CV Drugs 2

Question 1

what are the mechanisms of arrhythmias

Answer 1

• abnormal automaticity
• abnormal conduction
• disturbances in both automaticity and impulse conduction

Question 2

class I antiarrhythmic drugs =

Answer 2

sodium channel blockers, prolongs AP

Question 3

what is the drug of choice to treat atrial fibrillation in horses?

Answer 3

quinidine

Question 4

it’s possible to use quinidine for ventricular arrhythmias but what class IA drug would be a better choice?

Answer 4

procainamide, more effective

Question 5

T/F: class IA sodium channel blockers shorten APs while class IB sodium channel blockers prolong APs

Answer 5

FALSE, opposite

Question 6

what class IB sodium channel blocker is the drug of choice for treatment of ventricular tachycardia in dogs?

Answer 6

lidocaine (cats are sensitive! watch dosing)

Question 7

T/F: its always safer to treat for ventricular tachycardia

Answer 7

TRUE! lidocaine has very short half life

Question 8

what sort of effect do class II beta-blockers have?

Answer 8

inhibition of catecholamine effects on the heart

Question 9

of the class II beta-blockers that are selective B1 antagonists, which is used in the treatment of HCM in cats

Answer 9

metoprolol

Question 10

what are the three class II beta-blockers that are selective B1 antagonists?

Answer 10

esmolol (short-term), atenolol, and metoprolol

Question 11

why should you wean off class II beta-blockers gradually?

Answer 11

risk of upregulation of receptors (“sympathetic storm”)

Question 12

when are class II beta-blockers contraindicated?

Answer 12

is unstable or overt heart failure present

Question 13

in what type of patient do you see more adverse effects of class II beta-blockers?

Answer 13

geriatric or unstable patients (hypotension, lethary, depression, syncope, worsening CHF)

Question 14

what type of class II beta blockers are safer to use in patients w/ bronchoconstrictive disease?

Answer 14

selective B1 antagonism

Question 15

T/F: some adverse effects of amiodarone include GI, bone marrow suppression, hepatotoxicity, type I hypersensitivity w/ IV formulation

Answer 15

TRUE

Question 16

what class III K channel blocker is used for the treatment of ventricular arrhythmias in dogs and is often a 2nd or 3rd line antiarrhythmic?

Answer 16

amiodarone, limited use in horses, converts atrial fibrillation to sinus rhythm

Question 17

sotalol is a class III K channel blocker, what other type of blocker is it?

Answer 17

nonselective B-blocker

Question 18

T/F: amiodarone is contraindicated with overt or low output CHF

Answer 18

FALSE, sotalol

Question 19

which class III potassium channel blocker has more side effects?

Answer 19

amiodarone

Question 20

match the blockers to the class
class I                 beta blockers
class II                ca channel blockers
class III               k channel blockers
class IV              na channel blockers

Answer 20

class I=na channel blockers
class II=beta blockers 
class III=k channel blockers 
class IV=ca channel blockers

Question 21

what type of arrhythmia are ca channel blockers indicated for?

Answer 21

supraventricular arrhythmias ONLY

Question 22

what two anti-arrhythmic drugs are used in combination w/ horses to treat SVT?

Answer 22

quinidine (class IA na channel blocker) and diltiazem (class IV: ca channel blocker)

Question 23

what is the drug of choice for treatment of SVT and to decrease ventricular response rate in treatment of atrial fibrillation?

Answer 23

diltiazem

Question 24

what drug in what class has the greatest effects on the SA and AV nodes?

Answer 24

diltiazem

Question 25

what class of antiarrhythmics are contraindicated with radiographically documented pulmonary edema?

Answer 25

class IV calcium channel blockers

Question 26

T/F: diltiazem when given IV should be given very slowly

Answer 26

TRUE

Question 27

nothing is working!! how can i try to stop SVT in a patient w/ no drugs?

Answer 27

vagal maneuvers (carotid sinus massage, ocular pressure)

Question 28

T/F: hypovolemic patients can lead to fluid-responsive tachycardia

Answer 28

TRUE

Question 29

what three drugs would you consider for treating a 2nd degree AV block?

Answer 29

• isoproterenol
• theophylline
• glucagon

Question 30

what two drugs would you consider for treating sinus bradycardia?

Answer 30

• *do nothing! often underlying cause can’t be treated w/ drugs alone
• atropine
• glycopyrrolate

Question 31

what would indicate an atrial standstill on an ECG?

Answer 31

absence of p-waves

Question 32

T/F: atrial standstill is most commonly caused by severe hyperkalemia

Answer 32

TRUE

Question 33

which of the following is considered the drug of choice for treatment of ventricular tachycardia?

a. lidocaine
b. mexilitine
c. amiodarone
d. propanolol

Answer 33

a. lidocaine, mexilitine is the oral form

Question 34

which of the following is considered a drug of choice fro treatment of atrial fibrillation with high ventricular response rate?

a. lidocaine
b. esmolol
c. diltiazem
d. sotalol

Answer 34

c. diltiazem

Question 35

which of the following if best described as a selective beta-adrenergic antagonist?

a. quinidine
b. atenolol
c. carvedilol
d. sotalol

Answer 35

b. atenolol

Question 36

which of the following if least appropriate to use for treatment of ventricular arrhythmias?

a. mexilitine
b. sotalol
c. amiodarone
d. diltiazem

Answer 36

d. diltiazem

Question 37

what drug is known to help treat refractory ventricular arrhythmias and can act as an adjunct to treat malignant hyperthermia?

Answer 37

magnesium sulfate IV