Flashcards in Cardiovascular pharmacology I Deck (22):
which ion is responsible for phase 0 of the cardiac action potential - ventricular muscle?
calcium is important for which phase of the cardiac action potential - ventricular muscle?
why is the phase 2 downslope of the cardiac action potential gradual (ventricular muscle)?
balance between influx of calcium and efflux potassium
what ion is responsible for the sharp downward slope of phase 3 of the cardiac action potential - ventricular muscle?
how will drugs that block potassium channels change phase 3 of the cardiac action potential?
what is the funny current?
phase 4 of pacemaker tissue - upslope
what is the conformation of the sodium channel at rest? upon depolarization? inactivation state?
1. activation gate closed, inactivation gate open
2. activation gate open, inactivation gate open
3. activation gate open, inactivation gate closed
what is the result of enhanced late sodium current?
1. increased intracellular sodium
2. sodium exit with calcium entry (NCX)
3. increased intracellular calcium - cellular calcium overload
4. electrical instability, after-depolarizations, arrhythmias
5. mechanical dysfunction, abnormal contraction and relaxation
which ion is responsible for phase 0 of the cardiac action potential - SA node?
how long does the ERP last in ventricular muscle?
phase 0 - mid-phase 3
what does a low ERP/APD ratio mean?
easy to be depolarize by abnormal impulses
how does SA node tachycardia manifest on the ECG?
every QRS is preceded by a P wave, but they occur much faster than normal
how does atrial tachycardia manifest on the ECG?
some P waves without QRS complexes - 2:1 conduction rate (atria: ventricles)
how do early after-depolarization occur?
1. prolonged cardiac AP (slow HR, hypokalemia, drugs)
2. can lead to Torsades de Pointes
how do delayed after-depolarizations occur?
1. cytoplasmic or SR calcium overload (ischemia, stress, digitalis overdose, heart failure)
2. normal upstroke followed by abnormal depolarization
3. secondary upstroke
4. abnormal rhythm - spontaneous APs
what is the hallmark ECG sign for first degree AV block?
increased PR interval
what is the ECG sign for second degree AV block?
not all P waves pass
what is the ECG sign for third degree AV block?
1. large QRS complex - ventricular conduction origin
2. no P/QRS relationship (ventricles beat according to their own rhythm)
what is the reason for existence of a reentry mechanism?
two pathways, each with different conduction velocities
what is the mechanism of atrial premature beat / reentry mechanism?
1. fast pathway encountered during refractory period of normal SA beat
2. premature beat goes through slow pathway
3. once fast pathway repolarizes, loop forms (slow pathway returns back up the fast pathway)
what is a hallmark sign of accessory pathway mediated supraventicular tachycardia?
P waves occur after QRS