Supraventricular Tachycardia

Question 1

different types of SVT arise from or are propagated by the _____ or __ ____, typically producing a ______ complex tachycardia (unless aberrant conduction is present)

Answer 1

different types of SVT arise from or are propagated by the atria or AV node, typically producing a narrow complex tachycardia (unless aberrant conduction is present)

Question 2

name some regular atrial tachycardias?

Answer 2

• sinus tachycardia
• atrial tachycardia
• atrial flutter
  inappropriate sinus tachycardia
• sinus node re-entrant tachycardia

Question 3

name some irregular atrial tachycardias?

Answer 3

• atrial fibrillation
• atrial flutter with variable block
• multifocal atrial tachycardia

Question 4

name some regular av tachycardias?

Answer 4

• atrioventricular re-entry tachycardia
• AV nodal re-entry tachycardia
• automatic junctional tachycardia

Question 5

what 2 arrhythmias are commonly referred to as paroxysmal SVTs?

Answer 5

AV nodal re-entrant tachycardia and AV re-entrant tachycardia

Question 6

who normally gets paroxysmal SVT?

Answer 6

often seen in young people with no or little structural heart disease

Question 7

what category of arrhythmia does WPW fit into?

Answer 7

accessory pathway tachycardia - AVRT

Question 8

what is the difference between sinus tachycardia and SVT?

Answer 8

with SVT, impulses in the atria fire rapidly and cause interference with the SA node. But in sinus tachycardia, the heart is functioning normally; only the SA node is firing at a higher than normal rate.

Question 9

In AVRT there is a large circuit comprising the AV node, the His bundle, the ventricle and an abnormal connection from the _____ back to the ______.

Answer 9

In AVRT there is a large circuit comprising the AV node, the His bundle, the ventricle and an abnormal connection from the ventricle back to the atrium.

Question 10

what causes an accessory pathway

Answer 10

result from incomplete separation of the atria and the ventricles during fetal development.

Question 11

Clinically, the AVNRT often strikes suddenly without obvious ______, but ____, _____, ___ and _____ may aggravate or induce the arrhythmia.

Answer 11

Clinically, the tachycardia often strikes suddenly without obvious prov- ocation, but exertion, coffee, tea and alcohol may aggravate or induce the arrhythmia.

Question 12

what are the ECG features of AVNRT?

Answer 12

no visible P waves

narrow QRS

Question 13

what are the ECG features of AVRT?

Answer 13

P waves visible between QRS and T wave

Question 14

what are the ECG features of Atrial tachycardia?

Answer 14

organised atrial activity with P wave morphology different from sinus rhythm preceding QRS

Question 15

why does atrial tachycardia usually occur?

Answer 15

because of congenital heart disease, iatrogenic causes or atrial ischaemia

Question 16

how is acute SVT managed?

Answer 16

vagal manoeuvres

IV adenosine

IV verapamil

Question 17

which receptors does adenosine work on?

Answer 17

it activates A1 adenosine receptors coupled to Gi/o

Question 18

what does the adenosine binding to the receptor do?

Answer 18

opens ACh sensitive K channels (GIRK)

this hyperpolarises the AV node briefly, suppressing impulse conduction

Question 19

adenosine has a very ____ acting time?

Answer 19

short

Question 20

what does verapamil block?

Answer 20

it blocks L-type Ca channels

Question 21

what is the effect of blocking Ca channels?

Answer 21

slows conduction and prolongs refractory period in AV node and bundle of his

Question 22

verapamil is also a ____

Answer 22

vasodilator

Question 23

when would you not use verpamil

Answer 23

if someone has an already low BP

Question 24

how do you manage chronic SVT?

Answer 24

radio frequency ablation

maybe antiarrhythmics

Question 25

which classes of antiarrhythmics would be used in chronic SVT?

Answer 25

II and IV

Question 26

what is radiofrequency ablation?

Answer 26

this is the selective cautery of cardiac tissue to prevent tachycardia, targeting either an automatic focus or part of a re-entry circuit

Question 27

before radiofrequency ablation what medications should be stopped and how long before hand?

Answer 27

cease antiarrhythmic drugs 3-5 days before

Question 28

what kind of anaesthesia is used in the ablation procedure?

Answer 28

local

Question 29

how long is ablation usually?

Answer 29

1-2 hours

Question 30

ABLATION
- catheters placed in heart via ______ veins

• intracardiac ECG recorded during ______, _____cardia and during _____ manoeuvres
• catheter placed over _____/_____ and tip heated to __ - ____C

Answer 30

• catheters placed in heart via femoral veins
• intracardiac ECG recorded during sinus rhythm, tachycardia and during pacing manoeuvres
• catheter placed over focus / pathway and tip heated to 55-65C