Coronary Artery Disease Flashcards
Describe the pathway of blood through the heart.
- Blood enters the right atrium (1) through the superior (3) and inferior vena cava (11)
- The right atrium contracts, pushing blood through the tricuspid valve (12) into the right ventricle (10)
- The right ventricle contracts pushing the blood through the pulmonary valve (13) into the pulmonary artery (15) which leads to the lungs
- After picking up oxygen in the lungs, the blood returns to the heart through the pulmonary veins (6) into the left atrium (2)
- The left atrium contracts, pushing blood through the mitral valve (7) into the left ventricle (9)
- The left ventricle contracts, pushing blood through the aortic valve (8) into the aorta (4) from which it is then distributed to the rest of the body
What is coronary artery disease?
Coronary artery disease
- A condition in which the arteries that supply blood to the heart become narrowed or blocked due to a build-up of plaque (fat, cholesterol and other substances)
- i.e. results from atherosclerosis
Define angina and explain what causes it.
Angina
- Chest pain caused by lack of oxygen to the myocardium (myocardial ischemia)
- Results from occlusion or spasm of the coronary artery or myocardial hypertrophy
What is the difference between stable and unstable angina?
Stable angina
- Predictable, occurs during activity or stress
- Pain is short-term
- Relieved by rest and/or medication (nitrates)
- Caused by narrowed arteries (stable plaque)
Unstable angina
- Unpredictable, can occur at rest
- Pain lasts longer and is more intense
- May not relieved by rest or medications
- Caused by rupture of plaque and blood clot formation (unstable plaque)
Differentiate between NSTEMI and STEMI.
NSTEMI
- Chest pain with elevation of cardiac biomarkers and no ECG changes
STEMI
- Chest pain with elevation of troponins and ST elevation on ECG
Explain the effect of oxygen deprivation on cells and tissues using the words ischemia and infarction.
- Ischemia is a lack of oxygen to tissues
- Lack of oxygen leads to cellular dysfunction which can be restored if blood flow is restored quickly enough i.e. cells are still viable
- Indicated by T wave inversion ST depression on ECG
- Infarction is permanent cell damage or death (necrosis) that occurs when ischemia is severe or prolonged
- Results in irreversible damage to the cells
- Indicated by Q waves on ECG
List common signs and symptoms of myocardial infarction
- Pain
- Mid-sternal or substernal
- Compression or crushing quality
- Radiates to back, neck, jaw, shoulders or arms - SNS
- Dyspnea
- Anxiety
- Dizziness
- Sense of impending doom - ANS
- Pallor
- Diaphoresis - Cardiac
- Dysrhythmia
- HoTN - GI
- Nausea/vomiting
- Indigestion - Systemic
- Low grade fever
Which 2 populations are at greatest risk of not being diagnosed early with MI? Why?
- Women and the elderly due to atypical symptoms.
Explain the pathophysiology of the hypotension that sometimes occurs during an MI.
- Hypotension occurs due to poor cardiac output (amount of blood the heart pumps per minute) which is a key factor in maintaining BP
- During MI heart muscle becomes ischemic and may begin to die - Damaged heart muscle loses its ability to contract effectively - Loss of contractility results in reduced stroke volume (amount of blood ejected with each heartbeat) = less blood being pumped out into the body
Why might a person’s temperature and WBC be slightly elevated following a myocardial infarction?
- Myocardial infarction – death of heart muscle cells due to ischemia
- Inflammatory response as the body tries to repair the damaged tissue
- Body produces pyrogens which cause increase in body temp. - Body increases production of WBCs to help clear away dead tissue and cellular debris from the damaged myocardium
It takes up to 6-8 weeks for scar tissue to replace infarcted myocardial tissue. (True, False)
- TRUE – The process of scar formation generally takes about 6-8 weeks
Which cardiac biomarker is the gold standard for myocardial infarct diagnosis?
Troponin
- A protein complex found in cardiac muscle cells that is released into the bloodstream when heart muscle cells are damaged
- Gold standard for diagnosing a MI
- Usually rise within 3-4h of the infarction and stay elevated for up to 10-14 days
Explain why CK-MB is tested post-MI.
CK-MB
- A cardiac-specific enzyme that is elevated in the blood following MI
- Indicator of heart muscle damage
- Usually rise within 4-6h of infarction and stay elevated for 2-3 days
What is the most common cause of sudden death during a MI?
Ventricular fibrillation
- A life-threatening arrhythmia occurs when electrical signals in the ventricles become disorganized
- Heart quivers instead of contracting thus cannot pump blood, leading to cardiac arrest
- Common in the first hour after infarction thus early detection of MI is crucial
Mr. Cooper, 39 years old, suffers a myocardial infarction due to a thrombus in his left anterior descending artery. Which complication is he at risk for?
Arrhythmias
- Thrombus blocked blood flow through the LAD leading to damage of the heart muscle
- Damage to the heart muscle affects its contractility which is important for pumping oxygen throughout the body
- Results in arrythmia - a condition in which the heart beats with an irregular or abnormal rhythm
