Palpitations: a case-based approach to a racing heart

The case: a sudden racing heart

Meet "Aisha", a fictional 34-year-old office worker. One evening, while sitting quietly, her heart suddenly starts pounding very fast and regularly. It lasts about ten minutes, then stops as abruptly as it began. She feels a little breathless and lightheaded but does not faint. Over the next month it happens twice more. Aisha is frightened and books a GP appointment. This pattern — a fast, regular heartbeat that starts and stops suddenly — is a common way palpitations present. The GP's job is to work out whether this is a benign extra-beat, a treatable rhythm disturbance, or something needing urgent cardiology input. History is the most powerful tool here.

Asking the right questions

The GP asks Aisha to tap out the rhythm on the desk: was it regular or chaotic? Fast or slow? Did it start gradually or in an instant? They ask about triggers such as caffeine, alcohol, energy drinks, exercise, stress, and lack of sleep. Crucially, they screen for red-flag symptoms: chest pain, fainting or near-fainting, palpitations brought on by exertion, and a family history of sudden death or inherited heart conditions. They also ask about thyroid symptoms, anaemia, and anxiety, because these commonly cause palpitations. Aisha's regular, sudden-onset, sudden-offset pattern points towards a possible supraventricular tachycardia — a fast rhythm arising above the heart's main pumping chambers, which is usually not dangerous but can be treated.

Tests and capturing the rhythm

Examination is often normal between episodes, so tests aim to record the heart during an event. Every patient with palpitations should have a resting 12-lead ECG, plus simple blood tests including full blood count and thyroid function. Because Aisha's episodes are brief and infrequent, a standard 24-hour ECG monitor might miss them, so a longer patch monitor or an event recorder she activates during symptoms is more useful. NICE encourages capturing a rhythm strip during an actual episode whenever possible. Newer options, including some smartwatches and single-lead home devices, can record a tracing that a clinician then reviews — helpful, but not a replacement for formal assessment. The aim is a simple question: what is the heart doing when symptoms occur?

Diagnosis, treatment and referral

Aisha's event recorder captures a fast, regular narrow-complex rhythm consistent with supraventricular tachycardia. She is taught vagal manoeuvres — such as bearing down as if straining, or the modified Valsalva with legs raised — which can stop an episode safely at home. She is referred to cardiology, where options may include medicines that slow the rhythm or a catheter ablation, a keyhole procedure that can cure many cases by targeting the faulty electrical pathway. If instead her recording had shown atrial fibrillation, the focus would shift to stroke-risk assessment and anticoagulation decisions. The wider point: a clear diagnosis turns a frightening symptom into a manageable, often very treatable, condition with a definite plan.

When palpitations are an emergency

Most palpitations are not dangerous, but some combinations demand urgent action. Call 999 if palpitations come with severe chest pain or pressure, sudden severe breathlessness, fainting or collapse, or if someone becomes unresponsive. These may signal a heart attack or a dangerous rhythm. Seek urgent same-day help if palpitations are prolonged and will not settle, if they are triggered by exercise, or if you have known heart disease and feel very unwell. Fainting during palpitations is a particularly important warning sign and should always be assessed quickly. If you are ever unsure, err on the side of caution. This article is for education only and cannot diagnose you — if you feel very unwell or frightened, call 999 or seek urgent NHS advice.