Causes. Unlike some issues, where there’s only a single cause, there are several conditions that can lead to the disruption of the heart’s electrical signal process that causes tachycardia. Some possible causes of tachycardia are: damage to the heart as a result of heart disease, congenital heart conditions, anemia, exercise, stress, high or low blood pressure, and smoking. Also, an imbalance of electrolytes can be another cause. Electrolytes are chemical elements needed for the body to conduct electrical impulses. Drinking too many caffeinated drinks and abuse of recreational drugs may also cause some forms of tachycardia. In some cases, doctors are not always able to determine the exact cause of tachycardia.