Exam Cram

• SVT: supraventricular tachycardia; narrow complex tachycardia

• Presentation: palpitations & presyncope in under 40yrs

• ECG: narrow QRS, tachycardia, p waves present, rate c.200 bpm

• Management: 1. modified Valsalva, 2. Adenosine

Outline

Background

• Common arrhythmia

Assessment 

History

Examination

Investigations

• ECG: rate c. 200 bpm, narrow regular QRS, absent p waves

• Baseline bloods: FBC, Urea & electrolytes, LFTs, 

• Consider TSH, CMP, Coag

Diagnosis 

Diagnostic criteria: ECG diagnosis

Differentials: atrial flutter, Atrial Fibrillation (AF) 

Classification: (aetiology, severity, location)- idiopathic or secondary to Wolf Parkinson White (WPW) 

Management

Acute

1. DC Cardioversion if unstable

2. Modified Valsalva maneouvre

3. Adenosine

4. Verapamil

Long Term

1. Beta blockers

Med Reg Notes

Management

Acute

1. DC Cardiovert if unstable (200J)

   • Chest pain/ ischaemia

   • Shock/ hypotension

   • Syncope

   • Acute heart failure

2. Modified Valsalva Manouvre

• Blow into 10ml syringe, lie back and lift legs up

• Forcing expiration increases left arterial pressure (increasing afterload), reducing left venous pressure (reducing preload)

• Causes heart rate and JVP to initially drop

• Stimulates vagal nerve

3. Adenosine

• Moa: blocks AV node

• Indications: SVT

• Can feel like heart is going to stop, impending doom

• Has very short half life (2-3s)

• Dose 6mg -> 12mg -> 12mg

• Contraindication: complete heart block, asthma

4. Verapamil

Long Term Prophylaxis

• Bisoprolol

References and Resources

1. https://bnf.nice.org.uk/drugs/adenosine/

Written in 2024