Arrhythmias

Question 1

What drugs should be avoided in patients with pre-excited AF and why?

Answer 1

AV-nodal blocking agents as this will cause impulse to travel preferentially down accessory pathway. Can use fleicanide.

Question 2

What signs are helpful for differentiating VT from SVT with bundle branch block on ECG?

Answer 2

Northwest axis
Concordance throughout precordial leads, especially negative
Fusion beats/capture beats
…

Question 3

What are 5 differentials for a wide complex tachycardia?

Answer 3

Ventricular tachycardia
SVT with functional/fixed BBB
Pre-exicited tachycardia
Paced tachycardia
Artefact

Question 4

What are the two underlying aetiologies of VT?

Answer 4

90% due to myocardial scar related reentry

10% due to idiopathic ventricular arrhythmia syndromes - focal triggered mechanisms mostly in RVOT

Question 5

What is first line pharmacological treatment for SVT and how does it work?

Answer 5

Adenosine 6mg IV - transiently blocks conduction through AV noted

Question 6

If a patient has been in AF for >48 hours, prior to electrical or pharmacological cardioversion they either need ___ or ___.

Answer 6

3 weeks of anticoagulation or a TOE to exclude thrombus

Question 7

Which anti-arrhythmic is most effective at maintaining sinus rhythm post cardioversion for AF?

Answer 7

Amiodarone

Question 8

What drugs are contraindicated in WPW?

Answer 8

AV nodal blocking agents e.g. adenosine, Ca channel blockers