Condition- Supraventricular Tachycardia

Question 1

Define Supraventricular tachycardia

Answer 1

• Tachyacrrhythmias arising from above the level of bundles of His usually the atria or AVN. Results in:
  
  • regular
  • narrow-complex tachycardia (>100bpm)
  • with no p waves

Question 2

SVTs are subdivided into two categoried based on the type of re-entry circuit. What are they?

Answer 2

• Atrioventricular Nodal Re-entry Tachycardia (AVNRT)
• Atrioventricular Re-entry Tachycardia (AVRT)

Question 3

What is an AVNRT?

Answer 3

A localised re-entry circuit develops around the AVN leading to repeated ventricular depolarisation

Question 4

What causes AVRT?

Answer 4

• Normal AV conduction
• But accessory pathway which forms re-entry circuit between atria + ventricles

Question 5

Give an example of an AVRT and state which accessory pathway causes this condition

Answer 5

Wolff-Parkinson-White Syndrome

accessory pathway is called Bundle of Kent

Question 6

List some causes of Supraventricular tachycardia in healthy people (mostly drugs!!)

Answer 6

• amphetamines, cocaine, and acute alcohol intoxication, digoxin, caffeine
• associated with: cardiomyopathy, MI, great vessel surgery, congestive heart failure

Question 7

Which gender is at higher risk of developing supraventricular tachycardia?

Answer 7

FEMALES

Question 8

List some of the symptoms of supraventricular tachycardia

Answer 8

• palpitations
• chest pain
• SOB
• light-headedness
• fatigue
• syncope
• POLYURIA (becayse increase in atrial pressure => ANP release)

Question 9

List some signs of Wolff-Parkinson- White syndrome

Answer 9

• Tachycardia
• Secondary cardiomyopathy (S3 gallop, RV heave, displaced apex beat)

Question 10

How can you distinguish between AVRT and AVNRT?

Answer 10

On ECG

Acutely they both appear as narrow complex tachycardia.

Only after correcting the tachycardia, you see delta wave in AVRT but no wave in AVNRT.

Question 11

List some of the signs on ECG of AVRNT and AVRT

Answer 11

• Tachycardia
• Narrow QRS
• P waves may be buried in QRS
• regular rhythm
• Decreased PR interval
• After SVT terminated:
  
  • ECG appears normal in AVNRT
  • ECG has delta waves in AVRT

Question 12

Other than an ECG which other tests should you conduct on a patient with supraventricular tachycardia?

Answer 12

• Cardiac enzymes- to check for MI
• Electrolytes- can cause arrhythmia
• TFTs- can cause arrhythmia
• Digoxin level
• Echocardiogam

Question 13

Rcealls the steps for the medical management of SVT

Answer 13

1. If haemodynammically UNSTABLE: DC cardioversion
2. If haemodynamically STABLE (go through each of the steps until corrected:
   
   1. Vagal manoeuvres (for AVNRT)
   2. IV adenosine 6mg => 12mg => 12mg
   3. IV B-blocker/amiodarone
   4. DC cardioversion

Question 14

How can further episodes of AVNRT and AVRT be prevented??

Answer 14

Radiofrequency ablation

Beta-blocker therapy