Rx of Arrhythmias- Al-Mehdi Flashcards
automaticity of the heart determined by
HCN channel of SA node
NCX channel (Na+ in and Ca2+ out but then L type Ca2+ channel brings in Ca2+ and more from RyR) can also contribute to what
SA node automaticity
autonomic modulation of SA node automaticity: positive chronotropy
sympathetic (NE) binding B1 (Gs)
autonomic modulation of SA node automaticity: negative chronotropy
vagus (parasympathetic) Ach binding M2 (Gi)
antiarrhythmic drugs goal
restore electrical system of heart (by prolonging AP to try and figure itself out)
what do Na channel blockers for arrhythmia ultimately do to AP
1A: prolongs AP
1B: shortens AP
1C: no change
what do K channel blockers for arrhythmias ultimately do to AP
slower phase 3, 4, 1 (PROLONGS AP)
what do K channel openers for arrhythmias ultimately do to AP
speed up phases 3, 4, and 1 (shortens AP duration)
effect of Ca2+ channel blockers on nodal myocytes
prolonged phase 0 (prolonged AP)
beta blockers effect on SA/AV nodes
slower phase 4 (decrease chronotropy and dromotropy)
anti-arrhythmic drug that decreases diastolic potential (making it harder to reach threshold)
Adenosine
1A Na+ channel blockers mneumonic
Double Quarter Pounder
1A Na+ channel blockers
1B Na+ channel blockers mneumonic
Lettuce, mayo, tomato
1B Na+ channel blockers
1C Na+ channel blockers mneumonic
More Fries Please
1C Na+ channel blockers
what prolongs Na+ slope (phase 0) the most out of the Na+ channel blockers
1C class
“PACE Maker”
class II: beta blockers (SA node)
class II: beta blockers
“A Big Dog Is Scary”
class III: K+ channel blockers
class III: K+ channel blockers
Diltiazem
Verapamil
class IV: Ca2+ channel blockers (AV node)
most important and widely used class III: K+ channel blocking drug
Amiodarone
anti-arrhythmic drugs acting on cardiomyocytes in reentry
1A, 1B, 1C, III
drugs used in most atrial and ventricular arrhythmias (AVNRT, AFLUT, AFIB, VTACH)
1A (D,Q,P)
drug used as second choice in sustained VTACH in MI
Procainamide
SE’s for class 1A Na+ channel blockers
long QT
TdP
SE of this 1A Na+ channel blocker is CINCHONISM
Quinidine
SE of this 1A Na+ channel blocker is drug induced lupus
Procainamide
group of drugs that abolishes unidirectional block (treats diseased heart)
class 1B (L,M,T)
what is a concern for long QT
Torsades de pointes
good for post MI VTACH; preferentially binds to ischemic and disease cells (BEST FOR MI PATIENTS)
class 1B Na+ channel blockers
SE of class 1B drugs
CNS toxicity
contraindicated in diseased hearts (proarrhythmic)
class 1C Na+ channel blockers
SE of class 1C drugs (M,F,P)
produce arrhythmia
SE of this class 1C drug is metallic taste
Propafenone
Na+ channel blocker class with strongest binding
1C
Na+ channel blocker class with weakest binding
1B
class II (beta blockers) ultimately do what
decrease chronotropy and dromotropy
class II (beta blockers) SE
heart block, failure
fatigue, asthma
masks hypoglycemia
nightmares, erectile dysfunction
class III (K+ channel blockers) has highest risk of what
Torsades de pointes
safest class III (K+ channel blocker) to prescribe; it decreases sinus rate, increases PR, QRS, QT
Amiodarone
class III (K+ channel blockers) SE
long QT, TdP
SE’s of Amiodarone:
pulmonary fibrosis (do PFTs)
hyper/hypothyroidism (do TFT)
hepatotoxicity (do LFT)
DO NOT USE IN VTACH or WPW syndrome (worsen arrhythmia)
class IV (Ca2+ channel blockers)
SE’s of Diltiazem and Verapamil
edema, heart block, constipation
CYP3A4 inhibitors
Diltiazem and Verapamil
short acting anti-arrhythmic drug that can produce complete heart block (block AV node) (can completely stop heart in 60 sec)
Adenosine
short acting anti-arrhythmic drug that is used in AV nodal reentry tachycardia (AVNRT)
Adenosine
Adenosine blocks _____and opens_____ channel; what does it do to cAMP
Ca2+; K+; decreases (Gi)
SE of Adenosine
bronchospasm
do NOT use adenosine in what patients
asthma
MoA of Digoxin
blocks Na+/K+ ATPase and NCX activity and leading to increased intracellular Ca2+ and +inotropy
primary effect of Digoxin
+ inotropy
Digoxin is contraindicated in what
hypokalemia and WPW syndrome(causes + dromotropy in atria)
signs of Digoxin toxicity
yellow vision
anorexia
Rx Digoxin toxicity:
Anti-Digoxin fragements
this pathway is related to what arrhythmia
AFib
this pathway is related to what arrhythmia
AFlut
indicative of what arrhythmia
AV nodal reentry tachycardia
indicative of what arrhythmia
WPW syndrome
can extreme tachy or bradycardia maintain CO?
no; anything outside (50-150) CO drops
origin of SVTs
AV node/Bundle of His or above
indicative of what arrhythmia
Atrial Tachycardia
Atrial Tachycardia
why inverted p in atrial tachycardia?
signal travels backwards to SA node
most common pediatric arrhythmia
Atrial Tachycardia
wavy baseline; irregularly irregular
AFib
most common sustained arrhythmia
AFib
Acute Rx of AFib w/ no CHF:
I.V. beta blockers and Ca2+ channel blockers
Acute Rx of AFib w/ CHF:
I.V. AMIODARONE (b/c beta blockers and Ca2+ could make CHF worse)
OR DIGOXIN
long term Rx of AFib w/out CHF
beta blockers and Ca2+ channel blockers
long term Rx of AFib w/ CHF
DIGOXIN
to control rhythm in AFib
Class III (K+ channel blockers)
sawtooth
Atrial Flutter
Rx Atrial Flutter
class III (IBUTILIDE)
NO p waves
AV nodal reentry tachycardia
SVT that occurs in normal heart
AVNRT
Acute Rx of hemodynamically stable patient with AVNRT
carotid massage; valsalva
what do administer if carotid massage and valsalva don’t help with AVNRT
I.V ADENOSINE
Acute Rx of hemodynamically unstable patient with AVNRT
emergency cardioversion
chronic Rx of AVNRT
ablation
PR short; NO delta wave
LGL syndrome
in LGL syndrome, why is the PR interval short
b/c bypass AV node through James fiber
wide QRS, short PR; DELTA waves
WPW syndrome
why does WPW syndrome have short PR
bypass AV node through Bundle of Kent
PVC (preventricular contraction)
VTACH to VFib
STEMI on L
Torsades de pointes on R
2 main treatments for VTACH
I.V. AMIODARONE
cardioversion
what drug if used in patient with VTACH will produce VFIB
CCB’s
_____mostly occurs in diseased heart (MI)
ventricular tachycardia
what will be ineffective for Rx of VTACH
carotid massage
polymorphic VTACH w/ long QT
Torsades de pointes
Rx Torsades de pointes
I.V. MgSO4
B1B2 agonist used to treat Torsades de pointes
ISOPROTERENOL
main reason for 3rd degree heart block
age related fibrosis
drugs (I.V.) to use to control rate in acute AFIB
beta blockers and Ca2+ channel blockers
AFIB + CHF
AMIODARONE
AFIB + CAD
Sotalol
AFIB + WPW
Ibutilide
AFIB + WPW that can turn into VFIB
cardioversion (if hemodynamically unstable)
Flecainide
can be used in acute and longterm AFIB + CHF
DIGOXIN
what drugs need to be administered in patient with AFIB + CHF
DIGOXIN
FUROSEMIDE and ACEI
ANTICOAGS (WARFARIN)
In a patient with WPW syndrome who experiences atrial fibrillation with anterograde (AV) conduction over the accessory pathway (antidromic reciprocal tachycardia), the drug of choice is:
Procainamide (the other choices CI in WPW)
why can you use procainamide in WPW?
it prolongs the refractory period of atrial myocardium (AP duration is prolonged); reduces ventricular response
Which of the following statements regarding lidocaine is NOT correct?
- It is a local anesthetic that causes sodium-channel blockade.
- It has activity on both atrial and ventricular myocardium.
- The drug mexiletine is an oral drug with properties very similar to those of lidocaine.
- Prophylactic administration of lidocaine in the setting of myocardial infarction is not recommended.
- it does not work on atrial myocardium (only ventricular myocardium)