Cardiology: Cardiac Arrhythmias - Atrial flutter & AF I

Question 1

How do you manage a patient with (primary) tachycardia?

Answer 1

Assess using ABCDE
- Monitor SpO2 and give oxygen if hypoxic
- Monitor ECG and BP
- Obtain IV access
- ID and treat reversible cause (if possible)

If there are adverse features (e.g. shock, syncope, MI, HF) AND the heart is unstable:
- Deliver synchronised DC shock up to 3 times

Question 2

When assessing tachycardia, if you have ID that there are no adverse features, what is the next thing you are should assess? [1]

Answer 2

If the QRS is narrow (< 0.12s)

Question 3

Describe what determines the width of the QRS complex [1]

Answer 3

Normal cardiac conduction uses His-purkinje system to allow R & L ventricle to depolarise within 120ms: narrow QRS complex

Question 4

What does a narrow QRS complex tachycardia mean with regards to physiology? [1]

Answer 4

Narrow QRS complex tachycardia implies that ventricles are activated via a normal conduction system, therefore the mechansim of the tachycardia is supra ventricular.

Question 5

On a normal 25 mm/sec ECG, 0.12 seconds equals [] small squares.

Answer 5

On a normal 25 mm/sec ECG, 0.12 seconds equals 3 small squares.

Question 6

go through lectures and go through ecgs

Question 7

What are the three reasons for supra-ventricular tachycardia? [4]

Answer 7

Atrial flutter & atrial fibrillation
AVNodal reentrant tachycardia
AVN reentrant tachycardia

Question 8

Describe the pathophysiology of atrial flutter [4]

Answer 8

Counter clockwise circuit of electrical activity goes through the right atrium due to an extra electrical pathway. Signal goes around without interruption

The signal does not usually enter the ventricles on every lap due to the long refractory period of the atrioventricular node.

Get 2:1 ratio of atrial to ventricular contractions. Usually causes atrial rate to be usually around 300 beats per minute; and the ventricles to be 150 bpm

There can be 3:1 or 4:1 or variable conduction ratios

Question 9

Explain the different clinical features of atrial flutter [5]

Answer 9

Haemodynamic Manifestations:
- Loss of co-ordinated atrial contractions causes reduced ventricular filling and reduced CO
- Causes dyspnea; fatigue; lightheadedness; syncope

Palpitations

Chest pain
- Due to increased myocardial oxygen demand secondary to rapid ventricular rates or decreased diastolic filling time causing subendocardial ischaemia

Heart Failure Symptoms
- May get tachycardia induced cardiomyopathy
- Orthopnea; paroxysmal nocturnal dyspnea, and peripheral oedema

Thromboembolic Complications:
- predisposes patients to thrombus formation

Question 10

How do you investigate for atrial flutter? [1]

Answer 10

ECG: Flutter waves (saw toothed morphology) with atrial rate 250/300 bpm

Question 11

Describe the first line treatment algorithm for a patient with acute atrial flutter who is haemodynamically stable? [3]

Answer 11

Primary option: Use an atrioventricular nodal blocking drug for rate control:

Beta blocker:
- Bisoprolol or others

OR

Non-dihydropyridine calcium-channel blockers:
- Verapamil
- Diltiazem

Secondary options:
- Digoxin
may convert atrial flutter to atrial fibrillation, which can be easier to manage.

CONSIDER:
Initial anticoagulation:
- heparin
or
- enoxaparin

Long term anticoagulation:
- 1st: apixaban or ther DOAC
- 2nd: warfarin

BMJ BP

Question 12

Describe the second [1] and third line [2] treatment algorithm for a patient with acute atrial flutter who is haemodynamically stable?

Answer 12

2nd line:
- elective electrical cardioversion

3rd line: pharmacological cardioversion
- flecainide
OR
- amiodarone

Question 13

Describe the treament regime for chronic / recurrent atrial flutter [5]

Answer 13

1st line:
- Catheter ablation
- Long term anticoagulation strategy (see previos)

2nd lines:
- Long term rate control
- Long term anticoagulation therapy
- Long-term anti-arrhythmic therapy

Question 14

Describe the pathophysiology of atrial fibrillation [3]

Answer 14

• Myocytes in the atria contract largely independently of each other and in an unsynchronised pattern, leading to the macroscopic appearance of ‘fibrillation’
• This disrupts the electrical activity of the atria, with multiple groups of myocytes depolarising independently of the SAN and each other
• This results in an irregularly irregular ventricular contraction.

Question 15

Wht are common causes of AF? [5]

Answer 15

SMITH

S – Sepsis
M – Mitral valve pathology (stenosis or regurgitation)
I – Ischaemic heart disease
T – Thyrotoxicosis
H – Hypertension

Alcohol and caffeine are lifestyle causes worth remembering.

Question 16

Which endocrine pathologies are associated with AF? [2]

Answer 16

DM
Hyperthyroidism

Question 17

Which cardiac conditions are associated with AF? [5]

Answer 17

HTN: most common factor
HF
CAD
Valve pathologies: In particular, mitral valve disease and rheumatic heart disease.
Atrial flutter & WPWs

Question 18

Give three changeable risk factors that can cause AF [3]

Answer 18

Obesity
Sleep apnoea
Heavy alcohol use

Question 19

Describe the different classifications of AF [3]

Answer 19

.1. Persistent AF:
- Experience AF at all times (sustained for more than 7 days)

.2. Paroxysmal AF:
- Experiences AF at certain times. At all other times their heart contracts in sinus rhythm
- ‘AF that terminates spontaneously within 7 days of onset’

.3. Valvular Atrial Fibrillation:
- AF with significant mitral stenosis or a mechanical heart valve.
- NB: Atrial fibrillation without valve pathology or with other valve pathologies, such as mitral regurgitation or aortic stenosis, is classed as non-valvular AF.

Question 20

Describe the presentation of AF [7]

Answer 20

• Patients are often asymptomatic
• May be diagnosed after a stroke
• Palpitations
• SOB
• Dizziness or syncope
• irregularly irregular pulse
• Fatigue & anxiety: owing to rapid and irregular ventricular rate

Question 21

Describe the presentation of AF with haemodynamic instability [4]

Answer 21

Acute heart failure, causing:
* Shortness of breath, due to pulmonary oedema
* Raised JVP

Cardiogenic shock, the signs of which are:
Tachycardia
Hypotension

Syncope or pre-syncope

Cardiac chest pain, including myocardial infarction
- This is most common in patients with some level of pre-existing coronary heart disease

Question 22

The Ssgns of haemodynamic compromise in AF according to NICE CKS (2020) are what? [5]

Answer 22

• Heart Rate >150 bpm
• Blood Pressure < 90 mmHg
• Syncope or severe dizziness
• Shortness of breath
• Chest Pain

Question 23

What are the two differentials for irregularly irregular pulse? [1]

Answer 23

Atrial fibrillation
Ventricular ectopics

Question 24

Describe how you investigate AF [4]

Answer 24

Assessment of the radial pulse

ECG:
- Absent P waves
- Narrow QRS complex tachycardia
- Irregularly irregular ventricular rhythm

Long term electrical recordings such as 24 hour ECGs
- most commonly the case in patients with paroxysmal AF who receive ECG recordings between episodes

ECHO if presenting with AF and
- Valvular heart disease
- HF
- Planned cardioversion