Cardiology - Arrhythmias Flashcards
what is atrial fibrillation?
irregular, rapid rhythm whereby the atria fail to contract either efficiently, regularly or in coordination with the ventricles
how is AF classified?
- paroxysmal (<7 days)
- persistent (>7 days)
- permanent (>7 days + resistant to therapy)
how does the ventricular rhythm in AF present?
can be fast, slow or normal ventricular rhythm
what can cause atrial stress which can lead to AF?
- hypertension (most common)
- heart failure
- ischaemic heart disease
- valvular heart disease
- thyroid disease (hyperthyroidism)
- drug misuse / excessive alcohol
- acutely unwell
- preoperative patient
what is the presentation of AF?
- may be asymptomatic
- palpitations
- lethargy
- chest pain
- dyspnoea
- decreased exercise tolerance
- irregularly irregular pulse
what investigations are carried out when suspecting atrial fibrillation?
- ECG
- TFTs (hyperthyroidism is a reversible cause of AF)
- coagulation screen (as will be giving anticoagulation)
- U&Es (electrolyte derangement can cause AF)
- LFTs (possible reversible cause + important when thinking about anticoagulation)
- Echocardiography (to exclude structural heart disease)
- Transoesophageal echocardiography (to exclude left atrial clot if direct current cardioversion is being considered as can dislodge clot and cause stroke)
what is seen on an ECG when the patient has AF?
- wavy baseline
- no discernable P waves
- QRS normal but irregularly placed (R-R interval is variable)
how is AF managed?
- anticoagulation (DOACs - apixaban or warfarin (INR 2-3))
- rate control - beta blocker (bisoprolol) and/or CCB (verapamil)
- direct current cardioversion following 3-4 weeks of anticoagulation
what scoring system is used to calculate the stroke risk of a patient with AF? what does it comprise of?
CHA2DS2 - VASc score
- age
- sex
- CHF history
- hypertension
- stroke/TIA/thromboembolism history
- vascular disease history
- diabetes history
what is a supra ventricular tachycardia?
tachycardia (HR >100 bpm) originating above the ventricles - the QRS complex is normal (<3 small boxes) - a.k.a narrow complex tachycardia
what is the most common cause of SVT?
AV nodal re-entry tachycardia
how does AV nodal re-entry tachycardia (AVNRT) present on an ECG?
- P waves hidden in the QRS (or occur after QRS)
- Narrow QRS
- Tachycardia
what causes AVNRT?
re-entry circuit around the AV node
what causes atrioventricular re-entry tachycardia (AVRT)?
accessory pathway between the atria and ventricles
what is the most common form of AVRT?
Wolff-Parkinson-White syndrome
how does wolff-parkinson-white syndrome present on an ECG?
- short P-R interval
- Delta wave between the P wave and R (upward slope)
what causes atrial flutter?
re-entrant circuit in the right atrium
what does atrial flutter look like on an ECG?
- saw-tooth baseline
- normal QRS
- Tachycardia
what is the presentation of supraventricular tachycardias?
- asymptomatic
- palpitations
- shortness of breath
- fatigue
- heart failure if persistent SVT
what investigations are carried out when suspecting a SVT?
- ECG to diagnose
- echocardiogram to rule out structural disease and assess cardiac function
- TFTs and U&E - to look for reversible causes of SVT
what is the general management of SVTs?
- if causing cardiovascular instability, direct current cardioversion
- vagal manouveres - carotid sinus massage / valsalva manouvere
- IV adenosine if severe and vagal manouveres not working
- AVNRT - beta blockers (bisoprolol), CCB (verapamil)
- Wolff-Parkinson-White (AVRT) - flecainide or amiodarone
- catheter ablation to eradicate the abnormal circuit
what is a ventricular tachycardia?
3 or more consecutive ectopic ventricular beats occurring at a rate of >100 bpm
(broad-complex tachycardia, originating from a ventricular ectopic focus)
describe the rhythm of a ventricular tachycardia
it is always regular, even if the rhythm is abnormal
what are the different subcategories of ventricular tachycardia?
monomorphic (single ventricular ectopic focus)
polymorphic (multiple ventricular ectopic foci)
what is the presentation of ventricular tachycardia?
- can be pulsed or pulseless (pulsed = fast and weak, pulseless = cardiac arrest)
- palpitations
- presyncope
- syncope
- symptoms of HF (if prolonged VT)
what is the management of ventricular tachycardia?
- emergency direct current cardioversion if there is cardiovascular compromise
- beta blocker or amiodarone (class 3) can be used to reduce rate
- catheter ablation for abnormal circuit
what is ventricular fibrillation?
- no coordinated electrical or mechanical activity of the ventricles
- no cardiac output
what is seen on an ECG of a patient with ventricular fibrillation?
no discernible QRS complexes or P waves
what is the management of ventricular fibrillation?
emergency direct current cardioversion
those that survive are fitted with an implantable cardioverter defibrillator (ICD) to be used as prevention of another episode
