C Part of the complex, but also found in skeletal muscles Measured by immunoassays Troponins I and T levels greater than 0.01 ng/mL (with cardiac symptoms) and rising indicate cardiac injury 9. Cardiac Biomarkers ❖Myoglobin Function? High sensitivity for cardiac muscle damage but low specificity Its amount is proportional to the amount of muscle damage Myoglobin is useful when absent Levels rise early Usually 2-3 hours 9. Cardiac Biomarkers ❖Creatine kinase MB Enzyme involved in cellular energy metabolism Found in various tissues 3 isoenzymes Creatine kinase MM Creatine kinase MB (predominantly in myocardium) Creatine kinase BB Can be used to detect MI Levels rise within 3 to 4 hours after an MI It does not remain elevated (36 hours) It may be useful to diagnose reinfarction Less sensitive than troponins 9. Cardiac Biomarkers ❖C-reactive protein (CRP) Acute phase protein Liver Marker of inflammation (not specific) Pixabay.com Increased in atherosclerosis (Why?) Highly sensitive CRP (hs-CRP) test usefulness: Indicates presence of atherosclerotic plaque Determine risk for MI Not specific 9. Cardiac Biomarkers ❖Lactate dehydrogenase Found in diverse tissues Associated with energy metabolism Rise later than levels of troponins, myoglobin, and CK-MB Non-specific Rarely used to diagnose MI 10. MI Diagnosis- Other Tools ❖Electrocardiogram (ECG/EKG) Records the electrical activity of the heart Most important and specific test to diagnose MI Abnormal as soon as MI begins E.g., Q waves (transmural MI), ST segment elevation (or STEMI- hallmark-blockage) and T wave inversion (ongoing injury) Changes to ECG may not be present (30%) Cardiac markers are highly useful 11. MI Diagnosis- Other Tools ❖Echocardiogram Not primary diagnostic tool Ultrasound study Indicates heart’s ability to pump blood Valuable insights in cases of MI Wikimedia Commons, 2024 Abnormalities in motion of the wall Complications (e.g. ventricular septal defects) 12. MI Diagnosis - Other Tools Angiogram Not primary diagnostic tool Coronary angiography Detects blockage in the arterial system Contrast dye and x-ray are utilized Wikimedia Commons, 2024 13. MI Diagnosis History ECG changes Biochemical markers of MI Troponins I and T Myoglobin Creatine Kinase MB Each appears in the blood in its unique time frame after an MI MI classic feature: Severe crushing central chest pain (angina –like pain) Potential “silent” MI Up to 30% patients do not have specific changes on ECG 14. Angina Pectoris Chest pain due to coronary disease Reduced blood flow to the heart muscle Usually not associated with permanent damage to the heart muscle Angina pectoris (stable) Caused by reduced blood flow Coronary artery narrowing or spasm Often physical exercise and stress Relieved by rest and medication ECG changes during angina episode No specific changes Temporary and reversible ST-segment depression during angina episode Angina pectoris (unstable) 15. Acute Coronary Syndrome (ACS) When myocardial ischemia is suspected Conditions associated with low blood supply to the heart muscle Rupture of atherosclerotic plaque and thrombosis of a coronary artery It includes: ST-segment elevation myocardial infarction (STEMI) More severe heart attack Non-ST-segment elevation myocardial infarction (NSTEMI) Less severe heart attack Unstable angina Chest pain at rest (medical emergency) 16. Endocarditis Infection of the endocardium Commonly associated with: Viridans Streptococci Staphylococcus aureus Enterococcus sp. Wikimedia Commons, 2024 Endocarditis rarely affects individuals with a healthy heart Heart valve problems, previous cardiac damage, congenital heart defects Bacteria reach heart through the bloodstream Diagnosis: Clinical evaluation Bacteriologic test (blood cultures) from 2 separate sites C-reactive protein (CRP) Echocardiogram 17. Myocarditis Inflammation of myocardium Associated with chronic infection Viruses, bacteria, parasites and fungi Wikimedia Commons, 2024 Associated with drugs and autoimmune diseases Pixabay.com Lymphocytes damage the myocardium Severe myocarditis may lead to MI or stroke Stasis of blood and thromboses  18. Pericarditis Inflammation of the pericardium Acute or chronic Common causes: MI, trauma, viral infection, fungal infection, metastatic cancer, kidney failure, heart drugs Complications: Cardiac tamponade Compression of the heart Chronic pericarditis Wikimedia Commons, 2024 19. Endocarditis, Myocarditis and Pericarditis - Diagnosis Blood cultures White blood cell count Troponin and myoglobin levels Pixabay.com Antibody titers (identification of IgM and IgG levels) Imaging techniques (e.g., echocardiography) Cardiac MRI (can confirm diagnosis of myocarditis) 20. Congestive Heart Failure (CHF) Progressive disease Decreased ability to pump blood over time Causes: MI Hypertension Heart valvular disease https://youtu.be/GnpLm9fzYxU?si=9VXVAS-o5T4S0wuF Cardiomyopathies Stasis in the blood vessels occurs as diseases progresses Increased blood pressure Fluid moves out to the extracellular space Accumulation of fluids in lungs and extremities (signs and symptoms CHF) Shortness of breath, fatigue, peripheral edema 21. Congestive Heart Failure (CHF) - Diagnosis Not a single test available Symptoms are not specific Echocardiogram Measure blood volume Chest x-ray Fluid around the heart and cardiomegaly ECG- electrical activities - origin of CHF Biochemical tests B-type natriuretic peptide (BNP)- elevated Pressure/stretch of ventricles Electrolytes (high Na and low K) Decreased blood flow through kidneys Renin-angiotensin aldosterone system (RAAS) activation BUN and creatinine- elevated