Cardiovascular Week 1 Flashcards
Class I anti-arrhythmics
Sodium channel blockers
- depression of Phase 0, depolarization
Class Ia, Ib, Ic
Class II anti-arrhythmics
Beta adrenergic antagonist
- Atenolol, Acebutolol, Carvedilol, Esmolol, metoprolol, pindolol, propranolol, timolol
Class III anti-arrhythmics
Potassium channel blockers
- Amiodarone, Bretylium, Dofetilide, Ibutilide, Sotalol
Class IV anti-arrhythmics
Calcium channel blockers
- Diltiazem
- Verapamil
Class V anti-arrhythmics
Unclassified
Adenosine, Adenosine triphosphate, Atropine, Digoxin,
Class Ia anti-arrhythmic
Moderate sodium channel blockers;
moderate depression; prolonged depolarization (slower upstroke) & longer refractory period
- disopyramide
- procainamide
- qinidine
Class Ib anti-arrhythmic
Weak sodium channel blockers;
weak depression; shortened depolarization (shortened phase 2)
- lidocaine, mexiletine, phenytoin, tocainide
Class Ic anti-arrhythmic
Strong sodium channel blocker;
Strong depression; minimal effect on repolarization
- flecainide, propafenone, moricizine
What occurs in phase 0 of cardiac AP
rapid depolarization
- Fast Na channels open, Na rushes in
What occurs in phase 1 of cardiac AP
begin repolarization
- Fast Na channels begin to close
What occurs in phase 2 of cardiac AP
plateau
- SLOW Ca channels open,
Ca inward
What occurs in phase 3 of cardiac AP
repolarization
- Ca channels close
- K channels open, slow K eflux
What occurs in phase 4 of cardiac AP
RMP
What occurs in phase 0 of cardiac PACEMAKER AP
upstroke
- critical firing threshold -40mV
- slower & Ca mediated
What occurs in phase 3 of cardiac PACEMAKER AP
repolarization
- Ca & Na channels close
- K channels open; slow outward K
What occurs in phase 4 of cardiac PACEMAKER AP
gradual depolarization
- slow inward Na & Ca
4 ways to classify arrhythmia
- site of origin
- Narrow or broad complexes
- Regular or Irregular
- ↑ or ↓ HR
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
4 mechanisms of arrhythmia/electrical disturbance initiation & production in the heart
- altered automaticity
- delayed after-depolarization
- Re-entry
- conduction block
When does an arrhythmia require treatment? (3)
- can’t be corrected by removing cause
- hemodynamic instability
- disturbance predisposes more serious arrhythmia or co-morbidities
What are 3 non-pharmacological treatments to arrhythmias?
- pacing (external, temporary, permanent)
- prophylaxis (ablation)
- acute (vagal down, cardiovert)
Antiarrhythmic medications are administered to ___, ___, or ____ arrhythmias.
- Prevent
- Supress
- Treat
Medication used to treat:
sinus bradycardia
Class V: Atropine (IV)
Medications (2) & class used to treat: Ventricular rhythms
Class Ib (sodium channel blockers)
- Lidocaine (IV)
- Mexiletine
**NOT Class IV Ca Channel blockers
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?
- sodium channels
- potassium channels
- 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
- HR
- preload
- 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)
- 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
- 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
- phenyl-alkyl-amines
- benzothiazepines
- 1,4- dihydropyridines
Classification of verapamil
phenyl-alkyl-amine
classification of diltiazem
benzothiazepine
2 categories of Class IV (calcium channel blocker) use
- 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