In the adult tachycardia ACLS algorithm, a heart rate threshold defines tachycardia as greater than what value?

• A. >100
• B. >120
• C. >150
• D. >180

Answer: (C)

In the adult tachycardia with a pulse pathway, a high heart rate is used to signal when rhythm will more likely compromise perfusion and require quicker intervention. A rate above 150 beats per minute is the threshold that defines tachycardia in this algorithm because at or beyond this level diastolic filling time drops substantially, reducing stroke volume and cardiac output, which makes rapid rhythm control more urgent. This threshold helps guide the escalation of care, with more urgent steps (like synchronized cardioversion or pharmacologic therapy) considered when the rate is that high and the patient shows signs of instability or a broad/compatible tachycardia pattern. The other numbers don’t align with this specific ACLS guidance, which uses 150 as the practical cut‑off for tachycardia management decisions.