Supraventricular tachycardia: An overview of diagnosis and management

Abstract

Supraventricular tachycardia (SVT) is a common cause of hospital admissions and can cause significant patient discomfort and distress. The most common SVTs include atrioventricular nodal re-entrant tachycardia, atrioventricular re-entrant tachycardia and atrial tachycardia. In many cases, the underlying mechanism can be deduced from electrocardiography during tachycardia, comparing it with sinus rhythm, and assessing the onset and offset of tachycardia. Recent European Society of Cardiology guidelines continue to advocate the use of vagal manoeuvres and adenosine as first-line therapies in the acute diagnosis and management of SVT. Alternative therapies include the use of beta-blockers and calcium channel blockers. All patients treated for SVT should be referred for a heart rhythm specialist opinion. Long-term treatment is dependent on several factors including frequency of symptoms, risk stratification, and patient preference. Management can range from conservative, if symptoms are rare and the patient is low risk, to catheter ablation which is curative in the majority of patients.

Keywords: ECG; SVT; Supraventricular tachycardia; arrhythmia; narrow complex tachycardia.

Fig 1.

Diagnostic flow chart for electrocardiography in narrow complex tachycardia. AF = atrial fibrillation; AFlutter = atrial flutter; AT = atrial tachycardia; AVNRT = atrioventricular nodal re-entrant tachycardia, AVRT = atrioventricular re-entrant tachycardia, VT = ventricular tachycardia.

Fig 2.

Characteristic electrocardiography findings in supraventricular tachycardia. a) Atrioventricular nodal re-entrant tachycardia. (i) Electrocardiography strip during tachycardia with prominent pseudo r’ wave in lead V1. (ii) QRS complex from the same lead in sinus rhythm for comparison. Note the absence of the pseudo r’ wave present in tachycardia. b) Atrioventricular re-entrant tachycardia. (i) Narrow complex tachycardia with visible retrograde P-waves that appear separate to the QRS. (ii) Sinus rhythm snapshot showing the characteristic short PR interval, slurred upstroke and broad QRS complex. (iii) Pre-excited atrial fibrillation. Note the irregular rhythm (green arrows) and the variable QRS duration (blue arrows). This is a medical emergency. c) Atrial tachycardia. Narrow complex tachycardia with monomorphic P-waves and stable cycle length.

Fig 3.

Response to adenosine challenge. a) Inadequate delivery. There is no evidence of conduction/block in the atrioventricular node. This is highly suggestive of ineffective administration of adenosine. Rarely this can be indicative of high septal VT which may present with a narrow complex tachycardia. b) Atrioventricular block and termination of tachycardia achieved. The first three beats following termination are of junctional origin. The final beat shows restoration of sinus rhythm once the adenosine has been metabolised. c) Persistent tachycardia with slowing of ventricular response. Atrioventricular delay/block. P-waves continue to ‘march’ through despite atrioventricular block (arrows). Tachycardia continues with recovery of ventricular response rate following metabolism of adenosine.

Fig 4.

Flow chart of acute management of narrow complex tachycardia. AF = atrial fibrillation; AFlutter = atrial flutter; AVRT = atrioventricular tachycardia; bpm = beats per minute; CCB = calcium channel blocker; IV = intravenous; LVEF = left ventricular ejection fraction; VT = ventricular tachycardia.