module 8 antiarrhythmic class 4 Flashcards
Class 4 MOA
slow phase 4 spontaneous depolarization and slow conduction in tissues dependent on Ca
- dec. AV node conduction -> dec. HR
Class 4: Calcium channel blockers drugs
Non-dihydropyridine:
verapamin
diltiazem
Class 4 inications
atrial tachyarrhythmias
class 5 drugs
miscellaneous affects on AV node: adenosine atropine digoxin magnesium sulfate
adenosine MOA
dec. conduction velocity
prolongs refractory period
dec. automaticity in AV node
adenosine indication
SVT
- IV rapid push (extremely short half life)
adenosine AE
flushing
hypoTN
chest pain
atropine indication
symptomatic bradycardia
atropine MOA
anticholinergic
- inc. heart rate by blocking the M2 receptors on the SA. node
atropine adverse effects
dec. bodily secretions
- dry mouth
- inc. body temp d/t dec. sweat
urine retention
constipation
confusion
digoxin MOA
cardiac glycoside inhibits Na-K ATPase pump inc. intracellular Ca levels -> inc. myocardial contractility -> prolongs the refractory period at the AV node -> slows AV node conduction Positive inotropy
digoxin indication
controls the ventricular response rate of a-fib/flutter
- may be used in HF
digoxin monitoring
renal function
electrolytes
EKG
measure levels to prevent toxicity: small therapeutic index
- normal range: 0.8-2.0
- inc. risk toxicity with hypokalemia or renal insufficiency
digoxin considerations
large first pass effect
- IV dose is HALF of oral dose
s/s of digoxin toxicity
arrhythmia - PVC - 1st, 2nd, 3rd degree AV block yellow/green halos N/V/D anorexia palpitations syncope Tx: digibind IV
