Pulsating heart beat. Is it normal?

What you are seeing is most likely her carotid artery pulse. This artery runs up the side of the neck just below the angle of the jaw, and in a slim child lying still, you can often see it beating under the skin. It looks stronger after she has been running around, when she is warm, or when she has a fever. In most 8 year olds this is completely normal. A pulse that looks very forceful sometimes needs a closer look. Anaemia, fever, an overactive thyroid and a few heart conditions (a leaking aortic valve, or a small blood vessel near the heart called PDA that has stayed open after birth) can make the pulse look bounding. These are uncommon, and they usually come with other clues. She tires or gets breathless more easily than other children, looks pale, isn't gaining weight well, or a doctor has heard a murmur in the past. If none of this fits her, I would not worry. One more point. If what you see is a swelling or lump that throbs, and not just a beat under flat skin, get it examined. Lymph nodes in this area are very common in children and can sometimes seem to move with the artery underneath.

Next time you notice it while she sleeps, place two fingers there gently and count the beats for 30 seconds, then double it. For her age, roughly 60 to 100 a minute during sleep is normal. Notice whether the rhythm feels regular, and feel the left side too, since both sides usually feel about the same. If the count is in that range, she is active and growing well, and there is no lump, nothing more is needed. If the rate stays above about 110 to 120 while she is asleep, the rhythm feels irregular, or any of the clues above are present, she should be examined by a paediatrician or cardiologist, in person or online. Keep a note of the pulse count and a short video of the neck to show the doctor. An echocardiogram is needed only if there is a murmur or something unusual on examination.

Take her to the nearest emergency at once if she ever faints, complains of chest pain or a racing heart, or becomes breathless at rest. Otherwise, a visible neck pulse in a healthy, active child is very common and usually harmless.