Tachycardia 🫀

• Sinus tachycardia is a response, not a primary rhythm problem. The RCUK tachyarrhythmia algorithm does not apply.
• Typical drivers: pain, distress, fever or sepsis, blood loss or dehydration, hypoxia, PE, ACS, electrolyte disturbance, and drugs or caffeine.
• Do not try to normalise the heart rate with antiarrhythmic medication or synchronised cardioversion.

• Current NEWS, AVPU, and whether the patient looks unwell.
• Manual pulse: rate, and whether it is regular or irregular. Do not rely on the monitor number alone.
• Blood pressure. Chest pain, breathlessness, dizziness, or collapse?
• Has a 12-lead ECG been done? If not, request one now.
• Fever, obvious bleeding, uncontrolled pain, or a missed dose of VTE prophylaxis?
• Ask the nurse to get IV access, a full set of observations, and to uncover the patient so you can look for an infection source.

• Are they actually symptomatic, or was this an incidental high rate on observations?
• Known IHD, heart failure, or risk factors for ACS and thromboembolism.
• Caffeine (tea, coffee, energy drinks) and recent inhalers or nebs.
• Anticoagulants, antiplatelets, or NSAIDs if bleeding could be the cause of a compensatory tachycardia.
• Should they be on prophylactic LMWH, and has it been given? Missed prophylaxis belongs on the PE differential.

• Look for drugs that raise heart rate: frequent salbutamol, theophylline (toxicity), sympathomimetic eye drops such as phenylephrine, dipyridamole, anticholinergics, and excess levothyroxine.
• Check the BNF or local formulary for interactions before you add anything.

• ABCDE. Perfusion, capillary refill, and whether they are shocked or comfortable.
• Manual heart rate and pulse character (regular vs irregular).
• Volume status: dry mucosa, reduced skin turgor, JVP, oedema, and charted intake/output.
• Full exam for a source: chest, abdomen, skin, lines, wounds, and calves. Uncover the patient.

• 12-lead ECG to confirm sinus tachycardia before you attribute the rate to a reversible cause.
• Directed bloods: FBC, U&E (including K⁺ and Mg²⁺), CRP. If febrile or septic, add cultures and lactate and start the local sepsis pathway.
• Group and save, and crossmatch if you think they are bleeding.
• Urine dip if infection or hypovolaemia from renal losses is plausible.
• Troponin if ACS is in the differential.
• D-dimer only when PE is a genuine consideration after clinical assessment (see Wells score). It is not a default test for every fast heart rate.

• Unwell patients need resuscitation first. Stable patients can follow a treat-the-driver plan.
• ABCDE. Monitor ECG, BP, and SpO₂. Give oxygen if SpO₂ <94%. IV access.
• Treat what is driving the tachycardia: analgesia, settle agitation and anxiety, rehydrate, antiemetics for vomiting, and the sepsis pathway where indicated. The rate often falls once those are dealt with.
• Step up nursing observations. If infection is likely, include frequent temperature checks.
• Seek expert help if the tachycardia persists despite treating reversible causes, or if you are unsure of the rhythm.

• Use the RCUK adult tachyarrhythmia algorithm at the top of this page with a senior present. Interns should not run that algorithm unsupervised.
• On the ECG, note QRS width (narrow vs broad) and whether the rhythm is regular or irregular. That is how RCUK branches the algorithm.
• Narrow irregular tachycardia is probable AF: compare old ECGs, involve a senior for rate control and anticoagulation decisions. See the atrial fibrillation topic for more.
• Do not cardiovert or give antiarrhythmics for sinus tachycardia.

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