Anti-Arrhythmics

Question 1

what’s the goal of arrhythmia drugs?

Answer 1

reduce ectopic pacemaker activity
modify conduction or refractory to disable reentry

Question 2

what do class I anti-arrhythmics do?

Answer 2

block Na+ channels

Question 3

what do class IA anti-arrhythmics do?

Answer 3

blocks OPEN/ACTIVATED Na+ channels

Question 4

what do class IB anti-arrhythmics do?

Answer 4

blocks INACTIVE Na+ channels

Question 5

what do class IC anti-arrhythmics do?

Answer 5

blocks both open and closed Na+ channels

Question 6

what do class II anti-arrhythmics do?

Answer 6

reduce adrenergic activity of heart

Question 7

what do class III anti-arrhythmics do?

Answer 7

K+ channel block

Question 8

what do class IV anti-arrhythmics do?

Answer 8

Ca2+ channel block

Question 9

Quinidine is a class ___, ___ block

Answer 9

class IA
Na+ block
**also blocks M and alpha receptors

Question 10

Quinidine indications

Answer 10

supraventricular and ventricular arrhythmias
Tx re-entrant arrhytmia (atrial fibrillation)
in dogs and horses

Question 11

Quinidine binds to Na+ ___ channel to slow AP

Answer 11

active Na+ channels

Question 12

what are the adverse effects of Quinidine based on each receptor it affects (alpha, M)?

Answer 12

alpha - hypotension, reflex tachy
M - increases HR, increase AV conduction

Question 13

Quinidine adverse effects on dog vs horse

Answer 13

dogs - anorexia, V, negative inotropism
horse - colic, ataxia, nasal swell

Question 14

Quinidine contraindications

Answer 14

myasthenia gravis
AV block
digitalis toxicity or on digotoxin

Question 15

Procainamide is a class ___, ___ block

Answer 15

class IA
active Na+ block

Question 16

Procainamide indications

Answer 16

ventricular arrhythmia
*NOT very effective in horse

Question 17

Procainamide metabolite has class ___ activity before excretion

Answer 17

class III

Question 18

which drug does more vagal (M and alpha) blocks, Procainamide or Quinidine?

Answer 18

QUINIDINE

Question 19

Lidocaine is a class ___ , ____ block

Answer 19

class IB
INACTIVE Na+ block

Question 20

Lidocaine indications

Answer 20

local anesthetic
Tx ventricular arrhythmia (NOT supra)

Question 21

why does Lidocaine decrease AP duration and shorten ERP?

Answer 21

due to block of slow Na+ window currents

Question 22

does Lidocaine decrease contractility?

Answer 22

NO

Question 23

Lidocaine adverse effects

Answer 23

CNS signs in dogs - drowsy, muscle twitch, convulsions
hypotension
cardiac suppression and CNA excitation in cats

Question 24

Propanolol is a class ___, ___ block

Answer 24

class II
Beta block

Question 25

Propanolol indications

Answer 25

supraventricular tachycardia atrial fibrillation hypertension ventricular tachy (horses, if not lidocaine)

Question 26

Propanolol contraindication

Answer 26

concurrent RAO in horses

Question 27

Atenolol is a class ___, ___ block

Answer 27

class II Beta block

Question 28

Atenolol indications

Answer 28

supraventricular tachyarrhythmias hypertension hypertrophic CM in ferrets

Question 29

Atenolol is ___ acting than Propanolol

Answer 29

longer

Question 30

Esmolol is a class ___, ___ block

Answer 30

class II Beta block

Question 31

Esmolol indications

Answer 31

ACUTE management of supraventricular tachy decreases HR in dogs with ventricular tachy **use this to test if long acting beta block would work better

Question 32

Esmolol is ___ acting

Answer 32

VERY SHORT

Question 33

Sotalol and Amiodarone are class ___, ___ blockers

Answer 33

class III K+ block

Question 34

Sotalol indication

Answer 34

arrhythmiogenic CM in boxers

Question 35

Sotalol and Amiodarone effect on cardiac AP

Answer 35

prolongs AP and refractory period decreased efficacy

Question 36

Sotalol contraindication

Answer 36

asthma since a beta block

Question 37

Diltiazem is a class ___, ___ block

Answer 37

class IV Ca2+ block aka CCB

Question 38

Diltiazem indications

Answer 38

atrial fib supraventricular tachy hypertrophic CM hypertension

Question 39

Diltiazem blocks ___ channels

Answer 39

Ca2+ L type

Question 40

Diltiazem effect on HR, AV conduction, periphery

Answer 40

decrease HR decrease AV dilate periphery

Question 41

Diltiazem adverse effects

Answer 41

vasodilation, NO reflex tachycardia (since blocks AV) bradycardia GI/CNS issues increase liver enzymes negative inotropic effect

Question 42

Diltiazem causes ___ bioavailability of Propanolol

Answer 42

increased