Myocardial Infarction: Causes and Pathophysiology

Study Notes

Definition and Pathophysiology

Myocardial infarction (MI), also known as heart attack, occurs when the blood flow to the heart is blocked, causing damage to the heart muscle.
Blockage is usually due to a blood clot that forms in a coronary artery, which supplies blood to the heart.
Reduced blood flow leads to ischemia, causing damage to the heart muscle, and if prolonged, can lead to myocardial necrosis.

Causes and Risk Factors

Atherosclerosis: buildup of plaque in coronary arteries, leading to narrowing and blockage.
Coronary artery disease: narrowing of coronary arteries, reducing blood flow to the heart.
Hypertension, high cholesterol, smoking, diabetes, obesity, and lack of exercise are contributing risk factors.

Symptoms

Chest pain or discomfort (most common symptom)
Pain or discomfort in one or both arms, the back, neck, jaw, or stomach
Shortness of breath or difficulty breathing
Feeling of weakness, lightheadedness, or fatigue
Nausea or vomiting
Rapid or irregular heartbeat

Diagnosis

Electrocardiogram (ECG or EKG) to detect abnormal heart rhythms and signs of heart damage.
Blood tests to measure cardiac biomarkers, such as troponin, to detect heart muscle damage.
Imaging tests, such as echocardiogram or cardiac MRI, to evaluate heart function and structure.

Treatment

Medications:
- Thrombolytics to dissolve blood clots
- Antiplatelet agents to prevent platelet aggregation
- Beta blockers to reduce heart rate and blood pressure
- Statins to lower cholesterol
Interventional procedures:
- Percutaneous coronary intervention (PCI) to open blocked coronary arteries
- Coronary artery bypass grafting (CABG) surgery to bypass blocked arteries
Lifestyle changes:
- Quit smoking
- Exercise regularly
- Healthy diet and weight management

Complications

Heart failure
Cardiac arrhythmias
Cardiogenic shock
Ventricular rupture
Death

Definition and Pathophysiology

Myocardial infarction (MI) occurs when the blood flow to the heart is blocked, causing damage to the heart muscle.
Blockage is usually due to a blood clot that forms in a coronary artery, which supplies blood to the heart.
Reduced blood flow leads to ischemia, causing damage to the heart muscle, and if prolonged, can lead to myocardial necrosis.

Causes and Risk Factors

Atherosclerosis builds up plaque in coronary arteries, leading to narrowing and blockage.
Coronary artery disease narrows coronary arteries, reducing blood flow to the heart.
Hypertension, high cholesterol, smoking, diabetes, obesity, and lack of exercise are contributing risk factors.

Symptoms

Chest pain or discomfort is the most common symptom.
Pain or discomfort can occur in one or both arms, the back, neck, jaw, or stomach.
Shortness of breath or difficulty breathing can occur.
Feeling of weakness, lightheadedness, or fatigue can occur.
Nausea or vomiting can occur.
Rapid or irregular heartbeat can occur.

Diagnosis

Electrocardiogram (ECG or EKG) detects abnormal heart rhythms and signs of heart damage.
Blood tests measure cardiac biomarkers, such as troponin, to detect heart muscle damage.
Imaging tests, such as echocardiogram or cardiac MRI, evaluate heart function and structure.

Treatment

Medications dissolve blood clots, prevent platelet aggregation, reduce heart rate and blood pressure, and lower cholesterol.
Interventional procedures, such as PCI, open blocked coronary arteries.
Coronary artery bypass grafting (CABG) surgery bypasses blocked arteries.
Lifestyle changes include quitting smoking, exercising regularly, and maintaining a healthy diet and weight.

Complications

Heart failure can occur.
Cardiac arrhythmias can occur.
Cardiogenic shock can occur.
Ventricular rupture can occur.
Death can occur.

Description

Learn about the definition, pathophysiology, causes, and risk factors of myocardial infarction, also known as heart attack. Understand how blockage of coronary arteries leads to ischemia and heart muscle damage.