Coronary Artery Disease Flashcards
What is CAD?
Heart disease d/t impaired delivery of blood to the myocardium.
Results from atherosclerosis of coronary arteries.
AKA = ischemic heart disease
What happens to intramyocardial arteries during systole?
During systole, these arteries are compressed = most coronary perfusion occurs during diastole.
What factors influence coronary perfusion (3)?
- Perfusion pressure
- Coronary artery diameter/patency
- duration of diastole.
What is collateral circulation?
Collateral circulation is new vasculature (angiogenisis) that forms around a slow atheroma growth in order to preserve blood flow.
What factors contribute to collateral circulation?
- possible genetic predisposition for angiogenisis
- regular cardiovascular exercise stimulates collateral growth
NOTE: b/c of collateral growth, a patient may be unaware of a developing problem.
Presentation of CAD is dependent on…?
Extent of occlusion (partial or complete)
Speed of ischemic development (acute or chronic)
What is cardiogenic shock?
Heart is unable to pump enough blood and oxygen to the body’s vital organs. Can result from an MI.
CAD presents in what 3 different ways?
- Angina (stable (stable plaque) or unstable (transient thrombus on a plaque))
- Acute MI
- Heart failure (ischemic cardiomyopathy or cardiogenic shock))
Define Angina Pectoris.
Chest pain or discomfort caused by insufficient O2 supply to meet myocardial O2 demands.
What is the most common cause of Angina Pectoris?
Myocardial ischemia d/t CAD
What are some reasons, other than CAD for decreased myocardial infusion (4)?
- hypovolemia
- coronary vasospasm (e.g. cocaine overdose)
- coronary embolism
- heart failure
What are some reasons for decreased oxygen in the blood?
-anemia
- hypoxemia d/t to chronic respiratory disease (e.g. COPD)
- acute gas exchange impairments (pneumonia)
What are some causes of increased myocardial oxygen demand (5)?
- ventricular hypertrophy (d/t HTN, aortic stenosis)
- large pulmonary embolism
- tachycardia
- hyperthyroidism
- hyperthermia, physical exertion, stress/anxiety
How would someone experiencing angina describe their pain?
- substernal, sometimes epigrastic
- may be referred to inner arm, shoulder, neck, jaw or back
- described as pressure, tightness, heaviness, constricting, squeezing
- may come with associated symptoms: dyspnea, nausea or dizziness
Provide a description, the pathophysiology, duration and outcome of stable angina.
Description - exertion or emotional stress. Chronic stable angina is predicable.
Patho - narrowing of the atherosclerotic coronary arteries means then cannot dilate to meet increased oxygen demands = myocardial ishcemia
Duration = 2-5 mins. Pain stops with rest or nitro.
Outcome = no significant permanent damage to myocardium.
What are some aggravating factors for angina?
Any activity that increases myocardial demands or impedes O2 supply
- Eating a large meal (diverts blood flow)
- Cold temperatures (vasoconstriction increases BP and myocardial workload)
- cigarette smoke (vasoconstriction and increased HR = increased myocardial workload)
- lying down (increases venous return = increased myocardial workload)
Describe unstable angina including pathophysiology, duration and outcome.
Pain is more easily induced (occurs at rest) unpredictable
Transient, reversible complication with an unstable plaque (e.g. plaque rupture causes a thrombus which partially or completely obstructs blood flow)
Pain is prolonged but < 20 mins (body’s own fibrinolytic system breaks down clot)
No significant permanent damage to myocardium but precedes an MI and requires observation and treatment.
What is vasospastic angina?
AKA = prinzmetal or varient angina
Cause often unknown but cigarette smoke is a known trigger
Occurs at rest - often at night or early morning.
Lasts 5-15 mins and responds to nitro
Calcium channel blockers prevents episodes.
What is coronary microvascular dysfunction (CMD)?
Chest pain caused by abnormalities of the coronary microcirculation.
Endothelial dysfunction impairs dilation in response to exercise or stress and/or causes vasospasm
Primarily affects females (approx 75%)
Define acute myocardial infarction.
Acute MI is myocardial cell death caused by prolonged (>20 min) ischemia.
What is the primary cause of an acute MI?
Sustained coronary artery occlusion d/t thrombus formation on an atherosclerotic plaque.
Plaque erosion or rupture exposes the subendothelium or lipid core to stimulate thrombus formation.
What factors influence severity of infarction and myocardial damage (5)?
- degree of obstruction (partial or complete)
- artery affected
- site of occlusion along the artery (proximal vs distal)
- duration of ischemia before reperfusion occurs
- extent of collateral circulation
What is a transmural infarction (cause and outcome)?
= ST elevated MI (STEMI)
1. full thickness
2. complete obstruction
3. necroses endocardium to epicardium
Involves full thickness damage of the myocardium in 3-6 hours (without intervention)
Caused by the complete obstruction of a major coronary artery
Necrosis begins in the subendocardium (furthest from the blood supply) and spreads to the epicardium.
Reperfusion (Percutaneous Coronary Intervention - PCI or thrombolytics) needs to occur within… to prevent progression of damage to the full wall.
90-120 mins