Ischemia and Myocardial Infarction
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Questions and Answers

What is the critical time period beyond which ischemia can lead to myocardial infarct?

  • 40 minutes
  • 30 minutes
  • 20 minutes (correct)
  • 15 minutes

    • What is the type of angina that occurs due to abnormal vasospasm of coronary vessels?

  • Stable angina
  • Unstable angina
  • Prinzmetal angina (correct)
  • Variant angina

    • What is the cause of pain in stable angina?

  • Build up of lactic acid
  • Abnormal stretching of the ischemic myocardium
  • Both A and B (correct)
  • Neither A nor B

    • What is the result of sudden coronary obstruction over a ruptured or ulcerated atherosclerotic plaque?

    <p>Acute coronary syndromes</p> Signup and view all the answers

    What is the treatment for Prinzmetal angina?

    <p>Nitroglycerin and Calcium antagonists</p> Signup and view all the answers

    What is the consequence of lack of relief in stable angina?

    <p>Development of myocardial infarction</p> Signup and view all the answers

    What is the consequence of persistent vasospasm in Prinzmetal angina?

    <p>Development of myocardial infarction</p> Signup and view all the answers

    What is the underlying cause of stable angina?

    <p>Atherosclerotic coronary arteries</p> Signup and view all the answers

    What is the underlying cause of unstable angina?

    <p>Atherosclerotic plaque complication</p> Signup and view all the answers

    What is the consequence of prolonged ischemia (>20 minutes) in myocardial cells?

    <p>Irreversible damage</p> Signup and view all the answers

    What is the result of prolonged ischemia that lasts more than 20 minutes?

    <p>Irreversible damage</p> Signup and view all the answers

    What is the timeframe within which cardiac cells can withstand ischemic conditions before cellular death occurs?

    <p>20 minutes</p> Signup and view all the answers

    What is the underlying condition of individuals who experience unstable angina?

    <p>Worsening CAD</p> Signup and view all the answers

    What is the consequence of cellular death in myocardial tissue?

    <p>Tissue necrosis</p> Signup and view all the answers

    What is the signal that an infarct is near in unstable angina?

    <p>Increased frequency of episodes</p> Signup and view all the answers

    What is the common underlying cause of acute coronary syndromes?

    <p>Sudden coronary obstruction</p> Signup and view all the answers

    What is the consequence of ATP exhaustion in myocardial cells?

    <p>Sodium-potassium pump failure</p> Signup and view all the answers

    What is the possible consequence of unrelieved myocardial ischemia?

    <p>Culminating lethal response</p> Signup and view all the answers

    What is the characteristic of atherosclerotic plaque in individuals with unstable angina?

    <p>Complicated atherosclerotic plaque</p> Signup and view all the answers

    What is the underlying pathology of myocardial infarction?

    <p>Unrelieved myocardial ischemia</p> Signup and view all the answers

    What is the time frame within which EKG changes can be noted after hypoxia?

    <p>30-60 seconds</p> Signup and view all the answers

    What is the consequence of increased sympathetic activity?

    <p>Increased heart rate</p> Signup and view all the answers

    What is the characteristic of unstable angina?

    <p>Episodes increase in frequency</p> Signup and view all the answers

    What is the possible cause of rupture that leads to acute coronary syndromes?

    <p>All of the above</p> Signup and view all the answers

    What is a common etiology of myocarditis?

    <p>All of the above</p> Signup and view all the answers

    What is idiopathic dilated cardiomyopathy?

    <p>A type of heart disease with an unknown reason</p> Signup and view all the answers

    What is a common result of myocarditis?

    <p>Weakening of the heart muscle</p> Signup and view all the answers

    What is a possible consequence of myocarditis?

    <p>Heart transplantation</p> Signup and view all the answers

    What type of viruses are most commonly associated with myocarditis in North America and Europe?

    <p>Coxsackie viruses</p> Signup and view all the answers

    What is a possible cause of myocarditis?

    <p>All of the above</p> Signup and view all the answers

    What is a characteristic of the heart in myocarditis?

    <p>It becomes dilated and flabby</p> Signup and view all the answers

    What type of symptoms do coxsackie viruses and other enteroviruses often manifest as?

    <p>Flu-like symptoms</p> Signup and view all the answers

    What is the primary method of diagnosis for myocarditis?

    <p>Biopsy of the heart muscle</p> Signup and view all the answers

    What is the outcome in half of the cases of myocarditis?

    <p>Resolution of symptoms in 1-2 months</p> Signup and view all the answers

    What is the difference between cardiomyopathies and congestive heart failure?

    <p>Cardiomyopathies may develop as primary or secondary disorders, while congestive heart failure is a separate condition</p> Signup and view all the answers

    What is the characteristic of primary cardiomyopathies?

    <p>They are heart muscle diseases of unknown origin</p> Signup and view all the answers

    What is the characteristic of secondary cardiomyopathies?

    <p>They are caused by a known etiology, such as another cardiovascular disease</p> Signup and view all the answers

    What is the characteristic of dilated cardiomyopathy?

    <p>It is characterized by ventricular dilation</p> Signup and view all the answers

    What is the treatment goal for myocarditis?

    <p>To prevent myocardial damage</p> Signup and view all the answers

    What is the common outcome in the other half of the cases of myocarditis?

    <p>Progression to heart failure and arrhythmias leading to sudden death</p> Signup and view all the answers

    Study Notes

    Ischemia and Myocardial Infarction

    • Ischemia of less than 20 minutes is considered reversible, and cells remain viable
    • Ischemia progressing beyond 20 minutes leads to myocardial infarction (irreversible damage)
    • Clinical manifestations of ischemia include angina pectoris, which is severe pain originating from the heart in response to myocardial ischemia

    Angina Pectoris

    • There are three types of angina: stable, Prinzmetal (variant), and unstable
    • Stable angina:
      • Occurs when atherosclerotic coronary arteries cannot dilate to increase blood flow during physical activity, mental stress, or anger
      • Discomfort is transient (3-5 minutes) and reversible with rest and nitroglycerin
    • Prinzmetal angina:
      • Occurs due to abnormal vasospasm of coronary vessels, resulting in unpredictable chest pain
      • Typically occurs at rest, especially during REM sleep
      • May be caused by hyperactivity of the sympathetic nervous system or increased calcium influx into arterial smooth muscle
    • Unstable angina:
      • A combination of classic and variant angina
      • Seen in individuals with worsening coronary artery disease (CAD)
      • Episodes of unstable angina increase in frequency, signaling an impending infarction

    Myocardial Infarction

    • Results from prolonged ischemia (>20 minutes) causing irreversible damage
    • Death of myocardial cells following prolonged deprivation
    • Culminating lethal response to unrelieved myocardial ischemia

    Cardiac Cells and Ischemia

    • Cardiac cells can withstand ischemic conditions for ~20 minutes before cellular death occurs
    • EKG changes can be noted after 30-60 seconds of hypoxia
    • Cells can remain viable if blood flow returns within 20 minutes

    Cardiomyopathy and Myocarditis

    • Cardiomyopathy refers to any disease or injury of the heart not related to coronary artery disease, hypertension, or congenital malformations
    • Primary cardiomyopathies are heart muscle diseases of unknown origin (idiopathic)
    • Secondary cardiomyopathies arise from a known etiology, such as myocarditis, autoimmune disease, or toxins
    • Myocarditis is an inflammation of the heart muscle and conduction system without evidence of coronary artery disease or MI

    Myocarditis

    • Most often caused by viral infections of the myocardium (e.g., coxsackie viruses and other enteroviruses)
    • Can be caused by bacterial and fungal infections, systemic diseases like lupus, radiation therapy, and hypersensitivity reactions
    • Results in weakening of the heart muscle and decreased cardiac contractility
    • Can progress to dilated cardiomyopathy, a major cause of heart transplantation in the U.S.

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    Description

    This quiz covers the effects of ischemia on myocardial cells, including reversible and irreversible ischemia, angina, and myocardial infarct.

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