article_snippet: but it has been reported
article_snippet: David Coulthard, a former McLaren driver, said: ‘My experience of getting knocked out or having big shunts is that you remember the bit before, the bit after but not the bit in the middle.
article_snippet: When you get knocked out it does not come as a warning; it just happens.
article_snippet: ‘The brain is a fairly complex bit of kit, so if they are not able to see any brain injury of any sort it seems a bit medically confusing for me, so there is probably more from the story to come out over time.
article_snippet: an irregular heartbeat.
article_snippet: Another possibility, said Hartstein, would be carotid sinus hypersensitivity, whereby pressure on the main artery to the brain causes the heart rate to drop, blood pressure to fall and the sufferer to blackout.
article_snippet: A second impact in less than 21 days (the stipulated period of rest)