Cardiology: Cardiac Arrhythmias - Misc Flashcards
Describe the four possible rhythms in a cardiac arrest patient [4]
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)
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]
Amiodarone 300 mg IV over 10-20 min
Repeat shock
Then give amiodarone 900 mg over 24 h
go over
https://www.resus.org.uk/sites/default/files/2020-05/G2015_Adult_tachycardia.pdf
Broad complex tachycardia refers to a fast heart rate with a QRS complex duration of more than [] seconds or [] small squares on an ECG.
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.
Which pathologies are categorised as broad complex tachycardias? [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
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
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
Describe the pathophysiology of VT [1]
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.
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]
Synchronised DC cardioversion under sedation or general anaesthesia.
Intravenous amiodarone is added if initial DC shocks are unsuccessful.
Give four differential diagnoses to VT for a broad complex tachycardia [4]
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)
Describe what is meant by sick sinus syndrome [1]
What can cause sick sinus syndrome? [1]
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.
What does asytole mean? [1]
State 4 cardiac pathologies that increase risk of asytole [4]
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
What is the stepwise managment plan of unstable patients with those at risk of asytole? [4]
- 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
Describe the MoA of atropine [1]
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.
What is corrected QT interval (QTc)? [1]
What is prolonged QTc in men [1] and women [1]?
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
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]
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.
What does Torsades de pointes look like on an ECG? [1]
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.
Describe what is meant by ventricular ectopics [1]
How do they appear on ECGs? [3]
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.
Describe what is meant by heart block [1]
Describe the 3 types of heart block? [4]
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
Describe the resuscitation council treatment algorithm for adult tachycardias (with pulse) if the there are adverse features (e.g. shock, syncope, MI, HF) [5]
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
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]
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:
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]
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
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]
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
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]
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
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]
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
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]
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
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]
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
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]
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
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]
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
