Cardiology - Arrhythmias

Question 1

what is atrial fibrillation?

Answer 1

irregular, rapid rhythm whereby the atria fail to contract either efficiently, regularly or in coordination with the ventricles

Question 2

how is AF classified?

Answer 2

• paroxysmal (<7 days)
• persistent (>7 days)
• permanent (>7 days + resistant to therapy)

Question 3

how does the ventricular rhythm in AF present?

Answer 3

can be fast, slow or normal ventricular rhythm

Question 4

what can cause atrial stress which can lead to AF?

Answer 4

• hypertension (most common)
• heart failure
• ischaemic heart disease
• valvular heart disease
• thyroid disease (hyperthyroidism)
• drug misuse / excessive alcohol
• acutely unwell
• preoperative patient

Question 5

what is the presentation of AF?

Answer 5

• may be asymptomatic
• palpitations
• lethargy
• chest pain
• dyspnoea
• decreased exercise tolerance
• irregularly irregular pulse

Question 6

what investigations are carried out when suspecting atrial fibrillation?

Answer 6

• 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)

Question 7

what is seen on an ECG when the patient has AF?

Answer 7

• wavy baseline
• no discernable P waves
• QRS normal but irregularly placed (R-R interval is variable)

Question 8

how is AF managed?

Answer 8

1. anticoagulation (DOACs - apixaban or warfarin (INR 2-3))
2. rate control - beta blocker (bisoprolol) and/or CCB (verapamil)
3. direct current cardioversion following 3-4 weeks of anticoagulation

Question 9

what scoring system is used to calculate the stroke risk of a patient with AF? what does it comprise of?

Answer 9

CHA2DS2 - VASc score

• age
• sex
• CHF history
• hypertension
• stroke/TIA/thromboembolism history
• vascular disease history
• diabetes history

Question 10

what is a supra ventricular tachycardia?

Answer 10

tachycardia (HR >100 bpm) originating above the ventricles - the QRS complex is normal (<3 small boxes) - a.k.a narrow complex tachycardia

Question 11

what is the most common cause of SVT?

Answer 11

AV nodal re-entry tachycardia

Question 12

how does AV nodal re-entry tachycardia (AVNRT) present on an ECG?

Answer 12

• P waves hidden in the QRS (or occur after QRS)
• Narrow QRS
• Tachycardia

Question 13

what causes AVNRT?

Answer 13

re-entry circuit around the AV node

Question 14

what causes atrioventricular re-entry tachycardia (AVRT)?

Answer 14

accessory pathway between the atria and ventricles

Question 15

what is the most common form of AVRT?

Answer 15

Wolff-Parkinson-White syndrome

Question 16

how does wolff-parkinson-white syndrome present on an ECG?

Answer 16

• short P-R interval

- Delta wave between the P wave and R (upward slope)

Question 17

what causes atrial flutter?

Answer 17

re-entrant circuit in the right atrium

Question 18

what does atrial flutter look like on an ECG?

Answer 18

• saw-tooth baseline
• normal QRS
• Tachycardia

Question 19

what is the presentation of supraventricular tachycardias?

Answer 19

• asymptomatic
• palpitations
• shortness of breath
• fatigue
• heart failure if persistent SVT

Question 20

what investigations are carried out when suspecting a SVT?

Answer 20

• ECG to diagnose
• echocardiogram to rule out structural disease and assess cardiac function
• TFTs and U&E - to look for reversible causes of SVT

Question 21

what is the general management of SVTs?

Answer 21

• 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

Question 22

what is a ventricular tachycardia?

Answer 22

3 or more consecutive ectopic ventricular beats occurring at a rate of >100 bpm
(broad-complex tachycardia, originating from a ventricular ectopic focus)

Question 23

describe the rhythm of a ventricular tachycardia

Answer 23

it is always regular, even if the rhythm is abnormal

Question 24

what are the different subcategories of ventricular tachycardia?

Answer 24

monomorphic (single ventricular ectopic focus)

polymorphic (multiple ventricular ectopic foci)

Question 25

what is the presentation of ventricular tachycardia?

Answer 25

• can be pulsed or pulseless (pulsed = fast and weak, pulseless = cardiac arrest)
• palpitations
• presyncope
• syncope
• symptoms of HF (if prolonged VT)

Question 26

what is the management of ventricular tachycardia?

Answer 26

• 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

Question 27

what is ventricular fibrillation?

Answer 27

• no coordinated electrical or mechanical activity of the ventricles
• no cardiac output

Question 28

what is seen on an ECG of a patient with ventricular fibrillation?

Answer 28

no discernible QRS complexes or P waves

Question 29

what is the management of ventricular fibrillation?

Answer 29

emergency direct current cardioversion
those that survive are fitted with an implantable cardioverter defibrillator (ICD) to be used as prevention of another episode