Arrhythmias

Question 1

cardiac conduction pathway

Answer 1

1. begins in the SA nodes
2. travels from SA nodes to right and left atria causing the atria to contract
3. singel reaches atrioventricular (AV) node
4. bindle of His
5. the bindle of His divides into the right bundle branch for the right ventricle, and
6. left bundle branch
7. Purkinje fibers

Question 2

Phase 0 what class of antiarrhythmics

Answer 2

Class Ia, Ib, Ic
phase 0: heartbeat is initiated, when rapid ventricular depolarization occurs in response to an influx of Na, this causes ventricular contractions (QRS complex on ECG)

Question 3

select drugs increase or prolong QT interval

Answer 3

• antiarrhythmics: Class Ia, Ic, and III
• Anti-infectives: Antimalarials (e.g., hydroxychloroquine), azole (except isavuconazonium), macrolides, quinolones, lefamulin
• Antidepressants: SSRIs (highest citalopram and escitalopram), tricyclic antidepressants, mirtazapine, trazodone, venlafaxine
• Antiemetics: 5-HT3 receptors antagonists, Droperiodol, metoclopramide, promethazine
• Antipsychotics: first gen, second gen (highest with ziprasidone)
• oncology meds: androgen deprivation therapy (e.g., leuprolide), tyrosine kinase inhibitors (e.g., nilotinib), oxaliplatin

other: cilostazol, donepezil, fingolimod, hydroxyzine, loperamide, methadone, ranolazine, solifenacin, tacrolimus

Question 4

Class I

Answer 4

Ia: Disopyramide, Quinidine, Procainamide
Ib: Lidocaine, Mexiletine
Ic: Flecainide, Propafenone

Question 5

Class II

Answer 5

beta-blockers

Question 6

Class III

Answer 6

Dronedarone, Dofetilide, Sotalol, Ibutilide, Amiodarone

Question 7

Class IV

Answer 7

Verapamil, Diltiazem

Question 8

Double Quarter Pounder, Lettuce, Mayo, Fries Please!
Because Dieting During Stress Is Always Very Difficult

Question 9

Class I info

Answer 9

Na-channel blocker
proarrhythmic but negative inotropic, use caution in pt with underlying cardiac disease

Question 10

Class II info

Answer 10

beta-blockers
blocks sympathetic activity that triggers arrhythmia, indirectly blocks Ca channels, which decreases conduction speed. primarily slows ventricular rate in AF

Question 11

Class III info

Answer 11

K-channel blockers
Amiodarone and dronedarone block K channels primarily, CA channels, Na channels…

Amiodarone and dofetilide are preferentially used for AF in pt with HF

Sotalol blocks K channel and is a beta-blocker

Question 12

Class IV info

Answer 12

non-DHP CCBs
slow ventricular rate in AF. negative inotropic effect, don not use in HF pts and HFrEF

Question 13

Digoxin

Answer 13

Na-K-ATPase blocker
Suppresses AV node conduction (decreases HR), by enhancing vagal tone and increase force of contraction

Question 14

Adenosine

Answer 14

used for paroxysmal supraventricular tachyarrhythmia

Question 15

goal resting HR in symptomatic AF

Answer 15

<80
<110 asymptomatic

Question 16

Rate control

Answer 16

beta-blockers or non-DHP CCBs and sometimes digoxin

Question 17

rhythm control

Answer 17

• the goal is to restore and maintain NSY
  —> Class Ia, Ic or III or electrical cardioversion
• if AF is permanent, avoid rhythm-control strategy (risk outweighs the benefit)

Question 18

stroke prophylaxis

Answer 18

clots can form with pt is in AF- which can embolize and cause stroke when pt returns to NSR

for many pt it is safer to remain in AF w/ rate control than try to restore NSR
rate control strategy may require anticoagulation for stroke prevention
- NOACs (apixaban, rivaroxaban) preferred over warfarin for stroke prevention in non-valvular AF
- warfarin is indicated for AF and a mechanical heart valv

Question 19

amiodarone

Answer 19

Nexterone, pacerone

t1/2= 40-60 days
pulmonary toxicity, hepatoxic
non-PVC
avoid in pt with iodine sensitivity

Question 20

Diltiazem

Answer 20

Cardizem, Tiazac
contra in HFrEF, hypo (SBP<90)
HF may worsen symptoms
SE: gingival hyperplasia

Question 21

Verapamil

Answer 21

Calan SR

Question 22

Digoxin dose info

Answer 22

Digitek
therapeutic range .8-2ng/ml for AF lower range for HF
CrCL <50 ml/min decrease dose or frequency
decrease dose by 20-25% when converting for oral to IV

antidote: digifab

Question 23

Disopyramide

Answer 23

norpace
- reserved for life-threatening ventricular arrhythmias
- proarrhythmic, hypotension, myasthenia graves due to anticholinergic
-Class Ia

Question 24

Quinidine

Answer 24

take with food
may increase moratility
conta: 2/3rd degree heart block, use of other QT prolonging drugs

hemolysis, avoid in G6PD deficiency.
- Class Ia

Question 25

Procainamide

Answer 25

injection
active metabolite NAPA, renally cleared, decrease dose when CrCl<50

4-10mcg/ml

long term use can cause antinuclear antibodies, agranulocytosis, DILE

slow acetylation are risk of drug accumulation and toxicity
- Class Ia

Question 26

Lidocaine

Answer 26

Xylocaine
injection
used for refractory VT/cardiac arrest
- Class Ib

Question 27

mexiletine

Answer 27

take with food
class Ib

Question 28

Flecainide

Answer 28

tablet
store in tight, light-resistant container
contra in 2/3 degree block unless pt has a pace maker, HF, use with ritonavir
- Class Ic

Question 29

Propafenone

Answer 29

Rythmol SR
contra: HF, sinoatrial, AV disorder (unless pt has pace maker)

taste disturbance metallic
-Class Ic

Question 30

Dronedarone

Answer 30

multaq
increased risk of death, store and HF in pt with decompensated HF or permanent AF

cyp3A4 inhibitors and QT prolongation
-Class III

Question 31

sotalol

Answer 31

Betapace
non selective beta blocker and K channel blocker
CrCl <60 decrease frequency
- Class III

Question 32

Ibutilide

Answer 32

Corvert
injection
1mg over 10min
0.01mg/kg if <60kg
indicated only for pharmacologic conversion to NSR
correct hypo K and Mg
-Class III

Question 33

Dofetilide

Answer 33

Tikosyn
continuous ECG monitoring
CrCl for 3 days
drug of choice in HF
Class III

Question 34

adenosine

Answer 34

Adenocard
injection
6mg IV push
t1/2= less than 10 sec
paroxysmal supraventricular tachycardia