This is a speeding up of the heart rate, which is usually transitory (normally a few minutes duration) and secondary to exercise. An exercising teenager may have a heart rate of up to 200 beats per minute. Sinus tachycardia may be secondary to fever, anxiety, stress, anemia or thyroid problems. Rarely is it a finding in patients with heart failure or inflammation of the heart. Patients with short-lived sinus tachycardia do not require any medical treatment.