pharm exam 3 arrhythmias

Question 1

Conduction velocity is determined by regulation of the action potential, specifically the slope of phase ___ depolarization

Answer 1

0

Question 2

The ____/____ refractory period is the time during which cardiac cells cannot conduct nor propagate an action potential

Answer 2

effective/absolute

Question 3

The ___ refractory period is the time during which cardiac cells may conduct and propagate action potentials secondary to strong electrical stimuli

Answer 3

relative

Question 4

resting membrane potential

in the ventricle =

AV node =

SA node =

Answer 4

• 75 mv
• 70 mv
• 60 mv

Question 5

Upon depolarization, an influx of ___ raises the gradient from a negative value towards a positive value, allowing for conduction of the electrical current

During repolarization, the gradient returns back to baseline as ___ effluxes

Answer 5

cations (Na+ and/or Ca2+)

K+

Question 6

Mechanisms responsible for cardiac arrhythmias are generally divided into 2 major categories:

1)
2)

Answer 6

1) abnormal impulse formation
- abnormal automaticity
- triggered activity

2) abnormal conduction
- conduction delay
- re-entry

Question 7

During triggered activity, heart cells contract ___

example = torsades

Answer 7

twice

Question 8

____ produces no cardiac output and causes most cases of sudden cardiac arrest

Answer 8

v fib

Question 9

Arrhythmias are defined by location and rate

____ arrhythmias arise from abnormalities in the SA node, atrial tissue, AV node, or bundle of His.

____ arrhythmias originate from below the bundle of His.

Answer 9

Supraventricular

Ventricular

Question 10

T wave =

Answer 10

ventricular repolarization

Question 11

_____ reflects the duration of the ventricular action potential

Answer 11

QT interval

Question 12

Mechanism of sinus bradycardia:

what are some causes?

Answer 12

decreased SA node automaticity

MI, hypothyroidism, drug induced, hyperkalemia

Question 13

consistent prolonged PR interval =

Answer 13

First degree AV block

Question 14

prolongation of PR interval until a QRS complex is dropped =

Almost always a disease of the AV node

Answer 14

second degree AV block type 1 (wenckebach)

Question 15

PR interval remains constant and does not increase with each cardiac cycle prior to the ”dropped” QRS complex =

Almost always a disease of His-Purkinje System

Answer 15

second degree AV block type 2 (Mobitz II)

Question 16

third degree heart block aka

Answer 16

complete heart block

Question 17

condition in which the nerve impulse generated in the sinoatrial node (SA node) in the atrium of the heart can not propagate to the ventricles =

Answer 17

complete heart block

Question 18

mechanism of AV block:

what are some causes?

Answer 18

prolonged conduction

MI, drug induced, hyperkalemia, increased vagal tone, myocarditis, AV nodal disease

Question 19

Atrial Fibrillation and Atrial Flutter are ____ arrhythmias

Answer 19

supraventricular

Question 20

mechanism of supraventricular arrhythmia =

Answer 20

Enhanced automaticity and reentrant circuits

Question 21

v tach = 3 or more consecutive ___ at a rate exceeding 100 bpm and a wide QRS interval

Answer 21

PVCs

Question 22

Specific variety of ventricular tachycardia w/ QRS complexes that appear to twist around the ECG baseline =

Answer 22

torsades

Question 23

Sodium channel blockers MOA:
blocking the channels leads to a decrease in the slope of phase __. This causes a decrease in ___ velocity in non-nodal tissue (atrial and ventricular muscle, Purkinje system). Ultimately, blocking Na+ channels reduces the __ of action potential transmission w/i the heart. This can serve as an important mechanism of suppressing ___ that are caused by abnormal conduction

Answer 23

0 ; conduction

velocity
tachycardia’s

Question 24

Na+ Channel Blockers

__ drugs have the greatest decreasing effect on phase 0

__ drugs have the smallest effect on phase 0

__ drugs are intermediate in their effect on phase 0

Answer 24

1C

1B

1A

Question 25

Na+ Channel Blockers and Effective Refractory period (EFP) Class __: Increase ERP Class __: Decrease ERP Class __: No effect on ERP Increasing the ERP can interrupt tachycardia caused by reentry mechanisms by prolonging the duration that normal tissue is unexcitable

Answer 25

1A 1B 1C

Question 26

Disopyramide what drug class? restrict use to ___ ventricular arrhythmias

Answer 26

Na+ channel blocker, 1A | life-threatening

Question 27

Procainamide what drug class? Positive ANA may develop drug induced __ extremely short __ 50% metabolized to an active metabolite known as __ NAPA may accumulate in patients with __ If you don’t metabolize it quickly enough, it will have anti-arrhythmic effects!

Answer 27

``` Na+ channel blocker, 1A SLE (Lupus) half life NAPA renal failure ```

Question 28

Quinidine what drug class? VERY irritating to the __ can also cause __ Quinidine may increase mortality in treatment of __ or __

Answer 28

Na+ channel blocker, 1A GI tract Cinchonism atrial fibrillation or atrial flutter

Question 29

Cinchonism includes:

Answer 29

``` Blurred vision Tinnitus Hearing loss Diaphoresis Confusion Psychosis ```

Question 30

Lidocaine contraindication: __ syndrome: Sudden collapse into unconsciousness

Answer 30

Adam-Stokes

Question 31

Flecainide what class? Has ___ effects

Answer 31

Na+ channel blocker, 1C | pro-arrhythmic

Question 32

All Class __ Antiarrhythmics are PROARRHYTHMIC!

Answer 32

1

Question 33

β-Blockers: Class II MOA inhibit ___ influences on cardiac electrical activity, thereby decreasing __ rate, decrease conduction __ (which can block reentry mechanisms), and inhibit aberrant __ activity Also, BB's increase action potential duration and the __

Answer 33

sympathetic sinus ; velocity pacemaker effective refractory period (ERP)

Question 34

Esmolol beta blocker is only used for __ control of arrhythmia

Answer 34

rapid

Question 35

K+ Channel Blockers: 
Class III MOA These drugs bind to and block the K+ channels that are responsible for phase __ repolarization. Blocking these channels slows/delays __, which leads to an increase in action potential duration and an increase in __. these drugs are very useful in suppressing ___ caused by reentry mechanisms On the ECG, this increases the __

Answer 35

3 repolarization ERP tachyarrhythmias QT-interval

Question 36

Currently the most effective antiarrhythmic for ventricular arrhythmias; however, it is also the most toxic =

Answer 36

Amiodarone

Question 37

Amiodarone side effects: 1) Increased liver __ or __ levels (as high as 40-50% in some studies, check at baseline and Q6 months) 2) Pulmonary __ (check PFT at baseline and Q12 months) 3) __ color skin 4) __ deposits 5) Proarrhythmic 6) __tension 7) __thyroidism 8) Abnormal __ 9) Impaired ___ 10) Involuntary movement 11) __ disturbances 12) __cardia 13) AV block

Answer 37

AST or ALT fibrosis Blue-gray Corneal Hypo Hypo gait/ataxia memory Sleep brady

Question 38

Amiodarone half life ranges from __-__ days!! Initial response is __-__ , peak response takes __-__ PO duration: Up to __ days after D/C of therapy

Answer 38

35-110 2 days to 3 weeks ; 1 week to 5 months 50

Question 39

AKA: “less toxic Amiodarone”; but not as effective as Amiodarone at maintaining sinus rhythm =

Answer 39

Dronedarone

Question 40

__ in Class 3 is pregnancy X

Answer 40

Dronedarone

Question 41

``` Each of these can cause a substantial __ in Dofetilide plasma concnetrations. (↑ F and ↓ Cl) Verapamil Cimetidine Trimethoprim Ketoconazole Prochlorperazine Megestrol HCTZ ```

Answer 41

increase

Question 42

Dofetilide | BBW: Hospitalize minimum of __ days during initiation

Answer 42

3

Question 43

Ibutilide | BBW: May cause potentially fatal ___

Answer 43

arrhythmias

Question 44

``` Sotalol Contraindication: __ Formulations indicated for ventricular and atrial arrhythmias are different: Betapace = __ Betapace AF = ___ ```

Answer 44

asthma ventricular atrial

Question 45

only the ___ CCB's are approved as antiarrhythmics

Answer 45

nondihydropyridine

Question 46

Ca2+ Channel Blockers: 
Class IV MOA Decreases conduction velocity and prolongs __, especially at the __. Prolongs phase __ of the AP

Answer 46

repolarization | AV node ; 2

Question 47

Digoxin MOA in Atrial Fibrillation/Flutter: Activates __ efferent nerves to the heart (__ effect). Vagal activation can reduce the conduction of electrical impulses w/i the __ to the point where some of the impulses will be blocked. When this occurs, fewer impulses reach the ventricles and ventricular rate falls. Digoxin also increases ERP within the AV node

Answer 47

vagal ; parasympathomimetic AV node

Question 48

Digoxin toxicity When K+ levels are __, Digoxin can more easily bind to the pump exerting its __ effects

Answer 48

low | inhibitory

Question 49

Adenosine MOA POWERFUL __, especially in the coronary circulation; but VERY __ acting used for the rapid treatment of supraventricular tachycardias

Answer 49

vasodilator | short