5.1 Antiarrhythmics

Question 1

where does the fast cardiac action potential happen?

Answer 1

myocardium

Question 2

where does the calcium come from in fast cardiac AP?

Answer 2

SR

Question 3

which transporter resets AP to normal?

Answer 3

NAK ATPase

Question 4

which part of AP is prolonged by class 3 drugs in fast cardiac AP?

Answer 4

refractory period

Question 5

examples of class 4 CCBs

Answer 5

verapimil
diltiazem

Question 6

where does the slow cardiac AP occur?

Answer 6

pacemaker cells

Question 7

effect of CCBs on slow cardiac AP

Answer 7

decrease calcium entry so slope of phase 0
increase refractory period

Question 8

how do B agonists affect automaticity?

Answer 8

increase rate of automatic function of SA node

Question 9

how do muscarinic agonists and adenosine affect automaticity?

Answer 9

decrease rate of automatic function of SAN

Question 10

when would you switch from lidocaine to mexiletine?

Answer 10

when patient stable

Question 11

how does flecainide help WPW syndrome?

Answer 11

attached to extra circuit

Question 12

contraindications to flecainide

Answer 12

structural heart disease
ischaemia

Question 13

B blockers aren’t used in acute HF. which HF can they be used for?

Answer 13

stable

Question 14

how to give amiodarone. why?

Answer 14

oral/IV, via large central vein due to risk of thrombophelibits

Question 15

which tests should be done every 6 months when taking amiodarone>

Answer 15

LFT, TFT

Question 16

which drugs should be reconsidered when taking amiodarone?

Answer 16

warfarin digoxin due to inducing hepatic CYP enzymes

Question 17

absorption of sotalol

Answer 17

oral

Question 18

cardiac effects of sotalol

Answer 18

increase AP duration and refractory period
slow phase 4
slow AV conduction

Question 19

ECG effects of sotalol

Answer 19

increase QT
decrease HR

Question 20

uses of sotalol

Answer 20

SVT, VT

Question 21

side effects of sotalol

Answer 21

fatiguem insomnia, arrhythmias

Question 22

why cant you give verapamil/diltiazem with B blocker?

Answer 22

can if pacemaker
reduce HR too much=asystole

Question 23

mechanism of adenosine

Answer 23

nucleoside binds A1 receptors, blocks adenylyl cyclase, reducing cAMP, activates K current in AVN+SAN= hyperpolarisition

decrease HR

Question 24

cardiac effects of adenosine

Answer 24

slows AV conduction, short half life so give for acute e.g. narrow/wide complex tacky

Question 25

why is adenosine given for CAD scans?

Answer 25

short half life to show blood flow then compared to reflex tachy after it wears off

Question 26

why should adenosine be avoided in asthma?

Answer 26

goes to lungs first

Question 27

ivabradine
-mechanism
-cardiac effects
-side effects
-uses

Answer 27

-blocks If current in SAN
-slow SAN, no effect on BP
-flashing lights, teratogenic?
-sinus tachy, reduce HR in HF and angina, POTS

Question 28

atropine
-mechanism
-cardiac affects
-uses

Answer 28

-selectibe muscarinic antagonist
-block vagal activity to increase AV conduction, increase HR
-vagal bradycardia

Question 29

answer questions page 50 from 5.1 lec

Answer 29

.