Micro-Lesson
Stable vs Unstable Tachycardia
Objective: Separate rate recognition from urgency by assessing perfusion and clinical instability.
Street Context
A fast monitor is not automatically an emergency cardioversion decision. Instability is a patient assessment — hypotension, shock signs, ischemic chest pain, acute heart failure, or altered mentation — interpreted in context.
Key Points
- Identify the rhythm family first (narrow/wide, regular/irregular) using a systematic strip approach.
- Ask: is the patient perfusing adequately right now?
- Unstable findings are clinical — not “the number on the monitor alone.”
- Stable does not mean ignore: ongoing assessment, causes, and protocol pathways still matter.
- Reassess after every intervention; stability can change quickly.
Decision Checkpoint
You have a regular wide-complex tachycardia at 180. BP is 72/40 and the patient is diaphoretic and barely interactive. What defines “unstable” here — the rate, the QRS width, or the perfusion picture?
Practice
Review VT and SVT look-alikes in CardioStrip, then restate the instability criteria from memory.
Sources & Further Study
- ACLS educational concepts for tachycardia with pulse (education only).
- Always follow service protocol and medical direction for treatment pathways.
Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.