Tachyarrhythmias Flashcards
what does SVT stand for
supraventricular tachycardia
what does SVT involve
SAN, AVN, atria
5 types of SVT
- PSVT (paroxysmal supraventricular tachycardia)
- AVNRT (atrioventricular nodal re-entrant tachycardia)
- AVRT (atrioventricular reciprocating tachycardia)
- AF (atrial fibrillation)
- Atrial flutter
4 drugs that can treat PSVT
adrenaline, verapamil (4), diltiazem (4), amiodarone (3)
can get ventricular tachycardias which involve
Bundle of His, Purkinje Fibres and ventricles
what is more dangerous SVTs or VTs?
VTs
4 drugs mainly used to treat VT
amiodarone (3), flecainide (1c), disopyramide (1a) and lidocaine (1b)
what does VF stand for
ventricular fibrillation
5 different factors that can cause tachyarrhythmias
pre-existing CV diseases, electrolyte imbalance, drugs, emotions and lifestyle choices AND genetic disorders
6 types of drugs that can cause tachyarrhytmias
- asthma inhalers
- anti arrhythmias
- anti-hypertensive (this is a reflex reaction)
- antifungals
- antibiotics
- antihistamines
3 main mechanisms for tachyarrhythmias
- re-entry (AVNRT, micro re-entry and macro re-entry)
- EADs
- DADs
tachyarrhythmias are caused by…
sympathetic overactivity and an abnormal pacemaker
what does the re-entry mechanism cause?
paroxysmal supraventricular tachycardia
how to treat PSVT
Class 4: verapamil Class 2: beta blockers Class 3: sotalol Class 1c: flecainide Adenosine
what is micro-re-entry?
similar to AVNRT but occurs in the ventricular myocardium and purkinje fibres
what causes micro-re-entry
focal ischaemia or infarction
if a pulse is present, then use:
amiodarone (3), flecainide (1c) or lidocaine (1b)
which class of anti-arrhythmic drugs are not effective for ventricular tachycardia
class 4
what is macro re-entry ?
re-entry via congenital accessory pathway between the atria and ventricles
example of a macro re-entry disease
Wolff-Parkinson-White syndrome - caused by an abnormal pathway completely missing the SA node
how to treat macro re-entry
CATHETER ABLATION or flecainide (1c) or amiodarone (3)
what drugs are not effective in AVRT
AVN blockers
what is another way of saying macro re-entry
AVRT
what does EAD stand for?
early after depolarisation
what does DAD stand for
delayed after repolarisation
what causes EADs
the prolonging of the cardiac AP
what class of anti-arrhythmics can cause EADs
Class 3, 1a OR medicine that is know to inhibit repolarising K channels in phase 3 of the cardiac AP
during prolonged AP, are the Na channels activated?
no
what channel triggers the EAD
the L-type Ca channels in the heart can still recover and trigger EAD
what happens to the heart rate during an EAD
slows down
EADs can trigger
TdP, a type of ventricular tachycardia
what are DADs due to
calcium build up in the cardiac myocyte that doesn’t have enough time to recover to basal level in between APs
what promotes a Ca build up in the cell?
fast HR
drugs that increase Ca release
caffeine
another cause of DAD
digoxin overdose
what causes atrial fibrillation
micro re-entry or EADs
drug used to control the rate of atrial fibrillation
digoxin
what can be used to treat EADs and DADs
class 2 - beta blockers class 1c - flecainide class 3 - amiodarone class 4 - diltiazem
