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Medicine & Surgery: Cardiovascular > Arrhythmias and Conduction Defects > Flashcards

Arrhythmias and Conduction Defects Flashcards

1
Q

What are the cardiac causes of arrhythmias?

A
  1. IHD, CHF
  2. Structural changes
  3. Cardiomyopathy
  4. Post-MI
  5. Pericarditis
  6. Abnormal conduction pathways
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2
Q

What are the non-cardiac causes of arrhythmias?

A
  1. Caffeine, smoking, alcohol
  2. Pneumonia
  3. Drugs - B2 agonists, digoxin, L-dopa, TCAs
  4. Metabolic imbalance - K+, Ca2+, Mg2+
  5. Hypoxia, hypercapnia, metabolic acidosis
  6. Thyroid disease, phaeochromocytoma
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3
Q

What is this a presentation of?

Palpitations, dyspnoea, chest pain, presyncope/syncope, hypotension, pulmonary oedema, abnormal ECG.

A

Arrhythmia

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4
Q

What are the two groups of pathological tachycardias?

A
  1. Broad complex - QRS >120ms (3 small squares)

2. Narrow complex - QRS <120ms (3 small squares)

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5
Q

What could a regular broad complex tachycardia be and how is it treated?

A
  1. Assume ventricular tachycardia

2. Amiodarone

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6
Q

What could an irregular broad complex tachycardia be and how are they treated?

A
  1. AF and BBB - treat as per narrow complex guidelines

2. Polymorphic VT (Torsade de pointes) - IV Mg

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7
Q

What could a regular narrow complex tachycardia be and how is it treated?

A
  1. Supraventricular tachycardia

2. Vagal manoeuvres, IV adenosine

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8
Q

What is an irregular narrow complex tachycardia likely to be?

A

Probably AF

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9
Q

What is VT and what can it progress to?

A
  1. A broad complex tachycardia originating from a ventricular ectopic focus.
  2. Has the potential to precipitate ventricular fibrillation and hence requires urgent treatment.
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10
Q

What are the two main types of VT and what causes them?

A
  1. Monomorphic - commonly caused by MI

2. Polymorphic (e.g. Torsades de pointes) - precipitated by prolongation of the QT interval

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11
Q

What is the aetiology of VT?

A

> 90% caused by re-entry around scar tissue due to abnormal scarring usually due to prior ischaemia or infarction.

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12
Q

What is Torsade de pointes, what can it deteriorate to, and how is it treated?

A
  1. Rare, irregular, broad-complex, tachycardic arrhythmia associated with long QT interval.
  2. May deteriorate to VF and hence lead to sudden death.
  3. IV magnesium sulphate
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13
Q

What are the causes of long QT?

A
  1. Congenital
  2. Drugs - amiodarone, TCAs, fluoxetine, chloroquine, terfenadine, erythromycin (macrolides).
  3. Hypokalaemia, hypomagnesaemia, hypocalcaemia, acute MI, hypothermia, SAH.
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14
Q

Why are patients with an irregular broad complex tachycardia in combination with a BBB treated as per narrow complex guidelines?

A
  1. Narrow complexes with BBB can look like broad complexes.

2. If unsure, treat for VT as giving adenosine in VT is dangerous, giving amiodarone is less dangerous.

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15
Q

What is the immediate management of a VT?

A
  1. Connect to cardiac monitor and have defibrillator ready.
  2. Monitor O2 and give if <90%
  3. Correct electrolytes
  4. Check for adverse signs - systolic BP <90mmHg, chest pain, heart failure, myocardial ischaemia, syncope.
  5. If adverse signs present - immediate synchronised DC cardioversion, then amiodarone 300mg IV over 20 mins.
  6. If stable - amiodarone then DC cardioversion, then amiodarone 900mg over 24h via central line.
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16
Q

What is an SVT?

A

Any tachyarrhythmia arising from above the atrioventricular node.

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17
Q

What are the three different types of SVT?

A
  1. Sinus tachycardia - normal P wave followed by normal QRS, do not cardiovert
  2. Atrial tachyarrhythmias - AF, AFl
  3. Junctional tachycardia - AVNRT, AVRT
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18
Q

Which SVTs are regular and atrial?

A
  1. Sinus tachycardia
  2. Atrial tachycardia
  3. Atrial flutter
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19
Q

Which SVTs are regular and ventricular?

A
  1. Atrioventricular re-entry tachycardia (AVRT)

2. Atrioventricular nodal re-entry tachycardia (AVNRT)

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20
Q

Which SVTs are irregular and atrial?

A
  1. Atrial fibrillation

2. Atrial flutter with variable block

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21
Q

What is the most common cause of SVT other than AF?

A

AVNRT

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22
Q

What is this a presentation of?

Young female, sudden onset of rapid, regular palpitations, brief fall in BP causing presyncope/syncope, SOB, anxiety.

A

AVNRT

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23
Q

When does AVNRT typically occur?

A

Paroxysmal and may occur spontaneously or upon provocation with exertion, caffeine, alcohol, beta agonists, hypokalaemia.

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24
Q

What is AVNRT?

A

A functional re-entry circuit within the AVN.

25
Q

What is AVRT?

A

An accessory pathway allows electrical activity from the ventricles to pass to the resting atrial myocytes.

26
Q

What is this describing?

AVRT, short PR interval, delta wave.

A

Wolff Parkinson White syndrome

27
Q

What is atrial flutter?

A

Anticlockwise re-entry circuit in the right atrium. Fairly predictable atrial rate of 300bpm due to size of atria.

28
Q

What is the most common AV ratio in atrial flutter?

A

2:1 (2 atrial beats for every 1 ventricular)

29
Q

What is this describing?

Saw-tooth baseline ECG.

A

Atrial flutter

30
Q

What is the treatment for atrial flutter?

A
  1. Similar to AF regarding rate, rhythm control and need for anticoagulation.
  2. Synchronised DC cardioversion preferred.
  3. Radiofrequency ablation recommended for long term management.
31
Q

What is the key to management in SVT?

A

Identify whether the rhythm is regular or irregular (likely AF).

32
Q

What is the immediate management for the SVTs?

  1. Sinus tachycardia secondary to dehydration
  2. AVNRT/AVRT (regular)
  3. Underlying rhythm atrial in origin
A
  1. IV fluids
  2. Transiently block AVN
  3. AVN block won’t treat but will unmask atrial rhythm, aiding diagnosis and management.
33
Q

How do you block the AVN?

A
  1. Vagal manoeuvres 1st line (carotid sinus massage, Valsalva manoeuvre)
  2. IV adenosine 6mg, followed by 12mg (not for asthma as it obstructs airway, IV verapamil)
34
Q

How do you rate control and rate limit atrial fibrillation/flutter?

A
  1. Rate control - B-blockers (metoprolol)

2. Rate limiting - Ca-channel blocker (verapamil)

35
Q

What is AF?

A

A Chaotic, irregular atrial rhythm at 300-600bpm, cardiac output drops by 10-20%. Most common sustained arrhythmia. Risk of thromboembolic stroke.

36
Q

What are the risk factors and causes for AF?

A

HTN, increasing age, IHD, DM, CHF, valvular disease, cardiac/thoracic surgery, PE, hyperthyroidism, acute infections, caffeine, alcohol, hypokalaemia, hypomagnesaemia.

37
Q

What are the signs and symptoms in AF?

A
  1. May be asymptomatic or cause chest pain, palpitations, dyspnoea, syncope.
  2. Irregularly irregular pulse
38
Q

What is this ECG describing?
Irregularly irregular rhythm, no P waves, usually fast but can be slow, absence of isoelectric baseline, narrow QRS usually.

A

Atrial fibrillation

39
Q

How is suspected AF investigated?

A
  1. ECG
  2. Bloods - U&Es, cardiac enzymes, TFTs
  3. Echo - may show LVH, left atrial enlargement
  4. CXR - pneumonia, HF may precipitate AF
40
Q

How can you classify AF?

A
  1. First episode - initial detection
  2. Chronic paroxysmal - recurrent, self-terminates in <7 days
  3. Chronic persistent - lasts >7 days
  4. Chronic permanent - continuous, refractory to cardioversion, sinus rhythm cannot be restored
41
Q

In which patient groups would you favour rate control in AF?

A

> 65 years old and history of IHD

42
Q

In which patient groups would you favour rhythm control in AF?

A

<65 years old, symptomatic, first presentation, CHF, secondary to reversible cause.

43
Q

What is the management for acute AF?

A
  1. If adverse signs - A-E and synchronised DC cardioversion
  2. If stable and definitely started <48hrs ago - rate control with beta blockers/calcium channel blocker, or rhythm control with DC cardioversion/flecainide, also start heparin.
  3. If stable and AF started >48hrs ago - rate control
  4. Anticoagulate for >3 weeks in rhythm control.
44
Q

What is the management for chronic AF?

A
  1. Rate control - B-blocker or Calcium channel blocker 1st line.
  2. Rhythm control - CHA2DS2-VAS, HAS-BLED scores - warfarin (INR 2-3) or a DOAC
  3. Elective DC cardioversion, echo first for thrombi, if risk of failure, give amiodarone 4wks before and 12mths after.
  4. Elective pharmacological cardioversion - flecainide 1st choice (amiodarone in structural heart defect)
45
Q

What are the features if the CHA2DS2-VAS score and when should you anticoagulate?

A 
C - congestive heart failure (1)
H - hypertension (1)
A - age >74 (2)
D - diabetes (1)
S - stroke/TIA/thromboembolism (2)
V - vascular disease (1)
A - age 65-74 (1)
S - sex female (1)
Anticoagulate in male if 1 or more, in females if 2 or more.
46
Q

What are the features of the HAS-BLED score and what score indicates a high risk of bleed?

A

H - hypertension, uncontrolled, SYS >160 (1)
A - abnormal renal/liver function (1 each)
S - stroke history (1)
B - bleeding, major or predisposition (1)
L - labile INR (1)
E - elderly >65yrs (1)
D - drugs (NSAIDs, antiplatelets), alcohol >8u per week (1 each)
Score of 3 or more indicates high bleeding risk.

47
Q

What are the symptoms of bradyarrhythmias?

A

Often asymptomatic, fatigue, nausea, dizziness, syncope, light-headedness.

48
Q

What is heart block?

A

Disrupted passage of electrical impulse through the AV node.

49
Q

What is this describing?

Prolonged PR interval (>200ms), unchanged, no dropped QRS, no haemodynamic compromise.

A

1st degree heart block

50
Q

What is this describing?
Progressive prolongation of PR interval culminating in a non-conductive P wave, longest before dropped beat and shortest after. Usually due to reversible block.

A

2nd degree heart block (Mobitz I)

51
Q

What is the treatment for patients with symptomatic 2nd degree heart block (Mobitz I)?

A

Usually respond well to atropine

52
Q

What is this describing?
Intermittent non-conducting P waves without progressive prolongation of PR interval, P waves ‘march through’ at constant rate.

A

2nd degree heart block (Mobitz II)

53
Q

What is the treatment for patients with 2nd degree heart block (Mobitz II)?

A

Immediate admission for cardiac monitoring, temporary pacing, and a permanent pacemaker.

54
Q

What is this describing?
Complete absence of AV conduction, none of the supraventricular impulses conduct to ventricles. Severe bradycardia, hypotension, high risk of haemodynamic instability.

A

3rd degree heart block (complete)

55
Q

What is the treatment for patients with 3rd degree heart block?

A

Immediate admission for cardiac monitoring, temporary pacing, and a permanent pacemaker.

56
Q

What are the causes of 1st and 2nd degree heart block?

A

Normal variant, athletes (increased vagal tone), IHD (especially inferior MI), drugs (digoxin, BBs, CCBs).

57
Q

What are the causes of 3rd degree heart block?

A

IHD (especially inferior MI), end point of Mobitz I/II.

58
Q

What non-cardiac causes should you consider when managing bradycardia, and what is needed in patients with a high risk of asystole?

A
  1. Always consider general non-cardiac causes (vasovagal, hypothyroidism, Addison’s)
  2. Cushing’s triad - bradycardia, hypertension, irregular breathing = urgent senior input
  3. Transcutaneous pacing needed in patients with high risk of asystole (atropine/isoprenaline infusion in interim)
59
Q

What is the general management of bradycardia?

A
  1. If adverse features - atropine 500mcg IV
  2. If there is a satisfactory response - assess asystole risk.
  3. If unsatisfactory response/asystole risk - atropine 500mcg IV repeat up to 3mg/transcutaneous pacing/isoprenaline, adrenaline, alternatives.

Medicine & Surgery: Cardiovascular (30 decks)

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