Podcast
Questions and Answers
What are the two types of atherosclerosis lesions?
What are the two types of atherosclerosis lesions?
Stable or fixed plaque (stable angina) and Unstable plaque (unstable angina; MI)
What is the primary factor responsible for perfusion of coronary arteries?
What is the primary factor responsible for perfusion of coronary arteries?
Aortic blood pressure
Describe the pain typically associated with stable angina.
Describe the pain typically associated with stable angina.
Constricting, squeezing, or suffocating sensation
What is the purpose of collateral circulation in the context of coronary artery disease?
What is the purpose of collateral circulation in the context of coronary artery disease?
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What is the cause of variant or vasospastic angina?
What is the cause of variant or vasospastic angina?
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When do T wave and ST segment changes appear on an ECG during myocardial ischemia or injury?
When do T wave and ST segment changes appear on an ECG during myocardial ischemia or injury?
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What ECG changes may be present in the context of severe ischemia?
What ECG changes may be present in the context of severe ischemia?
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When does necrosis (irreversible myocardial cell death) occur during severe ischemia?
When does necrosis (irreversible myocardial cell death) occur during severe ischemia?
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What is the recommended timeframe for reperfusion using drugs or vascularization after an episode of severe ischemia?
What is the recommended timeframe for reperfusion using drugs or vascularization after an episode of severe ischemia?
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After a myocardial infarction (MI), what are the three zones of tissue damage identified?
After a myocardial infarction (MI), what are the three zones of tissue damage identified?
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What ECG pattern is most likely associated with acute anterior infarction?
What ECG pattern is most likely associated with acute anterior infarction?
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What is the main difference in timing between myoglobin and troponin in detecting cardiac injury?
What is the main difference in timing between myoglobin and troponin in detecting cardiac injury?
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What distinguishes Unstable Angina from Stable Angina in terms of pain severity?
What distinguishes Unstable Angina from Stable Angina in terms of pain severity?
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What transient ECG changes may occur during Unstable Angina?
What transient ECG changes may occur during Unstable Angina?
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How can Acute Myocardial Infarction be distinguished from Unstable Angina based on the pain description?
How can Acute Myocardial Infarction be distinguished from Unstable Angina based on the pain description?
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What is the main pathophysiological cause of severe pain in Acute Myocardial Infarction?
What is the main pathophysiological cause of severe pain in Acute Myocardial Infarction?
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What distinguishes Transmural from Subendocardial infarcts?
What distinguishes Transmural from Subendocardial infarcts?
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Study Notes
Coronary Heart Disease (CHD)
- Caused by impaired coronary blood flow, often due to atherosclerosis
- Coronary circulation involves coronary arteries that arise from the coronary sinus above the aortic valve
- Left and right coronary arteries supply the heart, with the left artery supplying the left ventricle and interventricular septum
Coronary Atherosclerosis and Pathogenesis of Coronary Artery Disease
- Two types of atherosclerosis lesions:
- Stable or fixed plaque (stable angina)
- Unstable plaque (unstable angina; MI) that can rupture and cause thrombus formation
Stable Angina (Angina Pectoris)
- Initial manifestation of ischemic heart disease in half of CHD cases
- Precipitated by situations that increase the heart's workload (exercise, cold, stress)
- Pain is constricting, squeezing, or suffocating, and is relieved by rest or nitroglycerine
- Typically located in the pericardial or substernal area of the chest and may radiate to the left side
Variant or Vasospastic Angina
- Caused by spasms of the coronary arteries
- Occurs in the absence of visible disease
- May be caused by a hyperactive sympathetic nervous system or a defect in calcium handling in vascular smooth muscle
Acute Coronary Syndrome
- Determining the risk of acute myocardial infarction (AMI) depends on presenting characteristics, ECG variables, serum cardiac markers, and timing of presentation
- ECG changes:
- T wave and ST segment changes occur first during myocardial ischemia or injury
- Q wave changes appear later and persist
- Serum markers:
- Creatine Kinase MB (CK-MB) elevates 4-8 hours after injury and declines to normal within 2-3 days
- Myoglobin elevates within 1 hour and peaks within 4-8 hours, but is not cardiac-specific
- Troponin elevates within 3 hours and remains elevated for 7-10 days, making it more capable of detecting infarction than CK-MB
Unstable Angina
- A state between stable angina and MI
- Results from atherosclerosis plaque disruption, platelet aggregation, and secondary hemostasis
- Pain is more severe and persistent, occurring at rest or with minimal exercise, and lasting more than 20 minutes
- ECG changes may occur, including ST-segment depression, ST-segment elevation, or T-wave inversion
- Cardiac markers:
- CPK is not elevated
- Troponin I or T may be slightly increased
Acute Myocardial Infarction (AMI)
- Abrupt onset of severe, crushing pain that radiates to the left arm, neck, or jaw
- Pain is prolonged and not relieved by rest or nitroglycerin
- Main pathophysiological cause of severe pain is an imbalance between oxygen supply and demand
- Two types of infarction:
- Transmural infarcts (ST-segment elevation AMI) involve the full thickness of the ventricles
- Subendocardial infarcts (non-ST-segment elevation AMI) involve the inner one-third to one half of the ventricles
Consequences of AMI
- Necrosis (irreversible myocardial cell death) occurs within 20-40 minutes of severe ischemia
- Reperfusion using thrombolytic agents or vascularization must occur within 15-20 minutes of the episode
- Three zones of tissue damage:
- Area of necrosis (ECG = Q wave)
- Area of injury (ECG = ST segment)
- Ischemic zone (ECG = T wave inversion)
Ventricular Tachycardia (VT) and Ventricular Fibrillation (VF)
- Most dangerous arrhythmias that require DC shock
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Description
Explore the basics of Coronary Heart Disease (CHD) caused by impaired coronary blood flow, usually due to atherosclerosis. Learn about the coronary circulation system, including the origins and functions of the left and right coronary arteries.
