Heart attack (myocardial infarction) pathophysiology | NCLEX-RN | Khan Academy

Summary

This script delves into the physiological process of a heart attack, or myocardial infarction, caused by atherosclerotic plaque build-up in the coronary arteries. It explains how plaque rupture and subsequent clot formation can obstruct blood flow, leading to oxygen deprivation in heart muscle cells. The script vividly describes the symptoms, the body's response, including referred pain and adrenaline surge, and the critical importance of timely treatment to prevent extensive cardiomyocyte loss and permanent heart damage. It also distinguishes between full-thickness (transmural) and partial-thickness (subendocardial) infarcts.

Takeaways

• 💔 The primary cause of heart attacks is atherosclerotic plaque build-up in the coronary arteries, which restricts blood flow to the heart muscle.
• 🩺 Myocardial infarcts, or heart attacks, occur when the heart muscle is deprived of oxygen due to blocked blood flow, leading to tissue death.
• 🏃‍♂️ Physical activity like playing soccer can increase blood flow and pressure in coronary arteries, potentially causing plaque rupture and clot formation.
• 🚫 A clot, or thrombus, can block blood flow in the coronary artery, depriving the heart muscle of oxygen and leading to pain signals sent to the brain.
• 🌡️ Pain from a heart attack can be mistaken for indigestion, as the brain may misinterpret the signals, causing discomfort below the heart and above the stomach.
• 🔍 Pain in the arms, specifically the left arm, can be a symptom of a heart attack due to shared nerve origins between the heart and arm.
• 🚨 Adrenaline release during a heart attack can increase heart rate, but it does not address the underlying clot and can exacerbate the situation.
• 💓 A complete blockage of the coronary artery can lead to cardiomyocytes (heart muscle cells) slowing their contraction rate and eventually stopping, affecting the heart's overall function.
• 🩸 Heart muscle cells under severe oxygen deprivation can rupture, releasing proteins like troponins into the bloodstream, which are key markers for diagnosing heart attacks.
• 🔍 Two main types of myocardial infarcts are identified: full-thickness (transmural) infarcts, affecting the entire heart wall, and partial-thickness (subendocardial) infarcts, affecting a smaller region.

Q & A

What is the primary cause of heart attacks?

The primary cause of heart attacks is atherosclerotic plaque build-up in the coronary arteries, which compromises blood flow to the heart muscle.

What happens when the heart muscle doesn't get enough blood flow?

When the heart muscle doesn't get enough blood flow, it doesn't receive enough oxygen, leading to a condition known as myocardial infarction or heart attack.

What is the medical term for heart attacks?

In medicine, heart attacks are referred to as myocardial infarcts.

What does 'myocardial infarct' mean in terms of heart muscle and oxygen?

Myocardial infarct refers to a lack of oxygen to the heart muscle, causing death of that heart muscle tissue.

How do cardiomyocytes contribute to the efficient pumping of the heart?

Cardiomyocytes, or heart muscle cells, are interconnected to work together more efficiently, ensuring proper heart pumping.

What happens when a plaque in the coronary artery ruptures?

When a plaque ruptures, it can lead to the formation of a thrombus, or blood clot, which can block blood flow downstream, reducing oxygen supply to the heart muscle.

Why do heart muscle cells send pain signals to the brain during a heart attack?

Heart muscle cells send pain signals to the brain when they become oxygen-starved, alerting the brain to take action to address the lack of oxygen.

What is referred pain and how is it related to heart attacks?

Referred pain is when pain is felt in a different part of the body due to the nerves connected to the heart also connecting to other areas like the arms or jaw. This can cause confusion and misinterpretation of the source of pain during a heart attack.

How does adrenaline affect the heart during a heart attack?

Adrenaline causes the heart to beat faster, but it doesn't help with the clot blocking the artery. This increased heart rate can further stress the already oxygen-deprived heart muscle.

What are troponins and why are they significant in diagnosing heart attacks?

Troponins are a type of structural protein found only in heart muscle cells. They leak into the bloodstream when cardiomyocytes rupture, making them a key biomarker for diagnosing heart attacks.

What are the two main types of myocardial infarcts and how do they differ?

The two main types of myocardial infarcts are full-thickness (transmural) infarcts, which affect the entire thickness of the heart wall, and partial-thickness (subendocardial) infarcts, which affect only a part of the heart wall.