ACLS Tachycardia Algorithm

Step 1: Confirm Tachycardia

Measure the patient’s heart rate to verify tachycardia, typically at 150 beats per minute or higher. Some patients may show instability at lower rates depending on their condition. Check for a pulse within 10 seconds. If no pulse is detected, immediately switch to the ACLS cardiac arrest algorithm. Only proceed with the tachycardia algorithm when you confirm a clear, palpable pulse and a heartbeat above 150 bpm.

Step 2: Establish Basic Support and Monitoring

Secure the patient’s airway and assist breathing if a respiratory problem happens. Provide supplemental oxygen to maintain saturation between 94% and 99% for hypoxemic patients. At the same time, check the heart rhythm and blood pressure, set up a pulse oximeter, insert an IV line, and perform a 12-lead ECG.

Step 3: Identify and Address Underlying Causes

Assess reversible causes that may trigger tachycardia while providing supportive care. Reversible causes can be identified by using the Hs and Ts framework of the ACLS algorithm. Treat these underlying conditions at the same time as rhythm management and patient assessment. Fixing the root cause can positively affect treatment response and improve patient outcomes.

Step 4: Assess Patient Stability

Understand hemodynamic stability through a systematic evaluation of key clinical indicators. Unstable patients have symptoms like hypotension, altered mental status, signs of shock, ischemic chest discomfort, or acute heart failure. However, stable patients maintain adequate blood pressure and organ perfusion despite fast heart rates. This stability assessment is important to decide treatment urgency and selection of intervention.

Step 5: Provide Treatment Based on Stability

The treatment approach depends directly on the patient’s stability. Unstable patients require immediate intervention, while stable patients need more rhythm-specific treatment.

For Unstable Patients

Immediate Synchronized Cardioversion:
Unstable patients with signs of shock, hypotension, or altered mental status require immediate synchronized cardioversion. Apply sedation if possible and use sync mode to avoid delivering energy during the T-wave. Energy selection depends on rhythm characteristics:

• Narrow regular complexes start at 50-100 joules
• Narrow irregular rhythms need 120-200 joules
• Wide regular patterns begin at 100 joules

For wide irregular rhythms, turn off synchronization and defibrillate immediately.

For Stable Patients

Wide QRS

Stable patients with wide QRS complexes require careful rhythm analysis and medication selection. Consider adenosine only if the rhythm is regular and monomorphic. For other wide-complex rhythms, use antiarrhythmic infusions like procainamide, amiodarone, or sotalol. Avoid these medications in patients with prolonged QT intervals or heart failure. Expert consultation is also recommended to ensure safe and effective management of tachycardia.

Narrow QRS

Stable patients with narrow QRS complexes typically respond well to vagal maneuvers and adenosine. Try vagal maneuvers first if the rhythm is regular. If unsuccessful, consider adenosine 6 mg rapid IV push for regular rhythm followed by a normal saline flush, then 12 mg if needed. For persistent narrow-complex tachycardia, consider beta-blockers or calcium channel blockers as appropriate.

Final Assessment

If the patient remains refractory to initial treatment, healthcare providers must reassess the situation. Evaluate the underlying cause more thoroughly, as missed reversible conditions like hypoxia or toxins may be preventing successful rhythm conversion. Consider increasing the energy level for the next cardioversion attempt and adding antiarrhythmic drugs to improve success rates. Also, consider expert consultation for complex cases or when standard treatments fail to restore stable rhythm.