10/07 Flashcards
what causes a block arrhythmia?
scar tissue
When do early afterdepolarizations show themselves on an EKG?
phase 2-3 slope
When do late afterdepolarizations show themselves on an EKG?
after phase 3 slope
first degree heart block:
PR prolongation
slowed but all P waves connect to QRS
second degree type 1
pr no longer second
longer longer longer drop
second degree type 2
complete disconnect between p and QRS
characteristic of circus block
reentry, the impulse reenters and stimulates a small contraction before the refractory period is over
what are the 4 classes of antiarrhythmic agents?
class 1: sodium channel blocker
class 2: beta blockers
class 3: potassium blocker
Class 4: calcium channel blockers
Class 1A antiarrhythmics do what?
Quinidine
procainimide
prolongation of action potential
increased effective refractory period
If refractory period is extended then all Na+ channels are closed so helpful in the early/late afterdepolarizations. slows down HR
Class 1B antiarrhythmics do what?
lidocaine
shorten the APD
decrease the Effective refractory period
Class 1C antiarrhythmics do what?
flecainide
No really effects on APD or EFR
but Na+ channels are still blocked
what is the drug of choice for VT?
amiodarone only drug with all 4 class effects but classified in class 3
verapamil targets the
heart, blocks both activated and inactivated calcium channel blockers so Hypotensive side effect
what drug is a class 2 antiarrhythmic and what does it do?
sotalol= beta blocker
slows rate
prolongs ADP
what is a class 3 antiarrhythmic and what does it do?
amiodarone= K channel blocker
prolongs ADP
