Arrhythmia Fibrillation Flashcards
what is atrial fibrillation (AF)
disorganised electrical activity of the atria resulting in an irregular heartbeat
can be paroxysmal, persistent or permanent (heart disease)
the most common sustained arrhythmia
incidence increases age
symptoms of AF
can be asymptotic or symptomatic; palpitations pre-syncope syncope chest pain dyspnea sweatiness fatigue
describe the pathophysiology of AF
multiple wavelets of reentry do not allow the atria to organise
the ectopic focus or foci are said to be located around or within the pulmonary veins
rapid atrial pacing will induce AF
lost atrial kick and decreased filling times (reduced diastole) => reduced cardiac output
treatment of AF
CCB and beta-blockers - terminate and prevent AF
electrical cardioversion by direct current (DCCV)
spontaneous reversion to sinus rhythm
describe paroxysmal AF
sudden recurrence, lasts less than 48 hours
normal hearts
describe persistent AF
lasts longer than 48 hours
can be cardioverted to normal sinus rhythm (unlikely to be spontaneous)
describe permanent AF
inability of pharmacologic or non-pharmacologic methods to restore normal sinus rhythm
lone (idiopathic) AF
absence of any heart disease and no evidence of ventricular dysfunction
a diagnosis of exclusion
could be genetic
significant stroke rate if >75 years old
tests for AF
ECG
common findings on ECG for AF
atrial rate is chaotic and disorganised
rhythm - irregularly irregular
ventricular rate - variable; dependant on; AV node conduction properties sympathetic and parasypathetic tone presence of drugs with act on AV node
recognition;
absence of P waves
presnce of F waves
complications of AF
can result in congestive heat failure (especially in the presence of diastolic dysfunction)
ventricular rate <60BPM suggest AV conduction disease
describe management of AF
rhythm control - maintain sinus rhythm
or
rate control - accept AF but control ventricular rate
anti-coagulation for both approaches if high risk for thromboembolism
treatment options - rate control during AF
slow down AV node conductionl
digoxin
beta-blockers
verapamil, diltiazem
treatment options - rhythm control during AF
restoration of normal sinus rhythm;
anti-arrhythmic drugs e.g. amiodarone
direct current cardioversion (immediate restoration of sinus rhythm via electric current to heat)
maintenance of normal sinus rhythm;
arrhythmic drugs
catheter ablation of atrial focus/pulmonary veins
surgery
electrophysiological effects of anti-arrhythmic drugs
I - sodium channels (phase 0), rhythm control
II - beta-receptors (phase 4), rate control
III - potassium channels (phase 3), rhythm control
IV - calcium channels (phase 2), rate control
describe radiofrequency ablation in AF
maintains sinus rhythm - ablates AF focus (usually in pulmonary veins)
rate control - ablation of the AV node to stop fast conduction to the ventricles
describe left atrial catheter ablation for AF
isolate tiggers in the pulmonary in LA vein isolation
+/- lines of block
what is atrial flutter
rapid and regular form of atrial tachycardia
usually paroxysmal
sustained by macro-reentrant circuit
circuit is confined to right atrium
episodes can last from seconds to years
chronic atrial flutter usually progresses to atrial fibrillation
can result in thrombo-embolism
ECG findings for atrial flutter
tachycardic p wave - saw tooth F wave QRS normal conduction - normal but physiologic 2:1 rhythm - regular but may be variable
pathophysiology of atrial flutter
With counterclockwise flutter, a macro-reentrant circuit exists
circuit is sustained by a critical isthmus.
Induction of counterclockwise flutter can be accomplished with rapid atrial pacing and/or the introduction of multiple premature beats near the low septum.
treatment of atrial flutter
control symptoms improve cardiovascular outcomes; lifestyle reduction rapid atrial pacing cardioversion Ia, Ic, or class 3 antiarrythmic - slow ventricular rate, restore and maintain sinus rhythm, may convert spontaneously. warfarin for prevention of thromboemolism
