arrythmias and treatments Flashcards
what is a arrythmia
abnormality in heart rate or rhythm
arrythmia epidemiology
5.3% UK
types of arrythmia based on location in the heart
supraventricular - above/at or in AV
ventricular
arrythmia symptoms
dizzy
palpitations
chest pain
fatigue
lose consciousness
cardiac arrest
how are arrythmias diagnosed
ECG
how are arrythmias managed pharmacologically
treat underlying cause
Vaughn williams drugs
what is radiofrequency ablation/cryoablation
Radiofrequency energy or freezing destroys tissue at point of arrythmia
how are arrythmias managed non-pharmacologically
electrical cardioversion
radiofrequency ablation
pacemaker
defibrillators
ICD - internal cardioversion defibrillators
what is electrical cardioversion
DC delivered via controlled electric shock across chest wall- anticoag 3 weeks prior and 4 weeks post
what is a pacemaker
Deliver small electrical impulses to myocardial tissue if detects inappropriate rhythm
what is defibrillation
Delivery of electric shock to myocardium via chest wall (VT/VF)
what is ICD - internal cardioversion defibrillator
Implanted into high risk patients with resistant VT’s to monitor rate & rhythm, Initially deliver rapid rate impulses (faster than arrhythmia) to try to regain control and then slow down, If fails, deliver internal electric shock
what is bradycardia
HR <60BPM
what are the different types of bradycardia
sinus bradycardia - SA node fires slowly
sinus node disease - SA node fails to generate electrical impulse
AV node disease/heart block - failure of AV node to conduct electrical impulses to ventricles
what are the three types of heart block
1st degree - long PR interval
2nd degree - not all Ps have QRS
3rd degree - QRS very slow
how is acute bradycardia managed
atropine to increase HR
how is chronic bradycardia managed
discover underlying cause
permanent pacemaker
what is tachycardia
HR >100BPM
what types of supraventricular tachycardia can happen
sinus tachycardia - fast, normal rhythm *can be infection, anaemia, low BP related)
sinus node re-entry tachycardia
AF
atrial flutter - AF but less frequent - saw tooth pattern
AV junction tachycardia
Wolff-Parkinson White syndrome - bypasses AV node (600bpm)
what are the types of ventricular tachycardia
ventricular tachycardia - >5 ventricular beats consecutively
ventricular ectopics
torsade’s des pointes - QT prolongation
ventricular fibrillation - rapid uncontrolled contraction - deadly
what are some causes of torsade’s des pointes
congenital
hypokalaemia
hypomagnesaemia
lithium
how is rhythm controlled in tachycardia
amiodarone
200mg tds 7/7, 200mg bd 7/7, 200mg od maintenance
how is rate controlled in tachycardia
digoxin
500mcg x 2 six hours apart, 125mcg maintenance
side effects of amiodarone
bradycardia
taste disturbances
grey skin
liver/thyroid dysfunction
digoxin side effects
N&V, blurred vision, anorexia, bradycardia
what are the Vaughn Williams antiarrhythmic drugs
- sodium channel blockers - flecainide
- beta blockers - atenolol
- potassium channel blockers - amiodarone
- CCBs - verapamil
how do class 1 Vaughn Williams antiarrhythmic drugs work
sodium channel blockers, slow depolarisation before contraction - slows HR
how do class 2 Vaughn Williams antiarrhythmic drugs
beta blockers, extends phase 4, less SA node firing
how do class 3 Vaughn Williams antiarrhythmic drugs work
potassium channel blockers, slows repolarisation, longer action potential and longer contraction
how do class 4 Vaughn Williams antiarrhythmic drugs work
CCBs, lengthens plateau phase, reduces force and rate of contraction
what two non-Vaughn Williams antiarrhythmic drugs are used for arrythmias
adenosine
digoxin
adenosine MOA
- Binds to adenosine receptor 1 (GPCR Gi receptor)
- Gi inactivated adenylyl cyclase
- Decrease in cAMP
- Decrease in action potential firing from SA node
digoxin MOA
- Inhibits Na/K ATPase and reverses Na/Ca exchanger
- Increased Na in cardiomyocyte - reverses Na/Ca exchanger so increased Ca in cell
- Increased Ca = increased contraction force
