Flashcards in antiarrhythmics Deck (29):
3 reason a person may get an arrhythmia?
2. cardiac injury
Cardiac arrhythmias result from
1. abnormal impulse _____ - arise from non-traditional ____
2. abnormal impulse _____ - abnormal pathways due to _____
3. _______ of both
1. formation - locations
2. conduction - blockages
name 8 types of arrhythmias
1. at nodal level
2. at conduction level
3. premature contractions
8. heart block
At the conduction level, there are 4 types of arrhythmias, what are they?
1. normal pattern of conduction but conduction splits and goes two ways
2. re entry
3. unidirectional block
4. prolonged refractory period
_____ heart block = His/Purkinje system cut in half, atria and ventricles work indpendently
generally, why are antiarrhythmias used?
Used to modify/restore aberrant electrophysiologic properties of cardiac muscle to normal aka depress parts of the heart that are beating abnormally
What are the 3 pharmacologic effects of antiarrhythmias?
1. change slope of depolarization
2. raise threshold for depolarization
3. alter conduction velocity in different parts of the heart
What are 4 NON- pharmacologic effects for arrhythmias?
1. electrical cardioversion
2. automatic implantable cardioverter devices
3. ablation therapy
what are 4 contraindications to giving an antiarrhythmia?
1. complete AV heart block
4. known hypersensitivity to the drug
5 indications that a person needs an antiarrhythmia
1. paroxysmal atrial tachycardia
2. paroxysmal ventricular tachycardia
3. atrial fibrillation
4. ventricular ectopic arrhythmias
5. digoxin-induced arrhythmias
antiarrhythmic medications work on 1 of 5 trans membrane phases of the cardiac cycle which alter the phases to control rhythm, what are the 5 phases?
Phase 0 - influx of Na ions -> depolarization
Phase 1 - partial repolarization through efflux of K ions
Phase 2 - plateau where net influx of Ca is slightly more than the efflux of K
Phase 3 - efflux of K
Phase 4 - restoration of ionic concentrations via Na/K & Na/Ca exhange pumps
What phases of the cardiac cycle are part of the absolute (effective) refractory period? (-50mV)
Phases 0, 1, 2, and most of 3
What is the name in the cardiac cycle during the middle of phase 3 to beginning of phase 4?
Relative refractory period
What happens in the absolute refractory period?
(synonymous with depolarization)
cells cannot respond to a stimulus, its a mechanism that protects the heart from all other ectopic impulses
When is the only time that a strong stimulus can cause depolarization?
Relative refractory period - occurs when repolarization is almost complete (cells may all respond differently)
The length of time between refractory periods varies between individuals, what 6 things affect it?
2. recreational drugs
4. electrolyte imbalance
5. myocardial ischemia
6. myocardial injury
In what phase are all the cells repolarized and ready to respond in a normal fashion?
Non refractory phase
What drives automaticity?
Spontaneous opening and closing of K channels (the net flow of these ions repolarized the cell, then depolarizes to threshold
What 3 areas of the heart have pacemaker activity?
1. SA node (main)
2. AV node
3. Purkinje Fibers
Why is the rate of depolarization (Phase 0) important?
Informs neighboring cells that something is happening
Why are threshold and resting membrane potentials important?
Determines how easily and how frequently cells can depolarize, the further away from these potentials that the cell is maintained, the harder it will be to get the cell to depolarize
.Effective Refractory Period in cells in ____ areas is ___ than in myocardial cells. Myocardial cells _____ quickly and have to wait for the pacemakers to repolarize before ___ again. Ensures that all cells are repolarized before being told to _____ again. Different arrhythmias require that the ERP be _____ or ______.
lengthened or shortened
when do you want to induce an arrhythmia?
For temporary heart block until a pacemaker is inserted and with ventricular arrhythmias due to AV node block
What are 3 drugs that can induce an arrhythmia?
2. Isoproterenol - beta 1 and beta 2 agonist
3. hypokalemic diuretics
rate of contraction
force of contraction
6 toxic reactions to antiarrhythmics
4. paradoxical arrhythmias
5. GI disorders
The ___ blocking effects of antiarrhythmic drugs and ______ (eg atropine) can act synergistically and lead to _____.