Arrythmias (zero to finals)

Question 1

What are arrythmias?

Answer 1

Abnormal heart rhythms.

They result from an interruption to the normal electrical signals that coordinate the contraction of the heart muscle.

Question 2

What are the 2 shockable rhythms in a pulseless patient?

Answer 2

Ventricular tachycardia

Ventricular fibrillation

Question 3

What are the 2 non-shockable rhythms in a pulseless patient?

Answer 3

Pulseless electrical activity (all electrical activity except VF/VT, including sinus rhythm without a pulse)

Asystole (no significant electrical activity)

Question 4

What is narrow complex tachycardia?

Answer 4

A fast heart rate with a QRS complex duration of less than 0.12 seconds.

Question 5

What are the four main differentials of a narrow complex tachycardia?

Answer 5

Sinus tachycardia (treatment focuses on the underlying cause)

Supraventricular tachycardia (treated with vagal manoeuvres and adenosine)

Atrial fibrillation (treated with rate control or rhythm control)

Atrial flutter (treated with rate control or rhythm control, similar to atrial fibrillation)

Question 6

Sinus tachycardia is not an arrhythmia. True/false?

Answer 6

True

Sinus tachycardia will take the normal P wave, QRS complex and T wave pattern.

it is not an arrhythmia, usually due to an underlying cause such as sepsis or pain.

Question 7

Appearance of supraventricular tachycardia

Answer 7

Supraventricular tachycardia (SVT) looks like a QRS complex followed immediately by a T wave, then a QRS complex, then a T wave, and so on.

There are P waves, but they are often buried in the T waves, so you cannot see them.

SVT has narrow (<0.12s) QRS complexes that are regular.

Question 8

How can SVT be distinguished from atrial flutter and atrial fibrillation?

Answer 8

It can be distinguished from atrial fibrillation by the regular rhythm and atrial flutter by the absence of a saw-tooth pattern.

Question 9

How to distinguish SVT from sinus tachycardia?

Answer 9

SVT has an abrupt onset and a very regular pattern without variability.

Sinus tachycardia has a more gradual onset and more variability in the rate.

The history is also important, where sinus tachycardia usually has an explanation (e.g., pain or fever), while SVT can appear at rest with no apparent cause.

Question 10

How can atrial fibrillation be identified on an ECG?

Answer 10

Can be identified on an ECG by absent P waves and an irregularly irregular ventricular rhythm.

Question 11

Appearance of atrial flutter on ECG?

Answer 11

In atrial flutter, the atrial rate is usually around 300 beats per minute and gives a saw-tooth pattern on the ECG.

Question 12

Treatment of atrial flutter in the presence of life-threatening features?

Answer 12

Patients with life-threatening features, such as loss of consciousness (syncope), heart muscle ischaemia (e.g., chest pain), shock or severe heart failure, are treated with synchronised
DC cardioversion under sedation or general anaesthesia.

Intravenous amiodarone is added if initial DC shocks are unsuccessful.

Question 13

What is a broad complex tachycardia?

Answer 13

Refers to a fast heart rate with a QRS complex duration of more than 0.12 seconds or 3 small squares on an ECG.

Question 14

What are the types of broad complex tachycardia?

Answer 14

Ventricular tachycardia or unclear cause (treated with IV amiodarone)

Polymorphic ventricular tachycardia, such as torsades de pointes (treated with IV magnesium)

Atrial fibrillation with bundle branch block (treated as AF)

Supraventricular tachycardia with bundle branch block (treated as SVT)

Question 15

Underlying pathophysiology of atrial flutter?

Answer 15

Normally the electrical signal passes through the atria once, stimulating a contraction, then disappears through the atrioventricular node into the ventricles.

Atrial flutter is caused by a re-entrant rhythm in either atrium.

The electrical signal re-circulates in a self-perpetuating loop due to an extra electrical pathway in the atria.

The signal goes round and round the atrium without interruption. The atrial rate is usually around 300 beats per minute.

Question 16

What is the ECG appearance of atrial flutter?

Answer 16

A sawtooth appearance on the ECG, with repeated P wave occurring at around 300 per minute, with a narrow complex tachycardia.

Question 17

Treatment of atrial flutter?

Answer 17

Treatment is similar to atrial fibrillation, including anticoagulation based on the CHA2DS2-VASc score.

Radiofrequency ablation of the re-entrant rhythm can be a permanent solution.

Question 18

What is the QT interval?

Answer 18

The QT interval is from the start of the QRS complex to the end of the T wave.

Question 19

What does a prolonged QT interval indicate?

Answer 19

A prolonged QT interval represents prolonged repolarisation of the heart muscle cells (myocytes) after a contraction.

Question 20

What is torsades de pointes?

Answer 20

Torsades de pointes is a type of polymorphic ventricular tachycardia. It translates from French as “twisting of the spikes”, describing the ECG characteristics.

Question 21

How does torsades de pointes appear on an ECG?

Answer 21

On an ECG, it looks like standard ventricular tachycardia but with the appearance that the QRS complex is twisting around the baseline.

The height of the QRS complexes gets progressively smaller, then larger, then smaller, and so on.

Question 22

Torsades de pointes will terminate spontaneously and revert to sinus rhythm or progress to ventricular tachycardia. Ventricular tachycardia can lead to cardiac arrest. True/false?

Answer 22

True

Question 23

What are causes of prolonged QT?

Answer 23

Long QT syndrome (an inherited condition)

Medications, such as antipsychotics, citalopram, flecainide, sotalol, amiodarone and macrolide antibiotics

Electrolyte imbalances, such as hypokalaemia, hypomagnesaemia and hypocalcaemia

Question 24

What are management options for prolonged QT interval?

Answer 24

Stopping and avoiding medications that prolong the QT interval
Correcting electrolyte disturbances

Beta blockers (not sotalol)

Pacemakers or implantable cardioverter defibrillators

Question 25

Acute management of torsades de pointes?

Answer 25

Correcting the underlying cause (e.g., electrolyte disturbances or medications)

Magnesium infusion (even if they have normal serum magnesium)

Defibrillation if ventricular tachycardia occurs

Question 26

When does first degree heart block occur?

Answer 26

First-degree heart block occurs where there is delayed conduction through the atrioventricular node.

Question 27

How does a first degree heart block typically present in an ECG?

Answer 27

On an ECG, first-degree heart block presents as a PR interval greater than 0.2 seconds (5 small or 1 big square).

Question 28

When does second degree heart block occur?

Answer 28

Second-degree heart block is where some atrial impulses do not make it through the atrioventricular node to the ventricles. There are instances where P waves are not followed by QRS complexes.

Question 29

What are two types of second-degree heart block?

Answer 29

Mobitz type 1 (Wenckebach phenomenon)

Mobitz type 2

Question 30

What is a mobitz type 1 - 2nd degree heart block?

Answer 30

Where the conduction through the atrioventricular node takes progressively longer until it finally fails, after which it resets, and the cycle restarts.

On an ECG, there is an increasing PR interval until a P wave is not followed by a QRS complex. The PR interval then returns to normal, and the cycle repeats itself.

Essentially there is a gradual lengthening of the PR interval until there is a missed QRS before repeating itself.

Question 31

What is a mobitz type 2 - 2nd degree heart block?

Answer 31

Where there is intermittent failure of conduction through the atrioventricular node, with an absence of QRS complexes following P waves. The PR interval remains normal.

There is usually a set ratio of P waves to QRS complexes, for example, three P waves for each QRS complex (3:1 block).

A 2:1 block is where there are two P waves for each QRS complex.

Question 32

What is a third degree heart block?

Answer 32

Third-degree heart block is also called complete heart block. There is no observable relationship between the P waves and QRS complexes.

Question 33

What is a bradycardia?

Answer 33

Refers to a slow heart rate, typically less than 60 beats per minute. A heart rate under 60 can be normal in healthy fit patients without causing any symptoms.

Question 34

3 main causes of bradycardia?

Answer 34

Medications (e.g., beta blockers)

Heart block

Sick sinus syndrome

Question 35

What is sick sinus syndrome?

Answer 35

Sick sinus syndrome encompasses many conditions that cause dysfunction in the sinoatrial node. It is often caused by idiopathic degenerative fibrosis of the sinoatrial node. It can result in sinus bradycardia, sinus arrhythmias and prolonged pauses.

Question 36

What is asystole?

Answer 36

Refers to the absence of electrical activity in the heart (resulting in cardiac arrest).

Question 37

What increases risk of asystole?

Answer 37

Mobitz type 2

Third-degree heart block (complete heart block)

Previous asystole

Ventricular pauses longer than 3 seconds

Question 38

Management of unstable patients and those at risk of asystole?

Answer 38

Intravenous atropine (first line)
Inotropes (e.g., isoprenaline or adrenaline)
Temporary cardiac pacing
Permanent implantable pacemaker, when available

Question 39

What is atropine and it’s side-effects?

Answer 39

Atropine is an antimuscarinic medication and works by inhibiting the parasympathetic nervous system. Inhibiting the parasympathetic nervous system leads to side effects of pupil dilation, dry mouth, urinary retention and constipation.