Anti-arrhythmia Therapy Flashcards
What causes cardiac cells to excite and contract
Na enters = depolarisation
Ca enters = contraction
K leaves = depolarisation
What do class 1 drugs do
Block Na channels so slow rate of depolarisation
Block AV node
Stabilise membrane
Example of class 1
Fleicanide
When is it used and when is it CI and what should you do prior to prescribing
AF / flutter for chemical cardio version
SVT with accessory pathway e.g. WPW
Some ventricular arrhythmia’s
CI Post MI Structural heart HF AV block Flutter
Need to do ECHO to look for structural heart as -ve inotropic
What are class 2 drugs and what do they do
BB
Block sympathetic system
Depress depolarisation
Depress SVT and VT
When is it 1st line
AF
What are class 3 drugs
Amiodarone
Sotalol
How do they work
K blocker
Increase AP duration
Prolonged repolarisation
When are they used
Difficult to treat arrhythmia
Life threatening VT, VF, AF, flutter
What is class 4 drug
CCB
- Verapamil
- Dilitizem
How do they work
Depress depolarisation
When are they used
Paroxysmal SVT
Control AF and flutter
What is digoxin
Cardiac glycoside
Inhibits Na / K pump
Positive inotrope - allows Ca to improve contraction
When is digoxin used
Heart failure - improve Sx due to inotropic but not mortality
AF for rate control
What must you monitor
U+E - K level
Toxicity
When is it commonly used
Elderly for rate control in AF with poor heart
Why should you use with caution
Renal excreted so increases in renal failure / AKI which elderly prone too
What do you do if this happens
Monitor U+E
Reduce dose
What other AA will increase level of digoxin / other factors which increase toxicity
Amiadarone
Other
- Hypokalaemia / Mg
- Hypernatraemia / Ca
- Hypothermia
- Hypothyroid
- Age
- Renal failure
- Acidosis
- MI
- Spirnolactone
- Thiazide
What are SE of digoxin
Hyperkalaemia - causing arrhythmia Gout Nausea Anorexia Confusion Gynaecomastia
What are signs of toxicity
Yellow glow (xanthopsia)
N+V
Confusion
Arrhythmia - AV block / Brady
ECG Reverse ST tick Flattened T wave Short QT Av block VT / VF
What do you do if toxicity
Measure digoxin level 8-12 hours after last dose U+E= monitor ECG Give digiband Correct electrolyte
When is amiodarone used
Atrial and ventricular tachycardia
What may amiadarone interact with
Digoxin - increases level
p450 inhibitor
Warfarin increased
What are SE of amiadarone
Thrombophlebitis of central vein Bradycardia Long QT Thyroid dysfunction - hypo and hyper Pulmonary fibrosis Hepatic toxicity - Discontinue if LFT spike >2/3x - Do not start if liver issue - Cirrhosis is rare Pneumonitis Grey / blue pigmentation Optic neuritis Corneal opacification Peripheral neuropathy Photosensitivity
What do you do prior to starting
U+E, LFT, TFT
CXR
What do you monitor every 6 months
TFT and LFT
What does adenosine do
Slows conduction through AV node causing transient heart block
When is it used
SVT to convert to sinus
How do you give
IV
Fast bolus as short bolus through large bore cannula followed by saline flash
What does it cause intially
Systole
Warn patients that may feel like death
When is it CI
Asthma / COPD due to bronchospasm
HF / Severe hypo / heart block
What are SE
Chest pain
Spasm
FLushing
WPW
What do you do for all class 3 (amiadaraone and stall) and fliecanide (class 1)
Monitor ECG as risk of QT prolongation
