Arrhythmias Flashcards
What is an arrhythmia?
Irregular rhythm of the heart
What is a bradyarrhythmia?
Heart rhythms with a rate of < 60 bpm
What are the risks associated with a bradyarrhythmia?
Risk of:
sudden cardiac death due to slowing or stopping of the heart
falls - especially in elderly people (due to fainting)
How could patients with bradyarrhythmia present?
Lethargy
SOB
Chest pain
Dizziness
Fainting (due to reduced cardiac output and cardiac and cerebral hypoperfusion)
Syncope - episodic and often infrequent (20-40% of patients report and episode of syncope with bradycardia, and this may recur in 10-15% of patients)
What is the aetiology of bradycardia?
Sinus node dysfunction
- sinus bradycardia
- sinoatrial nodal pauses/arrests
- sinoatrial nodal exit bock
AV conduction disturbances
- 1st degree AV-block
- 2nd degree AV block (Mobitz I, II, 2:1 block, high degree AV block)
- 3rd degree AV block
AV dissociation
- isorhythmic dissociation
- interference dissociation
What are the common causes of bradyarrhythmias?
More common in older people due to degeneration and fibrosis of the conducting system e.g.,
- sinus node disease
- AV block
Ischaemic heart disease
HTN
Thyroid dysfunction
AV blocking drugs e.g., β blockers, CCBs, digoxin
What investigations would you do for bradyarrhythmias?
Bedside
- 12-lead ECG : can be performed in primary care if patient is clinically stable
Bloods
- TFT : to exclude thyroid causes
- U&E : to check for electrolyte imbalance
Imaging
- ECHO : once bradyarrhythmia is diagnosed esp. in the presence of symptoms to assess LVEF as this will influence the choice of pacemaker
- MRI : in < 55 years old to exclude cardiomyopathy
What are the red flags that should prompt referral of a bradyarrhythmic patient to secondary care?
Patient clinically unstable (e.g., hypotension, impaired consciousness or chest pain)
Ongoing pre-syncope or syncope associated with any bradyarrhythmia
Syncope with the following features:
- abnormal ECG
- HF
- new or unexplained breathlessness
- syncope on exertion
- syncope without prodrome in a patient > 65 years old
- FHx of inherited arrhythmia or sudden cardiac death
Persistent (i.e., continuous and not intermitted) type 2 second-degree heart block or complete heart block whether asymptomatic or not
How is bradyarrhythmia managed?
Correct reversible causes e.g., bradyarrhythmia
Chest pain - after ischaemia is treated do further observation on a coronary care unit until bradyarrhythmia resolves
Don’t delay Tx of bradyarrhythmia even if the patient has metabolic derangement
No long term medical therapy (but isoprenaline or adrenaline is sometimes given in high dependency units)
If bradyarrhythmia persists discuss pacemaker treatment with patient
What are the rarer causes of bradyarrhythmias?
Inflammatory cardiac disease e.g., sarcoidosis
Infectious diseases e.g., Lyme disease, acute rheumatic fever, infectious mononucleosis
Cardiomyopathies e.g., Leiden dilated cardiomyopathy, amyloidosis
Neurological diseases e.g. myotonic dystrophy, limb girdle muscular dystrophy
Catheter ablation
What are the common pacemaker types, their indications and long-term complications?
What are the common bradyarrhythmias, their ECG features, risk factors, symptoms and Mx?
How can you classify tachyarrhythmias?
Narrow complex
Broad complex
How do you further classify narrow and broad complex tachyarrhythmias?
Regular
Irregular
Name the causes of regular narrow complex tachyarrhythmias
Sinus tachycardia
AVNRT
AVRT
Atrial flutter
What is AVNRT? What causes it?
AV nodal re-entry tachycardia
Two pathways i.e., dual conduction pathways that can pass impulses to and from the AV node
Usually starts following an early beat (ectopic)
Electrical short circuit then occurs where the electrical impulses rotates around the circuit and with each cycle pass to the ventricles
Results in a very fast heartbeat
What is AVRT/WPW?
AV re-entry tachycardia
Extra electrical pathway that bypasses the AV node i.e., accessory pathway
This pathway directly connects the atria to the ventricles
Electrical impulses reach ventricles before the normal electrical impulse i.e., pre-excitation
What does an ECG of a patient with WPW show?
Delta wave
What is an atrial flutter?
Occurs in atria
Similar to AF as electrical impulses are fired rapidly but the rhythm is regular and organised
Rhythm is due to a re-entry circuit within the atria, where the electrical impulse travels in circles leaving and arriving back at the same point
Atria can beat at 300bpm
Name the causes of irregular narrow complex tachyarrhythmias
Atrial fibrillation
Multifocal atrial tachycardia
What is AF?
One of the most common types of arrhythmias
Occurs in the atria
Electrical impulse originates in SA nodes, but many impulses are fired rapidly and at random throughout the atria down to the ventricles
Resulting heartbeat is irregular and usually fast
How does AF increase the risk of thrombus formation?
Rapid beating of atria means they are unable to empty all the blood they receive into the ventricles
This blood pooling can cause blood clot formation
Can cause embolus in brain (stroke)
Patients are placed on blood thinners to prevent this
Name the causes of regular broad complex tachyarrhythmias
Ventricular tachycardia
Supraventricular tachycardia (e.g., AVRT, AVNRT) with BBB
What is VT?
Electrical impulses arise in the ventricles
Ventricles start beating at an abnormally fast, irregular rate
What are the symptoms of VT?
Weakness
Dizziness
Chest pain
SOB
Collapse
What are the causes of VT?
Previous MI = scar tissues increases susceptibility to abnormal heart rhythms
Cardiomyopathy
Previous corrective congenital heart surgery
Inherited
N.B. small group of VT patients with structurally normal heart
Name the causes of irregular broad complex tachyarrhythmias
AF with BBB
Polymorphic VT (i.e., Torsade de pointes)
Pre-excited AF
What is the Mx of regular narrow complex tachyarrhythmias?
Vagal manoeuvres
Adenosine 6mg rapid IV bolus -> (if no effect) 12mg -> (if no effect) 12mg
Monitor/record ECG continuously
What is the Mx of irregular narrow complex tachyarrhythmias?
Probable AF
Control rate with beta-blockers (class 2 antiarrhythmics), CCB (class 4 antiarrhythmics)
Heart failure = digoxin or amiodarone
Assess thromboembolic risk and consider anticoagulation
If the Mx of regular narrow complex tachyarrhythmias works what should you do?
Probable re-entry paroxysmal SVT
- Record 12-lead ECG in sinus rhythm
- If SVT recurs treat again and consider anti-arrhythmic prophylaxis
If the Mx of regular narrow complex tachyarrhythmias does not work what should you do?
Seek expert help
Possible AF
- control rate (e.g., with beta-blockers)
What is the Mx of regular broad complex tachyarrhythmias?
VT
- Amiodarone 300mg IV over 20-60 min then 900mg over 24 h
SVT with BBB
- treat as for regular narrow complex tachycardia
What is the Mx of irregular broad complex tachyarrhythmias?
Seek expert help
DDx include:
- AF with BBB = treat as for irregular narrow complex
- Pre-excited AF = consider amiodarone
What is the Mx of irregular broad complex tachyarrhythmias?
Seek expert help
DDx include:
- AF with BBB = treat as for irregular narrow complex
- Pre-excited AF = consider amiodarone
What are the different of AVRT?
ORTHODROMIC - down the AV node and up the accessory pathway
ANTIDROMIC - down the accessory pathway and up the normal AV conduction
a) Which patients are given permanent pacemakers?
b) How is it inserted?
c) How does it work?
a) Patients with Tx resistant AF
b) implanted beneath the skin below the clavicle and connected to a pacing wire placed inside the heart. Done with AV node ablation
c) delivers a small electrical impulse to stimulate the heart to beat when it is going too slowly
a) Which patients are given radiofrequency energy/cryo energy catheter ablation?
b) How is it done?
c) How does it work?
a) those with an extra electrical pathway or group of cells who may not have responded well to meds or who cannot/would rather not take meds
b) scar tissue created
c) blocks the area of extra electrical activity causing the arrhythmias. High % of success in treating many types of arrhythmia
a) Which patients are given internal cardioversion?
b) How is it done?
c) How does it work?
a) patient in whom meds and external cardioversion have been unsuccessful in returning the heart’s rhythm back to a normal sinus rhythm
b) two catheter inserted into the vein in the groin and a small electrode pad is placed on the chest. Patient is sedated for the procedure
c) Low energy electrical shocks are delivered inside the heart.
a) Which patients are given an implantable cardioverter defib (ICD)?
b) How is it inserted?
c) How does it work?
a) patients who have life-threatening arrythmias
b) larger device than a pacemaker. Placed under the skin below the clavicle. Connected via leads that are placed in the heart
c) determines and stops fast ventricular arrhythmias by using extra paced beats a.k.a ‘anti-tachycardia pacing’ (ATP) or by delivering an electric shock to the heart. Also capable of pacing the heart if it goes too slowly
Tachyarrhythmia sources
https://www.bhf.org.uk/informationsupport/conditions/arrhythmias/atrial-flutter
https://www.youtube.com/watch?v=-enL5BclTUA&t=170s
https://geekymedics.com/narrow-complex-tachycardia/
https://www.resus.org.uk/sites/default/files/2020-05/G2015_Adult_tachycardia.pdf
https://www.uhs.nhs.uk/Media/UHS-website-2019/Patientinformation/Heartandlungs/Tachyarrhythmias-727-PIL.pdf
https://www.bhf.org.uk/informationsupport/conditions/arrhythmias/atrial-flutter
