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
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What are some causes of AF?
- Heart failure
- HTN
- IHD
- PE
- Mitral valve disease
- Pneumonia
- Alcohol
- Caffeine
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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
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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
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How does AF present on ECG?
- Absent P waves
- Irregular QRS complexes
- Different height QRS complexes
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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
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What are some contraindications to using flecainide for cardioversion?
- Structural heart disease
- Ischaemic heart disease
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
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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?
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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
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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
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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
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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?
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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
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What is pre-excited AF?
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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
Therefore pulse is regular with Atrial Flutter but irregular with AFib
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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
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How can we classify tachycardia arrhythmias?
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