Arrhythmias Flashcards
Consequences of AF
Irregularly irregular ventricular contractions
Tachycardia
Heart failure - poor filling of ventricles during diastole
Risk of stroke
Presentation of AF
Often asymptomatic (incidental)
Palpitations
SOB
Syncope (dizziness or fainting)
Symptoms of associated conditions (e.g. stroke, sepsis or thyrotoxicosis)
Two causes for irregularly irregular pulse
Atrial fibrillation
Ventricular ectopics
AF on an ECG
Absent P waves
Narrow QRS Complex Tachycardia
Irregularly irregular ventricular rhythm
Causes of AF (SMITH)
Sepsis Mitral Valve Pathology (stenosis or regurgitation) Ischemic Heart Disease Thyrotoxicosis Hypertension
Who does NICE suggest does not receive rate control for their AF?
Patient who has: Reversible cause for their AF New onset AF (within the last 48 hours) AF causing heart failure Remained symptomatic despite being effectively rate controlled
Options for rate control
Beta blocker is first line (e.g. atenolol 50-100mg once daily)
Calcium-channel blocker (e.g. diltiazem) (not preferable in heart failure)
Digoxin (only in sedentary people, needs monitoring and risk of toxicity)
When is rhythm control offered?
AF with:
Reversible cause
New onset (<48 hours)
Heart failure
Symptoms despite being effectively rate controlled
Preparation for delayed cardioversion
Patient should be anticoagulated for a minimum of 3 weeks prior to cardioversion
First line for pharmacological cardioversion
Flecanide Amiodarone (the drug of choice in patients with structural heart disease)
Drugs used in long term medical rhythm control
Beta blockers
Dronedarone
Amiodarone - useful in patients with heart failure or left ventricular dysfunction
Target INR for AF
2-3
DOACs vs warfarin
No monitoring is required
No major interaction problems
Equal or slightly better than warfarin at preventing strokes in AF
Equal or slightly less risk of bleeding than warfarin
What is the CHA2DS2-VASc score?
Does a patient with AF need anticoagulating?
RF for stroke or TIA
>1 = offer anticoagulation
CHA2DS2-VASc Mnemonic
C – Congestive heart failure H – Hypertension A2 – Age >75 (Scores 2) D – Diabetes S2 – Stroke or TIA previously (Scores 2) V – Vascular disease A – Age 65-74 S – Sex (female)
What is HASBLED?
Tool for establishing a patient’s risk of major bleeding whilst on anticoagulation
What are the four cardiac arrest rhythms?
Ventricular tachycardia
Ventricular fibrillation
Pulseless electrical activity
Asystole
How is Atrial flutter treated?
Rate control
beta blocker
How are Supraventricular tachycardias treated?
Vagal manoeuvres
Adenosine
Tachycardia treatment in unstable patient
Consider up to 3 synchronised shocks
Amiodarone infusion
Treatment for VT
Amiodarone infusion``
Conditions associated with atrial flutter
Thyrotoxicosis
Hypertension
Ischaemic heart disease
Cardiomyopathy
Treatment for Atrial Flutter (4)
Rate/rhythm control with beta blockers or cardioversion
Treat the reversible underlying condition (e.g. hypertension or thyrotoxicosis)
Radiofrequency ablation of the re-entrant rhythm
Anticoagulation based on CHA2DS2VASc score
What is SVT caused by?
Electrical signal re-entering the atria from the ventricles
Acute Management of Stable patients with SVT (6)
Continuous ECG monitoring
Valsalva manoeuvre - Blow hard against resistance - plastic syringe
Carotid sinus massage. Massage the carotid on one side gently with two fingers
Adenosine
An alternative to adenosine is verapamil (calcium channel blocker)
Direct current cardioversion may be required if the above treatment fails
What does adenosine do?
Slows conduction though the AV node
Interrupts the AV node / accessory pathway during SVT and “resets” it back to sinus rhythm
Often causes a brief period of asystole or bradycardia, however it is quickly metabolised and sinus rhythm should return
Key points in administering adenosine
Avoid if patient has asthma / COPD / heart failure / heart block / severe hypotension
Warn patient about the scary feeling of dying / impending doom
Give as a fast IV bolus into a large proximal cannula
What is the long term management of paroxysmal SVT
Medication (beta blockers, calcium channel blockers or amiodarone)
Radiofrequency ablation
What happens in WPW syndrome?
Extra electrical pathway connecting the atria and ventricles
(Bundle of Kent)
Treated with radiofrequency ablation of the accessory pathway
ECG changes in WPW syndrome
Short PR interval (< 0.12 seconds)
Wide QRS complex (> 0.12 seconds)
“Delta wave” which is a slurred upstroke on the QRS complex
Causes of long QT
Long QT Syndrome (inherited)
Medications (antipsychotics, citalopram, flecanide, sotalol, amiodarone, macrolide antibiotics)
Electrolyte Disturbance (hypokalaemia, hypomagnesaemia, hypocalcaemia)
First degree HB on ECG
PR interval greater than 0.20 seconds
Wenckebach’s phenomenon (Mobitz Type 1) on ECG
Increasing PR interval until the P wave no longer conducts to ventricles
Mobitz Type 2 on ECG
Usually a set ratio of P waves to QRS complexes
Third degree HB
Complete heart block
no observable relationship between P waves and QRS complexes
Significant risk of asystole
Treatment for unstable bradycardia or AV node block
FIRST LINE: Atropine 500mcg IV
Other inotropes (such as noradrenalin) Transcutaneous cardiac pacing (using a defibrillator)
Treatment for bradycardia or AV node block In patients with high risk of asystole (i.e. Mobitz Type 2, complete heart block or previous asystole)
Temporary transvenous cardiac pacing
Permanent implantable pacemaker
Side effects of atropine
antimuscarinic - inhibits the parasympathetic nervous system
pupil dilatation
dry eyes
urinary retention
constipation
