SUPRAVENTRICULAR TACHYCARDIA

Question 1

Define SVT

Answer 1

A regular narrow-complex tachycardia (> 100 bpm) with no p waves and a supraventricular origin.

Question 2

Which are the 2 types of SVT?

Answer 2

o AF technically counts as a type of SVT
o However, SVT generally refers to:
• Atrioventricular Nodal Re-entry Tachycardia (AVNRT)
• Atrioventricular Re-entry Tachycardia (AVRT)

Question 3

Explain the aetiology of AVNRT

Answer 3

o A localised re-entry circuit forms around the AV node

Question 4

Explain the aetiology of AVRT

Answer 4

o A re-entry circuit forms between the atria and ventricles due to the presence of an accessory pathway (Bundle of Kent)

Question 5

What are the risk factors for SVT?

Answer 5

o  Nicotine  
o  Alcohol  
o  Caffeine  
o  Previous MI  
o  Digoxin toxicity  

think anything that makes YOU feel palpitations

Question 6

Summarise the epidemiology of SVT

Answer 6

• VERY COMMON

* 2 x more common in FEMALES

Question 7

Recognise the presenting symptoms of SVT

Answer 7

• Palpitations
• Light-headedness
• Other symptoms: fatigue, chest discomfort, dyspnoea, syncope
• May have minimal symptoms or may present with syncope
• Symptoms vary depending on rate and duration of SVT
• Abrupt onset and termination of symptoms

Question 8

Recognise the signs of SVT on physical examination

Answer 8

AVNRT
o Normal except tachycardia

WOLFF-PARKINSON-WHITE
o Tachycardia
o Secondary cardiomyopathy (S3 gallop, RV heave, displaced apex beat)

Question 9

LIST appropriate investigations for SVT

Answer 9

o ECG
o Cardian Enzymes
o Electrolytes
o TFT's
o Digoxin Levels
o Echocardiogram

Question 10

Why do you perform an ECG, what are the possible results in SVT?

Answer 10

o Differentiating between AVNRT and AVRT - once the SVT has been terminated and normal rate and rhythm are re- established:
• AVNRT - appears normal
• AVRT - delta-waves (slurred upstroke of the QRS complex)

o 24 hr ECG monitoring - will be required in patients with paroxysmal palpitations

Question 11

Why do you order Cardiac Enzymes, what are the possible results in SVT?

Answer 11

Check for features of MI (especially if there is chest pain)

Question 12

Why do you check TFT’s for SVT?

Answer 12

May be the reason for arrhythmias

Question 13

Why do you check Electrolytes for SVT?

Answer 13

May be the reason for arrhythmias

Question 14

Generate a management plan for HAEMODYNAMICALLY UNSTABLE SVT

Answer 14

HAEMODYNAMICALLY UNSTABLE

o DC cardioversion

Question 15

Identify possible complications of SVT

Answer 15

• Haemodynamic collapse
• DVT
• Systemic embolism
• Cardiac tamponade

Question 16

Summarise the prognosis for patients with SVT

Answer 16

• Dependent on the presence of underlying structural heart disease
• If structurally normal heart - GOOD PROGNOSIS
• People with pre-excitation have a small risk of sudden death

Question 17

Generate a management plan for HAEMODYNAMICALLY STABLE SVT

Answer 17

HAEMODYNAMICALLY STABLE
–> vagal monouevres + chemical cardioversion
o Vagal manoeuvres (e.g. Valsalva, carotid massage)
( Carotid massage could dislodge atherosclerotic plaques, so is only performed in young patients )

If Vagal manoeuvres fail:
o Adenosine 6 mg bolus (can increase to 12 mg)
• Contraindicated in ASTHMA as it can cause bronchospasm

o Can give verapamil 2.5-5 mg if unsuccessful/adenosine contraindicated due to asthma
o Alternatives: atenolol, amiodarone

• If unresponsive to chemical cardioversion or tachycardia > 250 bpm or adverse signs
(low BP, heart failure, low consciousness)
o Sedate and synchronised DC cardioversion
o Amiodarone

Question 18

Generate a management plan for ONGOING SVT

Answer 18

AVNRT
• Radiofrequency ablation of slow pathway
• Beta-blockers
• Alternatives: fleicanide, propafenone, verapamil

AVRT
• Radiofrequency ablation

SINUS TACHYCARDIA:
• Exclude secondary cause (e.g. hyperthyroidism)
• Beta-blocker or rate-limiting CCB