Exam 2 Flashcards
Cardiac action potential phase 0
sodium channels open (Na+ in)
Phase I action potential
sodium channels close, potassium channels begin to open (K+) out
Phase II action potential
calcium and potassium channels open (Ca++ in and K+ out)
Phase III action potential
calcium channels close
Phase IV action potential
cells return to resting membrane potential (-70 mv)
all anti-arrhythmic drugs are potentially
pro-arrhythmic as well
anti-arrhythmic drug class Ia, Ib, Ic
sodium channel blockade
anti-arrhythmic drug class II
beta adrenergic receptor blockade
anti-arrhythmic drug class III
potassium channel blockade
anti-arrhythmic drug class IV
calcium channel blockade
what do anti-arrhythmic drug class Ia do
slow phase 0 depolarization, prolong action potential and slow conduction
what do anti-arrhythmic drug class Ib do
shorten phase 3 repolarization and decrease the duration of the action potential by blocking or inactivating sodium channels
what do anti-arrhythmic drug class Ic do
markedly slow phase 0 depolarization
what do anti-arrhythmic drug class II do
diminish phase 4 depolarization, thus depressing automaticity
what do anti-arrhythmic drug class III do
agents prolong phase 3 repolarization without altering phase 0
what do anti-arrhythmic drug class IV do
agents slow phase 4 depolarization and slow conduction particularly at the AV node
class of Quinidine/Quinidex
anti-arrhythmic–Class Ia
Quinidine/Quinidex indication
A-flutter, A-fib, AV, and ventricular arrhythmias
MOA of Quinidine/Quinidex
sodium channel blocker. diminished inward flow of sodium at phase 0 results in decreased automaticity and a lengthened refractory period
Char. of Quinidine/Quinidex
PO, IV. less commonly used because of significant adverse effect profile
side effects of Quinidine/Quinidex
potentially pro-arrhythmic, nausea, vomiting, diarrhea. Cinchonism
symptoms of cinchonism include
blurred vision, tinnitus, nausea, vomiting, headache, disoreintation and possible psychotic states
Quinidine/Quinidex may induce abnormal rhythm of ventricular tachycardia known as
Torsade de Pointes
Class of Mexiletine/Mexitil
anti-arrhythmic Class Ib