Faster heart rate >170 beats. Advise!

Hello doctor/s My brother in law is experiencing Faster heart rate which usually reaches more than 170 and continues for some hours and now it's happening 2-3 times a week. He was facing increased heart rate in the past also (7-8 yrs back) which used to normalise after a few minutes and was once in a while in the past. Now for the past few months he is experiencing this problem more often. He is into body building and spends quite a good time in the gym also. He is living in Newzealand for the last 6 years. Recently (2weeks ago), he consulted doctors there and after conducting echo, ECG, heart scan and other test they told him that there is some extra nerve near the upper to valves of the heart because of which electricity produced in the heart is more due to which his heart beat increases abnormally. They have suggest angiography and will remove/block that extra nerve which will take some hours and he has to rest for 2 days and then he can start his normal routine. Kindly advise