Arrhythmia Fibrillation

Question 1

what is atrial fibrillation (AF)

Answer 1

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

Question 2

symptoms of AF

Answer 2

can be asymptotic or symptomatic;
palpitations
pre-syncope
syncope
chest pain
dyspnea
sweatiness
fatigue

Question 3

describe the pathophysiology of AF

Answer 3

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

Question 4

treatment of AF

Answer 4

CCB and beta-blockers - terminate and prevent AF
electrical cardioversion by direct current (DCCV)
spontaneous reversion to sinus rhythm

Question 5

describe paroxysmal AF

Answer 5

sudden recurrence, lasts less than 48 hours

normal hearts

Question 6

describe persistent AF

Answer 6

lasts longer than 48 hours

can be cardioverted to normal sinus rhythm (unlikely to be spontaneous)

Question 7

describe permanent AF

Answer 7

inability of pharmacologic or non-pharmacologic methods to restore normal sinus rhythm

Question 8

lone (idiopathic) AF

Answer 8

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

Question 9

tests for AF

Answer 9

ECG

Question 10

common findings on ECG for AF

Answer 10

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

Question 11

complications of AF

Answer 11

can result in congestive heat failure (especially in the presence of diastolic dysfunction)
ventricular rate <60BPM suggest AV conduction disease

Question 12

describe management of AF

Answer 12

rhythm control - maintain sinus rhythm
or
rate control - accept AF but control ventricular rate

anti-coagulation for both approaches if high risk for thromboembolism

Question 13

treatment options - rate control during AF

Answer 13

slow down AV node conductionl
digoxin
beta-blockers
verapamil, diltiazem

Question 14

treatment options - rhythm control during AF

Answer 14

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

Question 15

electrophysiological effects of anti-arrhythmic drugs

Answer 15

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

Question 16

describe radiofrequency ablation in AF

Answer 16

maintains sinus rhythm - ablates AF focus (usually in pulmonary veins)
rate control - ablation of the AV node to stop fast conduction to the ventricles

Question 17

describe left atrial catheter ablation for AF

Answer 17

isolate tiggers in the pulmonary in LA vein isolation

+/- lines of block

Question 18

what is atrial flutter

Answer 18

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

Question 19

ECG findings for atrial flutter

Answer 19

tachycardic
p wave - saw tooth F wave
QRS normal
conduction - normal but physiologic 2:1
rhythm - regular but may be variable

Question 20

pathophysiology of atrial flutter

Answer 20

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.

Question 21

treatment of atrial flutter

Answer 21

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