Anti-arrhythmiic Drugs Flashcards
only ___ have been shown to reduce indcidence of sudden cardiac death
beta blocker
Finnish familial arrhythmia
mutant protein?
yotiao
function of yotiao?
anchors PKA to cardiac Ca2+ and IKs channels
during incr symp activity, not enough repol K+ current to match Ca2+
prolong phase 2, incr Ca2+, incr afterdepol
mechanism of reentry arrhythmia
1) prolong phase 2, incr inward current or decr outward current
2) incr Ca2+ –> EADs (via Ca2+ ch reactiv) or DADs (via NCX depol)
3) incr symp tone (trigger activity), incr Ca2+ entry
4) incr trigger afterdepol
5) re-entry –> torsades –> V-fib
re-entry underies which arrhythmias
1) atrial flutter
2) afib
3) torsades
4) v-fib
arrhythmias are triggered by ___ and maintained by ____
trigger by afterdepol
maintain by re-entry
which drug has both class III and class I action?
amiodarone because not only prolong refractory, but also decr conduction velocity (class 1)
effects of class 1 drugs?
1) decr conduction velocity by decr upstroke rate
2) incr refractory period of Na+ channels by use dependent block and prolong phase 2
3) decr re-entry
difference btwn class 1A/1C and 1B?
1A and 1C prolong repolarization
while class 1B shorten AP and shorten repol
how can re-entry be terminated (2 ways)
1) convert uni to bi directional block
2) prolong refractory time
how can unidirectional block be convert to bidirectional block
1) slow AP conduction velocity
2) incr refractory period
paradox in combating re-entry
1) by slowing conduction velocity, less likely conduction velocity will be shorter than refractory period
conflict btwn slowing conduction velocity and prolonging refraction
effect of class 3
blocker HERG IKr
incr phase 2 –> prolong refractory period (prolong phase 2, incr inactiv of Na+ channel)
effect of class 4
1) use dependent block of L-type Ca2+, decr upstroke rate, decr amplitude, decr conduction velocity
2) L channel block –> decr amplitude of AP –> activ fewer K+ channels –> slow repol (phase 3)
effect of adenosine
1) incr K+ current
2) decr L-type Ca2+ current
3) decr If in SA and AV
4) decr SA and AV node firing rate
5) decr conduction rate in AV
