Supraventricular tachycardia Flashcards
Define supraventricular tachycardia
Regular narrow-complex tachycardia (>100 bpm) w/ no p waves & a supraventricular origin
Supraventricular tachycardia generally refers to:
2 + other that is SVT
atrioventricular nodal re-entry tachycardia (AVNRT)
atrioventricular re-entry tachycardia (AVRT)
AF technically is a type of SVT
Aetiology of supraventricular tachycardia
2
AVNRT - a localised re-entry circuit forms around the AV node
AVRT - a re-entry circuit forms between the atria & ventricles due to presence of accessory pathway (Bundle of Kent)
Risk factors for supraventricular tachycardia
5
Nicotine Alcohol Caffeine Previous MI Digoxin toxicity
Epidemiology of supraventricular tachycardia
prevalence, gender
VERY COMMON
2x more common in females
Presenting symptoms of supraventricular tachycardia
6
May have minimal symptoms or may present w/ syncope
Symptoms vary depending on rate & duration of SVT
Palpitations
Light headedness
Abrupt onset & termination of symptoms
Other: fatigue, chest discomfort, dyspnoea, syncope
Signs of supraventricular tachycardia on physical examination
(1 +2)
AVNRT
Normal except tachycardia
Wolff-Parkinson-White syndrome
Tachycardia
Secondary cardiomyopathy (S3 gallop, RV heave, displaced apex beat)
Investigations for supraventricular tachycardia
6 types
ECG Cardiac enzymes Electrolytes TFTs Digoxin level Echocardiogram
Investigations for supraventricular tachycardia - ECG
2
Once SVT has been terminated & normal rate & rhythm are re-established:
- AVNRT: appears normal
- AVRT: delta waves (slurred upstroke of QRS complex)
24hr ECG monitoring - required in patients w/ paroxysmal palpitations
Investigations for supraventricular tachycardia - cardiac enzymes
Check for features of MI (especially if there’s chest pain)
Investigations for supraventricular tachycardia - electrolytes
Can cause arrhythmias
Investigations for supraventricular tachycardia - TFTs
Can cause arrhythmias
Investigations for supraventricular tachycardia - digoxin level
For patients on digoxin
Investigations for supraventricular tachycardia - echocardiogram
Check structural heart disease
Management of supraventricular tachycardia
4 divisions
Haemodynamically UNSTABLE
Haemodynamically STABLE
Unresponsive to chemical cardioversion OR tachycardia >250 bpm OR adverse signs
Ongoing management
Management of supraventricular tachycardia - haemodynamically unstable
DC cardioversion
Management of supraventricular tachycardia - haemodynamically stable
(1 + 3)
(vagal manoeuvres + chemical cardioversion)
Vagal manœuvres (e.g. Valsalva, carotid massage)
- Carotid massage can dislodge atherosclerotic plaques so only performed in younger patients
If they fail:
Adenosine 6mg bolus (can increase to 12mg)
- contraindicated in ASTHMA as it can cause bronchospasm
Can give verapamil 2.5-5mg if unsuccessful or contraindicated
Alternatives: atenolol, amiodarone
Management of supraventricular tachycardia - unresponsive to chemical cardioversion OR tachycardia >250 bpm OR adverse signs
(2)
Sedate & synchronised DC cardioversion
Amiodarone
Management of supraventricular tachycardia - ongoing
3 AVNRT, AVRT, 2 sinus tachycardia
AVNRT
Radiofrequency ablation of slow pathway
β-blockers
Alternatives: flueicanide, propafenone, verapamil
AVRT
Radiofrequency ablation
Sinus tachycardia
Exclude 2º cause (e.g. hyperthyroidism)
β-blockers or rate limiting CCB
Complications of supraventricular tachycardia
4
Haemodynamic collapse
DVT
Systemic embolism
Cardiac tamponade
Prognosis of supraventricular tachycardia
3
Dependent on presence of underlying structural heart disease
If structurally normal heart - GOOD prognosis
People w/ pre-excitation have small risk of sudden death
