Arrhythmias Flashcards
What is meant by a supra-ventricular arrhythmia?
An arrhythmia in which the origin is supernal to the ventricles, including the SAN, Atrial myocardium, AV node or His origin
What are some examples of supra ventricular tachycardias?
Atrial fibrillation
Atrial flutter
Ectopic atrial tachycardia
What are some examples of supra ventricular bradycardias?
Sinus bradycardia
Sinus pauses
What are some examples of ventricular arrhythmias?
Ventricular ectopics or premature ventricular complexes
Ventricular tachycardia
Ventricular fibrillation
Asystole
What are some examples of Atrio-Ventricular Node arrhythmias?
AV Node re-entry tachycardia
AV reciprocating or AV re-entrant tachycardia
AV Block (1st, 2nd, 3rd degree)
What are some clinical causes of arrhythmias?
Abnormal anatomy allowing re-entry circuits
Autonomic nervous system
Metabolic causes
Inflammation
Drugs
Genetic
What are some examples of ways in which the autonomic nervous system can result in arrhythmia?
Sympathetic stimulation due to stress, exercise, hyperthyroidism
Increased vagal tone causing bradycardia
What are some examples of metabolic causes of arrhythmias?
Hypoxia - Chronic pulmonary disease, pulmonary embolism
Ischaemic myocardium - Acute MI, angina
Electrolyte imbalance
What is an example of an inflammatory cause of arrhythmia?
Viral myocarditis
What is an example of a genetic cause of arrhythmia?
Congenital long QT syndrome
What is meant by an ectopic beat?
A rhythm that originates in places other than the SA node
What occurs in Wolf Parkinson White syndrome?
An extra conduction pathway forms in the heart allowing the bypassing of the AV node, therefore decreasing the PR interval and predisposing the person to supraventrcular tachycardia
What are some example of conditions that increase the phase 4 (funny current) slope of the SA node, and thus increase heart rate?
Hyperthermia
Hypoxia
Hypercapnia (High CO2)
Myocardial stretch
What are some examples of conditions that decrease the phase 4 (Funny current) slope and thus decrease heart rate?
Hypothermia
Hyperkalaemia
What ate the 2 main classes of triggered activity?
Delayed After-depolarisations
Early After-depolarisations (Phase 2 and 3)
What are some examples of conditions that result from prolonged after-depolarisations?
Digoxin toxicity
Torsades du Pointes in long QT syndrome
Hypokalaemia
What occurs in re-entry?
An action potential fails to extinguish itself and reactivates a region that has depolarised. This can occur in the presence of an obstacle around which an action potential can travel (Circus entry)
What are some common symptoms of arrhythmias?
Palpitations
Dyspnoea
Pre-syncope
Syncope
Shock
Sudden cardiac death
Angina
Heart failure
Anxiety
What investigates can be performed on someone with a suspected arrhythmia?
12 lead ECG
Bloods
Chest X-ray
Echocardiogram
Stress ECG
24-hour ECG Holter monitoring
Event recorder (Press a button to turn on ECG when the patient feels an arrhythmia)
Electrophysiological study
What can be done during an electrophysiological study?
The arrhythmia can be triggered to study its pathway and origin and then radio frequency ablation (Cauterisation of the origin to cause fibrosis) can be performed
What is meant by normal sinus arrhythmia?
Variation in heart rate due to reflex changes in vagal tone during respiration
Inspiration reduces vagal tone and thus increases heart rate
What are some causes of Sinus bradycardia?
Physiological e.g. in an athlete
Drugs such as ß-Blockers
ischaemia
What is the treatment for acute sinus bradycardia, such as in an acute MI?
Atropine and pacing (If there is haemodynamic compromise)
What are some causes of sinus tachycardia?
Anxiety
fever
Hypotension
Anaemia
Drugs
What are the treatment options for sinus tachycardia?
ß-Blockers
Treatment of the underlying cause
What are the 2 types of AV reciprocating tachycardia?
Orthodromic AVRT - Impulse travel from ventricular walls back to the AV node where it forms a circuit
Antidromic AVRT - Impulses travel from the AV node and directly into the ventricular wall, without the bundles of His
What are some acute management strategies for supraventricular tachycardia?
Increase vagal tone - Valsalva, carotid massage
Slow AV node conduction - IV Adenosine and verapamil
What are some chronic management strategies for supra ventricular tachycardia?
Avoid stimulants
Radiofrequency ablation and Electrophysiological study
ß-Blockers
Anti-arrhythmic drugs
What are some causes of AV node conduction block?
Ageing
Acute MI
Myocarditis
Amyloidosis
ß-Blockers
Ca2+ channel blockers
Calcific aortic valve disease
Post-aortic valve surgery
Genetic - Lenore’s disease, myotonic dystrophy
What is meant by 1st degree AV blocK?
AV nodal delay >0.2seconds, but without any symptoms
What is meant by 2nd degree AV block?
Intermittent block at the AV node leading to a dropped beat
What are the 2 types of 2nd degree heart block?
Mobitz type I
Mobitz type II
What is meant by Mobitz type I 2nd degree heart block?
Progressive lengthening of the PR interval (AV node delay) leading up to a dropped beat
What is meat by Mobitz type II 2nd degree heart block?
Constant 2:1 or 3:1 drop in beats
Requires permanent pacing
What is meant by 3rd degree AV node block?
Complete loss of communication between the SA and AV node
Required ventricular pacing
What are the 2 types of pacemaker?
Single chamber (Paces only the right atria or ventricle)
Dual chamber (Paces both RA and RV)
What are the 2 types of ventricular tachycardia?
Monomorphic - Regular pattern for tachycardia
Polymorphic - Chaotic tachycardia with no clear pattern
What is meant by ventricular fibrillation?
Chaotic ventricular electrical activity which causes the heart to fail to pump
What is the treatment for ventricular fibrillation?
Defibrillation and CPR
What are some acute treatment strategies for Ventricular tachycardia?
Direct current cardioversion
Correct triggers
What are some chronic treatment strategies for ventricular tachycardia?
Revascularisation
Anti-arrhytmic drugs (Associated with worse outcomes on their own)
Implantable cardiovertor defibrillator
catheter ablation
