Supraventricular Tachycardia Flashcards
What is supra ventricular tachycardia?
a regular narrow-complex tachycardia (> 100 bpm) with no p waves + a supraventricular origin.
Refers to:
Atrioventricular Nodal Re-entry Tachycardia (AVNRT)
Atrioventricular Re-entry Tachycardia (AVRT)
(though AF technically counts as a type of SVT)
What is the aetiological cause of Atrioventricular Nodal Re-entry Tachycardia?
A localised re-entry circuit forms around the AV node
What is the aetiological cause of Atrioventricular Re-entry Tachycardia?
A re-entry circuit forms between the atria + ventricles due to the presence of an accessory pathway (Bundle of Kent)
List 5 risk factors for SVT
Nicotine Alcohol Caffeine Previous MI Digoxin toxicity
Give 2 epidemiological facts on SVT
VERY common
F > M
List 6 symptoms of SVT
Syncope Palpitations Light-headedness Fatigue Chest discomfort Dyspnoea
Describe the nature of symptoms in SVT
May have minimal Sx or may present with syncope
Sx vary depending on rate + duration of SVT
Abrupt onset + termination of Sx
What are the signs of SVT?
AVNRT: tachycardia
AVRT (Wolff-Parkinson-White): Tachycardia + Secondary cardiomyopathy (S3 gallop, RV heave, displaced apex beat)
How do you differentiate between AVNRT and AVRT on ECG?
Once SVT has been terminated + normal rate + rhythm are re-established:
AVNRT: appears normal
AVRT: delta-waves (slurred upstroke of the QRS complex)
Other than an ECG what investigations should be carried out in SVT?
Cardiac Enzymes: Exclude MI (esp if there is chest pain)
Electrolytes: can cause arrhythmia
TFTs: can cause arrhythmia
Digoxin Level: digoxin toxicity can cause arrhythmia
Echocardiogram: check for structural heart disease
How do you manage a patient with SVT if haemodynamically unstable?
DC Cardioversion
How do you manage a patient with SVT if haemodynamically stable?
Vagal manouevres + chemical cardioversion
Vagal manoeuvres (e.g. Valsalva, carotid massage)
Carotid massage could dislodge atherosclerotic plaques, so only performed in young
If Vagal manoeuvres fail:
Adenosine 6 mg bolus
CI in ASTHMA (can cause bronchospasm)
Can give verapamil 2.5 - 5 mg if unsuccessful/ adenosine CI
Alternatives: atenolol, amiodarone
How do you manage a patient if unresponsive to chemical cardioversion or tachycardia > 250 bpm or adverse signs (low BP, heart failure, low consciousness)
Sedate + synchronised DC cardioversion
Amiodarone
Describe the ongoing management of SVT
AVNRT:
Radiofrequency ablation of slow pathway
B-blockers
Alternatives: fleicanide, propafenone, verapamil
AVRT:
Radiofrequency ablation
Sinus Tachycardia:
Exclude secondary cause (e.g. hyperthyroidism)
B-blocker or rate-limiting CCB
List 4 complications of SVT
Haemodynamic collapse
DVT
Systemic embolism
Cardiac tamponade
