My wife is 28 years old, weighs 56 kilos, is 1m 63cm tall, and for the past 5 years she experiances every 2 months a sudden rapid elevation in her heart rate. It forces her into the fetal position, she has to fight to breath, loses most of her sight and these episodes last about 20 minutes. They are not panic attacks, can you tell me what heart conditions she may have?