Management of Tachycardia with Heart Rate of 120 bpm

Initial Evaluation

The American Heart Association recommends assessing for signs of increased work of breathing and checking oxygen saturation via pulse oximetry in patients with tachycardia and heart rate of 120 beats per minute 1
The American College of Cardiology suggests providing supplementary oxygen if oxygenation is inadequate or patient shows signs of respiratory distress 1
Attach cardiac monitor, evaluate blood pressure, and establish IV access, as recommended by the American Heart Association 1
Obtain a 12-lead ECG to define the rhythm, as suggested by the American College of Cardiology 1
Evaluate for potential reversible causes of tachycardia, as recommended by the American Heart Association and the American College of Cardiology 1, 2

Determine if the patient is hemodynamically stable or unstable, as recommended by the American Heart Association 1
Assess for signs of instability, such as acute altered mental status, ischemic chest discomfort, acute heart failure, hypotension, or other signs of shock, as suggested by the American College of Cardiology 1, 2
Classify the tachycardia based on QRS duration, with narrow complex (<120 ms) being most likely supraventricular in origin, as recommended by the American College of Cardiology 3, 4
Wide complex (≥120 ms) tachycardia could be ventricular tachycardia or supraventricular tachycardia with aberrancy, as suggested by the American College of Cardiology 3, 5

For hemodynamically unstable patients, proceed to immediate synchronized cardioversion, as recommended by the American Heart Association and the American College of Cardiology 1, 2
Recommended initial energy doses for cardioversion are 120-200 J biphasic for atrial fibrillation, 50-100 J initially for atrial flutter and other SVTs, and 100 J initially for monomorphic VT, as suggested by the American College of Cardiology 1
For hemodynamically stable patients with heart rate of 120 bpm, identify the specific rhythm and treat accordingly, as recommended by the American College of Cardiology 1, 2
For narrow complex SVT, try vagal maneuvers, and if unsuccessful, administer adenosine, as suggested by the American College of Cardiology 3, 7
For atrial fibrillation or flutter, rate control with beta-blockers or calcium channel blockers is recommended, as suggested by the European Society of Cardiology 8
For wide complex tachycardia, treat as ventricular tachycardia unless proven otherwise, as recommended by the American College of Cardiology 3, 5

With heart rates <150 beats per minute, the tachycardia is more likely secondary to an underlying condition rather than the primary cause of any instability, as suggested by the American Heart Association and the American College of Cardiology 1, 2
Avoid verapamil or diltiazem in wide-complex tachycardias of uncertain origin, as they may cause hemodynamic collapse if the rhythm is ventricular tachycardia, as recommended by the American College of Cardiology 3
Treating the heart rate without identifying the underlying rhythm and cause is a common pitfall to avoid, as suggested by the American Heart Association and the American College of Cardiology 1, 2
Normalizing heart rate in compensatory tachycardias where cardiac output depends on the rapid rate is also a common pitfall to avoid, as recommended by the American Heart Association 1