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Guilherme Mazui

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What is the Difference Between Ischemia and Infarction?

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The main difference between ischemia and infarction lies in the degree of blood flow reduction and the consequences:

  • Ischemia: This term refers to a decreased blood flow to a tissue, resulting in hypoxia or insufficient oxygen supply to that tissue. In the context of the heart, it is called myocardial ischemia. It occurs when the heart's blood supply is reduced due to narrowed arteries or a clot, usually caused by atherosclerosis, which is the accumulation of fatty materials such as cholesterol.
  • Infarction: This term means that blood flow has been completely cut off, leading to necrosis or cellular death. In the heart, it is called myocardial infarction, and it occurs when blood flow is cut off for about 20 minutes, causing the affected part of the heart muscle to die.

ECG changes associated with myocardial infarction and ischemia can be difficult to differentiate. Generally, ischemia presents with inverted T waves and flat or downsloping ST-segment depression, while myocardial infarction shows ST-segment elevation, T wave inversion, and Q waves. The best way to differentiate acute myocardial infarction (AMI) from ischemia is to look at the ECG changes: AMI will typically cause ST elevation in two or more contiguous leads, while ischemia may only cause ST elevation in one lead. Additionally, AMI usually causes Q waves, while ischemia typically does not.

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  • What is the Difference Between Ischemia and Infarction?
  • Comparative Table: Ischemia vs Infarction

    • Comparative Table: Ischemia vs Infarction

    Here is a table comparing the differences between ischemia and infarction:

    Feature Ischemia Infarction
    Definition Ischemia refers to a reduced blood supply to the heart muscle, usually due to coronary artery disease, but without damage to the heart muscle. Infarction refers to the irreversible damage to the heart muscle caused by an acute myocardial injury due to prolonged ischemia.
    Cause Ischemia is caused by reduced blood flow to the heart muscle, typically due to atherosclerosis, which is the accumulation of fatty materials such as cholesterol. Infarction occurs when acute myocardial ischemia causes myocardial injury, leading to irreversible damage to the heart muscle.
    Symptoms In patients with chronic ischemia, no troponin is released, and there is inadequate oxygen supply to the myocardium without damage. Acute myocardial infarction (AMI) is identified by symptoms, new EKG changes, and/or cardiac imaging.
    ECG Changes In ischemia, a zone of ischemia typically produces ST segment depression, while a zone of injury produces ST segment elevation. In infarction, a zone of infarction produces a large Q wave in the QRS complex.
    Treatment Treatment for ischemic heart disease depends on the underlying disease process. In stable ischemic heart disease, antianginal drugs may be used to reduce the rate of occurrence and severity of angina attacks. Treatment for infarction focuses on restoring blood flow to the affected area of the heart muscle, which may involve medications, percutaneous coronary intervention, or coronary artery bypass graft surgery.

    To summarize, ischemia refers to a reduced blood supply to the heart muscle without damage, while infarction refers to the irreversible damage to the heart muscle caused by an acute myocardial injury due to prolonged ischemia. The causes, symptoms, ECG changes, and treatments for each condition differ as illustrated in the table above.

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    Guilherme Mazui

    Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.