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Which cardiac biomarker is most specifically associated with myocardial injury?
How long do troponin levels remain elevated after myocardial injury?
Which of the following biomarker tests is least specific for detecting cardiac events?
What is the typical time frame for myoglobin levels to rise after muscle damage?
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Which cardiac biomarker can help indicate the presence of atherosclerotic plaque?
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What is a key characteristic of Creatine kinase MB regarding myocardial infarction detection?
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Which cardiac biomarker is often useful for diagnosing reinfarction?
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Which biomarker is known to rise later than troponins, myoglobin, and CK-MB?
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What is a risk factor that can be determined using the high sensitivity C-reactive protein test?
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Which troponin assay is available to detect levels within a few hours of myocardial injury?
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What is the purpose of placing electrodes on the skin during an electrocardiogram?
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Which wave in an electrocardiogram represents the depolarization of the atrial cells?
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What condition is characterized by prolonged S-T segment changes on an electrocardiogram?
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Which of the following is NOT a factor considered in cardiac risk assessment?
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What is the primary cause of myocardial infarction?
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Which of the following accurately describes a characteristic of myocardial infarction?
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What role do natriuretic peptides play in cardiac risk assessment?
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Atherosclerosis is primarily associated with which process related to myocardial infarction?
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Which of the following conditions is indicative of hyperkalemia in an electrocardiogram?
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Which cardiac event is associated with the T wave in an ECG?
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Which bacteria is most commonly associated with endocarditis?
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Which condition is least likely to contribute to the development of endocarditis?
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What is a common complication associated with pericarditis?
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Which diagnostic test is specifically used to confirm myocarditis?
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What is a primary factor that may lead to myocarditis?
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Which symptom is most closely associated with congestive heart failure (CHF)?
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What mechanism primarily leads to damage in myocarditis?
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Which of the following is NOT a direct cause of pericarditis?
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Which test is utilized for evaluating inflammatory processes in various cardiac conditions?
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What process is indicated by increased blood pressure over time in CHF?
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Which of the following changes may be observed on an ECG during a myocardial infarction?
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What is the primary use of an echocardiogram in the context of myocardial infarction?
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What is the role of an angiogram in diagnosing myocardial infarction?
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Which cardiac marker is associated with the earliest rise after a myocardial infarction?
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What characteristic distinguishes unstable angina from stable angina?
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Which feature is commonly associated with a silent myocardial infarction?
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During a typical episode of stable angina, which ECG change is likely to occur?
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Which of the following conditions is classified under Acute Coronary Syndrome (ACS)?
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Identify the hallmark feature of myocardial infarction (MI).
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Study Notes
Heart Structure
- The heart has four chambers: two atria and two ventricles.
- The heart contains tricuspid and bicuspid (mitral) valves.
- The heart contains veins and arteries.
Heart Blood Flow
- The heart pumps blood throughout the body through a closed circulatory system.
- Deoxygenated blood travels from the body to the right atrium.
- Blood is pumped to the right ventricle and then to the lungs to pick up oxygen.
- Oxygenated blood is returned to the left atrium.
- Blood is pumped to the left ventricle, then to the body.
Electrocardiogram (ECG/EKG)
- An ECG records the electrical changes in the myocardium during a cardiac cycle.
- Electrodes placed on the skin detect these changes.
- Deflections on the ECG represent electrical changes in the myocardium.
- The distance between deflections indicates the time between phases of the cardiac cycle.
- The baseline represents the time between heartbeats.
Electrocardiogram Wave Forms
- The P wave represents atrial depolarization.
- The QRS complex represents ventricular depolarization.
- The T wave represents ventricular repolarization.
Impact of Electrolyte Changes on ECG
- Hypokalemia can cause a flattened T wave and prolonged QT interval.
- Hyperkalemia can cause peaked T waves, widened QRS complex, and potential cardiac arrest.
- Hypocalcemia can cause prolonged ST segment.
- Hypercalcemia can cause shortened QT interval.
Cardiac Risk Assessment
- Factors considered in cardiac risk assessment include age, sex, blood pressure, family history, and smoking.
- Lipid profiles include total cholesterol, LDL-C, HDL-C, and triglycerides.
- Fasting blood glucose or hemoglobin A1c are also used to assess risk.
- Natriuretic peptides control blood pressure, fluid balance, and electrolyte homeostasis.
- Troponin levels (Troponin I and T) are used to diagnose myocardial infarction (MI).
Myocardial Infarction (MI)
- MI is also known as a heart attack.
- MI results from necrosis caused by ischemia.
- Common symptoms include chest pain, shortness of breath, dizziness, and nausea.
- MI commonly results from blockage of coronary arteries, which supply oxygen to cardiac muscle.
- Atherosclerosis, an inflammatory process, contributes to MI.
Pathology of MI
- Atherosclerosis progressively narrows the lumen of arteries, reducing coronary perfusion.
- Unstable plaque rupture leads to clot formation (thrombosis), which suddenly occludes the artery, resulting in MI.
Cardiac Biomarkers
- Cardiac biomarkers are useful in detecting myocardial cell death.
Troponins
- Troponins, proteins involved in muscle contraction, rise within a few hours after an MI.
- Highly sensitive troponin assays can detect increases within 3 hours.
- Troponin levels remain elevated for over a week.
- Troponin I or T reference range is below 0.01 ng/mL.
Troponins I and T
- Troponins I and T are two of the most specific biomarkers for myocardial injury.
- They are part of the troponin complex in myocardial cells and are released when cells die.
- Troponin I is considered the most specific.
Troponin C
- Troponin C is also part of the troponin complex, but it is also found in skeletal muscle.
Myoglobin
- Myoglobin has high sensitivity for cardiac muscle damage, but low specificity.
- Levels are proportional to the amount of muscle damage.
- Myoglobin levels rise early, usually within 2-3 hours.
Creatine Kinase MB (CK-MB)
- CK-MB is an enzyme involved in cellular energy metabolism, and found in various tissues.
- CK-MB levels rise 3-4 hours after an MI, but do not remain elevated long-term.
- CK-MB is less sensitive than troponins.
C-reactive Protein (CRP)
- CRP is an acute-phase protein produced by the liver and is a marker of inflammation.
- Increased CRP indicates the presence of atherosclerotic plaque and can determine risk for MI.
- Highly sensitive CRP (hs-CRP) tests are useful in this regard.
Lactate Dehydrogenase
- Lactate dehydrogenase is found in many tissues.
- Levels rise later than troponins, myoglobin, and CK-MB.
- It is non-specific and rarely used to diagnose MI.
MI Diagnosis - Other Tools
- Electrocardiogram (ECG/EKG): This is the most important and specific test in diagnosing MI. Abnormal ECG readings can indicate MI, including Q waves (transmural MI), ST segment elevation (STEMI – hallmark of blockage), and T wave inversion (ongoing injury). However, changes to the ECG may not be present in up to 30% of cases, making cardiac biomarkers crucial.
- Echocardiogram: While not a primary diagnostic tool, echocardiography (ultrasound study) provides valuable insights into heart function after an MI, revealing abnormalities in wall movement and complications.
- Angiogram: Coronary angiography detects blockage in the arterial system using contrast dye and x-rays. It helps identify the location and severity of blockages.
- Chest X-Ray: Useful for identifying heart enlargement, pulmonary congestion, or pleural effusions.
MI Diagnosis
- MI is diagnosed based on clinical history, ECG changes, and cardiac biomarker elevations.
- Troponins I and T, myoglobin, and CK-MB each appear in the blood at different times after an MI.
- The classic symptom of MI is severe crushing central chest pain (angina-like pain).
Angina Pectoris
- Angina is chest pain caused by coronary artery disease resulting in reduced blood flow to the heart muscle.
- Angina pectoris (stable) is often precipitated by physical exertion or stress and is usually relieved by rest.
- ECG changes during an angina episode are usually temporary and reversible, with possible ST-segment depression.
- Angina pectoris (unstable) is a medical emergency requiring immediate attention.
Acute Coronary Syndrome (ACS)
- ACS refers to conditions associated with low blood supply to the heart muscle.
- ACS includes:
- STEMI (ST-segment elevation myocardial infarction)
- NSTEMI (non-ST-segment elevation myocardial infarction)
- Unstable angina (chest pain at rest)
Endocarditis
- Endocarditis is an infection of the endocardium, the inner lining of the heart.
- It is commonly associated with Viridans streptococci, Staphylococcus aureus, and Enterococcus sp.
- Endocarditis rarely affects individuals with healthy hearts but can occur in those with pre-existing heart valve problems, previous cardiac damage, or congenital heart defects.
- Bacteria reach the heart through the bloodstream.
- Diagnosis involves clinical evaluation, blood cultures, CRP levels, and echocardiography.
Myocarditis
- Myocarditis is an inflammation of the myocardium.
- It can be caused by viruses, bacteria, parasites, fungi, drugs, or autoimmune diseases.
- Lymphocytes damage the myocardium.
- Severe myocarditis can lead to MI or stroke.
Pericarditis
- Pericarditis is an inflammation of the pericardium, the sac surrounding the heart.
- It can be acute or chronic.
- Common causes include MI, trauma, viral infections, fungal infections, metastatic cancer, kidney failure, and heart drugs.
- Complications include cardiac tamponade (heart compression) and chronic pericarditis.
Endocarditis, Myocarditis, and Pericarditis - Diagnosis
- Diagnosis involves blood cultures, white blood cell counts, troponin and myoglobin levels, antibody titers, and imaging techniques like echocardiography.
- Cardiac MRI can confirm the diagnosis of myocarditis.
Congestive Heart Failure (CHF)
- CHF is a progressive disease that decreases the heart's ability to pump blood efficiently over time.
- It can be caused by MI, hypertension, heart valve disease, and cardiomyopathies.
- Stasis in the blood vessels occurs as the disease progresses, resulting in increased blood pressure and fluid accumulation in the lungs and extremities.
- Signs and symptoms of CHF include shortness of breath, fatigue, and peripheral edema.
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Description
Test your knowledge on the structure and function of the heart, including its chambers, valves, and blood flow. Explore the significance of the electrocardiogram and its waveforms in understanding cardiac health. This quiz covers essential concepts important for any student studying human biology or health sciences.
