Cardiovascular Week 1 Flashcards by Devon Kasberg

Class I anti-arrhythmics

Sodium channel blockers
- depression of Phase 0, depolarization
Class Ia, Ib, Ic

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Class II anti-arrhythmics

Beta adrenergic antagonist

- Atenolol, Acebutolol, Carvedilol, Esmolol, metoprolol, pindolol, propranolol, timolol

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Class III anti-arrhythmics

Potassium channel blockers

- Amiodarone, Bretylium, Dofetilide, Ibutilide, Sotalol

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Class IV anti-arrhythmics

Calcium channel blockers

Diltiazem
Verapamil

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Class V anti-arrhythmics

Unclassified

Adenosine, Adenosine triphosphate, Atropine, Digoxin,

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Class Ia anti-arrhythmic

Moderate sodium channel blockers;

moderate depression; prolonged depolarization (slower upstroke) & longer refractory period

disopyramide
procainamide
qinidine

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Class Ib anti-arrhythmic

Weak sodium channel blockers;

weak depression; shortened depolarization (shortened phase 2)

lidocaine, mexiletine, phenytoin, tocainide

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Class Ic anti-arrhythmic

Strong sodium channel blocker;

Strong depression; minimal effect on repolarization

flecainide, propafenone, moricizine

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What occurs in phase 0 of cardiac AP

rapid depolarization

Fast Na channels open, Na rushes in

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What occurs in phase 1 of cardiac AP

begin repolarization

Fast Na channels begin to close

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What occurs in phase 2 of cardiac AP

plateau

SLOW Ca channels open,
Ca inward

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What occurs in phase 3 of cardiac AP

repolarization

Ca channels close
K channels open, slow K eflux

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What occurs in phase 4 of cardiac AP

RMP

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What occurs in phase 0 of cardiac PACEMAKER AP

upstroke

critical firing threshold -40mV
slower & Ca mediated

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What occurs in phase 3 of cardiac PACEMAKER AP

repolarization

Ca & Na channels close
K channels open; slow outward K

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What occurs in phase 4 of cardiac PACEMAKER AP

gradual depolarization

slow inward Na & Ca

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4 ways to classify arrhythmia

site of origin
Narrow or broad complexes
Regular or Irregular
↑ or ↓ HR

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Underlying factors that may contribute to arrhythmia development (8)

Arterial hypoxemia
Electrolyte imbalance
Acid-base abnormalities
Myocardial ischemia
Altered SNS activity
Bradycardia
Administration of certain drugs
Enlargement of failing ventricle

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4 mechanisms of arrhythmia/electrical disturbance initiation & production in the heart

altered automaticity
delayed after-depolarization
Re-entry
conduction block

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When does an arrhythmia require treatment? (3)

can’t be corrected by removing cause
hemodynamic instability
disturbance predisposes more serious arrhythmia or co-morbidities

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What are 3 non-pharmacological treatments to arrhythmias?

pacing (external, temporary, permanent)
prophylaxis (ablation)
acute (vagal down, cardiovert)

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Antiarrhythmic medications are administered to ___, ___, or ____ arrhythmias.

Prevent
Supress
Treat

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Medication used to treat:

sinus bradycardia

Class V: Atropine (IV)

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Medications (2) & class used to treat:
Ventricular rhythms

Class Ib (sodium channel blockers)

Lidocaine (IV)
Mexiletine

**NOT Class IV Ca Channel blockers

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Medications used to treat: Supraventricular rhythms 2 classes 3 medications

Class V: - Adenosine (IV) - Digoxin Class IV: - Verapamil

Medications used to treat: Ventricular & Supraventricular 3 classes 2 medications in each class

Class Ia: - Procainamide - Disopyramide Class Ic: - Flecainide - Propafenone Class III: - Amiodarone - Sotalol

Medications used to treat: stress induced arrhythmias ``` 1 class 3 medications ```

Class II: - Atenolol - Propranolol - Sotalol (beta blockers)

Atropine class

Class V; | muscarinic receptor antagonist

Atropine indication

symptomatic bradycardia

Atropine dose

0.4-1mg | repeat as necessary

Use caution with atropine doses _____

Under 0.4mg d/t paradoxical response

Atropine onset

<1min

Atropine duration

30-60 minutes

Magnesium is Class ___ anti-arrhythmic

Class V

Magnesium has effects on which channels?

1. sodium channels 2. potassium channels 3. calcium channels

Magnesium can be given during ____

Torsades de Pointe

Magnesium dose

1gm over 20 minutes; can repeat

Digoxin class/categorization & MOA

cardiac glycoside - increases vagal activity - - leads to decreased activity of the SA node & prolongs conduction through AV node

Digoxin dose

0.5-1mg divided over 12-24 hours **reduce dose in elderly & renal

Digoxin onset

30-60 minutes

What kind of inotrope is digoxin?

positive inotrope, can use to treat CHF

Digoxin will decrease a person's : 3 cardiovascular values

1. HR 2. preload 3. afterload

Digoxin is good for

management of a-fib or a-flutter (especially in peds

Digoxin protein binding

weak

Digoxin elimination

1/2t is 36 hours

CON of digoxin

narrow therapeutic window | 0.5-1.2ng /mL

Excretion of digoxin

90% excreted by kidneys

Adverse effects of Digoxin | Cardiovascular

arrhythmias, heart block

Procainamide class

Class Ia - Intermediate Sodium channel blockers

Lidocaine class

Class Ib - Fast dissociation Sodium channel blockers

Amiodarone class

Class III - Potassium channel blockers - have many MOA/targets

Diltiazem class

Class IV - Calcium channel blockers

Verapamil class

Class IV - Calcium channel blockers

Adenosine class

Class V - unclassified

Procainamide dose

100mg IV Q5M (max 15mg/kg) until rate controlled infusion 2-6mg/min

Procainamide used to treat

Ventricular arrhythmias (not useful in atrial)

Procainamide protein binding

15%

Procainamide E1/2t

2 hours

Procainamide therapeutic level

4-8mcg/mL

Procainamide adverse effects (2)

1. myocardial depression leading to hypotension | 2. syndrome resembling LUPUS ERYTHEMATOUS

Lidocaine used to treat

ventricular arrhythmias *Not pro-arrhythmic Also in: re-entry rhythms, v-tach, v-fib, PVCs

POSITIVE characteristic of lidocaine

*not Pro-arrhythmic

MOA of lidocaine

1. delayed rate Phase 4 | 2. ↑ ventricular fibrillation threshold

Lidocaine dose | bolus & infusion

bolus 1-1.5mg/kg IV infusion: 1-4mg/min (max dose 3mg/kg)

Lidocaine protein binding

50%

Lidocaine metabolism

hepatic; CYP450 active metabolite

Lidocaine elimination

10% renal

Lidocaine adverse effects

CV: hypotension, bradycardia, lightheadedness, myocardial depression, sinus arrest, heart block, cardiac arrest Neuro: Sz, CNS depression, drowsiness, dizziness, confusion Resp: apnea, ventilatory depression Misc: tinnitus **Can augment pre-existing NMB

if patient is taking Mexiletine; check ___

cardiac clearance

Phenytoin AKA Dilantin can cause;

Steven Johnson Syndrome

pro-arrhythmic agents

Class Ic | Class III

non-selective beta blocker

propranolol

patient's on Class III; must monitor their ____ closely

potassium

Amiodarone class & site of action

Class III ; K channels Na channels Ca channels Alpha & beta receptors

Amiodarone is FIRST LINE

in VT/VF when resistant to electrical defibrillation

Amiodarone dose | bolus & gtt

bolus 150-300mg IV over 2-5 minute gtt 1mg/hr x6H, 0.5mg/hr x18 hours

Amiodarone protein binding

96%

Amiodarone metabolism

Hepatic; CYP450 INHIBITS CYP450; WILL PROLONG coumadin/warfarin/NMBD

Amiodarone therapeutic level

1-3.5mcg/mL

Adverse effects of Amiodarone

CV: PRO-ARRHYTHMIC effects, heart block, hypotension Neuro: disturbances Resp: pulmonary toxicity, pulmonary edema, ARDS GI: disturbances MISC: photosensitive rash, grey/blue skin discoloration, corneal deposits, sleep disturbances, abnormal LFTs (20%)

Amiodarone contains ___-

iodine; monitor for thyroid issues

MUST monitor ___ when pt is taking Amiodarone

POTASSIUM; HIGH risk of TdP

Class IV agent primary target

AV node

Calcium channels found in:

- neurons - skeletal muscles - vascular smooth muscles - glandular cells - blood coagulation

3 classifications of Class IV

1. phenyl-alkyl-amines 2. benzothiazepines 3. 1,4- dihydropyridines

Classification of verapamil

phenyl-alkyl-amine

classification of diltiazem

benzothiazepine

2 categories of Class IV (calcium channel blocker) use

1. vascular | 2. non-vascular

What are vascular Class IV medications used for

- angina - systemic HTN - pulm HTN - cerebral arterial spasm (post-bleed) - Raynaud's disease - migraine

what are non-vascular Class IV medications used for?

- bronchial asthma - esophageal spasm - dysmenorrhea - premature labor

Class IV anti-arrhythmic are used for

****VASOSPASTIC ANGINA PECTORIS; CAD