Supraventricular Tachycardias - AVNRT

Question 1

Definition

Answer 1

Atrioventricular nodal re-entrant tachycardia is when the re-entry point is back through the AV node

Question 2

Epidemiology

Answer 2

Women

Question 3

Risk Factors

Answer 3

Exertion
Coffee
Emotional stress
Coffee
Tea
Alcohol

Question 4

Pathophysiologic

Answer 4

Two pathways within the AV node in AVNRT:
- One has short effective refractory period and SLOW conduction
- One has a longer effective refractory period and FAST conduction

Question 5

Signs and Symptoms

Answer 5

Rapid regular palpitations with abrupt onset and sudden termination
Chest pain and breathlessness
Neck pulsations - prominent jugular venous pulsations due to atrial contractions against closed AV valves
Polyuria (due to the realise of atrial natriuretic peptide in response to increased atrial pressures during the tachycardia)

Question 6

Diagnosis

Answer 6

ECG - QRS will show typical bundle branch block
P waves are either not visible or are seen immediately before (normal) or after the QRS complex due to simultaneous atrial and ventricular activation.

Question 7

Treatment

Answer 7

Same as AVRT
FIRST LINE = Valsalva manoeuvre carotid massage - blow into syringes, vs resistance
SECOND LINE = IV Adenosine (will temporarily cease conduction, warn patient “FEEL LIKE DYING”
THIRD LINE = consider surgical radiofrequency ablation of bundle of kent