Cardiovascular- Arrhythmias Flashcards
What do potassium channels contribute to?
action potential duration
What do T-type calcium channels do?
initiate action potential
What do L-type calcium channels do?
sustain action potential
What are the stages of the action potential
Resting =4 Depolarization =0 Early repolarization= 1 Plateau= 2 Final repolarization =3
What are Class I antiarrhythmics?
Fast sodium channel blockers
Slows phase 0 depolarization
-lidocaine
-quinidine
What are Class II
Beta blockers
Suppresses phase 4 depolarization
-metoprolol
What are Class III
Repolarization prolongation
Prolongs phase 3 repolarization
-amiodarone
What are Class IV
Calcium Channel Blockers
Shortens action potential
-verapamil
-diltiazem
What are Class V
Calcium accumulation in cardiac cells
vagal effect
-digoxin
What is Vaughn-Williams- IA
Quinidine
What is Quinidine used for?
Atrial tachyarrhythmias
AV-junctional & ventricular arrhythmias
What are ADRs of Quinidine?
Diarrhea hemolytic anemia aggravates HF Liver failure Digoxin interaction
What is Vaughn-Williams- IB?
Lidocaine
What is Lidocaine used for?
Ventricular arrhythmias
What are some ADRs of Lidocaine?
Worsens certain arrhythmias
seizures
CNS effects
Contraindicated in 2nd or complete heart block
What is Vaughn-Williams- IC?
Propafenone (Rhythmol)
What is Propafenone indicated for?
life-threatening ventricular tachycardia or ventricular fibrillation
or refractory supraventricular tachycardia
What are ADRs of Propafenone?
Potential to worsen HF
Prone to drug-drug interactions that can raise warfarin and digoxin levels
CYP2D6
When must Propafenone be dose adjusted?
Patients with liver impairment
Concern over drugs that inhibit CYP2D6
Dose a Vaughn-Williams-1C
Propafenone 225 mg
One tablet q8 hrs
What are Vaughn-Williams II?
Beta Blockers
What metabolizes beta blockers?
CYP2D6, extensive first pass effect
Dose Metoprolol for a home dose
Metoprolol 50mg
One tablet twice a day
Give examples of Vaugn Williams III
Amiodarone
Dofetilide
Sotalol
What is amiodarone indicated for?
Supraventricular arrhythmias
Afib/flutter
Vtach or v-fib
What are some ADRs of Amiodarone?
Pulmonary toxicity
Photosensitivity
Possible bradycardia
Thyroid toxicity
What are some ADRs of Dofetildide?
QTc prolongation
What does Dofetilide do?
Prolongs action potentials in atria and ventricles
Dose Amiodarone
Amiodarone 200mg
1 tablet daily
What drugs are included in Vaughn-Williams IV
Verapamil
Diltiazem
What is Verapamil indicated for?
slows ventricular responses to afib/flutter
terminates PSVT
What are ADRs of verapamil?
Bradycardia
Hypotension
When is verapamil contraindicated?
WPW and a-fib
What is Diltiazem used for?
PSVT afib/flutter
Dose Diltiazem
20mg IV bolus now
infuse 10mg/hr
What is adenosine indicated for
PSVT associated with WPW
What are ADRs of adenosine?
Chest pain, flushing, tightness in throat
Dose adeonsine
6mg IV bolus
repeat at 12 mg if first dose ineffective
