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4th Year Cardiology > Arrhythmias > Flashcards

Arrhythmias Flashcards

1
Q

Tachyarrhythmias definition

How to manage?

Step 1

A

Heart rate > 100bpm

Is there a pulse? Arrest or peri-arrest?

If pulse then move on to step 2

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2
Q

Tachyarrhythmias management

There is a pulse

What is step 2?

A

Any adverse features?

  • Mycardial ischameia
  • Syncope
  • Shock - Systolic BP <90
  • Heart failure
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3
Q

Management of tachyarrhythmia with adverse features

A
  • Synchronised DC cardioversion - up to 3 shocks
  • Amiodarone 300mg IV over 20-30 minutes
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4
Q

Tachyarrhythmia management step 3

Tachyarrhythmia with no adverse features

A

ECG findings - Check QRS + rhythm

  • Broad QRS (regular)
  • Broad QRS (irregular)
  • Narrrow QRS (regular)
  • Narrow QRS (irregular)
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5
Q

Causes of broad complex regular tachyarrhythmias

A
  • Ventricular tachycardia (VT) - most common
  • SVT with BBB
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6
Q

How to manage ventricular tachycardia?

A
  • Monitor for adverse features (risk of decaying to cardiac arrest)
  • Amiodarone 300mg IV over 20 minutes
  • Amiodarone 900mg IV over 24 hours
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7
Q

Causes of broad complex irregular tachyarrhythmias

A
  • Torsades de pointes
  • Atrial fibrillation + bundle branch block (use previous ECGs to help distinguish)
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8
Q

What causes torsades de pointes?

A

QT prolongation

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9
Q

Features of torsades de pointes

A
  • Polymorphic VT = multiple different QRS shapes
  • QT prolongation
  • Distinguish from VF by presence of a pulse
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10
Q

How to manage torsades de pointes?

A

Magnesium sulphate 2g IV

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11
Q

Definition of supraventricular tachycardia

A

SVT describes any tachyarrhythmia that arises from above the level of the bundle of His

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12
Q

Key examples of supraventricular tachycardia

A
  • Atrial fibrillation
  • Atrial flutter
  • Paroxysmal supraventricular tachycardia
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13
Q

Main causes of narrow complex regular tachycardia

A
  • Sinus tachycardia (most common but not pathological)
  • Atrial flutter with regular AV conduction
  • AVNRT
  • AVRT
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14
Q

Management of pathological narrow complex regular tachycardia

A
  1. Monitor for adverse features
  2. Vagal manoeuvres
    • Carotid massage or Valsalva manoeuvre
  3. Adenosine 6mg IV as a rapid bolus
    • Continuous ECG trace
    • Feeling of impending doom
  4. Adenosine 12mg IV (can give twice)
  • If no response consider atrial flutter (AVNRT/AVRT less likely)
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15
Q

Causes of sinus tachycardia

A
  • Exercise
  • Pulmonary embolism
  • Infection (causing hypoxia, acidosis or sepsis)
  • Pain
  • Anxiety
  • Drugs: caffeine, cocaine, salbutamol, tricyclics antidepressants
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16
Q

Definition of atrial flutter

A

A type of sinus tachycardia that arises due to a re-entry circuit within the right atrium, resulting in an atrial rate of ~300bpm

17
Q

Causes of atrial flutter

A

Pirates

  • Pulmonary - PE and COPD
  • Ischaemic heart disease
  • Rheumatic heart disease
  • Anaemia, alcohol and advancing age
  • Thyroid disease - hyperthyroidism
  • Electrolytes - Mg2+ (low), K+ (low/high)
  • Sepsis and sleep apnoea
18
Q

What pulse is expected in atrial flutter?

A

Around 150bpm

Ventricular rate is determined by tha AV conduction ratio (most common 2:1). This is a physiological heart block/

19
Q

What is AVNRT?

What heart rate is seen?

A

Atrioventricular nodal re-entry tachycardia

140-280 bpm

20
Q

Difference between AVNRT and AVRT

A

AVRNT: a functional re-entry circuit within the AV node

AVRT: an anatomical circuit

21
Q

Causes of AVNRT

A
  • Occur spontaneously
  • Exertion
  • Drugs: caffeine, alcohol, sympathomimetics
22
Q

AVNRT pathophysiology

A

Premature atrial complex (PAC) (due to exertion/drugs/spontaneous), fast pathway still in refractory period so conduction travels around slow pathway (which has a shorter refractory period).

If the slow pathway conducts all the way around the fast pathway before anterograde fast conduction, a circus rhythm occurs.

23
Q

Pathophysiology of AVRT

A
  • An anatomical circuit exitsts that bypasses the AV node
  • This accessory pathway, sometimes called the bundle of Kent, is a key feature of Wolff-Parkinson-White syndrome
  • AVRT arises due to a re-entry circuit
24
Q

Causes of narrow complex irregular tachyarrhythmias

A
  • Atrial fibrillation (AF) - most common
  • Atrial flutter with variable block
25
Q

What risk does atrial fibrillation carry?

A

Risk of stroke due to clot formation in the fibrillating left atrium

26
Q

Which scoring systems may help make the decision whether or not to anticoagulation a patient with atrial fibrillation?

A

The decision to anticoagulate requires the balancing of thromboembolic and bleeding risk. CHA2DS2-VASC is used to calculate stroke risk for patients with AF, whilst HAS-BLED estimates the risk of major bleeding for patients on anticoagulation to assess risk-benefit in AF care.

27
Q

Causes of atrial fibrillation

A

Pirates:

  • Pulmonary - PE and COPD
  • Ischaemic heart disease
  • Rheumatic heart disease
  • Anaemia, alcohol, age related
  • Thyroid disease - hyperthyroidism
  • Electrolyttes - Mg2+ (low), K+ (low/high)
  • Sepsis and sleep apnoea
28
Q

Management of atrial fibrillation

A
  • Onset <48 hours
    • Rate or rhythm control
  • Onset >48 hours or unknown
    • Rate control and anticoagulation for 3 weeks (minimum)
    • Consider rhythm control
  • Adverse features
    • Electrial cardioversion
    • Pharmacological cardioversion
29
Q

Atrial fibrillation - why might you use rhythm control rather than rate control?

A
  • <65 years
  • Reversible cause
  • Patient preference
  • No hypertension
  • Paroxysmal
30
Q

Rate control medications used in atrial fibrillation

A
  • Beta blockers eg bisoprolol (contraindicated in asthma)
  • Calcium channel blockers eg verapamil (contraindicated in heart failure)
  • Digoxin (indicated in heart failure)

2nd line: digoxin + bisoprolol

31
Q

Rhythm control treatments of atrial fibrillation

A
  • Pharmacological
    • Amiodarone
    • Flecainide
  • Electrical
    • Synchronised DC cardioversion

Left atrial ablation: if drug treatment fails or is inappropriate

32
Q

Anticoagulation: compare warfarin and DOACs

Which would you use for atrial fibrillation secondary to valvular disease?

A

Warfarin requires INR monitoring and interacts with many drugs or food but can be easily revered in the event of haemorrhage (vitamin K).

DOACs e.g. rivaroxaban. These do not require monitoring, but the disadvantage is that DOACs are not easily reversed in the event of haemorrhage. That being said, reversal agents for many DOACs are now more readily available.

Warfarin is preferred in valvular AF where it has greater efficacy in lowering thromboembolic risk.

33
Q

What is the abnormality on the following ECG?

A

Broad complex tachycardia

34
Q

What abnormality does the following ECG show?

A

Narrow complex regular tachycardia

35
Q

What abnormality is seen in the following ECG?

A

Atrial fibrillation with rapid ventricular response

4th Year Cardiology (12 decks)

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