Arrhythmias

Question 1

What is an arrhythmia?

Answer 1

An arrhythmia is an abnormal heart rhythm that results from an interruption to the normal electrical signals coordinating the contraction of the heart muscle.

Question 2

What causes arrhythmias?

Answer 2

Arrhythmias are caused by disruptions in the normal electrical signals that coordinate heart muscle contractions. The specific causes can vary depending on the type of arrhythmia.

Question 3

What are the two categories of rhythms in a pulseless patient?

Answer 3

The two categories of rhythms in a pulseless patient are shockable rhythms and non-shockable rhythms.

Question 4

Which rhythms are considered shockable in a pulseless patient?

Answer 4

VT- Ventricular Tachycardia and VF- Ventricular Fibrillation

Question 5

Which rhythms are considered non-shockable in a pulseless patient?

Answer 5

The non-shockable rhythms in a pulseless patient are Pulseless Electrical Activity (PEA) and Asystole.

Question 6

What is Pulseless Electrical Activity (PEA)?

Answer 6

Pulseless Electrical Activity (PEA) is any electrical activity on the ECG, including sinus rhythm, without an associated pulse.

Question 7

What does it mean for a rhythm to be non-shockable?

Answer 7

A non-shockable rhythm means that defibrillation will not be effective in restoring a normal heart rhythm.

Question 8

What is the defining characteristic of narrow complex tachycardia on an ECG?

Answer 8

Narrow complex tachycardia is defined by a fast heart rate with a QRS complex duration of less than 0.12 seconds, which corresponds to less than 3 small squares on a standard 25 mm/sec ECG.

Question 9

What are the four main differentials of narrow complex tachycardia?

Answer 9

The four main differentials of narrow complex tachycardia are:
- Sinus tachycardia
- Supraventricular tachycardia (SVT)
- Atrial fibrillation
- Atrial flutter

Question 10

How is sinus tachycardia identified?

Answer 10

Sinus tachycardia is identified by a normal P wave, QRS complex, and T wave pattern. It is not an arrhythmia and is usually a response to an underlying cause such as sepsis or pain.

Question 11

What distinguishes supraventricular tachycardia (SVT) from sinus tachycardia on an ECG?

Answer 11

SVT is characterized by a very regular rhythm with an abrupt onset and a QRS complex followed immediately by a T wave. P waves are often buried in the T waves, making them hard to see. In contrast, sinus tachycardia has a more gradual onset, more variability in rate, and is usually linked to an underlying cause.

Question 12

How can atrial fibrillation be recognized on an ECG?

Answer 12

Atrial fibrillation can be recognized by absent P waves and an irregularly irregular ventricular rhythm on the ECG.

Question 13

What is the typical ECG appearance of atrial flutter?

Answer 13

Atrial flutter typically shows a saw-tooth pattern on the ECG due to atrial rates around 300 beats per minute. The ventricular rate is often 150 beats per minute due to a 2:1 conduction ratio (two atrial contractions for every one ventricular contraction).

Question 14

What are the indications for synchronized DC cardioversion in a patient with narrow complex tachycardia?

Answer 14

Synchronized DC cardioversion is indicated in patients with narrow complex tachycardia who exhibit life-threatening features such as loss of consciousness (syncope), heart muscle ischemia (e.g., chest pain), shock, or severe heart failure.

Question 15

What additional treatment is given if initial DC cardioversion shocks are unsuccessful?

Answer 15

Intravenous amiodarone is added if initial DC cardioversion shocks are unsuccessful in treating the narrow complex tachycardia.

Question 16

What is the defining feature of broad complex tachycardia on an ECG?

Answer 16

Broad complex tachycardia is characterized by a fast heart rate with a QRS complex duration of more than 0.12 seconds, or more than 3 small squares on an ECG.

Question 17

How is ventricular tachycardia or an unclear cause of broad complex tachycardia treated?

Answer 17

Ventricular tachycardia or an unclear cause of broad complex tachycardia is treated with intravenous (IV) amiodarone.

Question 18

What is the treatment for polymorphic ventricular tachycardia, such as torsades de pointes?

Answer 18

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

Question 19

What is the management approach for a patient with broad complex tachycardia and life-threatening features, such as loss of consciousness or severe heart failure?

Answer 19

These patients are treated with synchronized DC cardioversion under sedation or general anesthesia. Intravenous amiodarone is added if initial DC shocks are unsuccessful.

Question 20

What is the underlying mechanism causing atrial flutter?

Answer 20

Atrial flutter is caused by a re-entrant rhythm in the atrium, where an electrical signal re-circulates in a self-perpetuating loop due to an extra electrical pathway, leading to a rapid atrial rate of about 300 beats per minute.

Question 21

How does atrial flutter typically appear on an ECG?

Answer 21

Atrial flutter gives a sawtooth appearance on the ECG, with repeated P waves occurring at around 300 beats per minute, and a narrow complex tachycardia.

Question 22

What is the treatment approach for atrial flutter?

Answer 22

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 23

What is a prolonged QT interval in men and women?

Answer 23

A prolonged QT interval is more than 440 milliseconds in men and more than 460 milliseconds in women.

Question 24

What is the significance of a prolonged QT interval on an ECG?

Answer 24

A prolonged QT interval indicates prolonged repolarization of the heart muscle cells, which can lead to afterdepolarizations and potentially torsades de pointes, a type of polymorphic ventricular tachycardia.

Question 25

Describe the ECG appearance of torsades de pointes.

Answer 25

Torsades de pointes appears on an ECG as a twisting of the QRS complexes around the baseline, with the height of the QRS complexes getting progressively smaller, then larger, and so on.

Question 26

List some causes of a prolonged QT interval.

Answer 26

Causes of a prolonged QT interval include long QT syndrome (an inherited condition), medications (e.g., antipsychotics, citalopram, flecainide), and electrolyte imbalances (e.g., hypokalaemia, hypomagnesaemia).

Question 27

What is the acute management of torsades de pointes?

Answer 27

Acute management involves correcting the underlying cause (e.g., electrolyte disturbances or medications), magnesium infusion, and defibrillation if ventricular tachycardia occurs.

Question 28

What are ventricular ectopics, and how do they appear on an ECG?

Answer 28

Ventricular ectopics are premature ventricular beats caused by random electrical discharges outside the atria. They appear as isolated, random, abnormal, broad QRS complexes on an otherwise normal ECG.

Question 29

What is bigeminy in the context of ventricular ectopics?

Answer 29

Bigeminy refers to a pattern where every other beat is a ventricular ectopic, seen on an ECG as a normal beat followed by an ectopic beat, then another normal beat, and so on.

Question 30

How are ventricular ectopics managed in otherwise healthy individuals?

Answer 30

In healthy individuals with infrequent ectopics, management involves reassurance and no treatment.

Question 31

When should specialist advice be sought for ventricular ectopics?

Answer 31

Specialist advice should be sought for patients with underlying heart disease, frequent or concerning symptoms (e.g., chest pain or syncope), or a family history of heart disease or sudden death.

Question 32

What is first-degree heart block, and how does it present on an ECG?

Answer 32

First-degree heart block is a delayed conduction through the atrioventricular node, where every P wave is followed by a QRS complex. On an ECG, it presents as a PR interval greater than 0.2 seconds.

Question 33

What differentiates Mobitz type 1 from Mobitz type 2 heart block?

Answer 33

Mobitz type 1 (Wenckebach phenomenon) shows a progressively lengthening PR interval until a P wave is not followed by a QRS complex. Mobitz type 2 shows intermittent failure of conduction with absent QRS complexes following P waves, but the PR interval remains constant.

Question 34

What is the risk associated with Mobitz type 2 and third-degree heart block?

Answer 34

Both Mobitz type 2 and third-degree (complete) heart block carry a significant risk of asystole.

Question 35

What is third-degree heart block, and how does it present on an ECG?

Answer 35

Third-degree heart block, or complete heart block, occurs when there is no relationship between the P waves and QRS complexes, indicating a complete failure of conduction from the atria to the ventricles.

Question 36

What is bradycardia, and what are some common causes?

Answer 36

Bradycardia is a slow heart rate, typically less than 60 beats per minute. Common causes include medications (e.g., beta blockers), heart block, and sick sinus syndrome.

Question 37

What is sick sinus syndrome, and what does it encompass?

Answer 37

Sick sinus syndrome encompasses conditions that cause dysfunction in the sinoatrial node, often due to idiopathic degenerative fibrosis. It can result in sinus bradycardia, sinus arrhythmias, and prolonged pauses.

Question 38

What is asystole, and what conditions increase the risk of it?

Answer 38

Asystole is the absence of electrical activity in the heart, leading to cardiac arrest. Conditions that increase the risk of asystole include Mobitz type 2 heart block, third-degree heart block, previous asystole, and ventricular pauses longer than 3 seconds.

Question 39

What is the first-line treatment for bradycardia in unstable patients or those at risk of asystole?

Answer 39

The first-line treatment is intravenous atropine, followed by inotropes (e.g., isoprenaline or adrenaline) and temporary cardiac pacing if necessary. A permanent implantable pacemaker may be required.

Question 40

What are the options for temporary cardiac pacing?

Answer 40

Temporary cardiac pacing options include transcutaneous pacing using pads on the chest and transvenous pacing using a catheter fed through the venous system to stimulate the heart directly.