Arrhythmias Flashcards
What are the main presentations of arrhythmias?
Tachyarrhythmias present as palpitations
Bradyarrhythmias present as pre-syncope/syncope
Combination
Why might a severe tachyarrhythmia present as pre-syncope?
Decreased ventricular filling time (shorter diastole) > decreased cardiac output
What is the most common cause of rhythm disorders?
Ischaemic injury
What characteristics of palpitations is it important to clarify with the patient?
Fast heartbeat
Missed beats
Irregular beats
Awareness of forceful beats
Why do palpitations occur in ventricular ectopics?
Heart pauses to compensate for extra heartbeat Increased diastolic filling time More blood in ventricle More force to push blood out Can feel that force
What does the term cardiac origin mean?
Pathology limited to heart
Usually present with all symptoms of cardiac disease
How do people with a systemic origin of arrhythmias present?
Don’t have classical symptoms of cardiac disease
Have symptoms of other systemic disease; eg: thyrotoxicosis
How do you elicit a history of palpitations?
Character How rapid Ask patient to tap out rhythm Onset and offset Precipitants and relieving factors Associated symptoms
What are possible precipitants of palpitations?
Caffeine
Stressful situation
Lying in quiet room on left side
What does having palpitations when lying in a quiet room on your left side suggest?
Ectopics
What relieving factors works classically in supraventricular tachycardia?
Valsalva manoeuvre > increases parasympathetic activity
What are the possible associated symptoms with palpitations?
Chest pain
Dyspnoea
Syncope/pre-syncope
What specific things should you look out for in a cardiovascular exam when a patient presents with palpitations?
Heart rate and blood pressure
Apex beat
Murmurs
Signs of heart failure
How can blood pressure indicate management in a patient presenting with palpitations?
Tachycardia with low blood pressure > more acute
Tachycardia with high blood pressure > have more time
If a patient presents with increased heart rate at rest, palmar erythema, and a hot and sweaty palm, what does this indicate?
Probably stressed
Uncommonly, thyrotoxicosis
If a patient presents with increased heart rate at rest, and sweaty and cold palms, what does this indicate?
Probably serious cardiac problem
What does a regularly irregular heart rhythm indicate?
Unifocal ectopic
What does an irregularly irregular heart rhythm indicate?
Atrial fibrillation
Multifocal ectopic
What can you gather from an apex beat?
If in expected place but very forceful > left ventricular hypertrophy
If displaced > dilated heart
How does aortic stenosis cause arrhythmia?
Because of left ventricular hypertrophy
How does mitral stenosis cause atrial fibrillation?
Dilates atrium > stretched cardiomyocytes > disrupts electrochemical signal
What are the investigations for palpitations?
ECG in all patients
- Aim to document exact cardiac rhythm at time of palpitations
Echocardiogram
- Look for underlying structural heart disease
Stress testing/coronary angigography
- If suspicion of ischaemia
- Chest pain with palpitations
- To help determine coronary artery stenosis
Electrophysiology study
- If still can’t find cause of symptoms
What are the devices available for prolonged ECG monitoring?
Holter monitor - 24 hours
Event recorder - 7 days
Loop recorder - months-years
If the morphology of the QRS complexes is different in an ECG of a person with ectopics, what does that suggest?
Multifocal ventricular ectopic
How do you managed premature ventricular/atrial complexes (ectopics)?
Usually benign
Reassurance to patient
Cut down on caffeine intake
Occasionally need to treat with beta blockers/calcium channel blockers if very frequent and symptomatic
What does atrial fibrillation look like on an ECG?
No P waves
QRS complexes narrowed
Varied R-R interval > irregularly irregular rhythm
What type of arrhythmia is atrial flutter?
Supraventricular tachycardia
What causes atrial flutter?
Really irritable automaticity focus in atrium
Fires at 250-300 bpm
Causes atria to contract at 250-300 bpm
AV node acts as gatekeeper
- Ventricles contract at slower rate; eg: 150 bpm, because of refractory period of AV node
What does atrial flutter look like on an ECG?
Multiple P waves - not each one followed by QRS complex
- Represent irritable automaticity focus
- In “saw tooth” pattern
Regular R-R interval
What does 3:1 conduction in atrial flutter mean?
For every 3 P waves, there’s 1 QRS complex
Where is atrial fibrillation common?
Older age groups
Known cardiac disease
Cardiovascular disease factors
What happens in atrial fibrillation?
Lose organised signal in atria > atrial spasming
Signal AV node erratically > irregularly irregular rhythm
What are the risk factors for atrial fibrillation?
Diseased atrial tissue - Age - Inflammation; eg: from surgery - Enlarged atria - Hypertension - Valve disease; eg: mitral stenosis - Some lung diseases - Previous atrial fibrillation Hormonal abnormalities; specifically thyroid Alcoholism
What is the natural history of atrial fibrillation?
Silent Paroxysmal - First detection - Without treatment, stops within 48 hours Persistent - Last >48 hours Long-standing persistent - 1+ year Permanent - Normal rhythm now atrial fibrillation
What causes the symptoms in atrial fibrillation?
Rapid heart rate
What are the symptoms of atrial fibrillation?
Palpitations
Shortness of breath
Chest pain, especially during exertion
May be symptomatic
What condition(s) are you at an increased risk of having if you have atrial fibrillation?
Stroke
Peripheral embolus
How is atrial fibrillation managed?
Rule out precipitant; eg:
- Hyperthyroidism
- Infection
Look for cause
Decide whether to control heart rate or maintain sinus rhythm
Evaluate risk of stroke and how best to manage - balance against risk of bleeding
What does rhythm control in atrial fibrillation mean?
Put back into sinus rhythm
Why may you choose rate control over rhythm control in atrial fibrillation?
If atrial fibrillation has been going on for >48 hours, don’t want to reinstate atrial kick because probable thrombus will embolise
What are possible antiarrhythmic drugs that can be used to control the rhythm in atrial fibrillation?
Sotalol
Flecainide
- Contraindicated in structural heart disease
Amiodarone
What are possible drugs that can be used to control the rate in atrial fibrillation?
Beta blockers
Calcium channel blockers
Digoxin
Why is rate control usually safer than rhythm control in atrial fibrillation?
Rhythm controlling agents can sometimes cause other significant arrhythmias
What does catheter ablation aim to do in atrial fibrillation?
Maintain sinus rhythm by preventing signals propagating from atrial fibrillation origin sites
Where are common ablation sites for atrial fibrillation?
Around pulmonary veins
What is supraventricular tachycardia?
Abnormally high heart rate at rest
Abnormal heartbeat starts at/above AV node
What are the signs and symptoms of supraventricular tachycardia?
Can be asymptomatic Palpitations Chest pain Anxiety Shortness of breath Dizzy - Due to decreased cardiac output > decreased cerebral perfusion
What causes 90% of supraventricular tachycardias?
Re-entrant circuits within heart
What is the most common re-entrant supraventricular tachycardia?
AV nodal re-entry tachycardia
What is Wolff-Parkinson White syndrome?
2 electrical pathways instead of 1
Example of accessory pathway
- Usually connects atria directly to ventricles
- Due to short refractory period, electrical signal goes in loop: atria > ventricles > atria
Why is the AV node targeted in treatment for supraventricular tachycardia?
Almost all involve AV node in pathway
Treatments aim to interrupt circuit
What is postural orthostatic tachycardia syndrome?
Increase in heart rate when moving from supine to erect position
What are the risk factors for supraventricular tachycardias?
Inherited conditions Structural abnormalities Coronary artery disease Heart failure COPD Pulmonary embolism Alcoholism Hypertension Some medications
How is supraventricular tachycardia treated acutely?
Similar to atrial fibrillation
Vagal manoeuvres
Adenosine
IV verapamil
What should you warn your patient about before administering adenosine?
Flushing/feeling terrible for few seconds
How does adenosine work in treating supraventricular tachycardia?
Induces transient AV block
Why don’t you need to anticoagulate in supraventricular tachycardia?
No risk of thromboembolism
What is the longer-term treatment for supraventricular tachycardia?
If symptoms rare/isolated episode - no pharmacological intervention "Pill in pocket" approach Pharmacological interventions - Beta blockers OR - Calcium channel blockers Catheter ablation
What is ventricular tachycardia?
Arises from ventricles
Can reach up to 250 bpm
Decreased filling time > decreased cardiac output
Can lose pulse sometimes
What happens when the cause of ventricular tachycardia is focal?
Cells in ventricles irritated Irritation caused by - Hormones - Stress - Thyroid - Hypoxia - Stretch; eg: left ventricular hypertrophy Cells overfire
What happens when the cause of ventricular tachycardia is re-entrant?
Scar formation
Disrupts normal electrical conduction
Forms loop
Excites ventricles
What are the signs and symptoms of ventricular tachycardia?
Shorthness of breath > hypoxia
Chest pain > decreased myocardial perfusion
Palpitations
Lightheaded and dizzy > decreased cerebral perfusion
- Can sometimes lose consciousness
Why is ventricular tachycardia a medical emergency?
Can become ventricular fibrillation
What happens in ventricular fibrillation?
Ventricular walls spasm > no blood circulating
What are the features of ventricular tachycardia on an ECG?
Wide QRS complexes
Tachycardia
What are the risk factors for ventricular tachycardia?
Coronary artery disease Electrolyte imbalance; eg: hyperkalaemia Myocardial infarction Hypertrophic cardiomyopathy Dilated cardiomyopathy
When should you worry about palpitations?
Documented cardiac arrhythmia at time of symptoms Past history of cardiac disease Evidence of cardiac disease on baseline tests Family history of sudden cardiac death Severe symptoms High risk work enviro High level sporting activities Before/during pregnancy
What are the most common types of syncope?
Neurocardiogenic (vasovagal)
Cardiac
Postural hypotension
What is syncope?
Transient Loss of consciousness, self-limited Onset relatively rapid Leads to fall Recovery complete, rapid, spontaneous
What questions should you focus on in a syncope history?
Prodrome Situation Collateral history = witnesses - Specific length of loss of consciousness - Pallor Recovery History of previous episodes
What are the common symptoms of neurocardiogenic syncope?
Pre-syncope symptoms
- Diaphoresis
- Headache
- Nausea
- Visual changes
What are the common signs of neurocardiogenic syncope?
Facial pallor
Yawning
Pupillary dilatation
What are the common precipitating events of neurocardiogenic syncope?
Fear
Emotional distress
Instrumentation
Prolonged standing
What are the common symptoms of cardiac syncope?
May be no warning symptoms Rapid loss of consciousness Often associated injury May be exertional or occur when supine Associated with chest pain/palpitations Family history of sudden cardiac death Background of known cardiac disease
What is a significant orthostatic drop in blood pressure?
Between supine and erect
- Difference of >20 mmHg in systolic OR
- Difference of >10 mmHg in diastolic
What is heart block?
Arrhythmia where signal delayed/blocked
What is AV conduction block?
Signal delayed/blocked when trying to move from atria to ventricles
What is first degree AV conduction block?
Delayed… but still makes it
PR interval >0.2 s (5 small boxes)
What are the symptoms of first degree AV conduction block?
Asymptomatic
What is the treatment for first degree AV conduction block?
Identify electrolyte imbalances/causes from medications
Usually no further treatment
What is type 1 second degree AV conduction block?
Also called
- Mobitz I
- Wenckebach
PR interval becomes progressively longer until blocked completely > “dropped beat”
Eventually ventricles contract = ventricular escape beat
What are the symptoms of type 1 second degree AV conduction block?
Usually asymptomatic Sometimes - Lightheaded - Dizzy - Syncope
What is type 2 second degree AV conduction block?
Also called Mobitz II
Intermittent dropped beats
No progressive lengthening of PR interval
Each time atria do conduct, PR interval stays same length
Written as ratio of conducted:dropped; eg: 2:1 Mobitz II AV block
Can’t predict when next beat dropped
What are the symptoms of type 2 second degree AV conduction block?
Fatigue
Dyspnoea
Chest pain
Syncope
What is third degree AV conduction block?
Signal completely blocked
Ventricles struggle along with escape beats at very slow rates
What are the symptoms of third degree AV conduction block?
Syncope Confusion Dyspnoea Severe chest pain Risk of death
What is the treatment of third degree AV conduction block?
Medication to increase heart rate; eg: atropine
Transcutaneous pacing
- Through electrodes on skin
Permanent pacemaker
What are the indications for a permanent pacemaker?
Sinus node dysfunction - Symptomatic sinus bradycardia - Sinus pauses >2 sec (day) or >2.5 sec (night) Symptomatic 2nd/3rd degree AV block Intermittent 3rd degree AV block
How do you treat tachy-brady syndrome?
Difficult to treat without pacemaker
- Can’t control tachycardias without worsening bradycardias
Once pacemaker implanted, use AV node blocking agents to control rapid heart rates
