PSVT or Paroxysmal Supraventricular Tachycardia is a Narrow complex Ventricular Tachycardia that occurs abruptly when normal electrical impulses of the heart are disrupted. We have provided short notes on PSVT for your exam preparation for Cardiology subject below (especially for Plab part 1). Any queries are welcome in the comments section below.
ECG of Paroxysmal SupraVentricular Tachycardia
- The ECG will demonstrate an absolutely regular RR interval with Heart rate around 150-250
- It will also show Narrow QRS- <0.12 seconds QRS (on ECg, 3 small squares = 0.04×3)
- Also, there will be QRS followed by T wave (Absent P waves)
PSVT vs Afib Difference in ECG
It is easy yet crucial to differentiate PSVT from Atrial Fibrillation from ECG as both have absent P waves. You can easily distinguish as PSVT will have regular R-R interval while AF will have irregular R-R interval.
PSVT vs Torsades De Pointes on ECG
While Management of SVT involves Carotid massage and Valsalva Manuever followed by IV Adenosine, IV Magnesium Sulphate is given for Torsades de pointes, also known as Polymorphic Ventricular Tachycardia
Management of PSVT
- Initial step involves Valsalva manoeuvre and giving Carotid Massage
If the patient does not improves with above steps, we give Adenosine bolus for management.
- Intravenous Adenosine (6mg Rapid IV Bolus)
- Still not improved?- give additional 12mg Adenosine
- Still not improved?- give another 12mg Adenosine
- Still not improved?- Electrical DC “cardioversion”
- Adenosine is contraindicated in Asthmatics as it can cause Bronchospasm
- Verapamil (CCB) is preferred option in SVT in patient with Asthma
Prevention of future episodes
- Beta-blockers such as Propranolol or Radio-frequency ablation
Management of PSVT Short Notes
- First step
- Carotid massage and Valsalva maneuver
- 2nd step
- IV Adenosine 6mg
- Another IV Adenosine 12mg
- Another IV Adenosine 18mg
- 3rd step
- Verapamil or beta-blocker
- 4th step
- Cardioversion (DC Shock) (First step if hemodynamically unstable)
- ECG- Narrow QRS (<0.12 seconds) f/b T wave and no P wave with Regular R-R interval
- Prophylaxis- Beta blocker or Radio-frequency ablation
- CCB (Verapamil) instead of Adenosine in Asthmatics
Check out the video below if you are looking for detailed aspects of the topic:
Patients of Paroxysmal Supraventricular Tachycardia usually present with racing heart and their heart rates are spiking. Once Adenosine is administered, heart rate returns to normal within seconds. It may occur again after a while, and the process is repeated. Management is crucial and it is super important to differentiate it from Atrial Fibrillation as both have different management.
We hope these short notes help you out in exams. You can ask us your queries or leave feedback in the comments section below.