Arrhythmias Flashcards
What are some symptoms of an arrhythmia?
Palpitations
SOB
Chest pain
Fatigue
What investigations might you do in a suspected arrhythmia?
24hr ECG with event recorder
Blood tests especially thyroid function
Echo
What are the different therapeutic approaches to arrhythmias?
Rate control versus rhythm control:
Digoxin/Beta-blocker/CCB + warfarin/aspirin
vs
Class Ic/III drugs +/- DC cardioversion
Electrical approaches - pace and ablation of AV node
Anticoagulation
What are some different types of arrhythmia?
Supraventricular Tachycardia Atrial Fibrillation Atrial Flutter Ventricular Fibrillation Ventricular Tachycardia Torsade de Pointes due to CHB/AF
What are the different classes of antiarrhythmics? What is their mechanism, when might each be used and what are some example drugs?
Vaughan-Williams Classification
I - Na channel blockers
Ia - Quinidine - delay repolarisation and increases AP duration, used for AF, VTach, WPW, others
Ib - Lidocaine - accelerate repolarisation, decrease AP duration, used for V arrythmias only
Ic - Flecainide - little effect on AP duration/repol, used for severe V arrhythmias or AF/flutter
II - Beta Blockers - Atenolol/Bisoprolol - depress phase 4 depolarisation, SV and V arrythmias, first line for AF (bisoprolol)
III - K channel blockers - Amiodarone - increase AP duration, prolong phase 3 repolarisation, used for difficult arryhthmias - life threatening Vtach/VF, resistant AF/flutter
- amiodarone many interactions
IV - CCB - Diltiazem, Verapamil - depress phase 4 depolarisation - used for paroxysmal SVT, rate control for AF/flutter
Others - Digoxin, Adenosine
What is the mechanism for digoxin?
Cardiac glycoside Inhibits Na/K ATPase - positive inotrope, allows more calcium for contraction - used in HF and AF - must monitor K levls - commonly used in elderly - antidote = digibind
Nausea, vomiting, xanthopsia, brady/tachycardia, other arrhythmias may occur
What is the mechanism for adenosine?
Slows conduction through AV node Use to convert paroxysmal SVT to sinus rhythm Short half life Only administered as fast IV push May cause asystole for a few seconds
How might SVT present? What is the treatment?
Palpitations
SOB
Dizziness
No sure treatment
Radiofrequency ablation high success
WPW/re-entrant tachycardia similar
How is Atrial Flutter treated?
Control ventricular rate and thromboembolic risk
Usually cardioversion(?)
Prevent with AA drugs or RFA of cavotricuspid isthmus
How is AF treated?
Anticoagulants
- warfarin
- dabigatran
- rivaroxaban
- apixaban
Reduces stroke risk by 80%
How is ventricular fibrillation treated?
Defibrillator
How might ventricular tachycardia present? What are the treatments?
Palpitations Chest Pain SOB Syncope Usually from structural heart disease (do bloods, echo, angio)
Cardiac arrest risk
DC cardioversion or drugs to treat
Treat underlying cause
Consider ICD
What is torsade de pointes?
A type of ventricular tachycardia
Can be caused by Long QT or QT prolonging drugs
Treat with drugs, pacing, or ICD
What are the different types of (AV) heart block?
First-degree
- PR > 0.2s
Second-degree
- Mobitz I (Wenckebach) - Progressive PR delay until QRS dropped
- Mobitz II - PR intervals stay the same, but a QRS complex is still dropped (regularly or irregularly)
- 2:1 - 2 P waves per QRS, can’t tell if it’s type I or II
Third-degree (complete)
- completely separate rhythms for P and QRS
When might you consider placing a pacemaker?
Temporary in intermittent/sustained symptomatic bradycardia, particularly if causing syncope
Prophylactic if high risk of severe bradycardia
Permanent
- Symptomatic Mobitz I
- Mobitz II or 3rd degree
- AV block caused by neuromuscular disease
- after/pre AV-node ablation
- alternating L/RBBB
- sinus node disease with symptoms
- basically any symptoms/syncope
