Arrhythmias Flashcards
Palpitations: what hx questions?
- character (rapid/forceful/missed beats)
- how rapid?
- get them to tap out rhythm
- onset/offset
- precipitants
- relieving
- assoc (e.g. syncope, chest pain, dyspnoea, dizziness)
Which examination should be performed?
CV exam
- HR (rate and rhythm) and BP
- apex beat
- murmurs
- signs of heart failure
When to be concerned about these symptoms?
- documented arrhythmia at time of symptoms
- phx of cardiac disease
- fhx of sudden cardiac death
- severe symptoms
- high risk work enviro
- high level sporting activities
- before/during pregnancy
What are the features of cardiac syncope?
- onset: rapid and without warning
- during: duration < 30 secs
- spontaneous, rapid and complete recovery
- may have an injury
- assoc.: chest pain, palpitations, SOB
What is a first line investigation for palpitations?
- 12 lead ECG
- Holter monitor (24 hrs)
- Echo
- Blood tests: FBE (anaemia), U&E, Ca2+, Mg2+, TSH
What is the management of premature ventricular or atrial complexes (ectopics)?
- these are usually benign so reassure pt and advice against caffeine
- may require treatment with beta or Ca2+ channel blockers if frequent and symptomatic
What are the principles of management of AF?
- rule out precipitant
- look for a cause
What are the management decisions in AF?
- rate vs rhythm control
- stroke vs bleeding risk
How might stroke risk be assessed when deciding to anti-coagulate?
- obtain a CHADS2 score, where each of the following gets 1 point and the S gets 2
Congestive heart failure?
Hypertension?
Age >75 years?
Diabetes?
Stroke/TIA? - a score of 2 or more (high risk) is an indication for anticoagulation
- a score of 1 point may be an indication for antiplatelets drugs
What are the ECG features of AF?
- irregularly irregular
- no P waves
- absence of isoelectric baseline
- variable ventricular rate
What is a supraventricular tachycardia (SVT)?
- regular and narrow complex (100 bpm)
How can SVT be treated?
- vagal manoeuvres
- adenosine
- verapamil (L-type Ca2+ channel blocker)
- catheter ablation (success >95%)
What are 3 vagal manoeuvres?
- breath holding
- Valsalva manoeuvre
- Carotid massage
What is the most common cause of a SVT?
90% are caused by re-entrant circuits within the heart
What does the ECG look like after SVT reversion?
- often normal but may show WPW pattern of delta waves (slurred QRS due to early ventricular excitation)
What are the ECG findings of ventricular tachycardia?
- broad QRS complexes (>160 ms)
- HR >100
Is sustained VT a cardiac emergency?
Yes, low CO may result in reduced myocardial perfusion resulting in degeneration to VF
How is a haemodynamically unstable patient in VT managed?
- immediate DC reversion
How is a haemodynamically stable patient with VT managed?
- may try pharmacological reversion with amiodarone
- sedate and DC shock
What are the characteristics of a pt who is haemodynamically unstable?
- hypotensive
- chest pain
- cardiac failure
- decreased level of consciousness
What are the causes of VT and which is most common?
- re-entry (most common - due to an area of scarring)
- triggered activity (early or late after-depol)
- abnormal automaticity (impulse generation by a region of ventricular cells)
What is sick sinus syndrome?
Abnormal sinus node function with resultant bradycardia and cardiac insufficiency
What are some intrinsic causes of sick sinus syndrome?
- intrinsic: fibrosis, infiltrative disease, congenital, ischaemia, cardiomyopathies
What are some extrinsic causes of sick sinus syndrome?
- extrinsic: drugs (beta and Ca2+ blockers, digoxin), autonomic dysfunction, electrolyte disturbance, hypothyroidism
What is bradycardia-tachycardia syndrome?
- a type of sick sinus syndrome
- alternating brady with paroxysmal tachy often of supraventricular origin
- there may be delayed recovery (e.g. sinus pause) which can cause syncope
What are the clinical manifestations of brady-tachy syndrome?
- recurrent pre-syncope and dizziness
- syncope
- fatigue
- palpitations
What is the treatment for brady/tachy syndrome?
- correct extrinsic causes OR
- pacemaker insertion (hard to treat without a pacemaker because drugs to control tachy will worsen brady)
- once a pacemaker is inserted, can treat the tachycardia with beta or Ca2+ channel blocker
What are the ECG findings of a first degree heart block?
- prolonged PR interval (>200ms or one large square)
- every P wave is followed by a QRS
What are the ECG findings of a second degree Mobitz type I (Wenckenach) heart block?
- progressively lengthening PR interval and shortening RR until a QRS complex is missed
- intermittently blocked P waves
What are the ECG findings of a second degree Mobitz type II heart block?
- no progressive lengthening of PR interval
- still has missed QRS complexes (i.e. not a slowed signal like mobitz I, but signal does not go through)
What are the ECG findings of second degree high grade AV block?
- high P:QRS ratio (>3:1)
- PR interval constant
- slow ventricular rate
What are the ECG findings of third degree heart block?
- absence of relationship between P wave and QRS complex “AV dissociation”
- the atrial rate is faster than the ventricular rate which is of junctional or ventricular origin
What are the indications for a permanent pacemaker (PPM)?
- sinus node dysfunction (symptomatic bradycardia, sinus pauses >2s at day or >2.5 sec at night)
- symptomatic 2nd or 3rd degree AV block
- intermittent 3rd degree AV block
