Tachycardia Diagnosis and Management

Definition and Classification

The American Heart Association defines tachycardia as an arrhythmia with a rate of >100 beats per minute 1, 2, 3
Sinus tachycardia is defined as a heart rate >100 beats per minute originating from the sinus node 4
The upper rate of sinus tachycardia is age-related and can be calculated as approximately 220 beats per minute minus the patient's age in years 1

Heart rates <150 beats per minute are unlikely to cause symptoms of instability unless there is impaired ventricular function 2, 5
When cardiac function is poor, cardiac output can be dependent on a rapid heart rate, so "normalizing" the heart rate can sometimes be detrimental 1, 5
A rapid heart rate is often an appropriate physiologic response to stress (e.g., fever, dehydration, anemia, hypotension/shock) rather than a primary arrhythmia 1, 2

Initial evaluation of any patient with tachycardia should focus on signs of increased work of breathing, oxyhemoglobin saturation, blood pressure measurement, and 12-lead ECG to better define the rhythm 1, 2, 5
Therapy should be directed toward identification and treatment of the underlying cause 1
If the patient is asymptomatic with no signs of hemodynamic compromise, identify and treat the underlying cause rather than targeting the heart rate itself 1