Antiarrhythmics

Question 1

spontaneous depolarization is caused by inward positive current carried by ___ and ____ flow

Answer 1

Sodium and Calcium Ion Flow

Question 2

what can cause an abnormality in cardiac rhythm

Answer 2

dysfunction of impulse generation or conduction

Question 3

what is a slow heart rhythm

Answer 3

bradycardia

Question 4

what is a rapid heart rhythm

Answer 4

tachycardia

Question 5

what is a random beat of the heart

Answer 5

asynchronous fibrillation

Question 6

myocardium responds to stimulation by ______ of the membrane; leads to shortening of the contractile proteins and then relaxation ; respond to stimuli as a unit

Answer 6

depolarization

Question 7

how are action potentials generated

Answer 7

by pacemaker cells located in the SA node and AV nodes ; there are five phases

Question 8

What are the five phases of the action potential

Answer 8

phase o: fast upstroke, phase 1: partial repolarization, phase 2: plateau, phase 3: repolarization , phase 4: forward current

Question 9

in this phase , theres a rapid Na influx, through open fast Na channels

Answer 9

Phase o: fast upstroke

Question 10

in this phae, transient K channels open and K efflux returns TMP to 0 mV

Answer 10

Phase 1 : partial repolarization

Question 11

in this phase, influx of Ca through L type Ca channels is electrically balanced by K efflux through delayed rectifier K channels

Answer 11

Phase 2: plateau

Question 12

IN this phase, Ca channels close and the delayed K channels remain open and return the TMP to -90 mV

Answer 12

phase 3: repolarization

Question 13

in this phase, Na and Ca channels are closed , open K channels keep the action potential stable at -90 mV

Answer 13

Phase 4: forward current

Question 14

T or F: the force of contraction is directly related to the concentration of unbound cytosolic Ca

Answer 14

T

Question 15

Agents that increase Ca levels or increase Ca sensitivity _______ the force of contraction ( inotropic effect)

Answer 15

increase

Question 16

What are some source of ic Ca

Answer 16

voltage sensitive channels , exchange with Na, released from sarcoplasmic reticulum and mitochondria

Question 17

what would happen to cardiac muscle if cytosolic Ca levels remained high

Answer 17

cardiac muscle would be in a constant state of contraction

Question 18

How is Ca removed

Answer 18

NA exchange and uptake by Sarcoplasmic reticulum and mitochondria

Question 19

what are the two basic mechanisms of arrhythmias

Answer 19

disturbances in impulse formation and disturbances impulse conduction

Question 20

these conditions : ischemia, acidosis or alkalosis, electrolyte imbalance, autonomic influences, drug toxicity, and stretching of cardiac tissue can exacerbate__________

Answer 20

arrhythmias

Question 21

the SA node=

Answer 21

the pacemaker

Question 22

what can lead to abnormal automaticity

Answer 22

1. if sites other than SA node show enhanced automaticity ( generate competing stimuli)
2. If myocardial cells are damaged, they may remain partially depolarized ( reach fire threshold earlier)

Question 23

what are tx options for abnormal automaticity

Answer 23

drugs block either Na or Ca channels to reduce the ration to K ; decreases the frequency of discharge

Question 24

what can lead to abnormal impulse conduction

Answer 24

block of nerve impulses can cause short circuit ( re entry defect, premature contraction)

Question 25

what are tx options for abnormal impulse conduction

Answer 25

prevent re entry by slowing conduction and or increasing the refractory period

Question 26

what is the aim of drug therapy for arrhythmias

Answer 26

modify impulse generation and conduction

Question 27

These class of drugs bind to open or inactivated Na channels ; have a greater effect in frequently depolarizing ; don't interfere with normal heart beat; subdivided into IA, IB, and IC

Answer 27

Class I drugs

Question 28

These Class I subgroup drugs has a greater affinity for Na channels ; dissociate from Na channels slowly and they slow the rate of rise of the action potential

Answer 28

Class IA drugs

Question 29

this type of CLass IA drug is rapidly absorbed after oral administration; extensive metabolism by P450 enzymes; has adverse effects of arrhythmia , GI disturbances, and blurred vision

Answer 29

Quinidine

Question 30

this Class IA drug shows alpha blocking activity ; increases steady state concentration of digoxin

Answer 30

quinidine

Question 31

this Class IA drug is a derivative of procaine; short half life; lupus like syndrome can develop; Fewer GI side effects and has CNS side effects

Answer 31

procainamide

Question 32

This class IA drug has similar actions to Quinidine; metabolite is less active; side effects of dry mouth, urinary retention, blurred vision, and constipation

Answer 32

Disopyramide

Question 33

This class of drugs has a greater affinity for inactivated Na channels ; shortens repolarization

Answer 33

Class IB drugs

Question 34

This Class IB drug is also a local anesthetic; has little effect on atrial or AV junctions arrhythmias; Given IV; Large therapeutic index ; Mild CNS effects

Answer 34

Lidocaine

Question 35

These Class IB drugs are similar to lidocaine

Answer 35

Mexilitine and Tocainide

Question 36

this class IB drug is often used after MI

Answer 36

Mexilitine

Question 37

This Class IB drug has pulmonary toxicity

Answer 37

Tocainide

Question 38

this class of drugs has greater affinity for open Na channels ; depresses the rate of rise of the action potential; slowly dissociates from resting Na channels

Answer 38

Class IC drugs

Question 39

these two Class IC drugs have minimal biotransformation; long half life,; adverse effects of dizziness, blurred vision, HA, nausea, and arrhythmia

Answer 39

Flecainide and Propafenone

Question 40

this class of drugs are beta blockers ; diminish phase 4 depolarization ; useful in treating arrhythmias caused by increased sympathetic activity

Answer 40

Class II drugs

Question 41

this class II drug reduces incidence of sudden arrhythmic death after MI

Answer 41

propanolol

Question 42

this class II drug is the most widely used beta blocker to treat cardiac arrythmias; reduces the risk of bronchospasm

Answer 42

metoprolol

Question 43

this class II drug is short acting; used IV to treat arrhythmias that occur during sx or in emergency situations

Answer 43

esmolol

Question 44

This class of drugs diminishes the outward K current during repolarization of cardiac cells ; all have potential to induce arrhythmias

Answer 44

Class III K channel blockers

Question 45

This Class III drug is a complex drug; it shows Class I, II , III, and IV actions; has antianginal activity; therapy of choice for atrial fibrillation; most commonly Rx'ed;

Answer 45

amiodarone

Question 46

this Class III drug is incompletely absorbed ; half life of several weeks; adverse effects include discontinuation of tx, interstitial pulmonary effects, GI intolerance, tremor, ataxia, and dizziness, BLUE SKIN DISCOLORATION ( can manifest in the retina) , NAION and WHORL KERATOPATHY

Answer 46

amiodarone

Question 47

this class III drug is a amiodarone derivative ; shorter half life and side effects mainly GI

Answer 47

dronedarone

Question 48

This Class III drug has potent beta blocker activity ; lowest rate of acute or long term adverse effects

Answer 48

sotalol

Question 49

These Class III drugs have high risk of proarrhythmia; prolongs QT interval; 80% of drug eliminated unchanged

Answer 49

Dofetilide and Ibutilide

Question 50

this class of drugs are Ca channel blockers; they decrease inward current;

Answer 50

Class IV drugs

Question 51

These Class IV drugs are used to treat angina and HTN; absorbed well after oral admin; adverse effects include negative inotropic properties ( CI in pts with depressed cardiac function)

Answer 51

Verapamil and Diltiazem

Question 52

this Class IV drug is extensively metabolized by the liver

Answer 52

verapamil

Question 53

This "other antiarrhythmic drug" is a naturally occurring nucleoside; activates an inward rectifier K current and inhibits Ca current ; inhibits AV nodal conduction and increases the AV nodal refractory period

Answer 53

Adenosine

Question 54

This" other antiarrhythmic drug" Is less effective in presence of caffeine ( blocks adenosine receptors) ; adverse effects include flushing, shortness of breath, and chest burning

Answer 54

adenosine

Question 55

which drug shortens the refractory period in myocardial cells

Answer 55

digoxin

Question 56

this "other antiarryhtmic drug" can cause arryhtmia if too much ; supplementation aimed at balancing the gradients

Answer 56

potassium