Tachycardia: Faster Heart Beat, But Less Blood Flow
Tachycardia is defined as an increased heart rate usually over 100 beats per minute (bpm). Compare this to the average resting heart rate of a person which is about 60-70 bpm.
When we become more active our heart rate increases to meet the increased demand of muscles needing oxygen. As such, tachycardia is usually not a problem as the heart rate will return to the resting rate once the activity stops. But occasionally, usually because of a malfunction of the heart's electrical system, the heart rate stays high or climbs even higher.
If the heart begins to beat too fast there is not enough time in between heart contractions for blood to refill the heart chambers. As a result, and counter-intuitively, the heart will be pumping less blood than normal even though it is beating very fast.
Uncontrolled tachycardia can result in fibrillation, an irregular heart rhythm, which can result in cardiac arrest.
In cases where the person has collapsed and may be suffering from fibrillation, a defibrillator will be needed to restore regular heart rhythm.
Some people with chronic tachycardia may require daily medication or a pace maker.