Lecture 1 Anti-arrhythmics basic Flashcards
The beating heart relies on sequential changes in ____ ____
membrane potentials
what is the conduction pathway
SA-atria-AV node-common bundle–bundle branches–fasicles–purkinje fibers–ventricles
cardiac muscle contains ___ ____, allowing for simultaneous propagation of action potentials
gap junctions
myocardial APs occur in cardiac muscle, the ____ and _____
bundle of his, purkinje fibers
Myocardial AP:phase 0 = rapid ____ and depolarization, due to inward _____
upstroke; sodium
Myocardial AP: Phase 1 = initial _____ due to inactivation of voltage gated ___ channels and opening of some ____ channels
repolarization;Na, potassium (outward)
myocardial AP:phase 2 = ____ due to ____ influx through voltage gated channels, balancing ____ efflux. ____ influx triggers __ release from the SR and myocyte contraction
plateau, calcium;potassium; calcium, calcium
myocardial AP:phase 3 = rapid ____ due to massive ___ efflux due to pening of voltage gated ____ channels and closure of voltage gated ____ channels
repolarization, K;slow K; Ca
myocardial AP:phase 4 = resting potential due to high ___ permeability. what is the resting potential usually?
potassium negative 90 mV
myocardial tissue at resting potential:____ channels are typically closed = no movement of ions despite high concentration gradient. inward ____ ___ channels are open, allowing free movement
sodium;rectifier potassiumn
pacemaker APs occur in the ___ and ___ nodes. they have an _____ resting potential
SA, AV; unstable
PR interval is the time from ______ to _____. it corresponds to ____ conduction
atrial depolarization, ventricular depolarization;AV node
pacemaker AP:phase 0 = ____ due to opening of voltage gated ___ channels.
upstroke, calcium
pacemaker AP:phase 3 = inactivation of the ___ channels and increased activation of ___ channels = ___ efflux
calcium, potassium; potassium
pacemaker AP: phase 4 = slow spontaneous _____ depolarization as a result of increased ___ conductance (through what channnel?)
diastolic; sodium and potassium; “funny current”
the slope of phase ___ in the SA node determines HR
4
chronotropic effects: the sympathetic system causes an increase in phase ___ depolarization due to increased ____ channel opening
4; funny;easier to reach threshold
which has a longer AP, skeletal or cardiac muscle?
cardiac (much slower AP, longer contraction)
what channel is open during the refractory period in cardiac muscle? what channel is inactivated?
potassium; sodium
what are the 2 “triggered arrythmias”?
Early afterdepolarization (EAD); delayed after-depolarization (DAD)
ectopic foci are due to an abnormal ____ site, typically occuring after ____
pacemaker; ischemia
ischemic cardiac tissue is ___polarized relative to normal tissue,
de
an EAD occurs in the late phase ____. EAD’s are due to prolonged ____. a DAD occurs in the early phase ___. DAD’s are due to ____ overload
3, plataeu;4, calcium
____ are exacerbated by slow HRs, such as long QT arrhythmias (ie Torsades). ____ are exacerbated by rapid HRs, such as MI induced arrythmia
EAD,DAD
Torsades de pointes is predisposed by a long ____. It is a polymorphic ventricular ____, characterized by shifting ___ waveforms. can progress to ____
QT; tachycardia, sinusoidal;vFib
re-entry is due to ____ impulse exciting areas of the heart more than once (circuit movement). can be due to a ___ conduction time and a ___ refractory period
one; long, short
____ reentry is when there is reentry between the atria and ventricles due to a ____ pathway. what is an example?
global, acceossory;wolf parkinson white
Premature ventricular contraction:beat originates in the ____, causing the ventricles to contract before the ___ and resulting in a decrease in the amount of blood pumped to the body
ventricles; atria
