prior to June 30 I could hike and fly fish for miles and never show any signs of tachycardia. But all of a sudden since june 30th I am getting periods of up to 1.5 hours of sustained tach. I can get this whiel asleep, if I situp from prone position, if I walk just 10 ft. I become short of breath and often have accompaning pain over my heart, angina attacks. Some times the angine resolves with nitro but 2 times now I have had to go to er. Other symptoms include low o2 with oximeter reads 82-90 that comes & goes often stays when pulse is racing and leg and arm cramps while pulse is racing. I am under way less stress then I was just a month ago. A bit disturbed that cardio doc so far says wel that rate is nto that high. Rate may not be tha high to her but it is making me an invalid with the chest pains and shortness of breath. I am unwilling to live with a verdict that does not find a cause and get a resolution to the issue. any ideas