is there much stress on the heart when it beats really really fast?!

Best Answer - Chosen by Voters

The stress on the heart reflects the mechanical power being used, (the work in unit time) so if the heart is beating really really fast, then by definition almost, it's doing lots of work, pumping lots of blood, so yes, the stress imposed on it will be high.

But there are conditions to this statement. Sometimes a heart is beating really fast not because of exertion and physical stress, but simply to compensate for a low stroke volume, which means the organs of the body (in heart failure for instance) are not getting enough blood pumped round. In these circumstances the stress may not be all that high, because the amount of blood being pumped is low.

However, irrespective of the amount of blood being pumped, if the rate at which the heart beats beats is artificially and deliberately kept low, and prevented from rising, the stress imposed on the heart becomes vastly much greater, because it must pump more blood at every stroke, and the pressure much higher to compensate for it not pumping so fast.

Treyjust is just "tres wrong", ...-completely wrong. So wrong, in fact that it personifies all that is wrong with the medical profession' view of cardiovascular physiology.
The brain and heart are single-minded in their mission, which is to ensure (as far as is possible) that cardiac output meets the demands of the body.

"The Mathematical Relationship Between Heart Rate, Cardiac Output, and Pulse Pressure, in the Human Systemic Vasculature" by Roy Lowe

yeah. its not good for the heart to always be beating very fast bc it can tire it out for the long run. thats what my dr told me bc i have tachycardia

more than when it beats slow. Doesn't always have to be a bad thing. Work on cardio so your heart doesn't have to work as hard to pump blood.

YES