Cardiology: Cardiac Arrhythmias - Misc

Question 1

Describe the four possible rhythms in a cardiac arrest patient [4]

Answer 1

Shockable rhythms:
* Ventricular tachycardia
* Ventricular fibrillation

Non-shockable rhythms:
* Pulseless electrical activity (all electrical activity except VF/VT, including sinus rhythm without a pulse)
* Asystole (no significant electrical activity)

Question 2

A patient presents with narrow complex tachycardia with life-threatening features (e.g syncope).

He is initially treated with synchronised DC cardioversion under sedation or general anaesthesia.

This doesn’t work. What is the next step in this patients management? [1]

Answer 2

 Amiodarone 300 mg IV over 10-20 min
 Repeat shock
 Then give amiodarone 900 mg over 24 h

Question 3

go over
https://www.resus.org.uk/sites/default/files/2020-05/G2015_Adult_tachycardia.pdf

Question 4

Broad complex tachycardia refers to a fast heart rate with a QRS complex duration of more than [] seconds or [] small squares on an ECG.

Answer 4

Broad complex tachycardia 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 5

Which pathologies are categorised as broad complex tachycardias? [4]

Answer 5

Ventricular tachycardia or unclear cause

Polymorphic ventricular tachycardia, such as torsades de pointes

Atrial fibrillation with bundle branch block

Supraventricular tachycardia with bundle branch block

Question 6

Describe how you would treat the following causes of broad complex tachycardia [4]

• Ventricular tachycardia or unclear cause
• Polymorphic ventricular tachycardia, such as torsades de pointes
• Atrial fibrillation with bundle branch block
• Supraventricular tachycardia with bundle branch block

Answer 6

Ventricular tachycardia or unclear cause:
- IV amiodarone

Polymorphic ventricular tachycardia, such as torsades de pointes:
- IV magnesium

Atrial fibrillation with bundle branch block
- AF tx

Supraventricular tachycardia with bundle branch block
- SVT tx

Question 7

Describe the pathophysiology of VT [1]

Answer 7

Ventricular tachycardia (VT) occurs due to rapid, recurrent ventricular depolarisation from a focus within the ventricles.

This is commonly due to scarring of the ventricles following myocardial infarction.

Question 9

How do you manage patients with broad complex tachycardia and life-threatening features, such as loss of consciousness (syncope), heart muscle ischaemia (e.g., chest pain), shock or severe heart failure? [2]

Answer 9

Synchronised DC cardioversion under sedation or general anaesthesia.

Intravenous amiodarone is added if initial DC shocks are unsuccessful.

Question 10

Give four differential diagnoses to VT for a broad complex tachycardia [4]

Answer 10

SVT with abberancy:
- SVT but the QRS becomes broad because of bundle branch block

Paced rhythm:
- An electrocardiographic finding in which the cardiac rhythm is controlled by an electrical impulse from an artificial cardiac pacemaker

Anti-dromic AVRT

Pre-excitation tachycardias (WPW)

Question 11

Describe what is meant by sick sinus syndrome [1]

What can cause sick sinus syndrome? [1]

Answer 11

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 12

What does asytole mean? [1]

State 4 cardiac pathologies that increase risk of asytole [4]

Answer 12

Asytole: cessation of electrical and mechanical activity of the heart.

• Mobitz type 2
• Third-degree heart block (complete heart block)
• Previous asystole
• Ventricular pauses longer than 3 seconds

Question 13

What is the stepwise managment plan of unstable patients with those at risk of asytole? [4]

Answer 13

• Intravenous atropine (first line)
• Inotropes (e.g., isoprenaline or adrenaline)
• Temporary cardiac pacing:
  Transcutaneous pacing: using pads on the patient’s chest
  OR
  Transvenous pacing, using a catheter, fed through the venous system to stimulate the heart directly
• Permanent implantable pacemaker, when available

Question 14

Describe the MoA of atropine [1]

Answer 14

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.

Question 15

What is corrected QT interval (QTc)? [1]

What is prolonged QTc in men [1] and women [1]?

Answer 15

Corrected QT interval (QTc): estimates the QT interval if the heart rate were 60 beats per minute

Prolonged:
* More than 440 milliseconds in men
* More than 460 milliseconds in women

Question 16

What does a prolonged QT interval mean physiologically? [1]

What are the physiologically consequences of a prolonged QT interval? [1]

What is the name for this phenomenom? [1]

Answer 16

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

Waiting a long time for repolarisation can result in spontaneous depolarisation in some muscle cells

These abnormal spontaneous depolarisations before repolarisation are known as afterdepolarisations.

Question 17

Describe what is meant torsades de pointes from a physiological perspective? [1]

What type of tachycardia is torsades de pointes? [1]

Answer 17

Recurrent contractions without a normal repolarisation due to afterdepolarisations spreading throughout the ventricles, causing contraction before proper repolarisation

Type of polymorphic ventricular tachycardia

Question 18

What does Torsades de pointes look like on an ECG? [1]

Answer 18

Lke 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 19

Why specific treatment does Torsades de pointes require? [1]

What treatment should be given if the patient has Torsades de pointes but becomes unstable? [1]

Answer 19

Stable and Torsades de pointes:
- intravenous magnesium sulphate shortens the QT interval with

Unstable with Torsades de pointes:
- immediate DC cardioversion as with any unstable tachyarrhythmia.

Question 20

Describe the prognosis of untreatead torsades de pointes [2]

Answer 20

Torsades de pointes will terminate spontaneously and revert to sinus rhythm

OR

Progress to ventricular tachycardia. Ventricular tachycardia can lead to cardiac arrest.

Question 21

Which medications can cause prolonged QT intervals? [6]

Answer 21

• Antipsychotics,
• citalopram
• Flecainide
• sotalol
• amiodarone
• macrolide antibiotics (Azithromycin, clarithromycin, and erythromycin)

Question 22

Which electrolyte imbalances can cause QT elongation [3]

Answer 22

• hypokalaemia
• hypomagnesaemia
• hypocalcaemia

Question 23

Describe what is meant by ventricular ectopics [1]

How do they appear on ECGs? [3]

Answer 23

Premature ventricular beats caused by random electrical discharges outside the atria

ECG appearnce:
- Broad QRS complex (≥ 120 ms) with abnormal morphology
- Premature — i.e. occurs earlier than would be expected for the next sinus impulse
- Usually followed by a full compensatory pause
- Discordant ST segment and T wave changes.

Question 24

PVCs often occur in repeating patterns. State names for the most common [4]

Answer 24

Bigeminy — every other beat is a PVC
Trigeminy — every third beat is a PVC
Quadrigeminy — every fourth beat is a PVC
Couplet — two consecutive PVCs

Question 25

Describe what is meant by heart block [1] Describe the 3 types of heart block? [4]

Answer 25

**Heart block:** - interference of the normal transmission of conduction within the AVN **1st degree:** - Delay in the conduction of depolarisation from SAN to ventricles. **Constant prolongation of the PR interval > 200ms** **2nd degree: Mobitz Type I**: - **Progressive lengthening of the PR interval** until get a **dropped** **heart** **beat** - Looks like P wave without QRS **2nd degree: Mobitz Type II**: - **Constant PR interval** but **occasional** **dropped** **beats** - Looks like P wave without QRS - Can be fixed ratio block (look at number of P waves in R-R interval & compare to distant R wave) **3rd degree**: - Complete failure to conduct atrial impulses to ventricles via the AVN: **AV dissociation** - **Normal P waves** that have with **no association with QRS complexes** - The QRS complexes are occurring by **ventricular escape rhythms**: see broad QRS complexes

Question 26

Describe the resuscitation council treatment algorithm for adult tachycardias (with pulse) if the there are adverse features (e.g. shock, syncope, MI, HF) [5]

Answer 26

**Assess using the ABCDE approach**  Monitor SpO2 and give oxygen if hypoxic  Monitor ECG and BP, and record 12-lead ECG  Obtain IV access  Identify and treat reversible causes (e.g. electrolyte abnormalities) **Adverse features?** *Shock; MI; HF: Syncope* - **IF YES**:  **Synchronised DC shock x3**  **Amiodarone 300 mg IV over 10 - 20 mins**  **Repeat shock**  **Amiodarone 900 mg over 24hrs**

Question 27

What do you check for next on the treatment algorithm for adult tachycardias (with pulse) once you have have assessed that there are no adverse features present? [1]

Answer 27

**Assess using the ABCDE approach**  Monitor SpO2 and give oxygen if hypoxic  Monitor ECG and BP, and record 12-lead ECG  Obtain IV access  Identify and treat reversible causes (e.g. electrolyte abnormalities) **Adverse features?** *Shock; MI; HF: Syncope* - **IF NO** - **Check** **QRS** - **If < 0.12s**:

Question 28

What do you check for next on the treatment algorithm for adult tachycardias (with pulse) once you have have assessed that there are no adverse features present and the **QRS complex is < 0.12 secs**? [1]

Answer 28

**Assess using the ABCDE approach**  Monitor SpO2 and give oxygen if hypoxic  Monitor ECG and BP, and record 12-lead ECG  Obtain IV access  Identify and treat reversible causes (e.g. electrolyte abnormalities) **Adverse features?** *Shock; MI; HF: Syncope* - **IF NO** - **Check** **QRS** - **If < 0.12s** = **narrow complex tachycardia** **Next: check** **if** **rhythm is regular**

Question 29

What is the treatment algorithm for adult tachycardias (with pulse) once you have have assessed that there are no adverse features present and the **QRS complex is < 0.12 secs** and the **rhythm is regular**? [5]

Answer 29

**Assess using the ABCDE approach**  Monitor SpO2 and give oxygen if hypoxic  Monitor ECG and BP, and record 12-lead ECG  Obtain IV access  Identify and treat reversible causes (e.g. electrolyte abnormalities) **Adverse features?** *Shock; MI; HF: Syncope* - **IF NO** - **Check** **QRS** - **If < 0.12s** = **narrow complex tachycardia** **If** **rhythm is regular**:  Perform **vagal** **manoeuvres**  **Adenosine** **6 mg rapid IV bolus**  **If no effect give 12 mg**  **If no effect give further 12 mg**  **Monitor/record ECG continuously**

Question 30

What is the treatment algorithm for adult tachycardias (with pulse) once you have have assessed that there are no adverse features present and the **QRS complex is < 0.12 secs** and the **rhythm is regular** but sinus rhythm is NOT achieved? [1]

Answer 30

Assess using the ABCDE approach  Monitor SpO2 and give oxygen if hypoxic  Monitor ECG and BP, and record 12-lead ECG  Obtain IV access  Identify and treat reversible causes (e.g. electrolyte abnormalities) Adverse features? Shock; MI; HF: Syncope - IF NO - Check QRS - If < 0.12s = narrow complex tachycardia If rhythm is regular:  Perform vagal manoeuvres  Adenosine 6 mg rapid IV bolus  If no effect give 12 mg  If no effect give further 12 mg  Monitor/record ECG continuously **Diagnosis is probably atrial flutter: treat rate control - such as a beta blocker**

Question 31

What is the treatment algorithm for adult tachycardias (with pulse) once you have have assessed that there are no adverse features present and the **QRS complex is < 0.12 secs** and the **rhythm is regular** and sinus rhythm IS achieved? [1]

Answer 31

Assess using the ABCDE approach  Monitor SpO2 and give oxygen if hypoxic  Monitor ECG and BP, and record 12-lead ECG  Obtain IV access  Identify and treat reversible causes (e.g. electrolyte abnormalities) Adverse features? Shock; MI; HF: Syncope - IF NO - Check QRS - If < 0.12s = narrow complex tachycardia If rhythm is regular:  Perform vagal manoeuvres  Adenosine 6 mg rapid IV bolus  If no effect give 12 mg  If no effect give further 12 mg  Monitor/record ECG continuously **If sinus rhythm achieved**, **probably re-entry SVT (i.e. AVRT or AVNRT)**: - **Record 12 lead ECG in sinus rhythm** - **If SVT recurs treat again and consider anti-arrhythmic prophylaxis**

Question 32

What is the treatment algorithm for adult tachycardias (with pulse) once you have have assessed that there are no adverse features present and the **QRS complex is < 0.12 secs** and the **rhythm is IRREGULAR**? [3]

Answer 32

Assess using the ABCDE approach  Monitor SpO2 and give oxygen if hypoxic  Monitor ECG and BP, and record 12-lead ECG  Obtain IV access  Identify and treat reversible causes (e.g. electrolyte abnormalities) Adverse features? Shock; MI; HF: Syncope - IF NO - Check QRS - If < 0.12s = narrow complex tachycardia **If rhythm is irregular:** **Probable AF**:  Control rate with **beta-blocker or diltiazem**  If in heart failure consider **digoxin** or **amiodarone**  **Assess thromboembolic risk and consider anticoagulation**

Question 33

What do you check for next on the treatment algorithm for adult tachycardias (with pulse) once you have have assessed that there are no adverse features present and the **QRS complex is > 0.12 secs**? [1]

Answer 33

Assess using the ABCDE approach  Monitor SpO2 and give oxygen if hypoxic  Monitor ECG and BP, and record 12-lead ECG  Obtain IV access  Identify and treat reversible causes (e.g. electrolyte abnormalities) Adverse features? Shock; MI; HF: Syncope - IF NO - Check QRS - **If > 0.12s = broad complex tachycardia** **NEXT: check if regular or irregular**

Question 34

Describe the treatment algorithm for adult tachycardias (with pulse) once you have have assessed that there are no adverse features present, the **QRS complex is > 0.12 secs** and there is a **irregular rhythm** [2]

Answer 34

Assess using the ABCDE approach  Monitor SpO2 and give oxygen if hypoxic  Monitor ECG and BP, and record 12-lead ECG  Obtain IV access  Identify and treat reversible causes (e.g. electrolyte abnormalities) Adverse features? Shock; MI; HF: Syncope - IF NO - Check QRS - **If > 0.12s = broad complex tachycardia** **If regular** - could be:  **AF with bundle branch block** - treat as for **narrow complex** *Control rate with beta-blocker or diltiazem* *If in heart failure consider digoxin or amiodarone* *Assess thromboembolic risk and consider anticoagulation*  **Pre-excited AF** - consider **amiodarone**

Question 35

Describe the treatment algorithm for adult tachycardias (with pulse) once you have have assessed that there are no adverse features present, the **QRS complex is > 0.12 secs** and there is a **regular rhythm** [2]

Answer 35

Assess using the ABCDE approach  Monitor SpO2 and give oxygen if hypoxic  Monitor ECG and BP, and record 12-lead ECG  Obtain IV access  Identify and treat reversible causes (e.g. electrolyte abnormalities) Adverse features? Shock; MI; HF: Syncope - IF NO - Check QRS - **If > 0.12s = broad complex tachycardia** **If regular** - could be: **VT (or uncertain rhythm):**  **Amiodarone** **300** **mg IV over 20- 60 min then 900 mg over 24hr** OR **If known to be SVT with bundle branch block:**  **Treat as for regular narrowcomplex tachycardia**

Question 36

bradycardia resus

Question 37

device therapy

Question 38

The reversible causes of cardiac arrest are “4Hs and 4Ts”. Name them [8[

Answer 38

**H**ypoxia **H**ypokalaemia/hyperkalaemia **H**ypothermia/hyperthermia **H**ypovolaemia **T**ension pneumothorax **T**amponade **T**hrombosis **T**oxins