A rhythm with a heart rate greater than 100 bpm is known as a tachycardia, and a tachyarrhythmia is generally defined by a heart rate greater than 150 bpm. An unstable tachycardia is defined as a rapid heart rate which reduces cardiac output, and, thus, perfusion, causing serious signs and symptoms. Some signs and symptoms commonly seen with unstable tachycardia include:

Many causes of stable and unstable tachycardia are identified and treated within the ACLS algorithms. To treat these arrhythmias appropriately requires recognition as well as identification of any causative factors. Reversible causes should be identified and treated, if possible, prior to the initiation of invasive interventions.

Reversible Causes

Common causes of non-cardiogenic tachycardia include:

Review of the H's and T's may reveal other causes of tachycardia that should be treated outside of the ACLS algorithm.

Rhythms associated with stable and unstable tachycardia:

ACLS Tachycardia Interventions

When using the ACLS tachycardia algorithm, the first decision point is to determine if the patient is stable or unstable.

Patients with unstable tachycardia should be treated immediately with synchronized cardioversion. If pulseless tachycardia is present, the patient should be treated with the Pulseless Arrest Algorithm.

Stable tachycardia treatment rests upon the recognition of narrow or wide complex tachycardia. The treatment flow for each is represented below: