ACLS Algorithms Review: Unstable Tachycardia Algorithm

Everything you need to know about assessing and managing unstable tachycardia.

At its core, tachycardia is defined as a heart rate greater than 100 bpm. In such cases, the tachycardia algorithm should be used. Essentially, the heart is either beating too fast and/or ineffectively that cardiac output is reduced.


Common signs and symptoms of unstable tachycardia include:


- Low blood pressure

- Hypotension

- Altered mental status

- Ischemic chest discomfort

- Heart Failure



The key decision for treating patients experiencing tachycardia is to determine whether the tachycardia is causing clinical instability. Additionally, rescuers can improve their ability to perform prompt intervention through rapidly recognizing symptomatic tachycardia, and its serious symptoms.


As a general rule of thumb, serious problems are unlikely for a heart rate of less than 150 bpm.


The first step in managing unstable tachycardia is determining whether or not the patient has a pulse. In situations where the patient both has a pulse and is unstable, prompt synchronized cardioversion should be performed.


For a more detailed, step-by-step description of the Unstable Tachycardia Algorithm, see below:

Unstable Tachycardia Algorithm | eMedCert


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