Exam 2 - Arrhythmias Yang Flashcards
put the steps for electrical conduction in the heart in order:
a. excitation spreads down AV bundle
b. AV node fires
c. SA node fires
d. purkinje fibers distribute excitation through ventricular myocardium
e. excitation spreads through atrial myocardium
c, e, b, a, d
what does the P wave of ECG show?
atrial contraction
what does the QRS complex of an ECG show?
ventricular contraction
what does the T wave of an ECG show?
ventricular repolarization
what is automacity in regards to pacemaker cells?
they have the ability to generate action potentials regardless of input from outside of the cell (but outside factors for SNS and PNS can change this and have effects on HR)
which of these ion channels in the heart is an important one to avoid being targeted when developing new drugs?
a. HCN channels
b. K channels
c. Ca channels
d. Na channels
e. hERG channels
e. hERG channels
the inside of the cell is ___ mV and the outside is ___ mV
-70; 0
is sodium concentration higher inside or outside the cell?
outside
is potassium concentration higher inside or outside the cell?
inside
sodium potassium pump how many K and Na are pumped in/out?
3 Na out, 2 K in
pacemaker cells exhibit action potentials that are dependent on ___ for the upstroke of the spike
a. Ca2+
b. Na+
a. Ca2+
pacemaker cells exhibit action potentials that are dependent on ___ for the upstroke of the spike
a. Ca2+
b. Na+
b. Na+
which is FALSE about pacemaker cells?
a. Ca2+ dependent spikes
b. high automaticity
c. contractile cells
d. physiologically depolarized
c. contractile cells (they are specialized, non-contractile cells)
which is TRUE about ventricular myocytes?
a. specialized, non-contractile cells
b. hyperpolarized
c. high automaticity
d. Ca2+ dependent spikes
b. hyperpolarized
what is phase 3 of the pacemaker action potential?
a. the upstroke
b. repolarization
c. diastolic depolarization
b. repolarization
true or false: phase 1 and 2 are not present in the SA node action but is present in Purkinje fiber and myocyte action potentials
true
what is phase 0 of the pacemaker action potential?
the upstroke, mediated by Ca2+ channels
what is phase 4 of the pacemaker action potential?
a. the upstroke
b. repolarization
c. diastolic depolarization
c. diastolic depolarization
what is phase 1 of the myocyte action potential?
it is a brief repolarization, it is the notch at the top of the action potential
which current is responsible for phase 1 in myocyte action potentials?
a. INa
b. IKto
c. Ica(L)
d. IK
e. If
b. IKto (“transient outward” repolarizing K+ current)
what is phase 2 of the myocyte action potential?
a. upstroke
b. brief repolarization
c. intervening time between APs
d. plateau phase
d. plateau phase (due to mainly Ca2+ currents)
true or false: the neuronal action potential involves calcium channels
false
three beta blockers used as antiarrhythmics
esmolol
acebutolol
propranolol
how do class 2 antiarrhythmics affect the AP diagram?
causes shift to the right (decreases slope of phase 4)
(class 2 are BBs)
how do class 4 antiarrhythmics affect the AP diagram?
causes reduced peak
(class 4 are CCBs)
main clinical use of BBs for arrhythmias
used for arrhythmias involving catecholamines
which BB is NOT cardioselective?
a. esmolol
b. acebutolol
c. propranolol
c. propranolol (non-selective)
why does esmolol have a very short half life (~9 min)?
due to plasma esterase hydrolysis
2 clinical uses of CCBs for arrhythmias
-block re-entrant arrhythmias involving AV node
-protect ventricular rate in atrial flutter and A Fib
what are class 1 antiarrhythmics?
sodium channel blockers
what are class 3 antiarrhythmics?
potassium channel blockers (agents that prolong refractory period)
which drug class has a mixed block on Na+ and K+ channels?
a. class 1A
b. class 1B
c. class 1C
a. class 1A
which drug class leads to a prolonged QT interval? (also widened QRS)
a. class 1A
b. class 1B
c. class 1C
a. class 1A
which drug class has no clinically significant effect on ECG?
a. class 1A
b. class 1B
c. class 1C
b. class 1B
which drug class has strong Na+ channel block and a widened QRS complex on ECG?
a. class 1A
b. class 1B
c. class 1C
c. class 1C
quinidine, procainamide, and disopyramide are in which class of antiarrhythmics?
a. class 1A
b. class 1B
c. class 1C
a. class 1A
lidocaine, tocainide, mexiletine, and phenytoin are in which class of antiarrhythmics?
a. class 1A
b. class 1B
c. class 1C
b. class 1B
propafenone, flecainide, and moricizine are in which class of antiarrhythmics?
a. class 1A
b. class 1B
c. class 1C
c. class 1C
which class of antiarrhythmics blocks IKr, prolong AP and QT interval, as well as increasing effective refractory period?
a. class 1
b. class 2
c. class 3
d. class 4
c. class 3 (K+ channel blockers)
