Myocardial Infarction: Causes and Pathophysiology

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.