What Causes Pounding In Heart While Having Normal Pulse Rate?

I have recently been woken from sleep with my heart pounding but a normal pulse. I have numerous medical problems. I have CAD, tiny arteries with numerous stents, CHF, diabetes that is under control with pills, gerd, depression, arthritis in numerous areas and mild asthma. I am a 57 y/o female and am grossly obese though I have lost 40 pounds in the last 9 months. I have normal ekgs and echos.