There are varied causes for an unusual increased heart rate. One is tachycardia, it can be a usual rise in heart rate caused by exercise or a stress response (sinus tachycardia). Sinus tachycardia is considered a symptom, not a disease. Tachycardia can also be caused by an irregular heart rhythm (arrhythmia). There are medications that can also cause increased heart rate, but TKM has shown to be effective in each case.