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Questions and Answers
Which condition can occur due to transient decreases in oxygen delivery?
Which condition can occur due to transient decreases in oxygen delivery?
Microscopic infarcts are typically associated with significant ECG changes.
Microscopic infarcts are typically associated with significant ECG changes.
False
What is the typical presentation of a classic myocardial infarction?
What is the typical presentation of a classic myocardial infarction?
Severe, crushing substernal chest pain that can radiate to the neck, jaw, epigastrium, or left arm.
Myocardial necrosis begins in the ______ region and progresses to involve the entire wall thickness.
Myocardial necrosis begins in the ______ region and progresses to involve the entire wall thickness.
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What differentiates typical angina from myocardial infarction?
What differentiates typical angina from myocardial infarction?
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Atypical myocardial infarcts can be entirely asymptomatic in some patients.
Atypical myocardial infarcts can be entirely asymptomatic in some patients.
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_____ may occur when an occlusive thrombus lyses before a full-thickness infarction develops.
_____ may occur when an occlusive thrombus lyses before a full-thickness infarction develops.
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Match the symptoms with their corresponding conditions:
Match the symptoms with their corresponding conditions:
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What are common underlying conditions that can lead to atypical myocardial infarction?
What are common underlying conditions that can lead to atypical myocardial infarction?
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What is the major underlying cause of ischemic heart disease (IHD)?
What is the major underlying cause of ischemic heart disease (IHD)?
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Women are at a higher risk for myocardial infarction than men.
Women are at a higher risk for myocardial infarction than men.
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What percentage of myocardial infarctions occurs before the age of 40?
What percentage of myocardial infarctions occurs before the age of 40?
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Transmural infarctions involve the full thickness of the myocardium and are caused by __________ vessel occlusion.
Transmural infarctions involve the full thickness of the myocardium and are caused by __________ vessel occlusion.
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What typically leads to the necrosis of heart muscle in myocardial infarctions?
What typically leads to the necrosis of heart muscle in myocardial infarctions?
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Match the types of myocardial infarction with their characteristics:
Match the types of myocardial infarction with their characteristics:
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What is a common symptom of severe coronary arterial narrowing?
What is a common symptom of severe coronary arterial narrowing?
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What is a common clinical feature of Myocardial Infarction?
What is a common clinical feature of Myocardial Infarction?
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Inverted T waves are typically seen in patients with Myocardial Infarction.
Inverted T waves are typically seen in patients with Myocardial Infarction.
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What does CK-MB activity indicate in the context of a heart attack?
What does CK-MB activity indicate in the context of a heart attack?
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After a Myocardial Infarction, troponins are typically detectable within ___ hours.
After a Myocardial Infarction, troponins are typically detectable within ___ hours.
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Match the following cardiac biomarkers with their characteristics:
Match the following cardiac biomarkers with their characteristics:
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What is a potential consequence of a massive Myocardial Infarction?
What is a potential consequence of a massive Myocardial Infarction?
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Symptoms of Myocardial Infarction do not typically include nausea and light-headedness.
Symptoms of Myocardial Infarction do not typically include nausea and light-headedness.
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Which arrhythmia-related event accounts for most MI-related deaths occurring before hospitalization?
Which arrhythmia-related event accounts for most MI-related deaths occurring before hospitalization?
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An absence of change in CK and CK-MB levels during the first 2 days essentially ___ the diagnosis of MI.
An absence of change in CK and CK-MB levels during the first 2 days essentially ___ the diagnosis of MI.
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Study Notes
Ischemic Heart Disease
- Ischemic heart disease (IHD) involves several related syndromes caused by myocardial ischemia, an imbalance between cardiac blood supply (perfusion) and myocardial oxygen and nutritional needs.
- It's the leading cause of mortality worldwide, accounting for 7 million deaths annually.
- More than 90% of cases result from reduced coronary blood flow due to obstructive atherosclerosis.
- Less common causes include increased demand (e.g., heart rate or hypertension), diminished blood volume (e.g., hypotension or shock), diminished oxygenation (e.g., pneumonia), and reduced oxygen-carrying capacity (e.g., anemia or CO poisoning).
Angina Pectoris
- Angina pectoris is intermittent chest pain caused by transient, reversible myocardial ischemia.
- The pain is likely a consequence of ischemia-induced release of adenosine, bradykinin, and other molecules that stimulate autonomic afferents.
- Three types of angina are recognized:
- Typical or stable angina: episodic chest pain linked to exertion or increased demand (e.g., tachycardia). The pain is crushing or squeezing, radiating to the left arm or jaw. The pain is relieved by rest or nitroglycerin (a vasodilator).
- Prinzmetal or variant angina: occurs at rest and is caused by coronary artery spasms. Symptoms can be similar to typical angina, but can occur unexpectedly. It can affect normal vessels, not just those with existing plaques. Responds well to vasodilators.
- Unstable angina: characterized by increasingly frequent pain, precipitated by less exertion or even at rest. Often linked to plaque disruption, thrombosis, distal embolization, and/or vasospasm -- a precursor to myocardial infarction (MI).
Myocardial Infarction (MI)
- Also known as a "heart attack," MI involves necrosis (death) of heart muscle tissues due to ischemia.
- Atherosclerosis is the primary cause of MI, sharing the same risk factors.
- MI occurrences rise with age and increasing atherosclerosis.
- Approximately 10% occur before age 40, and 45% before age 65. Men are at higher risk than women initially, though the gap narrows with age.
- MI types include:
- Transmural infarction: involves the full thickness of the myocardium, usually due to coronary artery thrombosis.
- Subendocardial infarction: limited to the myocardium's inner third, usually due to transient decreases in oxygen delivery, increased oxygen demand, or when a thrombus lyses before complete infarction develops.
- Microscopic infarcts: occur in the setting of small-vessel occlusions, may not show significant ECG changes.
Clinical Features of MI
- Classic MI is typically associated with severe crushing, substernal chest pain that radiates to the neck, jaw, epigastrium, or left arm. Atypical symptoms can occur.
- Patients often present with a rapid, weak pulse, diaphoresis, weakness, lightheadedness, vomiting, and palpitations.
- Sometimes, cardiogenic shock might be present, which is marked by low blood pressure and fluid collection.
Electrocardiographic Abnormalities (ECG)
- ECG abnormalities, often including inverted T waves and deep Q waves, are common in MI.
- Arrhythmias are also frequent, potentially causing sudden cardiac death.
Laboratory Evaluation of MI
- Early MI indicators include rising CK-MB and troponin levels.
- CK-MB and activity peaks within 2-4 hours of MI, then returns to normal after approximately 72 hours, Absence of a significant change implies possible lack of MI.
- Troponins, typically not present in the bloodstream, rise within 2-4 hours of MI and remain elevated for days, providing a more precise and longer-term marker for the event.
- Absence of measurable changes in the first 2 days following chest pain often rules out MI as a diagnosis.
Consequences and Complications of MI
- Potential Complications include:
- Contractile dysfunction: some degree of left ventricular failure, manifested as low blood pressure, pulmonary congestion, and edema. Cardiogenic shock can occur.
- Right ventricular infarction: significant right-sided heart failure.
- Papillary muscle dysfunction: poorly contractile papillary muscles may result in post-infarct mitral regurgitation.
- Myocardial rupture (rare).
- Left ventricular wall rupture (rare).
- Ventricular septal rupture (rare).
- Arrhythmias (very common).
- Mural thrombus: occurs in combination with myocardial stasis and increased endocardial damage, potentially leading to thromboembolism.
- Pericarditis (inflammation around the heart): often occurs 2 to 3 days after MI.
- Ventricular aneurysm: a thinned, scar-tissue-filled section of a heart chamber, often after a large transmural infarct.
References - (These are not included to keep the summaries concise.)
- Robbins Basic Pathology (10th edition, by Vinay Kumar, Abul K. Abbas, and Jon C. Aster)
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Description
This quiz covers Ischemic Heart Disease (IHD), which is a leading cause of death worldwide due to myocardial ischemia. It discusses the underlying causes, including atherosclerosis and other factors, as well as details on angina pectoris and its manifestations. Test your knowledge on key concepts and statistics related to this critical health issue.
