Block 2-Reymann (Anti-arrhythmic) Flashcards

Question 1

Q

Classes of drugs

Answer

A

Fast channel blockers (Na+): Quinidine, Lidocaine, Flecainide
Beta-adrenoceptor blockers (Ca+2): Propranolol, atenolol, esmolol, sotalol
Inhibitors of repolar (K+): Amiodarone, Bretylium, dofetilide
CCB: Verapamil & Dilitiazem
Unclassified: Adenosine, Atropine, Digoxin, & Mg+2

Question 2

Q

Mechanism of Arrhythmias

Answer

A

Main promoting factors:
Ischemia-Hypoxia (^{Delayed Afterdepolar})
Acidosis, alkalosis, electrolyte imbalance
Excessive autonomic input (catecholamine exposure)
Drug toxicity (Digitalis)-Delayed afterdepolar
Overstretching of cardiac fibers
Scarred or functionally impaired tissue
ALL occur from:
Disturbances in impulse formation or conduction
Or combo of both

Question 3

Q

Examples of Arrhythmias

Answer

A

Premature Vent beat = 1 or 2 Depressed QRS out of normal Ekg
PSVT(parox suprevent tachy) = Equally spaced sinus rhythm Pwaves & QRS peak are close together
Atrial Fib = NO sinus ^{(IRREG/IRREG BEAT)}
Atrial flutter (AV block/2nd degree) = Depressed P wave w/small QRS peak
Atrial flutter w/1:1 Av conduction = Pwave connected to QRS
Monomorphic vent tachy = All QRS wave pointing down
Torsades de pointed (Bradycardia) = Irregular P wave & QRS w/splits
Vent fib = Death

Question 4

Q

Therapy of Cardiac Arrhythmias

Answer

A

Eliminate or minimize precipitating factors
Define type of arrhythmia(suprevent or vent)
Most ANTI-arrhythmic drugs can cause arrhythmias-Minimize risks of combined DRUG therapy
Termination of ongoing arrhythmias
Prevention of recurrent arrhythmias (could LEAD to death)

Question 5

Q

Class 1 (Fast Na+)

Answer

A

Subclasses:
1A = prolonged (quinidine, procainamide, disopyramide)
1B = Accelerated (lidocaine, mexlietine, tocainide)
1C = little effect (Flencainide, Propafenone)
Mech:
recovery of Na+ channel is Voltage-dependent
Na+ channel blocker delays recovery=Prolonged ERP
Shifts voltage-response relationship

Question 6

Q

Class 1A quinidine PK & PD

Answer

A

Anti-malaria drug & isomer of quinine
PK:
Oral , IV & 1/2 life 1 hour
Hepatic metab, 20% unchanged in renal excretion
Digitalis interaction
PD:
Blockade of Na+ channels in activated site=^{Reduction in Vmax PHASE 0}
Blockade of K+channels=_{Prolonged AP}
Antimuscarinergic effect (@ low doses)=^{Increase in AV-conduction }(death)
Alpha blocker activity @ high conc

Question 7

Q

Class 1A quinidine Use & EKG

Answer

A

Use:
Treat paroxysmal supravent tachy
Conversion of Atrial flutter or fib to Sinus rhythm (Second line treatment)
Need to use prior digitalization=Protective block (3:1)
Recovery from block is slower & less complete in depolarized cell than in FULLY polarized tissue
Result: Prolongation of refractory period in depolarize tissue
Blockade of K+=Prolongation of AP, ERP & reduction of MAX re-entry
EKG=
Long QRS ^{(delayed cond in Punkinje & HIS)}
Long QT & alterations in T
Variable PR ^{(slow AV-conduction)}

Question 8

Q

Class 1A quinidine (SE)

Answer

A

SE:
Paradoxical-Increase in sinus & AV conduction due to ANTI-muscar (atropine)-
Removal of protective AV-block
Vent tachy (3:1, 2:1, 1:1 AV)
Torsades- polymorphic Vent tachy (quinidine syncope)
Slowing of conduction-QRS prolongation greater than 30-50% indicates toxicity
Extracardiac effects:
Antimalarial activity
Hypotensive due to Alphablocker
Can cause GI issues
CNS Tinnitis in high doses

Question 9

Q

Procainamide Class 1A

Answer

A

Protected from enzymatic hydrolysis-LESS CNS effects
PK:
Oral & IV (arrythemia & hypotension)
Hepatic metab, Variable rate of acetylation of NAPA
PD: LIKE QUINIDINE
Less muscarinergic than quinidine
SE: LIKE QUINIDINE
CNS can lead to psychosis
Much more hypersensitivity - fever, rashes, arthritis, lupus like (ANA)
USE:
same as quinidine
Sustained Vent arrhythmias w/Acute MIs

Question 10

Q

Lidocaine Class 1B

Answer

A

Amide local anaesthetic
PK:
Only IV binds to alpha1acid-glycoprotein
PD:
Blockade of activated & inactivated Na channels= MORE prounounced effect on tissues w/long plateus (punkje & vent)
Little to NO effect on K+ channels-^{shortening of APD}
Main effect on depolarized, ^{Arrhythmogenic tissue}
SE:
Cardiac exacerbation of arrhythmias less than 10%
CNS tremor, paresthesias in TOXIC lvls coma or convulsions
Interactions: Agents that interfere w/hepatic perfusion or hepatic microsomal metab

Question 11

Q

Lidocaine Class 1B Uses

Answer

A

Drug of choice in _supression of VENT tachy & Afib _
Supression of arrhythmia associated w/Depolarization (^{POST MI & Digitalis Toxicity)}
Rx: IV loading dose 100-200mg
Monitor plasma lvls
Not for chronic use POST MI

Question 12

Q

Mexiletine & Phenyioin Class 1B

Answer

A

Mex orally active version of lidocaine
PK: Oral 1/2 life of 8-20 hours
PD: same as lidocaine
SE: happens with frequent dosing
Neurologic-nausea, tremor, lethargy
Allergies-rash, fever, Agranulocytosis ^{(Low WBC @ Bone marrow)}
_Phenytoin antiepileptic drug _
PK: IV 1/2 less than 17 hrs
PD: same as lidocaine
_SE: _
Neurologic-sedation, double vision, vertigo
Gingival hyperplasia ^{(swollen gums)}

Question 13

Q

Flecainide & Propafenone Class 1C

Answer

A

Very SLOW dissociation from Na channel DURING recovery.
Used in life threatening-refactory arrhythmia ONLY
Flecainide=Increased Mortality rate in POST-MI pts treated for premature Vent contractions
Use only oral for atrial arrhythmias

Question 14

Q

Beta-Blockers Class 2

Answer

A

_Anti-arrhythmic properties due Beta-blockade _
Propranolol ^{(non-selective)}
Atenolol^{ (B1)}
Esmolol^{ (SHORT acting 1/2 life 9min)}
Sotalol ^{(non-selective & K+ channel blocker)}
Cardio effects:
Depress SA-node = sinus bradycardia
Depresses auto of punkenje fibers
Prolongs ERP of AV node
SUPPRESSES ectopic vent depolar
(-) ionotrope

Question 15

Q

Beta-Blockers Class 2 (Propranolol)

Answer

A

Cardio SE:
Hypotension
Aggravation of CHF
Asystolia ^{(weakening of contraction/SYSTOLE)}
Extracardiac SE:
Predisposed Asthma & diabetes
Peripheral occulsive disease
Use:
Decrease risk of sudden death in ^{POST MI}
Control of supravent tachy
Exercise or stress induced ^{Vent arrhythmias}
Ischemic heart disease ^{(agina)}

Question 16

Q

Class 3 Inhibitors of Repolarization Mech.

Answer

A

Prolongs AP & ERP through inhibition of K+ channels
Amiodarone
Bretylium ^{(Indirect sympatholytic-Antihypertensive)}
Sotalol ^{(prolongs repolar-Class 3 OR Class 2 Beta-blocker)}
Dofetilide ^{(like sotalol w/LESS SEs)}
Ibutilide^{ (PURE class 3 ONLY ICU)}
On AP/ERP will see ^{LONGER Plateu phase}

Question 17

Q

Class 3: Amiodarone

Answer

A

Can also be Class 1A
PK:
1/2 life 30-120 days
Metabolite desthylamiodarone
Loading dose take 2 weeks for steady state
PD:
Blockade of inactivated Na+ channels MOST effects seen on Punkenje/Vent
Blockade of K+ channels=Long AP
Weak Ca+2 channel & NON-comp Beta-Blocker
SE:
conc in tissues (30 Fold) can be found in every organ ^{- BINDS TO PROTEIN}
Pulm fibrosis (5-15%)
corneal deposits
photodermatitis (25%)
Skin discoloration (5%)
Thyroid dysfunction (5%) -iodine
GI-Liver toxicity

Question 18

Q

Class 3: Sotalol (beta 1-blocker)

Answer

A

B1 blocker & K+ channel blockers
PK:
Oral & IV
PD:
Blockade of K+ channel=prolongation of AP
Nonselective B-blocker
SE:
Same SEs as Beta-blockers
Proarrythmic - ^{Torsades des pointes}
USE:
Treat prophylaxis of severe Vent tachy & atrial tachy

Question 19

Q

Class 4: CCB

Answer

A

decrease SA & AV nodal activity & protects vent
Verapamil & Dilitiazem: Block L-type Ca+2 channels & inactivated state
Most pronouced effect on AV-conduction
USE:
Treat Re-entrant ^{(circle current)} supravent tachy
Reduction of Vent rate in atrial fib & flutter
Treat ischemic HD^{ (angina)}
Treat Hypertension
Additive effect w/beta blockers

Question 20

Q

Misc class (Adenosine)

Answer

A

Neutotransmitter-GI coupled=Lowered cAMP
Hyperpolarize K+ channels open
PK:
IV w/half life 10seconds degraded by Adenosine deaminase to inactive inosine
PD:
Purine-P1 receptor agonist
Enchances K+ conductance & inhibits cAMP mediated Ca+2 influx:
Hyperpolarize in AV-node
Use:
Slowing AV node to prevent PSVT
SE:
Transient due to 10 sec 1/2 life
Flushing
AV-block 3
Bronchoconstriction-presist for 30 min in asthmatics (Gq/M3)

Question 21

Q

Misc class

Answer

A

K+ supplements
Mg+2:
Functional Ca+2 antagonist
Use:
In treatment of torsades des pointed ^{(vent arrythemias)}
Digitalis-induced arrhythmias
Prevention of arrythemia in ^{ACUTE MI}
Digoxin - Can SLOW AV conduction
Atropine - Used in bradyarrhythmia to decrease Vagal tone

Question 22

Q

Drug therapy for Atrial Fib

Answer

A

Slow down vent rate:
(-) dromotropic agents (stimulation to heart)
Digoxin
Verapmil, dilitiazem
Beta-adrenoreceptor blockers
Induce/Maintain sinus rhythm:
Blockade of fast AP
1A=Quinidine
1C=Felcainide & propafenon
3= amiodarone & dofelitide

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Block 2-Reymann (Anti-arrhythmic) Flashcards

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