Antiarrhythmics

Question 1

refers to AV block where some beats are dropped (e.g., progressive prolongation of PR interval until a beat is dropped immediately followed by shortest PR interval (= Mobitz type 1 = Wenckebach heart block)); number, superscripted letters, word

Answer 1

2nd degree

Question 2

therapy employed by cardiac electrophysiologists that has greatly decreased the need for chronic antiarrhythmic drug therapy

Answer 2

ablation

Question 3

agonist at GPCR that hyperpolarizes the cell membrane and suppresses the rate of spontaneous depolarization in the SA and AV nodes, making it useful for aborting reentrant supraventricular arrhythmias in these structures

Answer 3

adenosine

Question 4

receptors blocked by quinidine and procainamide but not disopyramide (2 words)

Answer 4

alpha adrenergic

Question 5

classified as a class III antiarrhythmic but has range of effects that allow it to function as a “magic shotgun” for control of rhythm disturbances, in part because it lacks the anticipated reverse use dependence

Answer 5

amiodarone

Question 6

effects associated with quinidine and disopyramide but not procainamide; reason disopyramide is selected to terminate vagally mediated atrial fibrillation

Answer 6

anticholinergic

Question 7

less common form of AVRT where accessory pathway activates ventricles and AV node returns current to atria; treated acutely with procainamide and longer term with flecainide; class II and class IV drugs are contraindicated since their effects on the AV node could precipitate ventricular fibrillation

Answer 7

antidromic

Question 8

risk factors for this include cardiovascular disease, diabetes, thyroid dysfunction, electrolyte imbalances, stimulants, alcohol and antiarrhythmic drugs

Answer 8

arrhythmia

Question 9

transient form of this is the treatment objective when using adenosine to treat supraventricular tachycardia

Answer 9

asystole

Question 10

treatment for bradycardia due to excessive parasympathetic tone

Answer 10

atropine

Question 11

1s degree means PR interval is longer than normal, 3rd degree means there is a complete dissociation between atrial and ventricular action potentials

Answer 11

AV block

Question 12

pausing the conduction signal here allows time for the atria to contract (abbr plus word)

Answer 12

AV node

Question 13

abbr for atrioventricular nodal reentrant tachycardia, the most common cause of supraventricular tachycardia (especially young women)

Answer 13

AVNRT

Question 14

abbr means there is an accessory pathway for atrioventricular communication (aka Wolff-Parkinson-White syndrome) which shows up as a delta wave during normal sinus rhythm; present in 1% of population and second most common cause of supraventricular tachycardia

Answer 14

AVRT

Question 15

slow HR and AV conduction by decreasing cAMP levels that regulate the hyperpolarized cyclic nucleotide regulated (HCN) channels in the SA and AV nodes

Answer 15

beta blockers

Question 16

seen in digoxin toxicity; a normal beat is followed by an ectopic ventricular beat

Answer 16

bigeminy

Question 17

skin discoloration color associated with amiodarone

Answer 17

blue

Question 18

responsible for the slow phase 0 depolarization in the SA and AV nodes, reason a drug like verapamil can slow the heart rate (abbr plus word)

Answer 18

Ca current

Question 19

refers to the classic adverse/toxic effects of quinidine: decreased hearing, tinnitus, blurred vision, delirium

Answer 19

cinchonism

Question 20

refers to a self-sustaining aberrant currents in the heart that occurs when timing is such that a wave of depolarizing current is able to pass in a retrograde direction through a one-way forward conduction block and encounters heart tissue that has already repolarized, and is therefore ready for another action potential

Answer 20

circus

Question 21

class of sodium channel antiarrhythmic drugs that has little effect on phase 0 slope (i.e., rate of depolarization) but tends to shorten action potential duration by binding to channel and hastening/prolonging time that channel is in inactivated state; this decreases the frequency that an individual Na channel can be activated; rapid firing due to this effect causes the cell to desensitize as its population of receptors get stuck for longer periods of time in the inactivated state (word, roman num and letter)

Answer 21

class Ib

Question 22

antiarrhythmic drug class that binds to the open state of voltage-gated sodium channels and dissociates very slowly; the loss of available Na+ channels can greatly decrease the rate of phase 0 depolarization and thereby the rate of signal conduction; action potential duration is relatively unaffected in a myocyte because the K+ channels are not directly affected and begin the normal repolarization process at a near normal time

Answer 22

class Ic

Question 23

antiarhythmics that are beta blockers (word plus roman num)

Answer 23

class II

Question 24

antiarrhythmics that block voltage-gated Ca2+ channels in the heart

Answer 24

class IV

Question 25

site of microdeposit accumulation during amiodarone therapy

Answer 25

cornea

Question 26

abbr. for aberrant depolarization during phase 4 when a Ca2+-overloaded sarcoplasmic reticulum "burps"

Answer 26

DAD

Question 27

prolongation of PR interval and ST ________ are associated with therapeutic levels of digoxin

Answer 27

depression

Question 28

Na+ - K+ ATPase blocker and positive inotrope, its ability to increase the refractory period and slow conduction in the AV node means it can be useful for ventricular rate control in those with atrial fibrillation (problem is its proarrythmic actions in His-Purkinje fibers and ventricle)

Answer 28

digoxin

Question 29

one of the Ca2+ channel blockers that is frequency/use dependent; often used for ventricular rate control in patients with atrial fibrillation or flutter

Answer 29

diltiazem

Question 30

orally active class III drug requiring special training to prescribe due to risk of torsades de pointes, but useful for treatment of atrial fibrillation/flutter in those with heart failure

Answer 30

dofetilide

Question 31

drug designed to maintain desirable properties of amiodarone while eliminating iodine and shortening half-life; unfortunately does not work as well and has been associated with increased mortality in those with severe heart failure or moderate heart failure after recent acute decompensation

Answer 31

dronedarone

Question 32

increasing action potential _______ is a means of slowing heart rate

Answer 32

duration

Question 33

abbr for aberrant depolarization during phase 3 of action potential; risk of this occurring is increased by drugs that block cardiac K+ channels and thereby increase the amount of time required for the myocyte to repolarize away from threshold potential down to the resting membrane potential

Answer 33

EAD

Question 34

refers to a heart beat originating in the wrong place (e.g., damaged myocardium that has a "hair trigger" due to its inability to fully repolarize (i.e., can only repolarize to just below threshold potential)

Answer 34

ectopic

Question 35

short-acting class II antiarrhythmic useful for situations where immediate adrenergic blockade is needed (e.g., to slow HR because of rapidly conducted atrial fibrillation)

Answer 35

esmolol

Question 36

flecainide binds tightly to the open state of Na channels, and is use dependent meaning that it is most likely to find an open channel when the HR is ___

Answer 36

fast

Question 37

pulmonary _____ is an adverse effect of amiodarone

Answer 37

fibrosis

Question 38

class Ic antiarrhythmic drug used to control supraventricular and ventricular arrhythmias when structural heart disease is absent

Answer 38

flecainide

Question 39

name given to the sodium current responsible for the spontaneous depolarization during phase 4 of the action potential now known to be conducted by HCN (e.g., HCN4 channels); these channels are activated by Hyperpolarization (e.g., -50 mV) and conductance is increased by increased Cyclic Nucleotides (cAMP)

Answer 39

funny

Question 40

potentially problematic since it averages ~50 days for amiodarone

Answer 40

half-life

Question 41

suggested when HR is <60 bpm in patients receiving digoxin, reason to withhold dose

Answer 41

heart block

Question 42

refers to a resting membrane potential that is more negative than normal; this slows HR by increasing the distance to the threshold potential

Answer 42

hyperpolarized

Question 43

class III agent administered as a rapid infusion to convert acute onset (but not chronic) atrial fibrillation or flutter to normal sinus rhythm; can cause torsades de pointes

Answer 43

ibutilide

Question 44

gate in a voltage-gated channel that closes to terminate a cycle of channel conductance

Answer 44

inactivation

Question 45

molecular component of amiodarone, can cause thyroid dysfunction

Answer 45

iodine

Question 46

blocked by Vaughn-Williams class III antiarrhythmics (abbr plus word)

Answer 46

K channels

Question 47

increase is responsible for phase 3 repolarization of ventricular muscle (abbr plus word)

Answer 47

K current

Question 48

prototypical class IB antiarrhythmic; a major use was to treat ischemia-induced ventricular arrhythmias, but amiodarone is now first-line therapy

Answer 48

lidocaine

Question 49

treatment for torsades de pointes

Answer 49

magnesium

Question 50

orally active class Ib antiarrhythmic drug

Answer 50

mexilitine

Question 51

Vaughn-Williams class I antiarrhythmics block voltage-gated _____ (abbr plus word)

Answer 51

Na channels

Question 52

responsible for phase 0 depolarization in ventricular muscle (abbr plus word)

Answer 52

Na current

Question 53

property of class Ia, Ic, II and IV drugs, but not amiodarone and dofetilide (which is reason these latter drugs can be used in patients with heart failure) (2 words)

Answer 53

negative inotrope

Question 54

state of the voltage and inactivation gates of a voltage-gated channel when current is flowing

Answer 54

open

Question 55

common form of AVRT with AV node conducting current to ventricles and accessory pathway returning current to atria; treated by vagal maneuvers, adenosine, class II or class IV drugs

Answer 55

orthodromic

Question 56

reason resting HR < 100 bpm, (i.e., ~spontaneous rate of SA node), too much causes bradycardia (2 words)

Answer 56

parasympathetic tone

Question 57

means the arrhythmia begins and ends abruptly

Answer 57

paroxysmal

Question 58

name given to the phase 2 portion of a ventricular action potential during which there is Ca2+ influx through voltage-gated Ca2+ channels

Answer 58

plateau

Question 59

major intracellular cation, resting membrane potential is due to its inability to exit from the cell down its concentration gradient (i.e., anion cannot follow), thereby creating the resting charge separation across the membrane

Answer 59

potassium

Question 60

condition during which digoxin--rather surprisingly-- has a long history of safe use as treatment for supraventricular tachycardia

Answer 60

pregnancy

Question 61

class Ia drug now typically selected for IV administration if needed to treat paroxysmal atrial tachycardia or recurrent ventricular tachycardia; poorly tolerated when used chronically with side effects that include drug-induced lupus and agranulocytosis

Answer 61

procainamide

Question 62

a class Ic antiarrhythmic drug

Answer 62

propafenone

Question 63

EKG portion widened by class Ia and class Ic drugs due to slowing of Na conduction in conduction pathway myocytes

Answer 63

QRS

Question 64

EKG interval increased by class Ic agents and even more so by class Ia agents due to their additional blockade of K+ channels (2 words)

Answer 64

QT interval

Question 65

prototypical class Ia blocker, has a moderate affinity for open Na+ channels that slows the rate of impulse conduction ; other effects include K+ channel blockade to prolong action potential duration and anticholinergic and alpha-blocking effects

Answer 65

quinidine

Question 66

type of tachycardia caused by accessory pathways; class Ic drugs are especially effective at treating this

Answer 66

re-entrant

Question 67

increasing or decreasing this period can disrupt the timing of recirculating currents in the myocardium

Answer 67

refractory

Question 68

this is delayed by K+ channel blockade

Answer 68

repolarization

Question 69

refers to the sodium channel state in which its voltage gate is closed (i.e., triggerable) and its inactivation gate is open

Answer 69

resting

Question 70

refers to fact that K+ channel blockers bind to the channels during the resting state, meaning that adverse proarrhythmic consequences are more likely when HR is slow (3 words)

Answer 70

reverse use-dependence

Question 71

calcium release channels in the sarcoplasmic reticulum also blocked by flecainide; mutations here can cause catecholamine triggered sudden death

Answer 71

RYR2

Question 72

cells here have the fastest rate of spontaneous depolarization and therefore control HR; first to get "bingo" causes others in region to respond (abbr plus word)

Answer 72

SA node

Question 73

with a half-life of ~10 ____, adenosine must be administered IV to cause its desired short-lived effect

Answer 73

seconds

Question 74

syndrome means that SA node is failing to originate a heart beat

Answer 74

sick sinus

Question 75

decreasing this during phase 4 in the SA node occurs with drugs such as propranolol or ivabradine

Answer 75

slope

Question 76

typical form of AVNRT, initiated when a premature beat reaches the slow pathway through the AV node that has recovered/repolarized more rapidly after having been extinguished by the previous beat (2 words)

Answer 76

slow-fast

Question 77

occurs in the cells of the SA and AV nodes, triggers the transmission of the action potential (2 words)

Answer 77

slow potential

Question 78

major extracellular cation, has both electrical and concentration gradients favoring cellular influx, but approximately no functioning influx pathways in the resting state of excitable cells

Answer 78

sodium

Question 79

beta blocker with class III antiarrhythmic effects, can cause torsades de pointes, useful for recurrent atrial fibrillation or ventricular tachycardia related to an old myocardial infarction(i.e., coronary artery disease)

Answer 79

sotalol

Question 80

contraindication for use of class Ic antiarrhythmic drugs (3 words)

Answer 80

structural heart disease

Question 81

refers to the voltage at which depolarization causes voltage-gated sodium channels to open in ventricular muscle, thereby causing phase 0 in the action potential

Answer 81

threshold

Question 82

potentially lethal ventricular tachycardia associated with drugs that prolong the QT interval (e.g., quinidine and dofetilide)… and later found for many other drugs already on the market

Answer 82

torsades de pointes

Question 83

maneuver that increases parasympathetic tone; can cause bradycardia or treat tachycardia

Answer 83

valsalva

Question 84

a frequency/use dependent Ca2+ channel blocker that can therefore be used as an anti-arrhythmic agent to control supraventricular tachycardias

Answer 84

verapamil