Antiarrhythmias continued Flashcards
What class of antiarrhymics is good for atrial arrhythmias, what class of medications is this class
Class 2, beta-blockers
What are the physiological effects of using beta-blockers for antiarrhythmias
Decreased sinus rate, increased PR-intervals, decrease phase 4 slope
What is the main effect of using antiarrhythymics, effects on ECG
Potassium channel blocker, slowing the rate of depolarization and increasing the refactory period
What are the primary class 3 AADs
Amiodarone, Dronedarone, Sotalol, Dofetillide
Which class 3 AADs affect not only potassium channels but also sodium, calcium, and beta receptors as well, what effect would this have on an ECG
Amiodarone and Dronedarone/ decreased sinus rate, increased PR interval, increased QRS complex, increased QT interval
Which class 3 AADs affect potassium and beta receptors
Sotalol
Which class 3 AADs affect potassium channels only
Dofetillide
T/F: Class 3 drugs are best used for maintaining normal sinus rhythm but not necessarily towards changing the sinus rhythm
True
What does amiodarone inhibit, what are potential drug drug interactions with amiodarone
3A4, 2D6, 1A2, 2C9, P-GP/ Increase warfarin (cut by 25-50%), increase digoxin (cut by digoxin), increase simvastatin (max of 20 mg)
What does dronaderone inhibit, what are potentail drug drug interactions
3a4, 2D6, p-gp/ increase digoxin concentrations 2.5 fold and increase simvastatin concentrations 4 fold (max 10 mg) with a substantial increase in dronaderone levels if taken with ketoconazole
Due to the kinetics of amiodarone how does its effects change from minutes to days, hours to days, weeks to months
Mostly effects beta receptors and calcium but is not a large amount of change, effects on potassium channels start to rise altering sodium, major impact on potassium is apparent
What is the loading dose for amiodarone, maintenance dose
400 mg TID with meals for 5 days then 400 mg per day for one month, 200 mg per day
T/F: Amiodarone IV and Oral should never overlap each other so if a patient is switched to oral IV amiodarone should be D/C
True
What are pertinent amiodarone side effects
corneal microdeposits/optic neuropathy, pulmonary fibrosis, liver toxicity
What are cautious side effects of amiodarone
photosensitivity/skin discoloration, neuropathy/myopathy, hyper/hypothyroidism, proarrhythmia, bradycardia/heart block
What is monoitored for amiodarone and how ofen are they checked
LFTs: every 6 months, TSH/TFTs: every 6 months, chest X-ray at baseline and every 12 months
T/F: Dronedarone can be taken with or without food
False: Dronedarone should be taken WITH food to increase the bioavailability
T/F: Dronedarone is not used as much as amiodarone because it does half as well
True
What are contraindications of dronedarone
Patients with heart failure, permanent atrial fibrillation, liver dysfunction
What drug has an interaction with dronedarone and has its dosing changed due to CrCl, how
Dabigatran/ CrCl 30-50 ml/min = dabigatran 75 mg twice daily, CrCl 15-30 ml/min = AVOID dabigatran
Which class 3 drug is usually used if someone has heart failure, notable drug interactions
Dofetilide/ hydrochlorothiazide, verapamil, azoles, QT prolonging drugs
T/F: Sotalol is also 100% renally excreted and for atrial fibraltion should not be used for a CrCl less than 40 and should not be used for a CrCl less than 10 for ventricular fibrillation
True
What is the main concnern for sotalol, dofetilide
Bradycardia, Torsades de pointes
What are the class 4 AADs, what is its physiological effect on ECG
Non-DHP calcium blockers, lowers sinus rate and increased PR-interval
What alternative agent is used for AVNRT/AVRT to reduce condition in the AV node
Adenosine
What is used to treat torsades de pointes
Magnesium
T/F: Amiodarone should have a 3 month washout period before using other AADs
True
What is a prolonged Qt interval that wouldn’t allow for dofetilide use, sobatol
Greater than 440 ms, greater than 450 ms
