Heart beat feels like every thump is heavy & forceful like it's really pumping hard, but i checked my heart rate with a pulsoxy an it's 79bpm causes?

May be true?: You need an echocardiogram. If you have certain valvular issues, (e.g. severe aortic insufficiency or severe mitral regurgitation) or a rare entity called "hypertrophic cardiomyopathy", you may be feeling an unusually forceful heat beat. Alternatively, you may have "cardiac awareness." An echo will sort this out. The treatments are different.