Supraventricular Tachycardia

Question 1

another name for supraventricular tachycardia

Answer 1

narrow complex tachycardia

Question 2

is SVT a diagnosis

Answer 2

no
SVT is an umbrella term for any cause of rapid heart rate originating from above or within the atrioventricular node

Question 3

two main categories of SVT

Answer 3

focal tachycardais
re-entrant tachycardias

Question 4

focal tachycardias

Answer 4

a tachycardia that originates from a single point (or points) in the atrium or AV node

Question 5

sinus tachycardia

Answer 5

this counts as a focal tachycardia
the ‘focus’ is the sinoatrial node
usually regular

Question 6

atrial tachycardia

Answer 6

a different focus in the atrium takes over from the sinoatrial node resulting in abnormal p waves preceding QRS complexes
often seen in patients with chronic lung disease
normally > 100bpm and regular
p waves will be positive in the inferior leads as they originate from the top of the atrium and propagate towards the inferior lead

Question 7

atrial tachycardia is often seen in patients with

Answer 7

chronic lung disease

Question 8

multifocal atrial tachycardia

Answer 8

the p waves will have different morphologies as the atrial focus changes from beat to beat

Question 9

junctional rhythms

Answer 9

the impulse originates from the AV node and propagates to the atrium and the ventricles simultaneously
p waves are not visible because they are buried in the QRS complex

Question 10

management of inappropriate sinus tachycardia

Answer 10

can be slowed using bet blockers or ivabradine (selective sinus node blocker), however it is usually best left alone

Question 11

management of appropriate sinus tachycardia

Answer 11

may be due to concurrent sepsis, anaemia, thyrotoxicosis, pain
should be left alone and the underlying cause treated

Question 12

management of atrial tachycardias

Answer 12

can usually be rate controlled with beta-blockers or calcium channel blockers

Question 13

re-entry tachycardias - atrial flutter

Answer 13

well known for it’s sawtooth baseline
classified as a macro-re-entrant tachycardia
this means there is a single re-entry circuit around the atrium which stimulates the AV node every time it passes

Question 14

Typical vs. atypical atrial flutter

Answer 14

typical atrial flutter runs nit-clockwise around the right atrium and across the cavotricuspid valve isthmus
atypical flutter can be clockwise in the right atrium, in the left atrium or around sites of previous surgery and can be difficult to identify as they lack the typical sawtooth appearance

Question 15

the sawtooth appearance of atrial tachycardia in best seen in

Answer 15

the inferior leads becaause it is caused by the circiut alternately heading toward and way from the leads as it speeds round the atrium

Question 16

atrial fibrillation

Answer 16

micro-re-entrant tachycardia
lots of tiny circuits contributing to chotic random fibrillation of tha atrium
irregularly regular

Question 17

AVNRT (atrio-ventricular node re-entrant tachycardia)

Answer 17

activates ventricles and atria almost simultaneously
pseudo R wave: retrograde p wave superimposed on the QRS complex
rapid regular tachycardia
treatment involves complete transient AV node blockade

Question 18

AVRT (atrio-ventricular re-entrant tachycardia)

Answer 18

this requires two pathways: the normal AV conduction system and an accessory pathway (AP)
accessory pathways my conduct antegrade (atria to ventricles) retrograde (ventricle to atria

Question 19

orthodromic AVRTs

Answer 19

down the AV node and up the accessory pathway

Question 20

antidromic AVRTs

Answer 20

down the accessory pathway and up the normal AV conduction

Question 21

management of AVRTs

Answer 21

electrically cardiovert the patient back to sinus rhythm
flecanide can be used to prevent AVRTs but ablation is usually the mainstay of treatment given risk of VF and sudden death

Question 22

what is the treatment of choice in a haemodynamically unstable patient due to the underlying SVT

Answer 22

cardioversion

Question 23

rate control for atrial fibrillaation and atrial flutter

Answer 23

beta blockers
calcium channel blockers
digoxin

Question 24

rhythm control for atrial fibrillation and atrial flutter

Answer 24

chemical cardioversion (amiodarone, flecanide)
electrical cardioversion (DC shock)

Question 25

ablation for atrial fibrillation and atrial flutter

Answer 25

more likely to succeed in atrial flutter than atrial fib
more likely to succeed in paroxysmal AF than persistent AF

Question 26

anticoagulation in atrial fibrillation and atrial flutter

Answer 26

according to stroke risk vs bleeding risk (CHADS2 VASc score)

Question 27

AF patients who should not be considered for AF

Answer 27

AF is not life-threatening
a patient with well-controlled AF and normal LV function has the same life expectancy as someone in sinus rhythm
symptomatic patients will well rate controlled AF will not feel better or life longer by returning them to sinus rhythm

Question 28

patients who should be considered for cardioversion

Answer 28

new-onset AF
symptomatic AF
LV dysfunction secondary to AF
patients with a reversible cause of AF (eg. post-surgical, post-infection)
pateints who have a reasonable chance of maintaining sinus rhythm

Question 29

patients who have a reasonable chance of maintaining sinus rhythm will

Answer 29

previous successsful cardioversion - although each subsequent cardioversion becomes less successful
minimal dilatation of the left atrium
no signiificant mitral valve disease

Question 30

management of AVNRT

Answer 30

induce AV node blockade
mechanical: vasovagal manouvres, carotid sinus massage
chemical: adenosine, beta blockers, verapamil

Question 31

management of AVRT

Answer 31

avoid AV node blockade as this can promote conduction down the AP and AF can convert to VF
electrical cardioversion is the best initial option although flecanide can be used to chemically cardiovert
ablation of the pathway is the curative option

Question 32

what is adenosine

Answer 32

a purine nucleoside that, administered intravenously, causes transient complete AV node blockade
it is a useful diagnostic tool as well as a treatment in the setting of narrow complex tahcycardia

Question 33

is adenosine safe in pregnancy

Answer 33

yes (its endogenous)

Question 34

can adenosine be used in asthma

Answer 34

usually can be used safetly in asthmatic unless they have brittle severe asthma

Question 35

effects of adenosine

Answer 35

you will see a few seconds of total AV block

Question 36

if you administer adenosine and you do not see AV block

Answer 36

one of two things have occurred:
1. you have not administered the adenosine properly and the adnosine has not reached the heart in time given its very short half life
2. the rhythm is not involving the AV node - it is therefore, ventricular tachycardia