4 - Tachyarrhythmias, AF and Atrial Flutter Flashcards
AF is the most common arrhythmia. What is AF and what are the risks of this arrhythia?
Chaotic irregular atrial rhythm at 300-600bpm with the AV node responding intermittently so irregular ventricular rhythm
Drops cardiac output by 10-20% as ventricles not primed by atria
Risk of embolic stroke, cardiac instability and death
What are some causes of AF?
- Heart failure
- HTN
- IHD
- PE
- Mitral valve disease
- Pneumonia
- Alcohol
- Caffeine
What are some signs and symptoms of AF?
Symptoms: asymptomatic, chest pain, syncope, palpitations, breathlessness, dizziness
Signs: irregularly irregular pulse, need to examine whole paitent as AF often not cardiac cause
What investigations do you do to diagnose AF?
- Pulse check if having symptoms for irregularity
- Same day ECG but if suspect paroxysmal then use 24h ECG, if need longer can consider loop recorder
- Blood tests: U+Es, cardiac enzymes, TFTs
- Echocardiography: looking for left atrial enlargement, mitral valve disease, poor LV function
How does AF present on ECG?
- Absent P waves
- Irregular QRS complexes
- Different height QRS complexes
What are the three management principles for AF?
- Anticoagulation to prevent stroke
- Rate control
- Rhythm control
Which patients should you always do an ECG for to check for AF?
- Irregular pulse
- Symptoms like dizziness, palpitations, syncope can have 24h monitoring
How should you manage acute AF is patient is:
- Unstable
- Stable and started within last 48 hours
- Stable and started over 48 hours ago
Unstable (e.g heart failure, shock): ABCDE, Senior input, DC cardioversion +/- amiodarone if unsuccessful. Then anticoagulate.
Stable <48h: rhythm control by DC cardiovert or give flecainide or amiodarone. Then anticoagulate
Stable >48h or unclear time of onset: rate control with bisoprolol or diltiazem and anticoagulate for at least 4 weeks before rhythm control
What are some contraindications to using flecainide for cardioversion?
- Structural heart disease
- Ischaemic heart disease
- Previou/Current MI
Why do you need to anticoagulate patients with unknown time of onset for AF before cardioversion?
May have already developed intracardiac clot so need to lower the risk of it embolising and causing a stroke
Once a diagnosis of AF has been made, how do you decide whether you should anticoagulate the patient?
Use CHA2DS2VaSC score to quantify risk of stroke or embolism
Score >2: Significant risk so needs anticoagulation
Score of 1: Intermediate risk in men and should consider anticoagulation based on bleeding risk. Low risk in women so don’t anticoagulate
Score of 0: Low risk so no anticoagulation
If someone has a CHADVASC score of 0 or 1 what do you need to do?
ECHO to look for structural heart disease as will add another point to their score
How do you assess the risk of bleeding with anticoagulating AF patients?
ORBIT score. Does not withhold anticoagulation but helps to identify and optimise risk factors for bleeding
Aspirin and NSAIDs in bleeding. Also alcohol means harmful drinking >14 units a week
Which anticoagulants are used when anticoagulating an AF patient?
DOAC like apixiban, rivaroxaban, edoxaban (Xa inhibitors) or dabigatran (direct thrombin inhibitor)
Can use warfarin but high rights of GI/brain bleeds, needs regular testing levels, restrictions on food and alcohol
What monitoring do you need to do when a patient is on a DOAC?
- Yearly renal monitoring as excreted by the kidneys
- Better than Warfarin at reducing strokes
What are the options for rhythm control in AF?
Can either restore the heart rhythm to normal or use medication to rhythm control
DC shock: need ECHO before to check for intracardiac emboli. If risk of failure use amiodarone for 4 weeks before
Medication: Flecainide 1st line unless structural heart disease (e.g scar from MI) then use Amiodarone
In acute AF rhythm control and anticoagulation are preferred. In chronic AF rate control and anticoagulation are preferred. When might you do rhythm control in acute AF instead of rate control?
- Symptomatic
- Young patient
- Presenting for first time with lone AF
What are the rate control options for AF and what HR are you aiming for?
1st line: BB (e.g bisoprolol/atenolol) or Rate Limiting CCB
2nd line: Add digoxin (only if sedentary patient)
3rd line: consider adding amiodarone
Aim for 90bpm at rest and 200-age on exertion
What is pre-excited AF?
Pre-excited atrial fibrillation (AF), also known as AF with pre-excitation, is a potentially dangerous heart condition that occurs when a person with an abnormal electrical pathway in their heart (called an accessory pathway) also develops atrial fibrillation.
Normal Heart Rhythm vs. Pre-excited AF:
In a normal heart, electrical signals originate in the atria (upper chambers) and travel down to the ventricles (lower chambers) through a specialized pathway called the atrioventricular (AV) node. This node acts as a gatekeeper, controlling the heart rate and ensuring the ventricles contract in a coordinated manner.
Accessory Pathway:
In people with an accessory pathway, there’s an extra electrical connection that bypasses the AV node, allowing signals to reach the ventricles directly. This can cause the heart to beat too fast, leading to a condition called pre-excitation.
Atrial Fibrillation:
Atrial fibrillation (AF) is a different heart rhythm problem where the electrical signals in the atria become chaotic and disorganized. This causes the atria to quiver instead of contracting effectively, and can also lead to a fast heart rate.
When these two conditions occur together (pre-excitation and AF), it creates a potentially dangerous situation. The chaotic electrical signals from the atria can be conducted very rapidly through the accessory pathway, leading to an extremely fast heart rate in the ventricles. This can be life-threatening and requires immediate medical attention.
Symptoms of pre-excited AF can include:
Palpitations (feeling like your heart is racing or pounding)
Dizziness or lightheadedness
Shortness of breath
Chest pain
Fatigue
How does atrial flutter differ to AF on ECG?
Atrial flutter has sawtooth baseline but regular QRS complexes unlike A Fib that has irregular complexes
btw the actual compexes in A fib are regular but the space between complexes are irregular
Therefore pulse is regular with Atrial Flutter but irregular with AFib
How is Atrial flutter treated?
- Same principles as AF: anticoagulate, rate control, rhythm control
- DC cardioversion preferred over pharmacological
- Amiodarone may be needed if rate control difficult
- High reccurrence rate so radiofrequency ablation recommended long term
How can we classify tachycardia arrhythmias?
What are some causes supraventricular tachycardias? (narrow complex tachycardias)
HR>100bpm but QRS<0.12s
Regular Narrow Complex Tachycardia: sinus tachycardia, focal atrial tachycardia, atrial flutter, AVRT, AVNRT
Irregular Narrow Complex Tachycardia: normal variant of sinus rhythm with ectopic beats, AF, multifocal atrial tachycardia
What are the most common causes of paroxysmal supraventricular tachycardia and why is it important to know this?
- Atrio-ventricular re-entry tachycardia (30%)
- AV nodal re-entry tachycardia (60%)
Helps with management. Both of these depend on AV nodal conduction so can be terminated by transiently blocking AV nodal conduction.
First line SVT always assume one of these in management
How do we manage an SVT?
Haemodynamically compromised (e.g hypotensive, pulomary oedema)
- Sedate and DC cardioversion
Haemodynamically Stable
- Correct any abnormalities, e.g sinus tachycardia due to dehydration give fluids
- 1st Line: Vagal manouevres if suspect AVNRT, AVRT
- 2nd Line: adenosine or CCB
- If neither of the above have resolved the tachycardia this rules out AVNRT and AVRT as you have blocked AV node
What are some vagal manouevres used to try and treat and SVT first line?
- Breath holding
- Valsalva manouevre (blowing into syringe or bearing down)
- Carotid Sinus massage
What are some important safety points to consider when doing a carotid sinus massage?
- Only do in young patients
- Auscultate for bruits before to reduce risk of stroke
- Only do one side at a time and wait 10 seconds before doing next one
If vagal manouvres do not work for an SVT then adenosine is given. How is this given and what side effects should you warn the patient about?
- Short acting drug that blocks AV node conduction. Given as IV bolus in antecubital fossa in threecock fashion followed by long saline flush
- Chest discomfort, transient hypotension, flushing
- Need to have crash trolley next to patient when using this drug. Avoid in asthmatics
What other drugs can you use for SVTs apart from adenosine, and what are the contraindications of these drugs?
- IV Verapamil: cannot be used in patients already on b-blockers or with LV dysfunction
- IV Flecainide: needs to be avoided in patients with past or present MI
If both adenosine and verapamil are contraindicated in an SVT send for cardioversion under GA or sedation
What is holiday heart syndrome?
Binge drinking or using marijuana in a person without any clinical evidence of heart disease can cause an acute cardiac rhythm usually atrial in origin
Most commonly AF or SVT
Resolves rapidly by abstaining from alcohol. Advise patients to avoid drinking excessively in the future
What are the causes of ventricular tachycardias?
HR>100bpm with broad complex QRS>0.12s
- VF (no pattern)
- Ventricular tachycardia
- Torsades de points
- Any narrow complex tachycardia with BBB
- Antidromic AVRT
Ventricular tachycardia is the most common broad complex tachycardia, especially after a STEMI. How do you manage these patients?
Haemodynamically compromised: sedate and DC cardiovert
Haemodynamically stable: Amiodarone 300mg IV over a few minutes or Lidocaine. Can also try B-blockers to suppress rate but need to be careful in hypotension and LV dysfunction
How do ventricular ectopics present and what do they look like on ECG?
Can be felt as palpitations, thumping or heart missing a beat. May have irregular pulse if frequent ectopics
Will have broad QRS complex on its own or in patterns
Ventricular ectopics are common in healthy people. When do we start to get concerned about them?
- Frequent ectopics (>60 an hour)
- Couplets and Triplets
- Post MI
Need to look if ectopics all look the same or different to see if coming from focal point or multifocal
What are some indications for temporary and permanent cardiac pacing?
Permanent:
- Complete AV block
- Mobitz type 2
- Persistent AV block after anterior MI
- Symptomatic bradycardias e.g sick sinus
- Heart failure
- Drug resistant tachyarrhythmias
What is cardiac resynchronization therapy?
Used for people with symptomatic heart failure with ejection fraction <35% and broad QRS
Synchronises cardiac contraction to reduce mortality
Biventricular pacing and sometimes an atrial lead. Can be combined with defibrillator
What is a fusion beat?
Union of native depolarisation and pacemaker impulse
What is the issue with long QT syndrome?
Prolonged repolarisation predisposes patient to ventricular arrhythmias
How does WPW appear on ECG and what drugs should you not give to these patients?
- Delta waves (slurred upstroke QRS)
- Shortened PR interval
- Widened QRS
Due to congenital accessorry conduction pathway that needs ablation
What is hypertrophic cardiomyopathy?
LV outflow tract obstruction due to assymetrical septal hypertrophy.
Leading cause of cardiac death in the young
Whay is myocarditis and what are some causes of this?
Inflammation of the myocardium with associated pericardial inflammation
What are some causes of pericaditis?
How is pericarditis treated?
- NSAIDs or Aspirin for 2 weeks with gastric protection
- Can give colchicine to reduce recurrence
- Rest until symptoms resolve
What is Kussmaul’s sign and what are some differentials when this sign is present?
JVP rising paradoxically with inspiration
Differentials: constrictive pericarditis, cardiac tamponade, massive PE,
How is cardiac tamponade diagnosed and managed?
Dx: Beck’s Triad, ECHO is diagnostic with echo-free zone around the heart, ECG
Mx: pericardiocentesis and then send off for culture, ZN stain, cytology
BECKS: DISTENDED MUFFLED LOW BP
Patients are in periarrest with broad complex tachycardias (V-Tach, VFib and Torsades de Pointes). How do you manage them?
Haemodynamically stable VT: correct hypoK+hypoMg, amiodarone via central line, if doesn’t work DC shock
Haemodynamically unstable VT: synchronised VT, correct electrolytes, amiodarone
VFib: non-synchronised DC shock
Tosades de Pointes: MgSO4
