SVT Flashcards
What is SVT?
Supraventricular tachycardia (SVT) refers to when abnormal electrical signals from above (supra-) the ventricles cause a fast heart rate (tachycardia).
What is narrow complex tachycardia?
fast heart rate with a QRS complex duration of less than 0.12 seconds
ECG findings
QRS complex followed immediately by a T wave, QRS complex, T wave and so on.
What are the types of SVT?
Atrioventricular nodal re-entrant tachycardia
Atrioventricular re-entrant tachycardia
Atrial tachycardia
What is atrioventricular nodal re-entrant tachycardia?
Re-entry point is back through the atrioventricular node
What is atrioventricular re-entrant tachycardia?
Re-entry point is an accessory pathway.
An additional electrical pathway, somewhere between the atria and the ventricles, lets electricity back through from the ventricles to the atria.
Having an extra electrical pathway connecting the atria and ventricles is called Wolff-Parkinson-White syndrome.
What is atrial tachycardia?
Electrical signal originates in the atria somewhere other than the sinoatrial node.
Not caused by a signal re-entering from the ventricles but from abnormally generated electrical activity in the atria.
Signs of WPW on an ECG
Short PR interval, less than 0.12 seconds
Wide QRS complex, greater than 0.12 seconds
Delta wave
Management of SVT in non-life threatining features
Step 1: Vagal manoeuvres
Step 2: Adenosine
Step 3: Verapamil or a beta blocker
Step 4: Synchronised DC cardioversion
What should a SVT patient have in management?
The patient should have continuous ECG monitoring during management.
What should patients with life threatening features have?
Lss of consciousness (syncope), heart muscle ischaemia (e.g., chest pain), shock or severe heart failure, are treated with synchronised DC cardioversion under sedation or general anaesthesia. Intravenous amiodarone is added if initial DC shocks are unsuccessful.
What are vagal removers and why are they helpful?
Vagal manoeuvres stimulate the vagus nerve, increasing the activity in the parasympathetic nervous system.
This can slow the conduction of electrical activity in the heart, terminating an episode of supraventricular tachycardia.
What can radiofrequency ablation cause?
Atrial fibrillation
Atrial flutter
Supraventricular tachycardias
Wolff-Parkinson-White syndrome
How can paroxysmal SVT be treated?
Long-term medication (e.g., beta blockers, calcium channel blockers or amiodarone)
Radiofrequency ablation
