A boy with a rare cardiac condition has been banned from laughing in case his chuckles trigger a fatal heart attack. Bradley Burhouse has a dangerously high heart rate and is on doctors orders to keep calm to ensure his ticker doesnt beat any faster. The brave seven-year-old has stopped exercising and his mother has been told to make sure he doesnt laugh too hard in case his heart develops a severely abnormal heart rhythm, which can cause sudden death. Hes not even allowed to play outside with his brothers Jack, 14, and Dalton, 12, and sister Maddison, 6. Bradley was diagnosed with ventricular tachycardia after he collapsed earlier this year. The rare condition in children means his resting heart rate is 120 to 200 beats per minute - at least twice as fast as the average person. Ventricular tachycardia is caused by faulty electrical signals in the lower heart chambers known as ventricles. These override the hearts normal rate and rhythm causing the ventricles to contract faster than normal. This causes the heart to pump out blood more quickly and the ventricles may not have enough time to fill up properly with blood. It can cause chest pain, dizziness and fainting fits. MOL