anti-arrhythmics

Question 1

3 ways to counter arrhythmias

Answer 1

decrease automaticity, increase refractoriness, decrease conduction velocity

Question 2

5 ways to decrease automaticity

Answer 2

increase threshold, decrease phase 4 slope, increase AP duration, slow SA/AV depolarization, increase maximum diastolic potential (more negative)

Question 3

3 Class IA

Answer 3

quinidine, procainamide, disopyramide

Question 4

2 class IB

Answer 4

Lidocaine, mexilitine

Question 5

2 class IC

Answer 5

flecainide, propafenone

Question 6

5 class II (beta blockers)

Answer 6

esmolol, metoprolol, propranolol, atenolol, timolol

Question 7

5 class III

Answer 7

amiodarone, dronedarone, dofetilide, sotalol, ibutilide

Question 8

2 class IV

Answer 8

verapamil, diltiazem

Question 9

Class IA target/mech

Answer 9

Na channels (slow action potential, flatter phase 0 slope), also affect potassium (prolong AP duration/repolarization)

Question 10

Class IB target/mech

Answer 10

weak Na block, shortened repolarization

Question 11

Class IC target/mech

Answer 11

strong Na block (affect on phase 0) and minimal repolarization effect

Question 12

overall mech for class I

Answer 12

slow the resetting of fast Na+ channels after AP- makes them selective for rapidly depolarizing tissue

Question 13

IA toxicities

Answer 13

prolonged QT and torsade

Question 14

IC toxicities

Answer 14

proarrhythmic, avoid w/ pts who have structural abnormalities

Question 15

class II mech for decreasing automaticity

Answer 15

decrease phase 4 slope by competing w/ adrenergic stimulation and slowing HCN channel opening

Question 16

class III mech for decreasing automaticity

Answer 16

block K+ channels and prolong repolarization

Question 17

class III toxicities

Answer 17

prolonged QT and torsade

EXCEPT amiodarone

Question 18

class IV mech to lower automaticity

Answer 18

slow depolarization in nodal cells by blocking Ca++ channels (responsible for phase 0 upstroke in pacemakers)

Question 19

adenosine mech for lowering automaticity

Answer 19

increase (more negative) maximum diastolic potential, bind to specific adenosine receptors, promotes K+efflux and inhibits adenylate cyclase (and cAMP) and thus the Ca++ channels as well

Question 20

PK of adenosine

Answer 20

short half life less than 30 seconds, must be administered by rapid IV bolus

Question 21

ways to inhibit reentrant arrhythmias

Answer 21

increase refractory period, slow conduction

Question 22

how to increase refractory period?

Answer 22

class IA and III- block K+ channels and repolarization, prolonging AP

Class IA-C and adenosine- inhibit recovery of Na+ (Ca++ for adenosine) channels prior to next AP, does not prolong current AP

Question 23

why want to slow conduction velocity?

Answer 23

blocking/slowing impulse along AV node can protect ventricles from atrial arrhythmias

Question 24

how to slow AV conduction?

Answer 24

Class II beta blockers (slow HCN Na+ influx) or class IV Ca++ blockers (slow Ca++ phase 0) or adenosine (hyperpolarization at maximum diastolic potential)

Question 25

side effects of amiodarone

Answer 25

neuropathy, night terrors, nausea, discoloration (blue), pulmonary fibrosis, thyroid problems, corneal deposits

Question 26

Tx for acute termination of SVT

Answer 26

block AV node- vagal maneuvers, adenosine

Question 27

long term management of AVNRT

Answer 27

ablation of slow pathway or beta blocker

Question 28

long term managment of AVRT

Answer 28

ablation of accessory pathway and/or flecanaide/propafenone (class IC) when there is pre-excitation (slows accessory)

ablation of accessory pathway and/or beta blocker (slows AV node) when no pre-excitation

Question 29

managment of a fib

depends on presence of structural heart disease

Answer 29

anticoag stroke prevention, rate control (class II, class IV, digoxin), rhythm control (when symptomatic or low EF), can do ablation or use class IC or III)

Question 30

acute management of VT

Answer 30

cardioversion if unstable/ACLS

w/ heart disease: cardioversion, procainamide, lidocaine, or amiodarone

w/o heart disease: for outflow VT use beta blocker and for fascicular VT use verapamil

Question 31

chronic managment of VT

Answer 31

AICD (automatic implanted cardioverter defib), up beta blocker, prevention w/ sotalol, amiodarone, or ablation

Question 32

why add rhythm control for a fib?

Answer 32

Sx despite rate control, LV dysfunction, reduce hospitalization

Question 33

rhythm control AAD options for a fib?

Answer 33

propafenone, flecanide (IC), sotalol, dofetilide, amiodarone, dronadarone (III)