Antiarrhythmics

Question 0

What state do VG channels need to be in for phase 0 to occurs

Answer 0

Resting state

Question 1

What is the “transition of voltage gates channels from inactive back to resting “?

Answer 1

Recovery

Dependent upon the cell membrane reaching a negative membrane voltage

Question 2

What process depends on depolarization with a Na+ channel?

Answer 2

Recovery

Question 3

What type if ion blocker can slow down repolarization?

Answer 3

K+ blocker

Question 4

Disturbances in impulse conduction may occur due to either _______ or _____.

Answer 4

block or reentry

Question 5

The ______ interval is very indicative of how well your AV node is working.

Answer 5

P-R

Question 6

What type of AV block is when you are not really blocking the AV node, you are just slowing it down?

Answer 6

First-degree AV block

Question 7

What does Torsades de Pointes mean?

Answer 7

“twisting of the points”

Question 8

What is Third-degree AV block also called?

Answer 8

Complete heart block

Question 9

_________ occurs when one impulse reenters and excites areas of the heart more than once.

Answer 9

Reentry

Question 10

__________ ________ may be confined to small areas or large portions of the myocardium.

Answer 10

Reentry circuits

Question 11

Some reentry circuits may be totally random and meander their way through the myocardial tissues causing ____________.

Answer 11

fibrillation

Question 12

A block may also cause the depression of one of the bundle branches, resulting in an abnormally slow and uncoordinated ventricular depolarization. Right or left bundle branch block would result in a widened ________ on the EKG.

Answer 12

QRS

Question 13

WHY does reentry occur?

Answer 13

1. obstacle to homogenous conduction (the impulses spreading through the myocytes do NOT travel at the same speed)
2. Unidirectional block
3. Conduction time around the block

Question 14

What can cause obstacles to homogenous conduction?

Answer 14

a fast accessory tract or an MI (injury/ischemia) that damaged some conduction tissue

Question 15

What occurs during unidirectional block?

Answer 15

the impulse will “die out” in one direction, but may continue through if it approaches from the other direction

Question 16

How can we prevent unidirectional block?

Answer 16

• convert the unidirectional block to bidirectional block

* speed up the time around the block

Question 17

What are the two primary methods to treating reentry circuits?

Answer 17

1. Speed the conduction around the depressed tissue
2. Increase the effective refractory period of the depressed area

(both cause bidirectional block)

Question 18

What is the refractory period?

Answer 18

How long it takes to get a critical amount of VG Na+ channels back to the resting period

Question 19

What are 2 things that drugs can do to treat reentry arrhythmias?

Answer 19

1. delay recovery by prolonging the inactivation state of VG Na+ channels
   2, prolong repolarization by blocking K+ channels

(drug classes do one of these)

Question 20

What is erratic atrial muscle depolarizations with multiple foci and is characterized by an IRREGULARLY-IRREGULAR tracing?

Answer 20

Atrial Fibrillation (A fib)

Question 21

What classes are responsible for RATE control of A fib?

Answer 21

Class II and IV (slow down AV node)

Digoxin can also slow down AV node at specific doses

Most A fib pts are treated with II and IV

Question 22

What classes are responsible for RHYTHM control of A fib?

Answer 22

Class I and III (fix re-entry circuits)

Question 23

What are usually characterized by wide, bizarre QRS complexes, followed by a pause (skipped beat)?

Answer 23

Premature Ventricular Contractions

Question 24

What drug classes can treat Premature Ventricular Contractions?

Answer 24

Class I and III (fix reentry)

Question 25

What is rapid succession of depolarizations resulting from ventricular foci?

Answer 25

Ventricular Tachycardia (impulses originate at ventricular pacemaker)

Question 26

What is sinus bradycardia?

Answer 26

Sinus bradycardia is a rhythm in which fewer than the normal number of impulses arise from the sinoatrial (SA) node. < 60 beats/minute, with sinus bradycardia being defined as a sinus rhythm with a rate below 60 beats per minute. (When the SA node is not sending the signal for HR as quickly as “normal”)

Question 28

What is Tau-recovery time?

Answer 28

how fast the drug will dissociate from the channel once the channel enters the resting state

Question 29

______ Na+ channels switch from inactive to resting the more negative the membrane becomes. A. more B. less

Answer 29

A. more

Question 30

VG Na+ channel blockers alter the channel’s: 1. 2.

Answer 30

1. Conductance properties | 2. Recovery time

Question 31

What factors can cause arrhythmias?

Answer 31

1. disturbances in impulse FORMATION 2. disturbances in impulse CONDUCTION 3. both FORMATION & CONDUCTION

Question 32

Where do disturbances in impulse formation usually occur?

Answer 32

SA node, AV node,and Purkinje fibers (because they have funny currents and are where the impulses originate from)

Question 33

What is the primary pacemaker?

Answer 33

SA node

Question 34

What are the "latent pacemakers"?

Answer 34

Purkinje fibers

Question 35

Purkinje fibers are particularly sensitive to _____ stimulation A. SNS B. PNS

Answer 35

A. SNS

Question 36

Excessive _______ stimulation may cause purkinje fibers to fire in the absence of the SA node signal, resulting in ventricular depolarization that is not in sync with the rest of the heart.

Answer 36

SNS

Question 37

Excessive SNS stimulation of purkinje fibers can cause:

Answer 37

* VENTRICULAR TACHYCARDIA | * VENTRICULAR FIBRILLATION

Question 38

What can cause disturbances in impulse CONDUCTION?

Answer 38

block or reentry

Question 39

What can cause block?

Answer 39

HIGH PNS activity that significantly depresses the AV node which slows or prevents conduction from atria to ventricles

Question 40

What drug class can you give to fix heart block?

Answer 40

antimuscarinic agents

Question 41

What type of AV block results in abnormally long PR intervals?

Answer 41

First-degree AV Block

Question 42

What type of AV block? | • Only every-other PR interval is able to conduct through the AV node.

Answer 42

Second-degree AV Block

Question 43

What type of AV block? No association of QRS complete to P-waves and cardiac function is ONLY persevered through an escaped junctional or ventricular pacemaker

Answer 43

Third-degree AV Block (Complete Heart Block)

Question 44

When the AV node is firing fast (normal), the PR interval is_______. A. short B. long

Answer 44

A. short

Question 45

Block can cause the depression of one of the bundle branches, resulting in an abnormally _____ and ______ ventricular depolarization.

Answer 45

Slow and uncoordinated

Question 46

Right or left bundle branch block would result in a widened _____ on the EKG

Answer 46

QRS

Question 47

impulses that interrupt phase 3 (EAD) or phase 4 (DAD) of the cardiac myocytes action potential

Answer 47

Afterdepolarizations

Question 48

frequently occur at low heart rates when the action potential duration (QT interval) is long

Answer 48

Early Afterdepolarization (EAD)

Question 49

Early Afterdepolarization (EAD) commonly occur due to?

Answer 49

Commonly occur with K+ blockers or due to congenital abnormalities of K+ channels (Long QT interval)

Question 50

Delayed Afterdepolarizations (DAD)?

Answer 50

usually occur at fast heart rates and are associated with calcium overload

Question 51

What can cause Delayed Afterdepolarizations (DAD)?

Answer 51

digoxin toxicity, excessive SNS activity

Question 52

What phase do EADs interrupt?

Answer 52

3

Question 53

what phase do DADs interrupt?

Answer 53

4

Question 54

What occurs when one impulse reenters and excites areas of the heart more than once?

Answer 54

reentry

Question 55

T/F? o Reentry circuits may be confined to small areas or large portions of the myocardium

Answer 55

True

Question 56

What 3 things must happen for reentry to occur?

Answer 56

1. Obstacle to homogenous conduction 2. Unidirectional block 3. Conduction time around the block

Question 57

What is Unidirectional block?

Answer 57

When the impulse “dies out” in one direction but may continue through if it approaches from the other direction.

Question 58

What is an obstacle to homogenous conduction?

Answer 58

•When the impulses spreading through the myocytes do NOT travel at the same speeds (Can occur due to a fast accessory tract or an MI that damaged some conduction tissue)

Question 59

What does "Conduction time around the block" mean?

Answer 59

The conduction time around the blocked area must be long enough so that when the impulse reaches the other side, the slow area is no longer refractory and can conduct in a retrograde fashion (if the impulse is going too fast, it will fly past the area where it would reenter, but if it is slow enough, it can enter the area that was blocked from the other side and reenter

Question 60

What are the two ways to treat reentry circuits?

Answer 60

1.Speed the conduction around the depressed tissue (not normally done pharmacologically) •“the person is going to fast to stop and open the door” 2.Increase the effective refractor period of the depressed area •“lock the door”

Question 61

Drugs that treat reentry arrhythmias do one of two things:

Answer 61

1. Delay recovery by prolonging the inactivation state of VG Na+ channel 2. Prolong repolarization by blocking K+ channels

Question 62

________ is the erratic atrial muscle depolarization with multiple foci. It is characterized by “irregularly-irregular” tracing.

Answer 62

Atrial Fibrillation

Question 63

How can we treat A fib?

Answer 63

We can treat A fib by: • Fixing the reentry circuits (RHYTHM control of A fib) • Slow down the AV node (RATE control of A fib)

Question 64

What drugs can fix the reentry circuits?

Answer 64

Na+ channel blockers (Class I) | K+ channel blockers (Class III)

Question 65

What are Premature ventricular contractions?

Answer 65

characterized by wide, bizarre QRS complexes, followed by a pause (skipped beat)

Question 66

What are the two types of Premature ventricular contractions?

Answer 66

1. unifocal | 2. multifocal

Question 67

Which type of Premature ventricular contractions is more dangerous?

Answer 67

Multifocal

Question 68

``` What class of agents • Primarily mess with VOLTAGE GATED Na+ channels • Will affect myocytes and purkinje fibers more than the nodal tissue • Class Ia, Ib, and Ic (based on affinity for channel and how long the drug remains bound) ```

Answer 68

Class I Agents: Na+ channel blockers

Question 69

What class of agents blocks SNS in heart so they decrease HR, decrease in FOC, increase in duration of contraction

Answer 69

Class II agents (BB)

Question 70

What class of agents prolong the action potential duration usually by blocking K+ channels

Answer 70

Class III agents

Question 71

What do you need to monitor in pts on class III agents?

Answer 71

QT interval

Question 72

What class of agents blocks L-type Calcium channels?

Answer 72

Class IV agents (CCBs)

Question 73

What is Sinus bradycardia?

Answer 73

Sinus bradycardia is a rhythm in which fewer than the normal number of impulses arise from the sinoatrial (SA) node. The normal heart rate has been considered historically to range from 60 to 100 beats per minute, with sinus bradycardia being defined as a sinus rhythm with a rate below 60 beats per minute.

Question 74

When the SA node is not sending the signal for HR as quickly as “normal”

Answer 74

Sinus bradycardia

Question 75

When the SA node is sending the signal for HR quicker than “normal”

Answer 75

Sinus tachycardia

Question 76

What is sinus tachycardia?

Answer 76

a heart rhythm originating from the sinoatrial node with an elevated rate of impulses, defined as a rate greater than 100 beats/min (bpm) in an average adult. The normal resting heart rate in the average adult ranges from 60–100 beats/min.