Supraventricular Tachycardia

Question 1

Define

Answer 1

Narrow complex tachycardia
↘ ECG shows rate of >100 bpm
↘ QRS complex duration <120 ms
P wave absent or inverted after QRS

Question 2

Causes

Answer 2

Abnormalities of impulse conduction (for re-entry tachycardias) Or disorders of impulse initiation (for autonomic tachycardias)

Question 3

Risk factors

Answer 3

previous MI, mitral valve prolapse, rheumatic heart disease, pericarditis, pneumonia, chronic lung disease, alcohol intoxication, digoxin toxicity

Question 4

Epidemiology

Answer 4

2/1000

May occur at any age but often occurs in younger pts in the absence of heart disease

Question 5

Symptoms

Answer 5

SVT is usually paroxysmal and episodes may occur regularly or very infrequently (sometimes years apart)
Episodes may only last for a few minutes or may last for up to several months
􏰀 Syncope, palpitations, dizziness
􏰀 ±Fatigue, light-headedness, chest discomfort, dyspnoea

Question 6

Investigations

Answer 6

1. ECG
2. cardiac enzymes
3. electrolytes, TFT
4. digoxin level
5. echocardiogram

Question 7

Management

Answer 7

If pt compromised, use DC cardioversion
􏰀 Vagal manoeuvres (breath holding, Valsalva manoeuvre, carotid massage)
􏰀 IV adenosine first line
􏰀 Second line Verapamil
􏰀 Alternatively atenolol or sotalol

Question 8

Complications

Answer 8

haemodynamic collapse
DVT
embolism
cardiac tamponade

Question 9

Prognosis

Answer 9

if structurally normal - good prognosis