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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
**_Mexiletine**_ / _**Lidocaine_** **Class / MoA / ECG Manifestation**
**_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
**_Propafenone**_ / _**Flecainide_** **Class / MoA / ECG Manifestation**
**_1c_** Channels Blocked: * *_Na+_** = ***_SLOW_*** association/dissociation * *RyR2 Ca2+** * *Propafenone +Beta+** ECG manifestations: ↑**PR** & **↑QRS** **Flecanaide is *SLIGHT ↑PR***
27
**Which Ic/Na+ AntiArrhythmic requires a RENAL DOSE ADJUSTMENT?**
* *_FLECAINIDE_** * *50mg / 100mg / 150mg BID** **CrCl _\<_ 35ml/min** = **start at LOWER dose**
28
**Which Ic/Na+ AntiArrhythmic requires a HEPATIC DOSE ADJUSTMENT?**
* *_PROPAFENONE_** * *SR:** 225mg / 325mg / 425mg **BID** * *IR**: 150mg / 225 / 300mg **TID** **_Mod-Severe Liver Disease_** ↓**Dose by 20-30%**
29
**Ic/Na+ Channel Antiarrhythmics** **DRUG INTERACTIONS?**
**_Flecainide_** **CIMETIDINE ↑Flecainide Levels** ↑**DIGOXIN levels** * *_Propafenone_** * *WARFARIN** & **GRAPEFRUIT** ↑Levels **_CONTRAINDICATED h/o MI_**
30
**Ia AntiArrhythmics** **ADR / Toxicities**
* *_Quinidine / Disopyramide / Procainamide_** * *Diarrhea / AntiCholinergic / GI** CYP3A4 Metabolism ↓**BP** * *Heart Block** / **Atrial Flutter** (**AV blocking Agent)** * *_TORSADES_** (quinidine 2-8%) * *_HF_** = **negative inotrope**
31
**Ic Antiarrhythmics** **ADR / Toxicities**
**_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
**Class II Antaarrhythmics** **MoA / ECG Manifestations**
**_BETA-BLOCKERS_** + ***_indirect Ca2+_*** blockers ↓**cAMP** & **Ca2+ influx** --\> ↓**condition velocity** ↓**phase 4 slope** = ↓**HR** **Block Catecholamines** ECG Manifestations: ↓**Sinus Rate** ↑**PR**
33
**_Amiodarone**_ + _**Dronedarone_** ## Footnote **Class / Channels blocked / ECG manifestions**
**Class 3** ALL Channels Blocked: **K+ Na+ Ca2+ Beta** ECG: **↑ QT ↓ Sinus rate, ↑ PR, ↑QRS,**
34
**_Sotolol_** ## Footnote **Class / Channels blocked / ECG manifestions**
**Class 3** Channels Blocked: **K+ Beta** ECG: **↑ QT ↓ Sinus rate *may* ↑ PR**
35
**_Dofetilide_** **Class / Channels blocked / ECG manifestions**
**Class 3** Channels Blocked: **K+ only** ECG: **↑ QT**
36
**_Amiodarone_** K+ Channel Blocker 400mg/d \> 200mg/d WF ## Footnote **DRUG INTERACTIONS**
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
**_Amiodarone_** K+ Channel Blocker 400mg/d \> 200mg/d WF ## Footnote **Monitoring + ADRs**
* *_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
**_Dronedarone_** Class 3 K+ Channel Blockers **400mg BID WF** ## Footnote **Contraindications / ADR**
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
**_Dronedarone_** Class 3 K+ Channel Blockers **400mg BID WF** ## Footnote **DRUG INTERACTIONS**
* *_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
**_DOFETILIDE_** Class 3 K+ Blockers --\> ↑ QT ## Footnote **DRUG INTERACTIONS**
**_HCTZ_** ↓dofetilide elmination --\> prefer Chlorithaladone **_VERAPAMIL_** - CI **_QT Prolonging Drugs_** **_AZOLES_** - caution
41
**_DOFETILIDE_** Class 3 K+ Blockers --\> ↑ QT ## Footnote **HOW TO DOSE?**
_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
**_SOTALOL_** Class 3 K+ Blocker ## Footnote **Dosing / Considerations**
**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
**_SOTALOL_** Class 3 K+ Blocker ## Footnote **ADR / Contraindications**
CONTRAINDICATED IF: **_QTc \< 450ms**_ or _**ATRIAL: CrCl \< 40mL/min_** **_Torsades_** Dofetilide Torsades **Bradycardia / Heart Block / CHF ↓BP** **Used in Heart Failure**
44
**_DOFETILIDE_** Class 3 K+ Blocker ## Footnote **ADR / Contraindications**
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
**_Ibutilide_** **Class / Use**
* *_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
**_Diltiazem**_ + _**Verapamil_** Non-DHP CCBs ## Footnote **CLASS / Channel Blocked / ECG Manifestations?**
* *_Class 4_** * *L-Type Ca2+** ↑**Time to get through _Phase 0_** ECG Manifestation: **↓ Sinus rate, ↑ PR**
47
**_ADENOSINE_** other class ## Footnote **USE / MoA**
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
**_DIGOXIN_** Use / Considerations
**_↑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
**_MgSo4_** **Use in Arrhythmias**
*UNKNOWN mechanism* * *_Treatment for TORSADES_** * *1-2g IV over 15 min**
50
**Which drugs require a WASHOUT period before starting ANOTHER arrhythmia drug?**
* *_3 MONTH_** * *Amiodarone washout period** needed before you can **_Start DOFETILIDE_** hospitilization only

PDAT5 CV (30 decks)

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