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DT3- EXAM 1 > Antiarrhythmic Drugs- Leah (3)* > Flashcards

Antiarrhythmic Drugs- Leah (3)* Flashcards

1
Q

Anti-arrhythmic effects (4)

A

1) Decreased automaticity
2) Decrease/ restore, block conduction
3) Make ERPs homogeneous OR…
4) ^ ERP –> slow heart rate

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2
Q

Describe the four classes of arrhythmia drugs:

A
  1. Class I- Na Channel block
  2. Class II- B block
  3. Class III- K+ block/ ^ APD/ERP
  4. Class IV- Ca++ channel block
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3
Q

How do Na channel blockers effect heart rate/rhythm? (3)

A
  1. DECREASE depolarization
    (phase 0 slope decreased on AP plot for MYOCYTES)
  2. DECREASE conduction + automaticity
    (Decrease phase 4 slope on AP plot for pacemaker cells SA/AV)
  3. Intuitive: increase THRESHOLD for AP
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4
Q

Most common cause of persistent arrhythmias?

How do infarctions facilitate this process (3)

A

Anatomical re-entry = heterogenous ERP

  • INFARCTION = SLOWER conduction + ERP
  • Normal conduction does not initially pass through infarcted site (longer ERP)
  • Conduction RE-ENTERs infarct @ wrong time/ wrong direction after ERP is over
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5
Q

Risk associated with drugs that increase effective refractory period?

Relevance (2)?

A

***Torsades de points: polymorphic V Tach–> fatal V Fib

  • Many drugs that increase QT are reserved for emergency or fatal arrhythmias
  • Not used in asymptomatic arrhythmias because of their high risk
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6
Q

Type I drugs are “state dependent”: what does this mean?

Describe the three subclasses of type 1 anti-arrhythmic drugs.

A
  • Na channel blockers are state dependent.
  • Only bind Na channels in the open/ active state.
  • Disassociate from inactive/ closed channels with varying speed
  • Speed of disassociation determines subclass.

1A- moderate effects
1B- small effects because (rapidly disassociate)
1C- large effects (slowly disassociate)

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7
Q 
What are three class 1A drugs?
Which is actually used in practice? Why?
A
  1. Procainamide***
  2. Quinidine
  3. Disopyramide
    “(I)A QUeen PROClaims DISO’s PYRAMID.”
  • PROCAINAMIDE is still used
  • IA drugs have some anti-Ach effects –> may ^AV conduction–> unpredictable effects
  • May increase or decrease AV conduction

PROCAINAMIDE: lowest anti-ach effects
DISCOPYRAMIDE: highest anti-Ach effects
(L Dose may precipitate CHF: no longer used)

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8
Q 
What are two class 1B drugs? 
When are they effective?
A
  1. Lidocaine***
  2. Mexiletine
    “I’d Buy LIDdy’s MEXIcan Tacos”
    I would NOT. I heard they make you delirious & might even give you seizures.
  • Only effective in the diseased heart
  • In a normal heart, they rapidly disassociate from inactive Na channels, have little efficacy.
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9
Q 
What are two class IC drugs? 
Important limiting factor in their use
A
  1. Flecainide***
  2. Propafenone
    “Can I have Fries Please”
  • *Cannot be used in patients with an organic heart disease
  • INCREASES CHF MORTALITY
  • Only used for patients with an idiopathic refractory arrythmia
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10
Q 
Three important class II drugs? 
Range of use for this class (4)?
A
  1. Propranolol (non selective)
  2. Esmolol (selective)
  3. Metoprolol (selective)

**Widest range of use; Not labeled for “only emergencies”.
Tx: CHF, postMI, PVCs, SV arrhythmias (afib/flutter)

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11
Q

Class III drugs (5)

Common side effect of this class?

A
  1. AMIODARONE ***most important, always on boards.
  2. Drondarone
  3. Ibutilide
  4. Dofetilide
  5. Sotalol* (Amiodarone substitute)
    “AIDS”
  • Because this class increases APD/ERP predominately, most drugs increase QRS/QT
  • ^ risk of torsade
  • Most reserved for emergency/refractory cases*
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12
Q

Most important class IV drug:

A

Verapamil

*Widest range of use second to B blocks

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13
Q

When might atropine and isoproterenol be used to treat arrythmias? How long are patients treated with these drugs?

A

Bradycardia, AV blocks
(When heart rate needs to INCREASE)
* Short-term until pacemaker is placed

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14
Q

What are three “vagomimetics” used to treat arrythmias?

What are their uses?

A
  1. Valsalva
  2. Carotid sinus massage
  3. Digoxin
  • Valsalva and carotid massage mimic increased BP; may terminate PSVT
  • Digoxin slows ventricular rate in a-flutter/fib
    Why? Because AV node NEEDS Na/K pump for action potential. Digoxin increases contraction BUT decreases AP rate for AV node!!
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15
Q 
Adenosine: 
Cardiac effects (2) / MOA 
Cardiac use/DOC (1)
ROA (1)
ADR (3)
CI + Replacement drug (2):
A

Effects/MOA:
^ K+ out of cell–> Hyperpolerization–> DECREASE automaticity + AV conduction

Use: DOC terminates PSVT
ROA: IV only (w/ short half life)
ADR: Bronchospasm, Flushing, Impending Doom
CI: COPD, Asthma (use verapamil)

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16
Q

Two drugs that markedly prolong QT on ECG:

A

Procainamide (I-A), amiodarone (III)

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17
Q

Three drugs that markedly increase QRS on ECG:

A

Procainamide (I-A)
Flecainide (I-C)
Amiodarone (III)

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18
Q

Most class I-IV anti-arrythmics slow down AV conduction and increase PR interval on ECG. What are two exceptions?

A
  1. Procainamide/ Class 1A.
    - anti-Ach properties make AV node effects unpredictable
    - PR could increase, decrease, or remain the same.
  2. Lidocaine/Class 1B:
    - Rapidly disassociate from Na channels
    - Often leave the PR interval unchanged
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19
Q

What drug classes cause increased risk of torsades?

A

Class 1A
Class III

*I believe dronadrone also causes torsades, yes! Sorry–forgot to respond earlier!

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20
Q

Effects of all class 1, 2, and 4 drugs on:

Conduction 
Phase 0 slope on AP plot 
Automaticity 
APD 
ERP
A
  • Decrease conduction
  • Decrease automaticity
  • Decrease phase 0 slope on AP plot
  • ^ APD
  • ^ ERP
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21
Q 
Effects of class 3 drugs on:
Conduction 
Automaticity 
ARP
ERP

+ important caveat

A

On their own, “class 3” drugs only ^ ERP/APD

HOWEVER, most drugs in this class have mixed mechanisms allowing them to also decrease conductivity/ automaticity

Ex: amiodarone has class III effects mainly, but it also has class I/IV activity

22
Q

Two drugs in the cardiac unit that may cause a reversible lupus-like syndrome?

A

Procainamide; Hydralazine

23
Q 
Procainamide: 
Class
Use 
ROA
ADRs (4) 
Active metabolite
A

1A
Emergency ventricular arrythmias
IV/oral

ADRs:

  1. ^QT/torsades esp with hypokalemia
  2. LUPUS
  3. AGRANULOCYTOSIS
  4. leukopenia

Active metabolite: NAPA (also has Na blocking properties)

24
Q 
Lidocaine:
Class
Use(2)
ROA 
ADRs (2)
A
  • Class 1B
  • Digoxin arrythmia/ life threatening ventricular arrythmia
  • IV only (first pass elimination)
  • delirium and seizures
25
Q

How is mexiletine different than lidocaine?

A

Same other than:

orally effective + some GI ADRs

26
Q

In what cases are lidocaine and mexilitine contraindicated?

A

Seizures/ hepatic disease

27
Q

Flecainide:
Class
Use

A

Class: IC
Use: deadly ventricular arrythmias/ SVT IN THE ASBENCE OF ORGANIC HEART DISEASE

28
Q

How does Propafenone differ from Flecainide?

A

Propafenone has some Beta blocking properties

Negative ionotropic

29
Q

Three important ADRs to keep in mind for B-blockers when using them to treat cardiac patients

A

1) Bronchospasm- (only B1 selective for asthma/COPD pts)
2) CHF/ AV block
3) Insulin induced hypoglycemia + loss of hypoglycemic tachycardia

30
Q

Esmolol:
Most common uses (2)
ROA?
Half life:

A 
IV admin POST OP for control of:
Atrial arrythmias (sinus tacky/ or Afib/flutter)

Very short half life

31
Q

Amiodarone***
Class
Use
ADRs (7)

A

Class III, with some I and IV properties
DOC: emergency ventricular arrythmias

ADRs:

  1. Pulmonary fibrosis
  2. Hepatotox
  3. Hypo/hyper thyroid
  4. QT ^/ torsades
  5. AV block + bradycardia
  6. Corneal microdeposits, photosensitivity
  7. Blue/gray nose + cheeks

(“DIRTY” drug due to having multiple mechanisms)

32
Q

Half life amiodarone

A

Very long because it is a lipophilic drug (up to 107 days)

33
Q 
Drondarone 
Class
Use 
ADRs
Half life
A

Class III with some class I activity
A fib/flutter
Liver injury/ CHF
24 hr t1/2

INCREASES CHF MORTALITY = RARELY USED

34
Q

Ibutilide/ dofetilide
Class
Use
ADR

A

Class three
Tx: A flutter/ fib
ADR: Torsades

HIGHEST TORSADES DUE TO SINGULAR K+ ACTIVITY = RARELY USED

35
Q

Sotolol***
Class
Use
ADR

A

Class III/ II (non-cardioselective BBer Ends in –olol!!!!!!!!!)
Tx: V tach
ADR: Torsades

CAN REPLACE AMIODARONE IN INTOLERANT PATIENTS

36
Q

Verapamil
Class
CV Effects
Uses

A

Class IV

  • Vasodilation
  • DECREASED contractility

Use: atrial arrhythmia (SVA, PSVT, AFIB /flutter)

37
Q

Drug of choice for ventricular arrythmias (commonly used by paramedics)

A

Amiodarone

38
Q

What drugs cannot be in patients with organic heart disease (2)

A
  1. Flecainide

2. Propafenone

39
Q

Which drug has an active metabolite “NAPA”?

A

Procainamide

40
Q

What drugs cause delirium and seizures (2)?

A

Lidocaine

Mexilitine

41
Q

Drug that is lipophilic and has an extremely long half life?

A

Amiodarone

42
Q

Drug that may cause pulmonary fibrosis

A

Amiodarone

43
Q

Four pro-arrythmic conditions:

A

1) Conduction block/re-entry
2) Any change in effective refractory period (ERP)
3) Increased automaticity (i.e. abnormal foci)
4) After depolarization

44
Q

Verapamil:
ADR (3):
CONTRA:

A
  1. HypoTN
  2. CHF/ AV block
  3. Constipation (Why? Because it blocks SM calcium release NONspecifically! Stops GI SM contraction too!!)

Contra: Sick Sinus Syndrome

45
Q

Verapamil:

DD interactions

A
  1. B-blockers (^ - inotropic effects)
  2. Digoxin (double decrease in AV cndxn)
  3. Anti-arrhthmics
  4. CYP3A4s (cimetidine)

“same 4 listed in the vasodilator lecture!!”

46
Q

First Aid:

Drugs causing Long QT

A

(“ABCDE”)

  1. AntiArrhythmics (class Ia, III)
  2. AntiBiotics (macrolides)
  3. Anti”C”ycotics (haloperidol)
  4. AntiDepressants (TCAs)
  5. AntiEmetics (ondansetron)
47
Q

Drugs contraindicated in Asthmatics/COPD

A
  1. non-specific Beta Blockers

2. Adenosine

48
Q

What is ondansetron?

Why is it relevant to this deck of cards?

A

Anti-emetic!!
At a party with alcohol and feeling queasy?
Keep ON DANCing with ONDANSetron.

**It prolongs QT like many of the anti- arrhythmics, ^ Torsades risk.

49
Q

Drug of choice for PVST?

A

Adenosine

50
Q

Drug that replaces amiodarone in patients who cannot tolerate amiodarone?

A

Sotolol, has the same main MOA

Also treats ventricular arrythmias

DT3- EXAM 1 (26 decks)

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