CAD / Acute Coronary Syndrome Flashcards
What are the 3 stages on EKG of MI?
1) ST-depression (represents ischemia not necessarily damage)
2) ST-elevation (represents injury not necessarily infarct)
3) Q-waves (represent infarct that is worsening)
What leads represent Lcx or LAD injury?
Lateral leads
I, aVL, V5-V6
What leads represents RCA injury?
Inferior leads
II, III, aVF
What leads represent LAD injury?
Anterior / septal leads
V1-V4
What do we define as an ST-elevation?
2 small boxes from baseline
What can be a problem with checking troponins?
you might check too early
they don’t really start to peak until about 4 hours after infarct
What peaks first troponin or CK-MB?
CK-MB peaks first (16 hours)
When does troponin peak?
24 hours
How long does CK-MB last?
48-72 hrs
useful for detecting reinfarction since troponin levels can stay elevated for 7-10 days after
What are markers of stable angina?
Exertional
No ST-elevation
No increase in biomarkers
What are the two pros of statins?
1) lower LDL
2) have anti-inflammatory effects to stabilize a plaque
What makes a plaque more stable?
a thick fibrin cap
How does nitroglycerin relieve chest pain?
1) arterial dilation decreases afterload which decreases the amount of O2 consumption needed (higher doses)
2) venous dilation decreases preload which decreases the amount of O2 consumption needed (lower doses)
What can be the 2 general causes of ischemic discomfort?
supply-demand imbalance / stenosis
acute coronary syndrome
What defines acute coronary syndrome?
there is a thrombus
If ST-elevation is absent but biomarkers are elevated, what do you have?
non-stemi
If ST-elevation is absent, biomarkers are absent but pain occurs at rest, what do you have?
unstable angina
Can NSTEMI be caused by either stenosis (suppply-demand) or acute coronary syndrome (thrombus) ?
yes!
if biomarkers are elevated, you are having cell death and an NSTEMI
Can STEMI be caused by either stenosis (suppply-demand) or acute coronary syndrome (thrombus) ?
No
STEMI is only caused by a thrombus
When you see Q-waves what does this indicate (specific)?
this indicates that you now have transmural infarction
What can be a lasting effect of MI?
heart failure
damaged areas of heart might not move as well and lead to dysfunction
What valve does a LAD heart attack often effect?
this can cause mitral regurgitation
ischemia can affect the papillary muscles and lead to mitral regurgitation
What can RCA infarct effect electrically?
can damage the vagus nerve which can then suppress the AV node through parasympathetic stimulation
also RCA gives blood to SA and AV node
What can PDA infarct effect eletrically?
PDA supplies the AV node
Infarct can lead to bradycardia or heart block
When should you not give a B-blocker in heart attack?
do not give if there is significant LV dysfunction
this could cause bradycardia / heart block
What happens to HR in heart failure?
CO = HR * SV
since SV decreases, HR will increase to try to stabilize CO
Reciprocal ST-depression
small depressions that occur in reciprocal leads when there are ST-elevations in other leads
What is main concern when giving a thrombolytic to treat MI?
intracranial hemorrhage / bleeding
What time should you be doing PCI by?
3 hours
What is a hard stop for giving thrombolytics?
high BP
When you have inferior lead ST-elevation, what else should you check for?
st-depressions in leads V1-V4 with tall R waves
What are other causes of ST-inversion besides MI?
pericarditis, BBB, LVH/RVH
What type of MI represents transmural infarction?
STEMI
What is common in the first 4 days after infarction?
ventricular tachycardia or arrthymia
5-10 days after MI what can happen?
papillary muscle rupture
interventricular septal rupture
Signs of papillary muscle rupture
Inferior MI
holosystolic murmur
heart failure / shock
acute pulm. edema from fluid backing up in LA
Signs of interventricular rupture
Hypotension
right heart failure comes before left sided
can also hear a systolic murmu
Difference between fibrinous pericarditis and Dressler
Dressler is an autoimmune reaction that can occur weeks after MI
Fibrinous pericarditis can occur as early as 2-4 days later
For 1 year after stent, what do you use?
aspirin and clopidogrel
antiplatelets
What does clopidogrel work on?
prevents ADP platelet activation
works on the P2RY12 receptor
What 4 drugs do you give in hospital when someone is having an MI? Why?
B-blocker (reduce O2 consumption)
Nitrate (reduce O2 consumption)
aspirin (anti-platelet)
heparin (anti-coagulant)
How does heparin work?
Heparin increases activity of antithrombin III which prevents thrombin from forming clots
What can happen in an inferior MI to autonomics? What should you be wary of?
inferior MI can stimulate vagal nerve and cause decreased heart rate
in this case, do not want to give beta blockers
When should you be wary of giving nitrates? Why?
When there is an inferior / right side MI
By decreasing preload in an already compromised right EF, you might reduce cardiac output and precipitate hypotension
Should you give thrombolytics when someone is having a supply-demand (stenosis) heart attack / angina?
No! You do not have a thrombus
Why do we often give nitrates and B-blocker together?
Decrease preload = decreased SV with nitrates
Decreased SV = increased HR to maintain CO
Increased HR = give beta blocker
How do B-blockers work?
they decrease heart rate and contractility by blocking sympathetic simulation of B1 receptors
What class of drugs is an example of a negative inotrope?
Ca2+ channel blockers (verapamil + diltiazem)
they will decrease heart rate and contractility
also b-blocker
Why might you not want to give a Ca2+ channel blocker?
they also increase preload
this could worsen heart failure
diltiazem and verapamil should be discontinued in HF
Why does QT prolongation occur?
due to delayed repolarization (phase 3) of the myocyte action potential
K+ channels are blocked
Why does PR prolongation occur?
delayed conduction through AV node
Ranolazine
novel agent that has anti-angina effects with NO CHANGE on BP / HR
decrease O2 demand by preventing intracellular Ca2+ overload
inhibits late phase of the Na+ current (less Na+ = less Ca2+)
Ranolazine effect at high dose
can cause QT prolongation since it blocks repolarization at high doses
Beta blockers effect on SA node
Less beta stimulation = less cAMP
less cAMP = less calcium
less calcium = phase 0 of SA node potential delayed
Which cardiac action potential uses Ca2+ in depolarization?
the SA node
Which cardiac action potential uses Na+ in depolarization?
the myocyte
Adenosine
direct negative inotropic effect
useful for treating supraventricular tachycardia (PSVT)
What is an example of cardiac glycoside?
digoxin
Digoxin MOA (2)
1) positive ionotropic
2) AV node inhibition: stimulates the parasympathetic nervous system
Lisinopril MOA
ACE inhibitor
ACE normally makes angiotensin which is a vasoconstrictor
By inhibiting ACE, you lower angiotension / vasoconstriction which helps to lower BP
2 examples of positive iontropes
Cardiac glycosides (digoxin)
Beta agonists (dobutamine, epi, norepi)
Which beta agonist has lowest risk of tachycardia?
norepinephrine
when do you use a Swan cath?
if you suspect papillary muscle rupture or intraventricular rupture after an MI
How does an intraventricular defect lead to hypotensive and pulmonary edema?
when LV pumps, blood can go to RV and out pulmonary artery causing backup in lungs
also you’re not pumping as much to systemic circulation which causes hypotension
What are signs of the neurocardiac reflex?
Bradycardia
Good perfusion
Post-MI (inferior)
What drug blocks a parasympathetic response?
atropine
use for the neurocardiac reflex
What is the neurocardiac reflex?
LV stretch makes it seem like there is an increased SV so you want to decrease HR
causes bradycardia
Kussmaul sign PE
upon inspiration JVP increases
(JVP should normally fall when you inhale because you are pulling blood into the RA)
What does Kussmaul’s sign indicate?
right heart dysfunction / limited right ventricle filling
paradoxically, right atrial pressure is rising during inspiration
If you have an inferior infarct, what are you worried about electrically?
the RCA could have reduced blood to SA / AV node
also the RCA could hit vagal nerve and increase parasympathetic
all this could lead to PR prolongation / AV block (I or Mobitz II)
If you have a anterior infarct, what are you worried about electrically?
LAD supplies bundles of HIS, BBB, etc. so you are worried about a AV block (Mobitz II or 3rd degree block)
What is heart rate response to heart failure normally?
tachycardia to try to make up for decrease in SV
CO= HR * SV
PVC vs. PAC on EKG
PVC looks like wide, random, big QRS complex
PAC looks like normal beat just thrown too early
Why can you see PVCs after a MI?
acute MI can cause an electrical storm and lead to electrical problems
What are some features of HPI that can tell you someone has unstable angina due to thrombus not stenosis?
new onset angina
angina in a crescendo pattern
angina at rest
What is frontline treatment for preventing MI in outpatient setting?
aspirin (prevent clot)
statin (manage LDL)
B-blocker (reduce O2 consumption)
What is a Q-wave?
a pathological Q-wave is when the Q part of the QRS complex really dips below normal
Q wave is stretched downward
If a MI is not totally occlusive what does it have to be?
an NSTEMI
What are the pre-cordial leads?
V1-V6
What does pulmonary edema indicate?
indicates left sided volume overload since you are backing up into the pulmonary vein
What does elevated JVP indicate?
right side volume overload since you are backing up into the vena cava
Mild bradycardia following an MI can indicate …
neurocardiac reflex
Should you give patients B-blockers if they have asthma?
No! They need vasodilation from B2 receptors in the chest
When you have an inferior wall block what is normally the culprit?
RCA!
What drug do you give for pulmonary edema?
diuretic
Major risk factors for ruptures following MI
Age, gender (female), and history of HTN
What is upper normal for JVP?
6-8cm
What medications should you avoid with the neurocardiac reflex?
anything that decreases preload and inotropy
What happens with mechanical dysfunction of right ventricle?
BP decreases
the pressure on right side rises
cardiac output to pulmonary artery (from RV) is low
peripheral resistance rises to try to raise BP
What 3 things is cardiogenic shock characterized by?
1) hypotension
2) reduced CO
3) elevated filling pressures
How do you treat cardiogenic shock?
need reperfusion
More fluid normally means what for pressure …
higher pressure!
What happens to pressures when volume depleted?
pressures drop
What can you use to treat PVCs?
beta blockers
Why do atrial flutter and Afib occur after MI?
increased intracardiac pressures and increased left atrial stretch
Rate control drugs for Afib
Beta blockers, Ca2+ channel blockers, digoxin
What other drug do you need to give with afib?
anticoagulation!
How can you tell VT versus SVT?
VT has wide-complexes and AV dissociation
How can you treat VT?
electrical or medical cardioversion
How can you determine if VT is driven by acute MI or actual damage?
< 48 hrs after MI = post-MI irritability
> 48 hrs after MI = damage / re-entrant pathways
Why is adding visualization of perfusion good in stress testing?
Perfusion is an early sign of ischemia
can detect things sooner
