MT2_5_Ischemic Heart Disease Flashcards
what falls under stable coronary disease?
- chronic stable angina
what falls under acute coronary syndromes?
- unstable angina
- non-st elevation MI
- st elevation MI
What is the most common cause of MI?
- coronary artery disease (atherosclerosis)..can be stable or unstable
where are the arteries located, and why is diastole important?
arteries are on the epicardial surface, and diastole is important bc that is when coronary artery perfusion occurs.
why does ischemia occur?
- when supply does not equal demand…for O2
What are the three things that affect coronary blood flow, and O2 SUPPLY?
- Coronary blood flow
- vessel potency–obstruction
- vasc. resistance of coronary arteries (dilatation)
- heart rate (since arteries are perfused during diastole)
- O2 carrying capacity
- Collaterals (development of new blood vessels)
What are the three things that affect myocardial oxygen DEMAND (MVO2)?
- heart rate (need more atp)
- contractility (contractile myocytes require atp)
- wall tension/wall stress (preload and after load)
How do we estimate MVO2?
- SBP times HR = rate pressure product
What are the most common causes of diminished coronary artery blood flow?
- **stable CAD +/- plaque rupture and atherothrombosis
2. coronary artery spasm (can occur w/o plaques)
define artheroclerosis
- disease affecting arterial blood vessels, due to deposition and invasion of macrophages into arterial walls
- this results in narrowing of artery lumen
- reduced vascular reactivity (so stiffening and endothelial dysfunction)
- unstable plaques can rupture
Define stable angina
- atherosclerosis leads to……
- diminished coronary artery lumen
- endothelial dysfunction
- reduced vessel compliance
resulting in a gradual reduction of coronary blood/O2 supply
= stable symptoms
Define acute coronary syndrome
- the plaques rupture, leading to atherothrombosis, and a rapid loss of coronary blood/O2 supply
Summarize the sequence of events of an atherosclerotic event
- plaque formation..chornic, leading to ischemia if MVO2 is INcreased
- plaque disruption (or vas-spasmes) due to a sudden change in pressure
- thrombus formation ( resulting in acute partial or complete obstruction of the artery)
- ischemia (which can occur even without an increase in MVO2 due to the decrease in supply) –> angina
- tissue necrosis (infarction) in a wavefront matter from the subendocardium to the epicardium
What does ACS severity depend on?
- degree
- duration
- location
- collateral circualtion
- time to revascularization
What system is activated during an acute infarction phase?
- neurohormonal systems (adrenenergic) which then worsen ischemia, expand infarct, and increase arrhythmic risk
What are the initial assessment tools?
- Hx/chest pain differential (due to ischemia or stable/unstable?)
- ECG
- Cardiac Biomarkers (troponin I or T)
How can we determine if it is angina?
- Description of pain
- Quality
- Duration
- Location
- Radiation - Precipitating Factors?
- exertion or stress (physical/emotional) - Relieving Factors
- rest, NTG,
- pain scale, diaphoresis, dyspnea, weakness, nausea, fever
What are the 3 main criteria for a typical angina? Atypical, and non-anginal chest pain?
- substernal chest discomfort with quality and duration that is
- provided by exertion or emotional stress
- and relieved by rest or NTG
Atypical: 2/3
Non-anginal: 0-1 of criteria
What is the difference between stable and unstable angina?
- stable is predictable and does not change in frequency, intensity, and duration
- unstable can be 1. at rest, 2. new onset w severe pain, and 3. pain that is more frequent, longer in duration, and pt has a lower threshold
What does T wave inversion represent?
- myocardial ISCHEMIA
What does ST segment depression represent?
- active myocardial ISCHEMIA, more sensitive to T wave inversion
ST segment elevation represent?
- ACUTE INFARCT thus causing injury
- must be more than 1mm in 2 contiguous leads
What does a Q wave represent?
- transmural infarct, can be old OR new…not diagnostic for an acute infarct
Troponin T/I is a regulatory protein that is very specific to cardiac tissue, and is proportional to amount of damage. The peak sensitivity is ____ therefore absence does not rule out damage
What are the troponin levels?
- 8-12 hours
- less than 0.01 is normal
- 0.01-0.12 is “leak)
- more than .12 is positive for MI
When is CK a diagnostic of an MI?
- CKMB fraction greater than 5% (with elevated CK) is a diagnostic for MI at 8-12 hours
What are the 3 main things used to diagnose an acuity of an ischemia?
- CP history
- ECG
- Biomarkers
For stable angina,
CP History
ECG
Biomarkers
- CP: typical or atypical angina, does not meet criteria for unstable symptoms
ECG: no change
Biomarkers: no change
Non-STE ACS
CP
eCG
Biomarkers
CP: typical or atypical angina, meets criteria for unstable symptoms history
ECG: may have acute T wave inversion, or ST depression
Biomarkers: no change is UNSTABLE ANGINA
acute rise is NSTEMI
STEMI
CP
ECG
Biomarkers
CP: typical or atypical, can be unstable
ECG: ST elevation
Biomarkers: acute rise, but can be normal in early stages of an MI
What is considered an unstable angina?
- patients presenting with worsening angina, w/o evidence of ST elevation on ECG or elevated cardiac biomarkers
STABLE angina is a ___state caused by ____ narrowing of the coronary arteries. Under normal conditions, patients will not experience symptoms, but when ___is increased, the symptoms of ischemia are present. So the goal is to ____and____O2 supply
chronic
artherosclerotic
MVO2
stabilize, balance
In ACS, an atherosclerotic plaque has been compromised, leading to ___and ___ process. If left unchecked, a complete ___of the artery will result. Therefore, therapy must be more ___and agents are added to combat the thrombotic and inflammatory process to restore normal blood flow.
How aggressively you manage the thrombotic aspect depends on the risk of further _____
Minority of the cases are due to ____
Symptoms can develop ___ of MVO2
prothormbotic and inflammatory
occlusion
aggressive
myocardial damage
vasospasms
independent
