40 Questions
What is the critical time period beyond which ischemia can lead to myocardial infarct?
20 minutes
What is the type of angina that occurs due to abnormal vasospasm of coronary vessels?
Prinzmetal angina
What is the cause of pain in stable angina?
Both A and B
What is the result of sudden coronary obstruction over a ruptured or ulcerated atherosclerotic plaque?
Acute coronary syndromes
What is the treatment for Prinzmetal angina?
Nitroglycerin and Calcium antagonists
What is the consequence of lack of relief in stable angina?
Development of myocardial infarction
What is the consequence of persistent vasospasm in Prinzmetal angina?
Development of myocardial infarction
What is the underlying cause of stable angina?
Atherosclerotic coronary arteries
What is the underlying cause of unstable angina?
Atherosclerotic plaque complication
What is the consequence of prolonged ischemia (>20 minutes) in myocardial cells?
Irreversible damage
What is the result of prolonged ischemia that lasts more than 20 minutes?
Irreversible damage
What is the timeframe within which cardiac cells can withstand ischemic conditions before cellular death occurs?
20 minutes
What is the underlying condition of individuals who experience unstable angina?
Worsening CAD
What is the consequence of cellular death in myocardial tissue?
Tissue necrosis
What is the signal that an infarct is near in unstable angina?
Increased frequency of episodes
What is the common underlying cause of acute coronary syndromes?
Sudden coronary obstruction
What is the consequence of ATP exhaustion in myocardial cells?
Sodium-potassium pump failure
What is the possible consequence of unrelieved myocardial ischemia?
Culminating lethal response
What is the characteristic of atherosclerotic plaque in individuals with unstable angina?
Complicated atherosclerotic plaque
What is the underlying pathology of myocardial infarction?
Unrelieved myocardial ischemia
What is the time frame within which EKG changes can be noted after hypoxia?
30-60 seconds
What is the consequence of increased sympathetic activity?
Increased heart rate
What is the characteristic of unstable angina?
Episodes increase in frequency
What is the possible cause of rupture that leads to acute coronary syndromes?
All of the above
What is a common etiology of myocarditis?
All of the above
What is idiopathic dilated cardiomyopathy?
A type of heart disease with an unknown reason
What is a common result of myocarditis?
Weakening of the heart muscle
What is a possible consequence of myocarditis?
Heart transplantation
What type of viruses are most commonly associated with myocarditis in North America and Europe?
Coxsackie viruses
What is a possible cause of myocarditis?
All of the above
What is a characteristic of the heart in myocarditis?
It becomes dilated and flabby
What type of symptoms do coxsackie viruses and other enteroviruses often manifest as?
Flu-like symptoms
What is the primary method of diagnosis for myocarditis?
Biopsy of the heart muscle
What is the outcome in half of the cases of myocarditis?
Resolution of symptoms in 1-2 months
What is the difference between cardiomyopathies and congestive heart failure?
Cardiomyopathies may develop as primary or secondary disorders, while congestive heart failure is a separate condition
What is the characteristic of primary cardiomyopathies?
They are heart muscle diseases of unknown origin
What is the characteristic of secondary cardiomyopathies?
They are caused by a known etiology, such as another cardiovascular disease
What is the characteristic of dilated cardiomyopathy?
It is characterized by ventricular dilation
What is the treatment goal for myocarditis?
To prevent myocardial damage
What is the common outcome in the other half of the cases of myocarditis?
Progression to heart failure and arrhythmias leading to sudden death
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.
This quiz covers the effects of ischemia on myocardial cells, including reversible and irreversible ischemia, angina, and myocardial infarct.
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