Antiarrhythmics

Question 1

5 Main Commonly Used Drug Classes in Cardiology

Answer 1

1. Diuretics (preload reducers)
2. Inotropes
3. Afterload Reducers
4. Neurohormonal modulators (RAAS/SNS)
5. Antiarrhythmics (chronotropes)

Question 2

Cardiomyocyte Action Potentials

Answer 2

Question 3

P wave?

Answer 3

atrial depolarization

Question 4

PR super wide on the ECG means?

Answer 4

1st degree AV block

Question 5

PR Interval/segment

Answer 5

AV nodal conduction

Question 6

QRS complex

Answer 6

representation of His-Purkinje fibers

Question 7

Where do you see the sinoatrial node on an ECG?

Answer 7

you don’t, it’s silent

Question 8

5 Causes of Arrhythmias in Dogs

Answer 8

1. Primary cardiac disease
2. Metabolic disorders
3. Drugs/Toxins
4. Autonomic Imbalance
5. The whole shebang (GDV/pain/trauma/hypoxia/sepsis/splenic problems, etc)

Question 9

consequences of arrhythmias

Answer 9

decreased cardiac fxn, dec. BP, limited tissue perfusion, limited exercise capacity, syncope, electrical instability, asystole, sudden cardiac death

Question 10

Supraventricular

Answer 10

obviously means ABOVE the ventricle, so sinus, atrial, or the AV jxn

Question 11

NO BODY KILLS CATS

Answer 11

Here’s your four classes of Antiarrhythmic Drugs!
-Sodium channel blockers
-Beta blockers
-Potassium channel blockers
-Calcium channel blocker

Question 12

Class 1 Antiarrhythmic Drugs

Answer 12

sodium channel blockers
quinidine, procainamide, lidocaine, mexiletine, propafenone

Question 13

Class 2 Antiarrhythmic Drugs

Answer 13

beta blockers
propranolol, atenolol

Question 14

Class 3 Antiarrhythmic Drugs

Answer 14

potassium channel blockers
amiodarone, sotalol***

Question 15

Class 4 Antiarrhythmic Drugs

Answer 15

calcium channel blockers
Diltiazem, amlodipine

Question 16

Can you give lidocaine to cats?

Answer 16

you really shouldn’t but technically can tolerate at hella low dose

Question 17

Can you give lidocaine orally?

Answer 17

sure but it ain’t gonna do anything (high first pass effect)

Question 18

What class 1 is used PO instead of lidocaine?

Answer 18

mexiletine

Question 19

Can you abruptly stop a betablocker?

Answer 19

NO OMG NO –> ventricular tachycardia and then sudden death

Question 20

Can you give beta blockers to a CHF patient?

Answer 20

probably not advised since they’ll just die faster

Question 21

3 Mechanisms of Arrhythmogenesis

Answer 21

1. Enhanced/abnormal automaticity
2. Reentry
3. Triggered activity

Question 22

Automaticity

Answer 22

accelerated generation of action potential (enhanced occurs in nodal tissue, abnormal is non-nodal tissues)

Question 23

Re-entry

Answer 23

impulse recirculates within the tissue causing repetitive reactivation without need for a new impulse

Question 24

Triggered activity

Answer 24

secondary scatter currents (afterdepolarizations) following initial impulse leading in oscillations in the membrane potential (DADs and EADs)

Question 25

Beta blocker MOA

Answer 25

decrease sympathetic nervous system (SNS) via beta receptor 1 (b1) and slows conduction through the AV node

Question 26

Are there beta blockers that are specific?

Answer 26

yes, and will only block b1, limiting side effects to other organs seen in non-specific/selective drugs

Question 27

MOA of Potassium Channel Blockers

Answer 27

prolongs repolarization

Question 28

Do class 3 drugs just block potassium channels?

Answer 28

nah, they have mixed properties usually (ex: sotalol and amiodarone)

Question 29

Adverse Effects of Amiodarone

Answer 29

hepatotoxicity, GI upset, neutropenia, hypothyroidism (so not a great first line drug)

Question 30

Diltiazem

Answer 30

class 4 antiarrhythmic for supraventricular arrhythmias

Question 31

Drug to treat ACUTE Ventricular Arrhythmias (VPCs/Vtach) (IV)

Answer 31

Lidocaine

Question 32

Drug to treat CHRONIC Ventricular Arrhythmias (VPCs/Vtach) (oral)

Answer 32

Sotalol

Question 33

Drug to treat ACUTE Supraventricular Arrhythmias (Atach/Afib) (IV)

Answer 33

Procainamide

Question 34

Drug to treat CHRONIC Supraventricular Arrhythmias (Atach/Afib) (oral)

Answer 34

Diltiazem

Question 35

Drug to treat ACUTE COMBINED Supraventricular and Ventricular Arrhythmias (IV)

Answer 35

Procainamide

Question 36

Drug to treat CHRONIC COMBINED Supraventricular and Ventricular Arrhythmias (oral)

Answer 36

amiodarone