What should you know about cardio neurogenic syncope?

Syncope happens when the brain temporarily receives too little blood. A reflex response can lower heart rate, widen blood vessels, or do both, particularly after pain, fear, heat, prolonged standing, or straining. A heart rhythm disturbance can also reduce blood flow suddenly. Anaemia, dehydration, and low blood glucose may make fainting more likely, while atrial fibrillation is one heart condition a clinician may consider.

Warning symptoms can include light-headedness, nausea, sweating, warmth, blurred vision, or muffled hearing. The person usually becomes unresponsive briefly and then gradually recovers, although a fall can cause injury. A clinician needs the witness account and details of posture, triggers, palpitations, medicines, and recovery to separate syncope from a seizure or another cause of collapse.

If warning symptoms begin, lie down and raise the legs if possible, or sit with the head lowered. Move away from heat and ask someone to stay nearby. If a person has fainted, check breathing, protect them from injury, and keep them lying flat until they feel fully recovered. Do not give food or drink while they are unconscious.

After recovery, arrange medical review for a first faint, repeated episodes, or a blackout without a clear trigger. Keep a record of what happened, including activity, posture, symptoms beforehand, medicines, and the time needed to feel normal again. Do not drive until a clinician has discussed safety.

Call emergency services if the person is not breathing normally, does not wake promptly, has chest pain, severe breathlessness, a sustained racing or irregular heartbeat, severe injury, new weakness, trouble speaking, or confusion. Urgent assessment is also needed when fainting occurs during exercise, while lying down, or in someone with known heart disease or a family history of sudden death.

Ask whether the episode fits reflex syncope or suggests a heart rhythm problem; whether you need an electrocardiogram, blood tests, or monitoring; how to prevent another episode; whether any medicine contributes; and when you can safely drive or exercise.