Cardiology emergencies: Bradyarrythmias Flashcards
(25 cards)
What is a bradyarrhythmia?
An abnormally slow heartbeat, with the heart rate being under 60bpm, that is caused by an irregular heart rhythm
What are the different types of bradyarrhythmias?
Slow People Should Try Coffee
S: Sinus bradycardia
P: Pause eg. Sinus arrest
S: Sick sinus syndrome
T: Types of AV block (1st degree, Wenckebach, Mobitz 2, 3rd degree)
C: Conduction blocks eg. Bundle branch block, fascicular block
How do you explain to a patient the causes of bradycardias?
STAGC RDJ
Sick sinus syndrome
Thyroid underactive (hypothyroidism) and electrolyte imbalances (potassium, calcium, magnesium)
Athletic heart or age over 65yrs (age-related degeneration)
GI mesenteric traction
Cardiac: Ischaemic heart disease and cardiomyopathy
Rest/sleep (normal sleep or obstructive sleep apnea): Increased vagal tone
Drugs (beta-blockers, verapamil and diltiazem, digoxin)
Jaundice and infections
How do you explain to a patient the 5 common symptoms of bradyarrhythmias?
Fatigue
Dizziness or lightheadedness
Fainting
SOB
Low exercise tolerance
How do explain to a patient what causes the symptoms of bradyarrhythmias?
Bradyarrhythmias cause the heart to beat slower and less regularly than usual.
This means that less blood is pumped out of the heart around the rest of the body (low perfusion causes hypoxic symptoms):
–Less blood pumped to the brain causes dizziness, lightheadedness, fainting
—Less blood pumped to the lungs causes shortness of breath and low exercise tolerance (less oxygen is put into blood to give to muscles)
How do you explain to a patient how bradyarrhythmias are diagnosed?
Main test: ECG
Further tests to confirm diagnosis:
Holter monitor: It records 24-48 hour tape of heatbeat
Electrophysiology study: Catheters inserted into heart through a cut in the groin, to map electrical pathways and find source
Exercise stress test: Monitoring the heart’s electrical activity and blood pressure while the patient does exercise, like walking on a treadmill, to confirm if bradyarrhythmia is causing mild/moderate/severe symptoms
Blood tests: Thyroid hormone level and electrolyte levels
Sleep study: Indicated if patient could have OSA
Tilt table test: Shows how the body reacts to changes in position. It can help find the cause of fainting or dizziness
How do you explain to a patient what sick sinus syndrome is, and why it happens?
Malfunction of the SA node, which causes bradyarrhythmias
The sino-atrial node is the natural pacemaker in the heart, and its role is to produce electrical signals that trigger different areas of the heart to pump in order.
In sick sinus syndrome, the SA node fails to generate impulses properly, or impulses are blocked from leaving the node. This causes abnormally slow, irregular, or pausing heart rhythms
Can also cause tachyarrhythmias: Tachy-brady syndrome
What is the main ECG finding of sick sinus syndrome?
Sinus bradycardia: Regular 60bpm rate with present p waves
Sinus pauses or arrests: Sudden flatlines for 2-3 seconds
Tachy-brady syndrome: Alternating fast (e.g. AF, atrial tachycardia) and slow rhythms (bradycardia or pause)
SA exit block: Intermittent dropped p waves
How do you explain to a patient what sinus arrest is?
SA node, the heart’s natural pacemaker, temporarily stops generating electrical impulses, causing a pause in the heart’s rhythm that last several seconds-minutes
Ventricle cells take over as back-up pacemaker: Escape rhythm
What is the main ECG finding in sinus arrest?
Sudden flatline lasting 2-3 seconds
Pause may be irregular in length, not a multiple of the normal P–P interval
How do you explain to a patient what sinus bradycardia is?
Heart rate is slower than normal, specifically below 60 beats per minute in adults, while maintaining a normal regular rhythm
How do you explain to a patient what fascicular block is, and explain why it happens?
Complete left bundle is not blocked, but rather only the left anterior or left posterior fascicles are blocked (LAFB, LPFB)
What is right bundle branch block, and what causes it?
Electrical signal to the right ventricle is delayed or blocked, causing the right side of the heart to beat after the left
Depolarisation through the bundle of His occurs only via the left bundle branch. The left branch still depolarises the septum as normal. This left impulse eventually depolarises the right ventricular walls
What is the ECG finding of right bundle branch block?
MaRRoW
M shaped QRS complex in lead VI
W shaped slurred S wave in lead V6
What is left bundle branch block, and what causes it?
Electrical signal to the left ventricle is delayed or blocked, causing the left side of the heart to beat after the right
Depolarisation through the bundle of His occurs only via the right bundle branch. Septum is abnormally depolarised from right to left. This right impulse eventually depolarises the left ventricular walls
What is the ECG finding of left bundle branch block?
WiLLiaM
W shaped slurred S waves in lead VI
M shaped QRS complex in lead V6
What is 3rd degree heart block?
Complete atrioventricular dissociation, so no atrial impulses are conducted to ventricles, so ventricular escape rhythms occur to let ventricles beat independently
What are the main ECG findings of third degree heart block, and explain why?
Regular P-P intervals (distance between P waves) and regular R-R intervals, but no association with each other
Very bradycardic
If a patient has symptomatic bradycardia, what is the initial assessment?
Assess with ABCDE approach and give appropriate interventions eg. maintain airway, give oxygen
Constant cardiac monitoring with 12-lead ECG, pulse oximetry, blood pressure
Establish IV access
After the initial assessment of symptomatic bradycardia, what should you check?
Does the patient have unstable or stable bradycardia
Unstable bradycardia: Chest pain, hypotension, confusion/altered mental status, pallor (due to haemodynamic instability)
Stable bradycardia: No significant symptoms indicating haemodynamic instability (probably normal bp)
How should a patient with stable bradycardia be treated?
Continuous cardiac monitoring with 12-lead ECG, pulse oximetry, blood pressure
Keep atropine and transcutaneous pacing pads at bedside, in case patient becomes haemodynamically unstable - switch to unstable bradycardia algorithm
How should a patient with unstable bradycardia be treated?
- Give 1mg atropine IV, can repeat every 3-5 min until max. 3mg has been given
- Ineffective atropine: Transcutaneous pacing
- Ineffective transcutaneous or transvenous pacing: Add IV dopamine infusion (5-20 mcg/kg per minute) or IV adrenaline infusion (2-10 mcg per min)
- Still ineffective: Transvenous pacing and cardiology
Why should patients with bradycardia be constantly monitored in hospital, even if they don’t have symptoms?
There is a risk of asystole
What is the long-term treatment for asymptomatic bradycardia?
Routine follow up
Treat reversible causes
