Arrythmias Flashcards
what supraventricular arrythmias exist?
- supraventricular tachycardia
- atrial fibrillation/atrial flutter
- ectopic atrial tachycardia
- sinus tachycardia
Bradycardia:
- sinus bradycardia
- sinus pauses
What ventricular arrythmias exist?
- ventricular ectopics or premature ventricular complexes (PVC)
- ventricular tachycardia
- ventricular fibrillation
- asystole
what atrio-ventricular node arrythmias exist?
- AVN re-entry tachycardia
- AV reciprocating or AV re-entrant tachycardia
- AV block: 1st/2nd/3rd degree
What are the 6 main causes of arrythmias?
Abnormal anatomy:
- left ventricular hypertrophy
- accessory pathways
- congenital heart defect
Autonomic nervous system:
- inc. vagal tone = bradycardia
- sympathetic stimulation
Metabolic causes:
- hypoxia
- ischaemic myocardium
- electrolyte imbalances
Inflammation:
-viral myocarditis
Drugs:
-directly or via ANS
Genetics:
-e.g. congenital long QT syndrome
what are ectopic beats? what two different main causes are there for this? how can an ectopic focus cause tachycardia?
Beats or rhythms that originate in places other than SA node:
- altered automacity e.g. ischaemia/catecholamines
- triggered activity e.g. digoxin/long QT syndrome
-the ectopic focue may cause single beats or a sustained run of beats that can take over sinus rhythm if it’s faster
what has to be true for a re-entry arrythmia to exist? how can this cause a tachycardia? what causes a re-entry arrythmia to exist?
- requires more than 1 conduction pathway
- with a different speed of depolarisation and refractory period
-this can cause a tachycardia if there is self-perpetuating circuit
Causes:
- structural abnormalities e.g. scar, accessory pathways, congenital heart disease
- functional abnormalities e.g. conditions that depress conduction velocity or shorten refractory period
What abnormal physiology can increase the phase 4 slope of the myocyte action potential and cause increase in heart rate? 5
- hyperthermia
- hypoxia
- hypercapnia
- cardiac dilation
- hypokalaemia (prolongs repolarisation)
What abnormal physiology can decrease the slope of phase 4 of the myocyte action potential and cause a decreased heart rate? 2
hypothermia
hyperkalaemia
what does triggered activity mean? when does this take place?
this is when there is a slight depolarisation in phase 3 of the myocyte action potential and if this reaches threshold = sustained train of depolarisations
Takes place:
- digoxin toxicity
- torsade de pointes
- hypokalaemia
What are the symptoms of cardiac arrythmia? 7
Palpitations, ”pounding heart”
Shortness of breath
Dizziness
Loss of consciousness; ”Syncope”
Faintness: “presyncope”
Sudden cardiac death
Angina, heart failure
What investigations are used in the management of cardiac arrythmias? 7
12 lead ECG (in tachycardia , during SR)
CXR
Echocardiogram - assess for structural heart disease
Stress ECG: Look for myocardial ischaemia, exercise related arrhythmias
24 hour ECG Holter monitoring
Event recorder: (capture the arrhythmia)
Electrophysiological (EP) study: Induce clinical arrhythmia to study mechanism and map
arrhythmia
What is sinus bradycardia classed as? what are 3 causes? what is the treatment in the acute scenario and if haemodynamically compromised?
<60bpm
Causes:
- physiological e.g. athlete
- Drugs e.g. Bblocker
- Ischaemia (common in inferior STEMI)
Treatment:
- Atropine if acute
- pacing if haemodynamic compromise e.g. hypotension, CHF, angina, collapse
What is sinus tachycardia classed as? what is the treatment?
- > 100bpm
- treat underlying cause/BBlockers
What is the treatment for atrial ectopic beats?
- generally none
- BBlockers
- avoid stimulants e.g. caffeine/cigarettes
what is the acute management of supraventricular tachycardia?
- increase vagal tone: vasalva/carotid massage
- IV adenosine
- IV verapamil
