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Transition Block 1 > Cardiac Arrhythmias > Flashcards

Cardiac Arrhythmias Flashcards

1
Q

what is the most common sustained arrhythmia?

A

atrial fibrilation

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2
Q

types of A fib?

A

paroxysmal
persistent
permanent (chronic)
can be symptomatic or asymptomatic

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3
Q

what is A fib?

A

disorganised electrical activity in the atria resulting in an irregular heartbeat as the irregular activity passes into the ventricles sometimes

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4
Q

describe the mechanisms of A fib

A

ectopic foci in muscle sleeves in the ostia of the pulmonary veins

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5
Q

how can A fib be terminated?

A

pharmacological cardioversion with anti-convulsants (30% effective)
electrical cardioversion by direct current (90% effective)
spontaneous return to sinus rhythm

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6
Q

describe paroxysmal A fib

A

lasts less than 48 hrs

often recurrent

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7
Q

describe persistent A fib

A

lasts greater than 48 hrs but can still be cardioverted to sinus rhythm
unlikely to revert back to sinus rhythm spontaneously

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8
Q

describe permanent a fib

A

inability to restore sinus rhythm via pharmacologic or non-pharmacological methods

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9
Q

diseases associated with a fib

A 
hypertension
heart failure
sick sinus rhythm (tachy brady syndrome)
obesity
thyroid disease
valve disease
alcohol abuse
heart surgery
COPD, pneumonia
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10
Q

what is lone (idiopathic) AF?

A

AF in the absence of any heart disease and no evidence of ventricular dysfunction
can be genetic
causes significant stroke risk if >75

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11
Q

symptoms of AF?

A 
palpitations
pre-syncope
syncope
chest pain
dyspnoea
sweatiness
fatigue
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12
Q

ECG features of AF?

A

atrial rate >300
irregularly irregular rhythm
variable ventricular rate (dependent upon AV node properties, sympathetic and parasympathetic tone)
characteristic features such as absence of P waves and presence of F waves
T waves also often invisible
ventricular rate can range from 100-160

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13
Q

how is AF affected by nervous stimulation?

A

AV node controls ventricular response to chaotic atrial rate

AV node conduction is facilitated by sympathetic tone and inhibited by parasympathetic tone

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14
Q

pharmacological agents which do what are helpful in AF?

A

agents which decrease conduction in the AV node as they control ventricular rate (eg beta blockers and CCBs)

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15
Q

can ventricular rate be slow in AF?

A

yes
can co-exist with periods of fast ventricular rate
pacemaker may be needed to control fast ventricular rate

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16
Q

how does AF cause problems?

A

loss of atrial kick (theyre just twitching really fast instead of contracting properly) > decreased filling time (diastole) > reduced cardiac output > can result in heart failure
blood can pool in ventricles causing it to become stagnant and clots to form
AF in patients with pre-excitation (wolf parkinson white) can result in ventricular fibrillation and sudden cardiac death

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17
Q

what does ventricular rate <60 suggest in AF?

A

AV node conduction disease

18
Q

how is AF managed?

A 
rhythm control (maintain sinus rhythm)
rate control (accept AF but control rate)
anti-coagulation in all cases
19
Q

describe rate control on AF

A

treatment focuses on rate in patients where restoration of sinus rhythm is not possible
drugs include
- digoxin
- beta blockers
- CCBs (verapamil, diltiazem)
drugs used alone or in combination
if drugs dont work then more invasive pacing is used

20
Q

describe rhythm control in AF

A

major goal in AF is sinus rhythm
can restore sinus rhythm via drugs (flecainide, sotalol, amiodarone etc) or direct current cardioversion (DCCV)
sinus rhythm can be maintained via anti-arrhythmic drugs, catheter ablation of atrial focus/pulmonary veins or surgery (maze procedure)

21
Q

what is the goal of electrical cardioversion?

A

immediate restoration of sinus rhythm

22
Q

how many classes of anti-arrhythmic drug are there?

A

4

23
Q

class 1 AADs?

A

block Na channels (phase 0 of action potential)

mainly used for rhythm control

24
Q

class 2 AADs?

A

block beta receptors (Beta blockers) in phase 4 of AP

used for rate control

25
Q

class 3 AADs?

A

block K+ receptors in phase 3 of AP

used for rhythm control

26
Q

class 4 AADs?

A

block calcium channels in phase 2 of AP

used for rate control

27
Q

how do AADs work?

A

blocking ionic currents across cell membranes that create the APs

28
Q

examples of class 1 AADs?

A

lignocaine
quinidine
flecainide
propafenone

29
Q

examples of class 2 AADs?

A

propanalol (beta blockers)

30
Q

examples of class 3 AADs?

A

amiodarone
sotalol
dronedarone

31
Q

examples of class 4 AADs?

A

verapamil (calcium channel blockers)

32
Q

when is anticoagulation strongly recommended in AF?

A

thyrotoxicosis
hypertrophic cardiomyopathy
valvular AF (mitral valve disease)
non-valvular AF with 2 or more risk factors

33
Q

what score is used to determine stroke risk in AF?

A

CHADSVASc

  • congestive heart failure/LV dysfunction
  • hypertension
  • age >75
  • diabetes
  • stroke history (worth 2)
  • valvular disease
  • age 65-74
  • sex (female)
34
Q

why is radiofrequency ablation used in AF?

A

to maintain sinus rhythm by ablating AF focus (usually in pulmonary vein)
for rate control by ablating the AV node to stop fast conduction to the ventricles

35
Q

how is left atrial catheter ablation used for AF?

A

isolates triggers in the pulmonary veins by isolating pulmonary vein inside left atria

36
Q

what is atrial flutter?

A

rapid and regular form of atrial tachycardia

sustained by a macro-reentrant circuit confined to the right atrium

37
Q

how long does atrial flutter last?

A

usually paroxysmal with episodes lasting seconds - years

38
Q

risks in atrial flutter?

A

chronic atrial flutter can often progress to AF

may result in thromboembolism

39
Q

ECG features of atrial flutter?

A

saw tooth rhythm strip

40
Q

how can atrial flutter be managed?

A 
rapid atrial pacing
RF ablation
cardioversion
medications - class 1 or 3 AADs
may resolve spontaneously 
warfarin to prevent thromboembolism

Transition Block 1 (14 decks)

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