#10 - Ischemic Heart Disease (Brown) Flashcards
List the 4 ways ischemic heart disease can manifest clinically
- chest discomfort
- heart failure / shortness of breath
- abnormal EKG/ stress test
- arrhythmia
What percentage of death due to cardiac disease are “sudden deaths”?
60%
How many sudden deaths are instantaneous?
1/3
How many sudden deaths occur outside the hospital?
70%
Most sudden cardiac deaths are due to which type of arrhythmia?
ventricular fibrillation
T/F: Most sudden cardiac deaths are caused by acute MIs.
False. Most are associated with atherosclerosis and remote MI’s but the majority are due to arrhythmias, NOT caused by acute MIs.
T/F Most deaths due to MI are “sudden death” but most sudden deaths are not due to MI
True.
What are the 4 direct determinants of myocardial oxygen DEMAND?
- intraventricular systolic pressure.
- ventricular cavity radius
- heart rate
- contractility in the muscle (more actin/myosin units- more energy)
NOTE: stroke volume is not a determinant of oxygen demand!
T/F diastolic pressure is more important than systolic pressure for coronary artery blood flow.
True.
(Why?? during systole, when the ventricle contracts, it squeezes the arteries, closing them. Therefore they fill during diastole)
What are the 3 main determinants of myocardial blood flow.
- perfusing pressure (diastolic more important than systolic)
- resistance to flow (arterioles, atheroclerosis,)
- right atrial pressure
What are the 3 ways resistance in the coronary arteries can change?
- arterioles - they are in charge of normal autoregulation
- obstructions (atherosclerotic plaques/ coronary artery spasm
- myocardial wall tension compresses the intramural portion of the arteries during systole, occluding flow
What are the 2 categories of causes of IHD?
- disease of increased oxygen demands
- diseases of the coronary arteries (atherosclerosis/spasm)
Which diseases cause ischemic heart disease through increased oxygen demands.
aortic valve disease (stenosis/insufficiency) –> hypertrophy of the LV wall, with inadequate capillary growth to supply blood to new tissue –> ischemia.
T/F- the diagnosis of ischemic heart disease depends on the coronary angiogram
FALSE. Diagnosis is based on the history.
Describe the type of pain in angina
tightness, aching, squeezing, pressure or weight, or burning.
List 5 things that can increase heart rate/BP and help to provoke a heart attack. (Hint: remember Netter picture).
- heavy meal
- cold temperature
- activity early in the day (higher HR)
- activity involving arms
- cigarrettes.
netter picture from the ppt: guy leaving restaurant in the cold, carrying heavy briefcase. he was also smoking.
How long does angina last?
usually 3-5 minutes.
sometimes 5-15 min
rarely 15-20 min
Never more than 30 min after rest or nitroglycerin.
What are the 3 criteria for clinical diagnosis of angina? How do tthey relate to typical angina, atypical angina, and noncardiac chest pain?
1) substernal chast discomfort with a characteristic quality and duration.
2) chest discomfort is provoked by exertion or emotional stress\
3) relieved by rest or nitroglycerin
Typical angina = all 3
Atypical (probable) angina = 2/3
noncardiac chest pain = 1 or none /3
T/F: Physical exam is very useful for diagnosing stable angina.
False. It is often unrevealing, especially if the angina is not presently occurring. This is why they make people do the stress test.
What are the 3 main tests used for diagnosis of ischemic heart disease?
- EKG (during rest doesn’t show much)
- Treadmill test (along with concurrent testing)
- coronary angiography (remember angiography doesn’t make the diagnosis by itself)
When should (and shouldn’t) a treadmill test be used in the evaluation of ischemic heart disease?
It should be used for patients with stable, typical angina, or probable angina.
DO NOT order this test for someone with unstable angina or an acute MI - that person needs to be hospitalized!!
What are the advantages of a treadmill test?
- it is most practical (most available and cheapest)
- correlates patient’s BP/HR with symptoms and ST depression on EKG
Coronary angiography shows a patient with angina has vessels that are 40% occluded. What is the conclusion? Does this person have severe or mild disease?
Mild. This is likely not causing severe disease. Coronary arteries are twice as wide as they need to be, so the lumen must be
Definition of MI
a more prolonged imbalance between blood flow and oxygen demand, which is documented to have produced myocardial necrosis.
How do you make a diagnosis of MI?
Almost always, associated with angina.
However, EKG changes or biochemical changes (troponin) is necessary to make the diagnosis.
How long does angina from an MI last?
usually 1/2 hour to several hours.
Clinical presentation of an MI
BP and HR vary
Fever may be present (reaction to necrosis)
-angina, often accompanied by sweating nausea vomiting or weakness
-almost all patients will have S4 gallop.
S3 may be present
-pericardial friction rub - 24 hrs after onset of pain
What heart sound is almost always heard in an acute MI patient?
S4 gallop
T/F: physical exam is very important in an Mi patient.
True.
Which EKG changes are diagnostic of MI?
- pathological Q waves
- ST-T changes.
What is the window for testing troponin for an MI?
it peaks at 6-8 hours but may remain normal for 1-2 weeks.
What are the major complications of acute MIs?
1) arrhythmias of all types (PVCs, tachycardia, ventricular fibrillation) - remember that ventricular fibrillation is major cause of death from acute MI)
2) Heart failure.
3) hypotension
How might heart failure due to an acute MI manifest?
at first, only the finding of an S3 gallow and persistent relative sinus tachycardia at rest.
T/F: If there is no ST elevation in an MI (but positive troponin), there is likely a pathological Q wave present.
FALSE. Q waves tend to accompany ST changes. If ST elevation present, Q wave likely (not always) present. And vice-versa.
Definition of unstable angina?
angina without stable, exertional pattern, without ST elevation on EKG or elevated troponin.
This includes
-new onset angina (even if exertional)
-exertional angina but occurring with increasing frequency or with preipitation by lesser degrees of exertion
-angina at rest or during sleep
-prolonged angina of >20 -30 min duration
Definition of stable angina
angina with a predictable exertional pattern which has been present for >1 month.
What is the major mechanism for all the acute coronary syndromes?
unstable/ruptured atherosclerotic plaque.
Which is NOT a determinant of myocardial oxygen demand?
- intraventricular systolic pressure.
- ventricular cavity radius
- stroke volume
- heart rate
- contractility in the muscl
Stroke volume.
Think of it this way: lowering your blood pressure means your heart would have a larger stroke volume with the same amount of energy output/o2 requirements. Stroke volume is dependent on more than the energy the heart is expending. On the contrary, the heart could be working its ass off, but b/c of atrial valve stenosis, get low stroke volume.
What is a determinant of all 3: oxygen delivery, blood pressure, and myocardial demands?
Heart rate
You see a patient who has angina at rest. Is this sufficient for a diagnosis of atypical angina?
Yes. Hospitalize that shit!
