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PDAT5 CV > 32/33 - Arrhythmias > Flashcards

32/33 - Arrhythmias Flashcards

1
Q

Hormones & Channels
for the
SA&AV Node

A

ACETYLCHOLINE

Catecholamines** + **Ca++ Channels
same for chambers

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2
Q

Hormones & Channels
for the
Heart Chambers
R/L Ventricle + R/L Atriums

A

Na+** & **K+ Channels
unique to chambers

Catecholamines** + **Ca Channels
also for SA/AV nodes

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3
Q

What is the FUNNY CURRANT?
IF

A

PACEMAKER CELL
in the SA Node

creates the AUTOMATICITY for the
start of depolarization

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4
Q

Cardiac Conduction

P / QRS / T

A
  • *P-Wave**
  • *DEpolarization of ATRIUM**

QRS
DEpolarization of VENTRICLE
+ masks the repolarization of ATRIUM

  • *T-Wave**
  • *Repolarization of Ventricle**
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5
Q

What is the
RR-Interval?

A

RR Interval is:
HEART RATE

Distance between QRS PEAKS

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6
Q

QTc Prolongation Definition

Male + Female

A

Male > 470

Female > 480

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7
Q

How to calculate QTc from ECG?

Calculation + Quick & Dirty Method

A

QTc** = **Qt / √RR

Quick & Dirty method to see if prolonged QTc:

T-wave ends BEFORE the HALFWAY POINT
between the
R-R PEAKS

(sec)

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8
Q

Mechanisms of Arrhythmias
Enhanced Automaticity

Causes + Characteristics

A

Drugs: Catecholamines
Conditions: Hypoxia / HypoKalemia
Cardiac Dilation / EXERCISE

Characteristics:
Onset is UNRELATED to initiating event = PVC
Initiating beat IDENTICAL to Subsequent beats
onset is preceded by GRADUAL acceleration & termination
by gradual deceleration

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9
Q

Mechanisms of Arrhythmias
TRIGGERED
DAD = Delayed After Depolarization

Causes + Characteristics

A
  • *Ca2+ Overload**
  • *MI / Adrenergic Stress / DIGitalis Intoxication**

More common at:
FAST cardiac rates

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10
Q

Mechanisms of Arrhythmias
TRIGGERED
EAD = Early After Depolarization

Causes + Characteristics

A
  • *PROLONGation of AP**
  • *1a + 1c Drugs**

Most common when:

  • *HR is SLOW**
  • HypoKalemia*
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11
Q

Mechanisms of Arrhythmias
RE-ENTRY
Anatomical ReEntry

Causes + Characteristics

A

Causes:
Additional Pathway** / **Scarred Ventricle

Characteristics:
Presence of an anatomically DEFINED circuit
Heterogeneity in refractoriness among regions in circuit
SLOW conduction

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12
Q

Mechanisms of Arrhythmias
RE-ENTRY
Functionally Defined Re-entry

Causes + Characteristics

A

Causes:

  • *HEART DISEASES**
  • *CAD / LV dysfxn / MI**

Characteristics:
Non-excitable tissue is at the core = Refractory
DOESNT have to stay in the SAME anatomical position
HARDER to TREAT, continuously moving

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13
Q

Mechanisms of Arrhythmias
Enhanced Automaticity

MANAGEMENT

A

INHIBITION OF AUTOMATICITY

↓Slope of Phase 4
BB’s

  • *Elevate Threshold Potential**
  • *Na+ / Ca+** Channel Blockers

↑Max Diastolic Potential
Adenosine / Acetylcholine

↑Action Potential Duration
K+ Channel Blockers

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14
Q

Mechanisms of Arrhythmias
TRIGGERED
DADs

TREATMENT

Ca2+ Overload / FAST cardiac Rates

A

INHIBITION OF DADs

  • *↓Ca2+ Influx_ > ↓_SR Load_ & ↓_Ca2+ release from SR**
  • *Ca** Channel Blockers
  • *↑Threshold Required** to create the Abnormal Upstroke
  • *Na+** Channel Blockers (Ic)
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15
Q

Mechanisms of Arrhythmias
TRIGGERED
EADs

TREATMENT

Prolongation of AP 1a/1c drugs
HR IS SLOW / HypoKalemia

A

INHIBITION OF EADs

  • *Shorten the AP duration**
  • *ISOPROTERENOL** to acceleratte the HR

Mg2+
without normalization repolarization / QT

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16
Q

Mechanisms of Arrhythmias
ANATOMICAL REENTRY

TREATMENT

slow conduction

A

Anatomically Reentry

  • *↑Refractory Period**
  • *K+** Channel Blockers / Ca2+ Blockers (SA/AV node)
  • *BetaBlockers** (Sa/AV node)
  • *Adenosine** (AV nodes)

↓Conduction Velocity
Na+ Channel Blockers / Ca2+ Channel blockers
Adenosine + Beta Blockers

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17
Q

Mechanisms of Arrhythmias
Functionally Defined Re-entry

TREATMENT

non-excitable refractable

A

Functionally Defined Reentry

  • *↑Refractory Period**
  • *K+** Channel Blockers
  • *Na+** Channel Blockers
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18
Q

Atrial Fibrilation

Mechanism + Origin

A

ALL 3
Automaticity + Triggered + Reentry

Origin:
Atria / Thoracic Veins / Pulmonary Veins / SVC / Vein of Marshall

VARIABLE
AV or VA conduction

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19
Q

Atrial Flutter

Mechanism + Origin

A

REENTRY

Origin:
RA / LA (infrequent

VARIABLE
AV or VA conduction

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20
Q

Ventricular Tachycardia

Mechanism + Origin

A

ALL 3
Automaticity + Triggered + Reentry

Origin:
Ventricles

AV Dissociation + Variable

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21
Q

TdP TachyCardia

Mechanism + Origin

A

ALL 3
Automaticity + Triggered + Reentry

Origin:
Ventricles

AV Dissociation

22
Q

Class I Antiarrhythmic Drugs
Vaughan-Williams Classifications

What Channel / What Drugs?

A

Na+ Channel Blockers

  • *1a**
  • *Quinidine / Disopyramide / Procainamide**
  • *1b**
  • *Mexiletine / Lidocaine**
  • *1c**
  • *Propafenone / Flecainide**
23
Q

Class III Antiarrhythmic Drugs
Vaughan-Williams Classifications

What Channel / What Drugs?

A

K+ Channel Blockers

Amiodarone** + **Dronedarone
K+ / Na / Ca / Beta

Sotalol
K / Beta

Dofetilide
K+ only

24
Q

Quinidine** / **Disopyramide** / **Procainamide

Class / MoA / ECG Manifestation

A

1A

Channels Blocked:

  • *Na+** - Intermediate association/dissociation
  • *K+**

ECG manifestations:
↑ QT; ↑ QRS (high dose)

25
Q

Mexiletine** / **Lidocaine

Class / MoA / ECG Manifestation

A

1B

Channels Blocked:

  • *Na+**
  • *FAST** association/dissociation

ECG manifestations:

  • May* ↓Sinus Rate
  • generally does NOT affect QRS or QT*

Lidocaine has affinity for INACTIVE receptor

26
Q

Propafenone** / **Flecainide

Class / MoA / ECG Manifestation

A

1c

Channels Blocked:

  • Na+** = *_SLOW_ association/dissociation
  • *RyR2 Ca2+**
  • *Propafenone +Beta+**

ECG manifestations:
↑PR & ↑QRS
Flecanaide is SLIGHT ↑PR

27
Q

Which Ic/Na+ AntiArrhythmic requires a
RENAL DOSE ADJUSTMENT?

A
  • *FLECAINIDE**
  • *50mg / 100mg / 150mg BID**

CrCl < 35ml/min = start at LOWER dose

28
Q

Which Ic/Na+ AntiArrhythmic requires a
HEPATIC DOSE ADJUSTMENT?

A
  • *PROPAFENONE**
  • *SR:** 225mg / 325mg / 425mg BID
  • *IR**: 150mg / 225 / 300mg TID

Mod-Severe Liver Disease
↓Dose by 20-30%

29
Q

Ic/Na+ Channel Antiarrhythmics

DRUG INTERACTIONS?

A

Flecainide
CIMETIDINE ↑Flecainide Levels
↑DIGOXIN levels

  • *Propafenone**
  • *WARFARIN** & GRAPEFRUIT ↑Levels

CONTRAINDICATED h/o MI

30
Q

Ia AntiArrhythmics

ADR / Toxicities

A
  • *Quinidine / Disopyramide / Procainamide**
  • *Diarrhea / AntiCholinergic / GI**

CYP3A4 Metabolism

↓BP

  • *Heart Block** / Atrial Flutter (AV blocking Agent)
  • *TORSADES** (quinidine 2-8%)
  • *HF** = negative inotrope
31
Q

Ic Antiarrhythmics

ADR / Toxicities

A

Flecainide** + **Propafenone

  • *Heart block** / HF exacerbation
  • *Propafenone can ↓HR**
  • *Atrial Flutter** (AV blocking Agent)
  • *Ventricular Tachycardia**
  • *CONTRAINDICATED for h/o MI**

Dizziness / fatigue / blurred vision / nausea
metallic taste - Propafenone

32
Q

Class II Antaarrhythmics

MoA / ECG Manifestations

A

BETA-BLOCKERS
+ indirect Ca2+ blockers

↓cAMP & Ca2+ influx –> ↓condition velocity

↓phase 4 slope = ↓HR

Block Catecholamines

ECG Manifestations:
↓Sinus Rate ↑PR

33
Q

Amiodarone** + **Dronedarone

Class / Channels blocked / ECG manifestions

A

Class 3

ALL Channels Blocked:
K+ Na+ Ca2+ Beta

ECG:
↑ QT
↓ Sinus rate, ↑ PR, ↑QRS,

34
Q

Sotolol

Class / Channels blocked / ECG manifestions

A

Class 3

Channels Blocked:
K+ Beta

ECG:
↑ QT
↓ Sinus rate
may ↑ PR

35
Q

Dofetilide

Class / Channels blocked / ECG manifestions

A

Class 3

Channels Blocked:
K+ only

ECG:
↑ QT

36
Q

Amiodarone
K+ Channel Blocker
400mg/d > 200mg/d WF

DRUG INTERACTIONS

A

Inhibits A LOT:
3A4 / 2D6 / 1A2 / 2C9 / PGP

  • *WARFARIN**
  • 2D6 not empiric* –> ↓dose 25-50%

DIGOXIN
PGP ↓dose by 50% right a way

SIMVASTATIN
max dose is 20mg

37
Q

Amiodarone
K+ Channel Blocker
400mg/d > 200mg/d WF

Monitoring + ADRs

A
  • *LFT_ / _CXR_ / _TSH**
  • *PFT** sometimes

IV Formulation (polysorbate 80) –> ↓BP

Corneal Microdeposits / Optic neuropathy - reversible

PULMONARY FIBROSIS - NOT REVERSIBLE

Skin Discoloration / PHOTOsensitivity

Hypothyroidism > hyperthyroidism

Liver Toxicity / TORSADES / Bradycardia / Heat Block

38
Q

Dronedarone
Class 3 K+ Channel Blockers
400mg BID WF

Contraindications / ADR

A

CI:
SYMPTOMATIC HF - Class 4 or 2/3 w/ recent hospitilization
PERM AFib
Liver Dysfunction

Side effects:
GI mainly
↑SCr - BENIGN effect, just a reduction in secretion
Torsades Rare
↓BP / Heart Block / BradyCardia

39
Q

Dronedarone
Class 3 K+ Channel Blockers
400mg BID WF

DRUG INTERACTIONS

A
  • *DIGOXIN**
  • *empirically ↓dose**

SIMVASTATIN - 10mg MAX

  • *CYPA4 Inhibitors** - AVOID
  • *ketoconazole**

DABIGATRAN
CrCl 30-50 ml/min: dabigatran 75mg twice daily
CrCl 15-30 ml/min: avoid dabigatran

40
Q

DOFETILIDE
Class 3 K+ Blockers –> ↑ QT

DRUG INTERACTIONS

A

HCTZ
↓dofetilide elmination –> prefer Chlorithaladone

VERAPAMIL - CI

QT Prolonging Drugs

AZOLES - caution

41
Q

DOFETILIDE
Class 3 K+ Blockers –> ↑ QT

HOW TO DOSE?

A

NEEDS TO BE HOSPITILIZED FIRST ~3 Days
NEED QTc < 440 to use

ACTUAL body Weight
CrCl < 20 = CONTRAINDICATED
>60 = 500mcg BID / 40-60 = 250 BID / 20-40 = 125 BID
VVV
Check QTc Every 2-3 hours after Dose
VVV
First Dose: if ↑QTc < 15%=Continue
If ↑QTc > 15% or >500msec = ↓Current Dose
VVV
if at ANY TIME after SECOND DOSE:
↑QTc > 500 msec –> DC DOFETILIDE

42
Q

SOTALOL
Class 3 K+ Blocker

Dosing / Considerations

A

L - Isomer = Beta + K+ Blocker
D = K+ only

  • *100% RENAL EXCRETION**
  • special renal dosing*

ORAL Dosing:

  • *80mg BID** –> titrate ↑80mg every 3 days
  • *Atrial Max = 160mg BID**
  • *Ventricular Max = 320 BID**
43
Q

SOTALOL
Class 3 K+ Blocker

ADR / Contraindications

A

CONTRAINDICATED IF:
QTc < 450ms** or **ATRIAL: CrCl < 40mL/min

Torsades Dofetilide Torsades

Bradycardia / Heart Block / CHF
↓BP

Used in Heart Failure

44
Q

DOFETILIDE
Class 3 K+ Blocker

ADR / Contraindications

A

Contraindicated if:

  • *Baseline QTc >440**
  • *ABW CrCl < 20**
  • *QTc Increase > 500** after second dose

TORSADES > Sotalol

Bradycardia / Heart Block / CHF
↓BP

Used in Heart Failure

45
Q

Ibutilide

Class / Use

A
  • *Class 3 K+ Channel Blocker**
  • slow* Na+ Blocker

used INPATIENT to:
CONVERT patient in AF/AFI –> NSR (normal sinus rhythm)

IV Only
due to 1st pass

ADE:
TORSADES

46
Q

Diltiazem** + **Verapamil
Non-DHP CCBs

CLASS / Channel Blocked / ECG Manifestations?

A
  • *Class 4**
  • *L-Type Ca2+**

↑Time to get through Phase 0

ECG Manifestation:
↓ Sinus rate, ↑ PR

47
Q

ADENOSINE
other class

USE / MoA

A

Activates K+ Channels
shortens AP / HYPERpolarization / slows normal Automaticity

↓cAMP
caused by sympathetic stim. ↑AV node Refractoriness

Used in:
ReEntry PSVT (AVNRT / AVRT) to reduce AV node conduction
Test dose to see if adenosine is able to:
BREAK THE ARRHYTHMIA
if it RETURNS = AVNRT/AVRT, if NOT it is NOT in the AV node

48
Q

DIGOXIN

Use / Considerations

A

↑Parasympathetic activity
↑ vagal tone
↓ AV nodal conduction
↓ Heart rate

Toxicity:

  • *↑Na Intracellularly** / ↑Resting Potential / ↑Automaticity
  • *= Extra Beats + DADs**

TAKES TIME to WORK
0.5 -2ng/mL therapeutic range

49
Q

MgSo4

Use in Arrhythmias

A

UNKNOWN mechanism

  • *Treatment for TORSADES**
  • *1-2g IV over 15 min**
50
Q

Which drugs require a WASHOUT period before starting ANOTHER arrhythmia drug?

A
  • *3 MONTH**
  • *Amiodarone washout period**

needed before you can
Start DOFETILIDE
hospitilization only

PDAT5 CV (30 decks)

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