Supraventricular Tachycardia

Question 1

What characterises a narrow complex tachycardia.

Answer 1

Rate >100BPM and QRS

Question 2

What sort of tachycardia does SVT cause.

Answer 2

Narrow complex.

Question 3

What is the treatment for SVT. (4)

Answer 3

If adenosine fails, give verapamil (not if no a beta blocker).
If no response, give a further 5mg IV over 3mins (

Question 4

How should you treat narrow complex tachycardias.

Answer 4

As AF as it is the most likely cause.

Question 5

What characterises a SVT.

Answer 5

Narrow complex QRS.

Re entry circuit or automatic focus involving the atria.

Question 6

What is AVNTR.

Answer 6

Atrioventricular nodal re-entrant tachycardia is due to re-entry in a circuit involving the AV node and its two right atrial input pathways: a fast and a slow pathway.

Question 7

What does AVNRT produce.

Answer 7

A regular tachycardia of 120BPM.

Question 8

How long can AVNRT last.

Answer 8

From a few seconds to many hours.

Question 9

What may be a features of AVNRT.

Answer 9

Polyuria due to the release of ANP.

Question 10

What is normally seen on an ECG in a patient with AVNRT. (3)

Answer 10

Tachycardia.
Normal QRS complex.
There may be rate-dependent bundle branch blocks.

Question 11

What are the symptoms of AVNRT. (4)

Answer 11

Awareness of a rapid, foreceful regular heart beat.
Chest discomfort.
Lightheadedness.
Breathlessness.

Question 12

How do you treat AVNRT. (5)

Answer 12

Treatment is not always necessary.
Episode can be terminated by carotid sinus pressure or by the Valsalva manoeuvre.
Adenosine or verapamil will restore sinus rhythm.
IV beta blockers or flecainide can also be used.
In rare cases, DC cardioversion is needed.

Question 13

What is the treatment in patients with recurrent SVT. (2)

Answer 13

Catheter ablation (>90% success). 
Prophylaxis with oral beta blockers, verapamil or flecainide.

Question 14

What are the main forms of SVT. (8)

Answer 14

Sinus tachycardia. 
AVNRT. 
AVRT. 
AF.
Atrial flutter. 
Atrial tachycardia. 
Multifocal atrial tachycardia. 
Accelerated junctional tachycardia.

Question 15

What are the ECG features of AVNRT. (2)

Answer 15

No visible P waves.

Or inverted P waves immediately before or after QRS complex.

Question 16

What are the ECG changes in AVRT.

Answer 16

P waves visible between QRS and T waves.

Question 17

What is WPW.

Answer 17

A type of AVRT.

Question 18

What is seen in multifocal atrial tachycardia on an ECG. (2)

Answer 18

Multiple P wave morphologies.

Irregularly irregular RR intervals.

Question 19

What is seen in atrial tachycardia on an ECG.

Answer 19

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

Question 20

What is inappropriate sinus tachycardia.

Answer 20

It is a persistent increase in resting HR unrelated to or out of proportion with the level of physical or emotional stress.

Question 21

What are the symptoms of SVTs. (9)

Answer 21

Tachycardia. 
Anxiety. 
Dizziness. 
Dyspnoea. 
Neck pulsation. 
Central chest pain. 
Weakness. 
Polyuria.
Syncope (10-15%).

Question 22

What are the side effects of adenosine. (5)

Answer 22

Bronchospasm. 
Flushing. 
Chest pain. 
Heaviness of the limbs. 
Sense of impeding doom.

Question 23

What are some causes of atrial tachycarrhythmias. (5)

Answer 23

Hypertension. 
Valvular heart disease. 
Coronary artery disease. 
Thyrotoxicosis. 
Electrolyte disturbance (hypokalaemia).