Cardiology: Myocardial Ischemia and Angina Pectoris

Study Notes

Symptoms of myocardial ischemia are due to insufficient coronary blood flow and are related to the location and degree of vessel obstruction.
Angina pectoris is a common symptom of myocardial ischemia, characterized by episodes of paroxysmal pain or pressure in the anterior chest.

Angina pectoris is caused by insufficient coronary blood flow to meet the oxygen demand of the myocardium.
Physical exertion or emotional stress increases myocardial oxygen demand, making angina worse.
Types of angina include:
- Stable angina: predictable and consistent pain that occurs on exertion and is relieved by rest and/or nitroglycerin.
- Unstable angina (preinfarction angina or crescendo angina): symptoms increase in frequency and severity and may not be relieved with rest or nitroglycerin.
- Variant angina (Prinzmetal's angina): pain at rest with reversible ST-segment elevation, caused by coronary artery vasospasm.

Angina pain varies from mild to severe and may be described as tightness, choking, or a heavy sensation.
Pain is frequently retrosternal and may radiate to the neck, jaw, shoulders, back, or arms (usually left).
Anxiety frequently accompanies the pain.
Other symptoms may include dyspnea/shortness of breath, dizziness, nausea, and vomiting.

Treatment seeks to decrease myocardial oxygen demand and increase oxygen supply.
Medications used to treat angina include:
- Nitroglycerin
- Beta-adrenergic blocking agents
- Calcium channel blocking agents (e.g., Amlodipine)
- Antiplatelet and anticoagulant medications
- Aspirin
- Clopidogrel and ticlopidine
- Heparin
- Glycoprotein IIB/IIIa agents (antiplatelet)

Stop all activity and sit or rest in bed.
Assess the patient while performing other necessary interventions (e.g., VS, respiratory distress, pain assessment).
Administer oxygen and medications as ordered or by protocol (usually NTG).

Myocardial infarction occurs when an area of the myocardium is permanently destroyed due to reduced blood flow in a coronary artery.
This is usually caused by the rupture of an atherosclerotic plaque and subsequent occlusion of the artery by a thrombus.

Clinical manifestations include chest pain and other symptoms.
Diagnosis is made using ECG and laboratory tests, including biomarkers such as:
- CK-MB: begins to increase within a few hours and peaks within 24 hours of an MI.
- Myoglobin: starts to increase within 1 to 3 hours and peaks within 12 hours after the onset of symptoms.
- Troponin T or I: protein found in the myocardium, regulates the myocardial contractile process, and is a reliable marker of myocardial injury.

Goals of medical management are to minimize myocardial damage, preserve myocardial function, and prevent complications.
Obtain diagnostic tests, including ECG, within 10 minutes of admission to the ED.
Treatment may include medications such as:
- Aspirin
- Nitroglycerin
- Morphine
- Beta-blockers
- Angiotensin-converting enzyme inhibitor
Evaluate for percutaneous coronary intervention or thrombolytic therapy.
Bed rest may be necessary.