Antiarrhythmic drugs Flashcards
Principal site of action
AV NODE- which drugs?
A- adenosine
B - BB
C - CCB (verapamil, diltiazem)
D - digoxin
Principal site of action
Ventricles - which drugs?
lignocaine (LA)
Principal site of action
Atria, ventricles, accessory pathways (throughout the heart)
A - amiodarone
D - disopyramide
D - dronedarone
F - flecainide
Antiarrhythemic drugs are negative inotropes, therefore we need to avoid using these in which condition?
HF
Which of the antiarrythmic drugs can we use in HF as an exceptions?
digoxin and amiodarone
What drugs can we use for bradyarrhythmia?
ST: atropine injuection (vagus nerve blocker), isoprenaline infusion (BB of heart)
pacemaker
What drugs can we use for tachyarrhythmia? (either SVA or VA)
DC shock, ablation (tissue destroying), drugs, implantable defibrillator
In which tachyarrhythmia do drugs work better?
SVA
In which tachyarrhythmia do implantable defibrillator work better?
VA
Antiarrhythmic drugs are proarrhythmic. what does this mean?
AA can cause another arrhythmia and prolong QT interval
What happens in QT interval?
R wave might run into T wave (depol and repol simultaenously –> ventricular fibrillation)
What happens to the rates in ventricles and atria in AF?
Rapid atrial rate at 400bpm
slower in ventricles
(AF: irregular - 160-180bpm,
Atrial flutter: regular - 150bpm)
In rate control of AF? which rate is controlled?
the ventricular rate
NOT the atria rate
Is the resting heart rate slower in HF?
yes
When is rhythm control preferred over rate control?
for 1st presentation,
if pt is less than 65 years old,
if symptomatic with AF
If before 48 hours since AF, it means
less chance of atria stunning (less chance of blood clots in the heart)
If after 48 hours since AF, it means we need…
pharmacological tx or DC shock
Before pharmacological tx or DC shock, you need to give them anticoagulants for how long?
for 3 weeks
up to 6 weeks
e.g. warfarin, dabigatran, rivaroxaban, apixaban
what do we use for maintenance of sinus rhythm after cardioversion?
sotalol
flecainide
amiodarone
but only 50% stay in sinus rhythm
Drugs that block the AV node for rate control are…
1st line: CCB (v/d), BB (metoprolol, atenolol)
2nd: digoxin (in elderly)
3rd: amiodarone, sotalol, flecainide
What are the ADE of D/V?
Constipation (a lot in verapamil)
bradycardia, heart block
What are the ADE of digoxin?
nausea vomiting anorexia, confusion in elderly
What are the ADE of amiodarone?
nausea vomiting in the beginning,
nightmares, neurotoxicity, photosensitivity, thyroid dysfunction, skin pigmentation, taste disturbances, poor vision at night
What pre-tx is needed for amiodarone?
TFT, LFT, electrolytes (esp potassium)
Explain the complex dosing regimen for amiodarone
- 200mg TDS 7 days
- 200mg BD 7 days
- 200mg OD
AF significantly increases the risk of stroke.
What are the two antithrombotic groups?
anticoagulants
antiplatelets
What does warfarin do?
What are issues with warfarin?
What are the DI of warfarin?
it thins your blood
it has narrow therapeutic range and you need to individualise the doses and monitor INR all the time and take the doses at the same time each day (for all anticoagulants)
Food, alcohol and affect warfarin
What are the NOACS?
Dabigatran (150mg BD)
Rivaroxaban (20mg OD)
Apixaban (5mg BD)
When should you reduce the dose of the NOACs?
low CrCl (80yr
What are the antiplatelet examples?
aspirin, clopidogrel (or together)
When do they use antiplaelets in AF?
in people who do not want to take oral anticoagulants
Who do we use the ChA2DS2VASc score on?
for people with AF
At which HAS-BLED score is the patient rated at high risk of bleeding?
3 or higher
When first starting warfarin, taking drug that increase warfarin effect will require
reduced dose of warfarin
taking drug that decrease warfarin effect will require
usual starting dose and CAREFUL MONITORING
Where is NOAC contraindicated?
in renal impairment (severe)
Which criteria is included in the Cardiac risk chart?
Age, BP, gender, diabetes, cholesterol ratio
Verapamil interacts with which drugs?
BB, digoxin, AA (dabigatran), carbamazepine
