Cardiac Arrhythmia 2 Flashcards
What is the atrial activity described as in atrial fibrillation?
Chaotic and disorganised
What is the heartbeat like in atrial fibrillation?
Irregularly irregular
What are the three variations of atrial fibrillation?
Paroxysmal
Persistent
Permanent (chronic)
How does atrial fibrillation present?
Can be asymptomatic or symptomatic
What is sustained atrial fibrillation facilitated by?
Increased parasympathetic tone, atrial refractory periods are decreased, shortening the wave length, making it easier fir AF to sustain itself
What is chronic atrial fibrillation associated with?
Heart disease
What is paroxysmal atrial fibrillation associated with?
Normal hearts
What increases the incidence of atrial fibrillation?
Age
Where are the ectopic foci in atrial fibrillation?
In muscle sleeves in the ostia of the pulmonary veins
What are the methods of atrial fibrillation termination?
- Pharmacologic cardioversion with anti-arrhythmic drugs (30% effective)
- Electrical cardioversion (90% effective)
- Spontaneous revision to sinus rhythm
What drugs can be used to terminate atrial fibrillation?
Flecainide
Sotalol
Amiodarone
Define paroxysmal atrial fibrillation?
Paroxysmal and lasting less than 48 hrs
Often recurrent
Define persistent atrial fibrillation?
An episode of AF lasting longer than 48hrs, which can still be cardioverted to NSR
Unlikely to spontaneously revert to NSR
Define permanent Atrial fibrillation?
Inability of pharmacologic methods to restore NSR
Name some of the cardiac conditions associated with atrial fibrillation?
Hypertension CHF Sick sinus rhythm Coronary heart disease cardiac valve disease congenital heart disease pericarditis Tumours
Name some non-cardiac conditions associated with atrial fibrillation?
Obesity Thyroid disease Familial Alcohol abuse Cardiac surgery COPD, pneumonia Septicaemia Vagal cause- high endurance athletes
Define lone (idiopathic) atrial fibrillation
Absence of any heart disease and no evidence of venticular dysfunction
A diagnosis of exlusion
What could be the cause of lone atrial fibrillation?
Genetic?
What is associated with lone atrial fibrillation?
Significant stroke risk of >75 years of age
What are the symptoms of atrial fibrillation?
- Palpitations
- pre-syncope
- syncope
- chest pain
- dyspnoea
- sweatiness
- fatigue
What would you see on an ECG of atrial fibrillation?
Atrial rate: >300bpm Rhythm: Irregularly irregular Ventricular rate: variable Absence of P waves Presence of f waves
What is the ventricular rate dependant upon in atrial fibrillation?
AV node conduction properties
Sympathetic and parasympathetic tone
Presence of drugs which act on the AV node
What is AV nodal conduction facilitated by?
Sympathetic tone and inhibited by parasympathetic tone
What drugs are useful in controlling ventricular rate in atrial fibrillation?
beta blockers and calcium channel blockers which are effective at slowing conduction and prolonging refractoriness in the AV node
What may co-exist with AF?
Periods of fast ventricular rate, which may require a pacemaker to allow for pharmacologic control
How does atrial fibrillation effect diastole?
lost atrial kick and decreased filling times
What can atrial fibrillation result in?
Congestive heart failure, especially when there is diastolic dysfunction
What do ventricular rates of <60bpm suggest in atrial fibrillation
AV conduction disease
What should be done in the presence of atrial fibrillation and AV conduction disease?
Caution taken with anti-arrhythmic and rate controlling drugs
May require permanent pacing
What are the objectives of managing atrial fibrillation?
Rhythm control (maintain SR) OR Rate control (Accept AF but control ventricular rate)
Anti-coagulation if high risk for thromboemolism
Which drugs are used for rate control in atrial fibrillation?
If restoration to SR is not possible, slow down AVN conduction;
- digoxin
- b blockers
- verapamil, diltiazem
How can you restore sinus rhythm in atrial fibrillation?
- pharmacological cardioversion with anti arrhythmic drugs (amiodarone)
- direct current cardioversion
How do you maintain SR in a patient who had atrial fibrillation?
- anti-arrhythmic drugs (flecainide, sotalol, amiodarone)
- catheter ablation of the atrial focus/pulmonary veins
- surgery (maze procedure)
What is the aim of electrical cardioversion?
Immediate restoration of sinus rhythm by terminating the arrhythmia via the delivery of a dose of electrical current to the heart at a specific moment in the cardiac cycle
What determines the electophysiolocal effects of AADS?
Depending on which ion channel they block Class I- Na+ channels (rhythm) Class II- B receptors (rate) Class III- K+ channels (rhytmn) Class IV- Ca2+ channels (rate)
Name some Class I antiarrhythmics?
Lignocaine, quinidine, flecainide, propafenone
Name a Class II antiarrhythmic?
Propanolol
Name some Class III antiarrhythmics?
Amiodarone, sotalol, dronedarone
Name a class IV anti-arrhythmic?
Verapamil
What is torsades des pointes?
Rapid and distinct VT with a twisting configuration of QRS morphology
What is the HR in torsades des pointes?
200-250bpm
What is the rhythm of torsades des pointes?
Irregular
How can torsades des pointes be recognised?
Long QT interval
Wide QRS
Continuously changes QRS morphology
What is torsades des pointes associated with?
Prolonged repolarization
What causes torsades des pointes?
Acquired or congenital
Which type of mitral valve disease has the highest stoke risk?
Mitral Stenosis
What gender and age is at increased risk of thromboembolism?
Female >75
What heart decisions predispose to thromboembolism?
Hypertension
Heart failure
Previous thromboembolism/stroke
CAD
What non cardiovascular conditions predispose to thromboembolism?
Diabetes
Thyrotoxicosis
What is the indication for anticoagulation in valvular atrial fibrillation?
If the cause is mitral stenosis or regurgitation
What are the indications for anti-coagulation in non valvular atrial fibrillation?
Age >75 Hypertension Heart Failure Previous stroke/thromboembolism CAD/DM Diabetes
What is the acronym for remembering anti-coagulation indication in atrial fibrillation?
CHADSVAS
What is the use of radiofrequency ablation in atrial fibrillation?
Maintain SR
- by ablating AF focus
For rate control
-ablation of the AVN to stop fast conduction to ventricles
What is atrial flutter?
Rapid and regular form of reentrant atrial tachycardia
What is the usual character of atrial flutter?
Normally paroxysmal
What is atrial flutter sustained by?
Macro-reentrant circuit located in the right atrial myocardium
How long do episodes of atrial flutter last?
Seconds to years
What does chronic atrial flutter progress to?
Atrial fibrillation
What is chronic atrial flutter suggestive of?
Underlying heart disease
What is the atrial and ventricular rates in atrial flutter?
Atria: 300bpm (220-430)
Ventricle: 150bpm
What is the pathological wave form?
Saw tooth f wave
What is the QRS complex like in atrial flutter?
Normal
What is the conduction like in atrial flutter
Normal but often in a 2:1 ration
What is the rhythm like in atrial flutter?
Regular but may be variable
How is initiation of atrial flutter achieved?
rapid atrial pacing and or the introduction of multiple premature beats near the low septum
How is termination of atrial flutter achieved?
rapid atrial pacing, cardioversion, medication (Ia, Ic, III anti arrhythmic drugs)
What are the two goals in the treatment of atrial flutter?
Terminate the flutter and prevent recurrence
Control the ventricular response
What are the treatment options of atrial flutter?
-RF ablation
-Pharmacologic therapy
>slow the ventricular rate
>resore sinus rhythm
>maintain sinus rhythm once converted
-Cardioversion
-Warfarin for prevention of thromboembolism
