A practical Foundation Year and FY1 guide to tachycardia on the ward, covering instability, reversible causes, ECG assessment, SVT, AF, broad-complex tachycardia and escalation.
Tachycardia on the Ward
A heart rate of 154 appears in red on the observations chart.
Before deciding that the patient simply “has tachycardia”, there are two questions to answer: is the fast rate a physiological response to something else, or is this a primary tachyarrhythmia — and is the patient unstable because of it?
For Foundation Year doctors, particularly FY1s, the aim is to recognise instability, identify reversible causes, obtain and interpret the ECG systematically, and involve a senior before moving into rhythm-specific drug treatment or cardioversion.
That distinction changes everything.
Sinus tachycardia from sepsis, pain, hypovolaemia or hypoxia is treated by correcting the cause.
An unstable tachyarrhythmia may need urgent synchronised cardioversion.
A stable arrhythmia can usually be approached by looking at QRS width and regularity on the ECG.
The first decision: Do not treat the heart-rate number in isolation. Assess the patient first, then the rhythm.
1. Start with the patient, not the ECG
Use ABCDE and obtain a full set of observations. While doing this, look specifically for adverse features that suggest the tachyarrhythmia is causing haemodynamic compromise:
- Shock or marked hypotension
- Syncope associated with severe or ongoing hypotension
- Myocardial ischaemia
- Severe heart failure or pulmonary oedema
Also obtain IV access, place the patient on cardiac monitoring, and record a 12-lead ECG as soon as practical. Give oxygen only when clinically indicated and to the appropriate target saturation range.
2. Ask whether this could be sinus tachycardia
Many fast heart rates are physiological responses rather than primary arrhythmias. Look for and treat common drivers such as:
- Pain or anxiety
- Fever or sepsis
- Hypovolaemia or bleeding
- Hypoxia
- Anaemia
- Electrolyte abnormalities
- Pulmonary embolism
- Thyrotoxicosis or other metabolic causes
- Medication or stimulant effects
Foundation Year doctor tip: If the ECG shows sinus tachycardia, treat the cause. Do not try to “normalise” the rate with antiarrhythmic drugs or cardioversion.
3. If unstable: synchronised cardioversion is the pathway
If the tachyarrhythmia is causing life-threatening compromise, call for help, bring the crash trolley and prepare for synchronised DC cardioversion. Sedation or anaesthesia is usually required if the patient is conscious and time allows.
Important: If adverse features are present, call for senior/resuscitation help immediately and prepare for synchronised cardioversion. Do not spend time trying to fully classify the rhythm before escalating.
If cardioversion is unsuccessful, antiarrhythmic treatment and repeat synchronised cardioversion become senior-led decisions.
A current NHS tachyarrhythmia algorithm lists amiodarone 300 mg IV over 10–20 minutes as one option after unsuccessful shocks, followed by repeat cardioversion. NHS tachyarrhythmia algorithm
4. If stable: look at QRS width first
Once you are satisfied there are no adverse features, the ECG pattern becomes the next decision point. The practical sequence is: QRS width → regularity → likely rhythm.
| ECG pattern | Think about | Foundation Year doctor action |
|---|---|---|
| Broad + regular | VT until proven otherwise; SVT with aberrancy is possible | Call senior early. A broad regular tachycardia should not be casually treated as SVT. |
| Broad + irregular | AF with bundle branch block, pre-excited AF, polymorphic VT / torsades | Urgent senior review. If torsades is suspected, magnesium may be required under the emergency pathway. |
| Narrow + irregular | Usually atrial fibrillation; atrial flutter with variable block is possible | Assess duration, rate, symptoms, comorbidity and anticoagulation status. Use the acute AF pathway. |
| Narrow + regular | Re-entry SVT or atrial flutter with fixed conduction | If stable, try an appropriate vagal manoeuvre; if it persists, discuss adenosine with a senior. |
5. Broad-complex tachycardia: treat uncertainty seriously
A broad-complex tachycardia can be ventricular tachycardia or a supraventricular rhythm conducted with bundle branch block. If you are not certain, involve a senior rather than assuming it is benign.
Broad regular tachycardia maps to VT/uncertain; broad irregular tachycardia maps to possibilities including AF with bundle branch block and polymorphic VT. This is a useful way to organise your differential, but treatment should be senior-led.
6. Narrow irregular tachycardia: think atrial fibrillation
A narrow irregular tachycardia is commonly AF. Confirm the rhythm on a 12-lead ECG and assess whether the patient is stable, when the arrhythmia started, whether there is a reversible trigger and whether anticoagulation needs consideration.
For acute AF without life-threatening haemodynamic instability, NICE recommends either rate or rhythm control if onset is less than 48 hours; if onset is more than 48 hours or uncertain, rate control is generally used.
For long-term rate control, a standard beta-blocker or rate-limiting calcium-channel blocker is usually first line, with digoxin reserved for selected circumstances.
Acute decompensated heart failure needs senior specialist input before choosing rate-control drugs. NICE NG196: atrial fibrillation
Foundation Year doctor tip: Before prescribing rate control, check blood pressure, heart failure, renal function, current medicines and the likely duration of AF.
7. Narrow regular tachycardia: vagal manoeuvres, then adenosine if appropriate
For a stable regular narrow-complex tachycardia, use vagal manoeuvres first. In practice, use a recognised manoeuvre such as a modified Valsalva rather than routine carotid sinus massage.
If the rhythm persists and adenosine is appropriate, it should be given with continuous ECG monitoring and rapid IV administration through a suitable large/proximal vein.
BNF dosing starts with 6 mg, followed by 12 mg after 1–2 minutes if needed.
Any further dosing should follow the current BNF and your emergency pathway. BNF: adenosine
Important precaution: Before adenosine, make sure the rhythm is regular and narrow-complex and that there is no concerning pre-excitation pattern or another reason the pathway does not fit. If uncertain, ask a senior first.
8. If adenosine terminates the rhythm
If the tachycardia terminates, obtain a 12-lead ECG in sinus rhythm. If episodes recur, consider antiarrhythmic prophylaxis under specialist guidance and cardiology referral for probable re-entry paroxysmal SVT.
9. If adenosine does not terminate a narrow regular rhythm
A rhythm that remains regular and narrow despite appropriate vagal manoeuvres and adenosine may be atrial flutter or another atrial tachycardia. Do not keep escalating adenosine indefinitely — escalate for senior review.
10. Investigate the trigger while you manage the rhythm
- 12-lead ECG and comparison with previous ECGs
- Full observations and continuous cardiac monitoring if clinically indicated
- FBC for anaemia or infection
- U&Es, potassium and magnesium
- Renal function before drugs that depend on renal clearance
- Glucose
- CRP or infection-focused tests if clinically indicated
- Troponin when myocardial ischaemia is part of the clinical picture
- Thyroid testing when clinically appropriate rather than as an emergency reflex test
11. Reassess after every intervention
Do not document only the new heart rate.
Reassess blood pressure, symptoms, chest pain, breathlessness, conscious level and the rhythm itself.
A slower heart rate does not automatically mean the patient is better if they remain hypotensive or develop heart failure.
12. When should you escalate immediately?
- Shock or severe/ongoing hypotension
- Syncope with haemodynamic compromise
- Myocardial ischaemia
- Severe heart failure or pulmonary oedema
- Broad-complex tachycardia you cannot confidently classify
- Polymorphic VT or suspected torsades
- Possible pre-excited AF
- Failure of initial treatment
- Recurrent tachyarrhythmia with deterioration
- Any situation where you are unsure which antiarrhythmic drug is safe
A practical ward example
The observations chart flags a heart rate of 158.
The patient is alert, blood pressure is stable and there is no chest pain or pulmonary oedema.
The ECG shows a regular narrow-complex tachycardia.
- ABCDE first: there are no adverse features.
- Confirm the ECG is regular and narrow-complex.
- Look for reversible causes and obtain IV access/monitoring.
- Try an appropriate vagal manoeuvre.
- If it persists, discuss and prepare adenosine with continuous ECG monitoring.
- If the rhythm terminates, capture a 12-lead ECG and document the response.
- If it does not terminate or the patient deteriorates, escalate promptly.
The Foundation Year tachycardia rule
PATIENT FIRST → UNSTABLE OR STABLE? → 12-LEAD ECG → SINUS OR ARRHYTHMIA? → QRS WIDTH → REGULARITY → TREAT THE CORRECT PATHWAY → REASSESS → ESCALATE
The key message
A fast heart rate is not a diagnosis.
First decide whether the patient is unstable, then decide whether the tachycardia is a physiological response or a primary arrhythmia.
Only then should you move into rhythm-specific treatment.
Educational note: This article is intended as an educational guide for Foundation Year doctors. For individual patients, follow current Resuscitation Council/NICE/BNF guidance and your NHS organisation’s peri-arrest arrhythmia pathways, and seek senior advice when appropriate.
