Arrhythmias Flashcards
Where does the arrhythmia come from if the QRS complex is not widened?
Above the ventricle
What are ectopic beats?
Beats or rhythms which originate in areas of the heart other than the SA node.
What an ectopic beats cause?
Single beats to take over the entire pace of the heart and dictate the entire rhythm
What are examples of supraventricular arrhythmias?
Supraventricular tachycardia, atrial fibrillation/flutter, ectopic atrial tachycardia, sinus bradycardia/pauses
What are AV node arrhythmias caused by?
AV node re-entry through an accessory pathway
What are examples of ventricular arrhythmias?
Premature ventricular complex, ventricular tachycardia, ventricular fibrillation, asystole
What are some clinical causes of arrhythmias?
Anatomical abnormalities, autonomic factors, metabolic, inflammation, drugs, genetics
What does altered automaticity mean?
The arrhythmia depends on an increase or decrease in he phase 4 AP slope
What causes an increase in the phase 4 AP slope?
Hyperthermia, hypoxia, hypercapnia, cardiac dilation, ischaemia/necrosis, hypokalaemia
What causes a decrease in the phase 4 AP slope?
Hypothermia and hyperkalaemia
What is triggered activity?
Sometimes in phase 3 AP a small depolarisation can occur which if it reaches a significant magnitude can cause a cascade of depolarisations
What 3 things does re-entry require?
Available circuit, unidirectional block and different conduction speed in limbs of circuit
What are common symptoms of arrhythmias?
Palpitations, SOB, dizziness, syncope, sudden cardiac death, worsening of a pre-existing condition
What investigations are used for arrhythmias?
ECG, CXR, echo, stress ECG, 24 hour ECG, event recorder, electrophysiological study (triggers arrhythmia)
What are the symptoms of atrial ectopic beats and what can be used to treat it?
Often asymptomatic but can be palpitations- generally no treatment but beta-blockers and avoiding stimulants may help
What can cause sinus bradycardia?
Can be physiological or can by due to drugs or ischaemia
How can you treat sinus bradycardia?
Atropine (and temporary pacemaker if needed) if acute, pacing if chronic.
What can cause sinus tachycardia and how is it treated?
Physiological, anxiety, fever, hypotension, anaemia, drugs. Treat underlying cause and use beta-blockers
What is the most common arrhythmia in young women?
Supraventricular tachycardia
How do you treat supraventricular tachycardia?
Vagal manoeuvres/adenosine/verapamil if acute and avoiding stimulants or class II/IV drugs if chronic
What is ablation?
Selective cautery of cardiac tissue to prevent tachycardia
What should you do before ablation?
Stop anti-arrhythmic drugs at least 3-5 days before
What is 1st degree heart block and how is it treated?
PR interval longer than normal- no treatment, just follow ups
What is 2nd degree heart block?
Intermittent block at the AV node
What will Mobitz type I show on an ECG?
Progressive PR lengthening until a beat is completely missed
What will Mobitz type II show on an ECG and how is it treated?
Usually 2 or 3 beats to every missed beat. Permanent pacemaker is inserted.
What is 3rd degree heart block?
No APs get through the AV node (P wave and QRS complex are interdependent)
What type of pacing is used for Mobitz type II and 3rd degree heart block?
Transcutaneous if acute and transvenous if chronic
What can premature ventricular complex be to do with?
IHD, hypertension, LVH, heart failure
When is treatment needed for premature ventricular complex?
If it is worse on exercise- give beta-blockers
What does an ECG of VT show?
Large, sustained reduction in arterial pressure
How would you treat VT?
If stable, consider pharmacological meausures, if unsure of diagnosis give adenosine, in long term, correct ischaemia and implant defibrillator
What are some ECG patterns to look for in VT?
Broad QRS, fairly regular rhythm, no P waves or measurable PR interval
What is VF?
Chaotic ventricular activity which causes the heart to lose its function as a pump
How is VF treated?
Defibrillation and CPR
What kind of heartbeat does AF have?
Irregular
What is paroxysmal AF?
Lasting less than 48 hours but often recurrent
What is persistent AF?
An episode of AF lasting longer than 48 hours which can be cardioverted to normal sinus rhythm but this is unlikely to occur spontaneously
What is permanent AF?
No methods can restore normal sinus rhythm
As well as many heart diseases, what can AF be associated with?
Thyroid disease, alcohol abuse, COPD, pneumonia, septicaemia and tumours
What are the symptoms of AF?
Palpitations, dizziness, chest pain, dyspnoea, sweatiness and fatigue
What is AF caused by?
Multiple wavelets of re-entry and an ectopic focus around the pulmonary veins
What will AF show on an ECG?
Atrial rate of greater than 300bpm, irregularly irregular rhythm, absence of P waves, presence of F waves (just after QRS), normal QRS
AF causes a loss of atrial kick. What can this result in?
Congestive heart failure, especially when there is already diastolic dysfunction
What does a ventricular rate of less than 60bpm suggest?
AV node conduction disease
What is the aim of rhythm control in AF and how is this done?
Maintain SR through pharmacological or direct current cardioversion
What is the aim of rate control in AF and what drugs do this?
Control ventricular rate- digoxin, beta-blockers, verapamil or diltiazem alone or in combination
When would you use anticoagulation in AF?
If the patient is at high risk for thromboembolism
What factors increase the risk of bleeding?
Hypertension, abnormal renal/liver function, stroke, bleeding, labile INRs, elderly, drugs or alcohol
Where can be ablated in AF?
Pulmonary veins or AV node
What is Torsades de Pointes?
Very rare and deadly form of VT with a twisting configuration of QRS and prolonged repolarisation
How is TdP recognised on an ECG?
Long QT interval, wide QRS, continuously changing QRS morphology
What are some events leading to TdP?
Hypokalaemia, drug induced prolongation of AP, renal impairment
What is atrial flutter?
Rapid and regular form of atrial tachycardia which is usually paroxysmal
How is atrial flutter sustained?
Re-entrant circuit confined to the right atrium
What do chronic cases of atrial flutter become?
AF, and many cases result in thrombo-embolism
What does atrial flutter show on an ECG?
Fast rate, F waves, normal QRS, regular but variable rhythm
What is the treatment for atrial flutter?
Ablation, pharmacological therapy to slow ventricular rate and maintain sinus rhythm, cardioversion and warfarin
What is the most common mutation causing arrhythmias?
Mutations in the potassium voltage gated channels
What does congenital long QT syndrome cause?
Polymorphic VT (TdP)
What brings on a VT caused by LQTS?
Exercise, emotional stress, sleep
Who is sudden cardiac death more common in?
Young males but adult females
What should people with LQTS avoid?
AP prolonging drugs, strenuous swimming, loud noises
What is Brugada syndrome?
Increases risk of polymorphic VT/VF, AF is also common
What will Brugata syndrome show on an ECG?
ST elevation, RBBB in V1-V3 (may only be seen with provocation testing)
Who is Brugata syndrome more common in?
Males
What should you prescribe people with catecholaminergic Polymorphic Ventricular Tachycardia
Beta-blockers and flecainide
What genes are affected in hypertrophic cardiomyopathies?
Myosin (sarcomeric) genes
What is arrhythmogenic right ventricular cardiomyopathy?
Fibro-fatty replacement of cardiomyocytes- risk of SCD
