Anti-arrhythmic agents

Question 1

The conduction system of the heart is through the:

Answer 1

SA node–> atria–> AV node–> bundle of His–> bundle branches–> purkinje fibers–> ventricles

Question 2

The slow response action potential are for the

Answer 2

Pacemaker cells

Question 3

Describe phase 0 of the action potential in cardiomyocyte cells:

Answer 3

Phase 0: rapid depolarization (fast sodium channels open; fast inward flow of Na+)

Question 4

Describe phase 1 of the action potential in cardiomyocyte cells:

Answer 4

Begin repolarization (sodium channels close)

Question 5

Describe phase 2 of the action potential of cardiomyocyte cells:

Answer 5

Plateau (slow calcium channels open; slow inward flow of Ca2+)

Question 6

Describe phase 3 of the action potential of cardiomyocyte cells:

Answer 6

Repolarization (calcium channels close; potassium channels open; slow outward K+ current)

Question 7

Describe phase 4 of the action potential of cardiomyocyte cells:

Answer 7

Pacemaker potential; return to resting membrane potentials

Question 8

The absolute refractory period is the period when

Answer 8

another action potential cannot be generated

Question 9

Pacemaker cells have

Answer 9

automaticity so they can self-excite

Question 10

Describe phase 0 of the pacemaker cells:

Answer 10

upstroke, critical firing threshold is 40 mV, slower and Ca2+ mediated

Question 11

Describe phase 3 of the pacemaker cells:

Answer 11

repolarization; inactivation of Ca2+ and Na+ channels; activation of K+ channels

Question 12

Describe phase 4 of the pacemaker cells:

Answer 12

Gradual depolarization; slow inward Na+ and Ca2+ currents

Question 13

The cardiac pacemaker is the

Answer 13

Sinoatrial node

Question 14

Normal sinus rhythm is

Answer 14

60-100 beats/min.

Question 15

Conduction slows through

Answer 15

the AV node

Question 16

The P wave is the

Answer 16

atrial depolarization

Question 17

The QRS complex is the

Answer 17

ventricular depolarization

Question 18

The T wave is the

Answer 18

ventricular repolarization

Question 19

An arrhythmia is a

Answer 19

disturbance in the electrical activity of the heart

Question 20

Arrhythmias are classified according to:

Answer 20

site of origin of abnormality (atrial/junctional/ventricular)
Complexes on ECG (narrow/broad)
Heart rhythm (regular/irregular)
Heart rate is increased or decreased

Question 21

Mechanisms of arrhythmia production include

Answer 21

altered automaticity, delayed after-depolarization, re-entry, and conduction block

Question 22

A conduction block is

Answer 22

an impulse fail to propagate in non-conducting tissue

Question 23

Re-entry is

Answer 23

refractory tissue reactivated repeatedly and rapidly due to unidirectional block, which causes abnormal continuous circuit

Question 24

Delayed after-depolarization is

Answer 24

a normal action potential of cardiac cell triggers a train of abnormal depolarizations

Question 25

Altered automaticity is

Answer 25

latent pacemaker cells take over the SA node’s role; escape beats

Question 26

Factors underlying cardiac arrhythmias include

Answer 26

arterial hypoxemia, electrolyte imbalance, acid-base abnormalities, myocardial ischemia, altered SNS activity, bradycardia, administration of drugs, enlargement of a failing ventricle

Question 27

When do cardiac arrhythmias require treatment?

Answer 27

They cannot be corrected by removing the precipitating cause
hemodynamic stability is compromised
the disturbance predisposes to more serious cardiac arrhythmias or co-morbidities

Question 28

Acute non-pharmacological treatment of cardiac arrhythmias include

Answer 28

vagal maneuvers & cardioversion

Question 29

Non pharmacological treatment of cardiac arrhythmias include:

Answer 29

pacing (external, temporary, and permanent) & prophylaxis- radiofrequency catheter ablation or implantable defibrillator

Question 30

Antiarrhythmic agents are used to

Answer 30

prevent, suppress, or treat a disturbance in cardiac rhythm

Question 31

Cardiac rhythm disturbances include:

Answer 31

atrial fibrillation, atrial flutter, SVT, ventricular tachycardia, ventricular fibrillation, bradyarrhythmias, heart block

Question 32

If there is a new onset dysrhythmia

Answer 32

the surgery will most likely be cancelled

Question 33

According to the Vaughan Williams classification of antiarrhythmic drugs, class 1:

Answer 33

are sodium channel blockers and they work at phase 0

Question 34

According to the Vaughan Williams classification of antiarrhythmic drugs, class 2:

Answer 34

are beta adrenergic blockers and primarily work at phase 4

Question 35

According to the Vaughan Williams classification of antiarrhythmic drugs, class 3 drugs:

Answer 35

are potassium channel blockers and act at phase 2 & phase 3

Question 36

According to the Vaughan Williams classification of antiarrhythmic drugs, class 4 drugs:

Answer 36

are calcium channel blockers and act at phase 2

Question 37

According to the Vaughan Williams classification of antiarrhythmic drugs, class 5 drugs:

Answer 37

are unclassified drugs

Question 38

Class 1 drugs can further be subdivided into:

Answer 38

Class 1A, 1B, and 1C and they all work at phase 0

Question 39

Class 1A drugs work by

Answer 39

causing moderate depression and prolonged repolarization

Question 40

Class 1B drugs work by

Answer 40

weak depression and shortened repolarization

Question 41

Class 1C drugs work by

Answer 41

strong depression with little effect on repolarization