Introduction
Myocardial infarction (MI), or heart attack, occurs when blood flow to a part of the heart is blocked for a long enough time to cause damage or death of the heart muscle.
Types
1. ST-Segment Elevation Myocardial Infarction (STEMI):
Severity: Severe type where a major coronary artery is completely blocked.
ECG Changes: ST-segment elevation on the electrocardiogram.
2. Non-ST-Segment Elevation Myocardial Infarction (NSTEMI):
Severity: Less severe; artery is partially blocked.
ECG Changes: No ST-segment elevation but may show other signs of heart damage.
Etiology
Atherosclerosis: Rupture of an atherosclerotic plaque and subsequent blood clot formation.
Coronary Artery Spasm: Severe spasm reducing blood flow to the heart.
Pathogenesis of Myocardial Infarction
1. Plaque Rupture: Atherosclerotic plaque in a coronary artery ruptures.
2. Thrombus Formation: A blood clot forms at the rupture site, completely blocking blood flow.
3. Ischemia and Necrosis: Lack of oxygenated blood leads to death of heart muscle tissue (infarction).
Signs and Symptoms
Chest Pain: Intense, persistent pain or pressure.
Radiating Pain: Pain may extend to arms, neck, jaw, or back.
Shortness of Breath: Due to impaired oxygen delivery.
Other Symptoms: Sweating, nausea, vomiting, light-headedness, fatigue.
Management and Treatment
1. Emergency Treatment:
Immediate medical attention.
Oxygen therapy.
Pain relief (e.g., morphine).
Nitroglycerin.
2. Medications:
Thrombolytics: Dissolve blood clots.
Antiplatelet Agents: Aspirin and clopidogrel.
Beta-blockers: Reduce heart workload.
ACE Inhibitors: Lower blood pressure.
Statins: Lower cholesterol.
3. Medical Procedures:
Percutaneous Coronary Intervention (PCI): Angioplasty and stenting to open blocked arteries.
Coronary Artery Bypass Grafting (CABG): Surgery to bypass blocked coronary arteries.