ACLS Provider: Course

Tachycardia Algorithm

Tachycardia is defined as a heart rate of more than 100 beats per minute in adults. While a rapid heart rate can be a normal physiological response to exercise, stress, or excitement, sustained or excessively rapid tachycardia can significantly strain the heart, reducing cardiac output and potentially leading to serious complications. The ACLS Tachycardia Algorithm provides a structured approach to assessing and managing tachycardia, focusing on differentiating between stable and unstable presentations and guiding appropriate interventions.

Step 1: Is the Patient Stable or Unstable?

Unstable Tachycardia: Unstable tachycardia is defined by the presence of signs and symptoms indicating inadequate organ perfusion due to the rapid heart rate. These include:

  • Hypotension: Low blood pressure (systolic BP typically <90 mmHg) due to reduced cardiac output.
  • Altered Mental Status: Confusion, disorientation, decreased level of consciousness, or syncope (fainting) resulting from decreased cerebral perfusion.
  • Signs of Shock: Pale, cool, clammy skin, weak and rapid pulse, and delayed capillary refill, indicating inadequate peripheral perfusion.
  • Ischemic Chest Pain (Angina): Chest pain or pressure due to insufficient oxygen supply to the heart muscle caused by the increased heart rate and reduced diastolic filling time.
  • Acute Heart Failure: Shortness of breath, pulmonary edema (fluid in the lungs), and other signs of heart failure due to the heart's inability to pump blood effectively.

Immediate intervention is required in unstable tachycardia to prevent further deterioration and potential cardiac arrest.

Stable Tachycardia: Stable tachycardia is characterized by the absence of the serious signs and symptoms listed above. The patient may experience palpitations, but their hemodynamic status is relatively preserved. However, even in stable tachycardia, it's essential to identify and treat the underlying cause to prevent complications and improve patient comfort.

Step 2: Identify the Rhythm

  • Narrow QRS Complex (SVT): A narrow QRS complex (typically <0.12 seconds) suggests a supraventricular origin of the tachycardia, meaning the electrical impulse originates above the ventricles (in the atria or AV node). Common causes include sinus tachycardia, supraventricular tachycardia (SVT), atrial fibrillation, and atrial flutter. These rhythms are often treated with vagal maneuvers or adenosine.
  • Wide QRS Complex (VT): A wide QRS complex (≥0.12 seconds) suggests a ventricular origin of the tachycardia (ventricular tachycardia or VT) or a supraventricular tachycardia with aberrant conduction (e.g., bundle branch block). Wide-complex tachycardias can be more hemodynamically unstable and are typically managed with antiarrhythmic drugs like amiodarone or synchronized cardioversion.

ACLS Tachycardia Algorithm:

  1. Evaluate and maintain the airway, provide oxygen, and monitor the ECG: These are the essential initial steps in managing any patient with a cardiac rhythm disturbance.
  • Airway: Ensure a patent airway and be prepared to provide advanced airway management if needed.
  • Oxygen: Administer supplemental oxygen to maintain adequate oxygen saturation.
  • ECG Monitoring: Continuously monitor the patient's ECG to identify the specific rhythm and assess response to treatment. A 12-lead ECG is crucial for accurate rhythm diagnosis when feasible.
  1. For unstable tachycardia, perform synchronized cardioversion immediately: Synchronized cardioversion delivers an electrical shock timed to avoid the vulnerable period of the cardiac cycle (the T wave), reducing the risk of inducing ventricular fibrillation. The appropriate energy level for cardioversion depends on the specific rhythm.
  2. For stable tachycardia: The management depends on the QRS complex width:
  • Narrow QRS Complex (SVT):
    • Vagal Maneuvers: Initially, attempt vagal maneuvers (e.g., carotid sinus massage, Valsalva maneuver) to slow the heart rate. These maneuvers stimulate the vagus nerve, which can slow AV nodal conduction and terminate some SVTs.
    • Adenosine: If vagal maneuvers are unsuccessful, adenosine is the first-line medication for stable, regular, narrow-complex tachycardias (SVT). Adenosine is a very short-acting AV nodal blocking agent that can transiently interrupt the re-entry circuit causing the SVT.
  • Wide QRS Complex Tachycardia:
    • Antiarrhythmic Drugs: If the patient is stable with a wide QRS complex tachycardia, antiarrhythmic medications such as amiodarone or procainamide may be considered. Expert consultation with a cardiologist is recommended in these cases to help guide medication selection and dosing.