Arrhythmia's Flashcards
vaughan williams classification class I
block Na channels
1a) inc action potential
1b) dec action potential
1c) slows conduction velocity
vaughan williams classification class II
B-adrenoceptor antagonists
vaughan williams classification class III
prolonged action potential and prolong refractory period
vaughan williams classification class IV
calcium channel antagonists
major problems with A fib
atrial thrombi, PE (R atrium), cerebral emboli/stroke (L atrium)
ischemic stroke risk in a fib
stroke risk in A fib is 2 x > in pt’s without A fib
only 15-44% of pt’s who would benefit from prophylactic anticoag’s receive tx
first step in tx of A fib
ensure hemodynamic instability!
tx strategy if stable A fib
<48 hrs, consider early cardioversion
>48 hrs or don’t know, administer anticoagulant therapy and initiate PO rate control agents (consider cardioversion after 3 weeks)
tx strategy if A fib is unstable
administer immediate DC cardioversion with synchronized shock
rhythm controllers
safest of all the antiarrhythmics is amiodarone
can give if you have an iodine allergy!
Dronedarone
rhythm controller
no iodine to limit toxicity
CHADS2 index
CHF: 1 pt HTN: 1 pt age > 75: 1 pt DM: 1 pt stroke (h/o or TIA): 2 pt
rate vs rhythm summary
avoidance of anti arrhythmic drugs is desirable (most are pro-arrhythmic, esp long term)
rhythm control provided no adv in mortality
rate control can now be considered a primary approach for A fib (and CHF)
rhythm control can be abandoned early if not fully satisfactory
pharmacological conversion of A fib
simpler but less efficacous
major risk is toxicity of drugs
most effective if preformed < 7 days of developing A fib
much less effective if A fib onset > 7 days
electrical and Drug Conversion of A fib
both carry risk of thromboembolism if A fib > 48 hrs
both carry similar thromboembolism risk
