CVS Week 2 Flashcards
describe the impact of fixed vessel narrowing in the setting of stable coronary artery disease
in the presence of mild to moderate atherosclerosis, there is still preservation of coronary blood flow
however, in extensive narrowing, there is a pressure drop across the stenosis, leading to limited vessel flow
what are 3 factors that determines the hemodynamic significance of stenotic lesions
length of lesion and extent of narrowing
degree of compensatory vasodilation
myocardial O2 demand
how does endothelial dysfunction contribute to, and exacerbate, myocardial ischemia
impaired release of vasodilators, leading to a net vasoconstrictive effect
decline in antithrombotic properties of vasodilators such as NO and prostacyclins
describe the impact of metabolic disruption during ischemia
normally, the healthy myocardium uses fatty acids as the predominant substrate
however, when there is restricted O2 supply during ischemia, there is limited oxidative phosphorylation, resulting in increased rate of glycolysis and a shift from net lactate uptake to lactate production
what are 4 non-atherosclerotic factors that can result in ischemia
rapid elevation of myocardial O2 demand e.g rapid tachycardia
decreased blood O2 carrying capacity (anemia)
coronary vasospasm
congenital abnormalities or trauma to coronary arteries
what is coronary artery disease (CAD)
pathological process characterised by atherosclerotic plaque accumulation in the epicardial arteries, whether obstructive or non-obstructive
what are two types of stable CAD/chronic coronary syndrome (CSS)
fixed obstructive CAD
ischemia w non-obstructive coronary arteries (INOCA)
what are 3 types of angina
chronic stable
unstable
prinzmetal’s variant
describe chronic stable angina
demand ischemia
coronary flow impaired under conditions of high O2 demand leading to ischemia
describe unstable angina / prinzmetal angina
supply ischemia
coronary flow impaired under resting conditions leading to ischemia
what are the 3 characteristics/criteria of angina
constricting discomfort in the front of the chest or in the neck, jaw, shoulder, arm
precipitated by physical exertion
relieved by rest or nitrates within 5 min
typical angina meets how many things in the angina criteria
all 3
atypical angina meets how many things in the angina criteria
2 of the 3
non-anginal chest pain meets how many things in the angina criteria
one or none
describe grade 1 angina
angina only with strenuous exertion
presence of angina during strenuous, rapid, or prolonged ordinary activity (walking or climbing the stairs)
describe grade 2 angina
angina w moderate exertion
slight limitation of ordinary activities when performed rapidly, after meals, in cold, in wind, walking uphill etc.
describe grade 3 angina
angina w mild exertion
having difficulties walking one or two blocks, or climbing one flight of stairs at normal pace and conditions
describe grade 4 angina
angina at rest
no exertion needed to trigger angina
what are the 2 contemporary types of acute coronary syndrome (ACS)
non-ST elevatin myocardial infarction (NSTEMI)
ST-elevation myocardial infarction (STEMI)
traditionally, unstable angina also used to be considered as a type of ACS. why is this not the case anymore?
traditionally, UA was defined by absence of an elevated biomarker (troponin) level.
however, now that we have moved from sensitive tests to highly sensitive tests, the biomarker troponin can be seen to be present more often than before, meaning the diagnosis of UA under these conditions has now changed to NSTEMI
what is cardiac troponin
specific and sensitive biomarker of cardiac injury
what is the most common reason of ACS
obstruction of coronary artery blood flow by thrombus that develops as a result of underlying atherosclerotic plaque complication
what are 4 less common causes of ACS
spontaneous coronary artery dissection (SCAD)
coronary artery spasm
coronary microvascular dysfunction
MI w non obstructed coronary arteries (MINOCA)
describe plaque rupture
most frequent
develops in a lesion w a necrotic core and thin overlying fibrous cap
following disruption of fibrous cap, a luminal thrombus develops due to physical contact b/w platelets and thrombogenic necrotic core
describe plaque erosion
characterised by absence of endothelium rather than fibrous cap disruption
most eroded lesions lack a necrotic core and have a thick fibrous cap
lead to disturbance of flow resulting in toll-like receptor 2 activation, recruitment of neutrophils and subsequent promotion of de-endothelialisation. this allows blood to come in contact w plaque collagen to form neutrophil-rich thrombus
terms STEMI and NSTEMI correctly used in patients with…
clinical characteristics compatible w myocardial ischemia
AND
demonstrate elevated troponin
what 3 things must be taken into account to diagnose ACS
symptoms
ECG
serum troponin
describe symptoms patients with acute MI may present with
pain - chest (most common), abdomen, intrascapular, throat, jaw
dyspnea
diaphoresis (sweating)
nausea/vomiting
palpitations
weakness
the typical symptoms of an MI may not be present in…
women
diabetics
older individuals
an ECG allows initial categorisation of a suspected MI into one of three groups. what are the 3 groups
STEMI
NSTEMI
undifferentiated chest pain (non-diagnostic ECG)
describe ST elevation
result of transmural infarct
not often seen, but earliest change is dev of hyperacute or peaked T wave (localised hyperkalemia)
then, elevation of J point
then, ST elevation pronounced
then, ST segment may eventually become undistinguished from T wave
what other conditions can ST elevation be seen in
myocarditis
acute pericarditis
benign early repolarisation variant
describe STEMI
complete thrombotic occlusion of coronary vessel
transmural infarction (‘full thickness’)
describe NSTEMI
partial thrombotic occlusion of coronary vessel
subendocardial infarction (as blood can still be supplied to surrounding tissue in areas where the vessel isnt occluded)
describe non-ST elevation
result of subendocardial infarct
manifest by ST depression and/or T wave inversions without ST segment elevations
ST-T wave abnormalities may be diffuse in many leads or more commonly localised to leads associated w region of ischemic myocardium
describe non diagnostic ECG
initial ECG often not diagnostic in those ultimately diagnosed w acute MI
for any in whom suspicion of ACS remains high, repeat ECG in 20-30 min intervals
what is troponin
complex of 3 regulatory proteins (C, I and T) integral to skeletal and cardiac muscle contraction
cardiac troponin I and T are specific and sensitive biomarkers of cardiac injury
an elevation must be interpreted in context of history and ECG
rise and fall must be document in acute MI (change of 5 requires cardiology opinion)
what are 6 life threatening conditions
ACS
stress cardiomyopathy
aortic dissection
pulmonary embolism
tension pneumothorax
esophageal rupture
outline stress cardiomyopathy
transient regional systolic left ventricular dysfunction in setting of stress
substernal pain similar to acute MI
outline aortic dissection
acute chest and back pain
sharp pain
ripping or tearing quality
outline pulmonary embolism
dyspnoea, followed by pleuritic pain and cough
outline tension pneumothorax
sudden onset of pleuritic chest pain and dyspnea
outline esophageal rupture
associated w straining and vomiting
what are 3 non life threatening cardiac conditions
stable myocardial ischemia/angina
peri(myo)carditis
aortic stenosis
outline peri(myo)carditis
sharp pain
pleuritic
decreased by leaning forward
radiates to trapezius ridge
associated w fever
outline aortic stenosis
exertional pain
dyspnea
presyncope/syncope
what are 5 non life threatening pulmonary conditions
pneumothorax
pneumonia
malignancy
asthma/COPD exacerbation
pleuritis
what are 4 non life threatening GI conditions
GORD
peptic ulcer disease
esophageal motility disorders
esophagitis
when should troponin be measured to diagnose MI
for high sensitivity troponin-T, negative test taken after 2 hrs after symptom onset is reliable for ruling out MI
if first test is negative within 2 hrs, do another test within 3 hrs
for standard sensitive troponin test, need to get negative troponin at least 6-8 hrs after symptom onset
which leads of ECG correspond with the lateral region of the heart
l, aVL, V5, V6