Unstable means hypotension, altered mental status, signs of shock, ischemic chest pain or acute heart failure.
Before you read
Test yourself first: 3 questions
Question 1 of 3
A patient has a regular, narrow-complex tachycardia at 190, a systolic pressure of 70 and is confused. The priority is:
Answer: A. Hypotension and altered mental status make this tachycardia unstable, and unstable tachycardias with a pulse are treated with synchronized cardioversion, timed to avoid the vulnerable part of the cardiac cycle. Unsynchronized shocks are for pulseless rhythms.
Question 2 of 3
A patient with a known accessory pathway has a regular, narrow-complex tachycardia at 210 per minute with retrograde P waves visible after each QRS. What is the most likely mechanism?
Answer: A. Most reentrant tachycardias in accessory pathway patients are orthodromic: the impulse travels forward through the normal AV node and His-Purkinje system, producing a narrow QRS, and returns to the atria through the pathway. Antidromic reentry uses the pathway forward and gives a wide, maximally pre-excited QRS, and conducted atrial fibrillation would be irregular. Vagal maneuvers and nodal agents are appropriate for the narrow, regular orthodromic form.
Question 3 of 3
A regular wide-complex tachycardia in a patient with known cardiac disease should be managed as:
Answer: A. Most wide-complex tachycardias are ventricular, and the probability rises sharply with structural heart disease, so the safe default is to treat it as VT. Assuming an aberrantly conducted supraventricular rhythm and treating it that way can destabilize true VT, while treating SVT as VT rarely causes comparable harm.
Keep the streak going with more questions like these, each with a full rationale.
What is tachycardias & bradycardias?
Signs of poor perfusion caused by the rhythm drive electrical therapy; a stable patient allows time for a 12-lead and medication. The exam tests the fork, not the doses.
Key points to remember
- Unstable means hypotension, altered mental status, signs of shock, ischemic chest pain or acute heart failure.
- Unstable tachycardia with a pulse: synchronized cardioversion.
- Stable narrow regular tachycardia: vagal maneuvers, then adenosine.
- Symptomatic bradycardia: atropine first; if ineffective, transcutaneous pacing or a chronotropic infusion.
- Sinus tachycardia is a response, not a disease — treat the cause (fever, pain, bleeding, hypoxia).
Field priorities
- Decide stable versus unstable before choosing any therapy.
- Get a 12-lead in the stable patient — width and regularity pick the path.
- A pulseless rhythm goes to the arrest algorithm: defibrillate, never synchronize.
Coaching the patient
- Sinus tachycardia rarely exceeds 220 minus the age; a fixed rate near 150 suggests flutter or SVT.
- Pacing: confirm electrical capture on the monitor and mechanical capture by a pulse.
Red flags: act now
- Bradycardia with altered mental status or hypotension
- Wide-complex tachycardia — treat as VT
- Second-degree type II or third-degree block
Tachycardias & Bradycardias: FAQs
What are the priority actions for Tachycardias & Bradycardias in the field?
Decide stable versus unstable before choosing any therapy. Get a 12-lead in the stable patient — width and regularity pick the path. A pulseless rhythm goes to the arrest algorithm: defibrillate, never synchronize.
What findings in Tachycardias & Bradycardias change your plan or your transport decision?
Bradycardia with altered mental status or hypotension. Wide-complex tachycardia — treat as VT. Second-degree type II or third-degree block.
What do I need to know about Tachycardias & Bradycardias for the NREMT?
Unstable means hypotension, altered mental status, signs of shock, ischemic chest pain or acute heart failure. Unstable tachycardia with a pulse: synchronized cardioversion. Stable narrow regular tachycardia: vagal maneuvers, then adenosine. Symptomatic bradycardia: atropine first; if ineffective, transcutaneous pacing or a chronotropic infusion.
What should the crew communicate or document for Tachycardias & Bradycardias?
Sinus tachycardia rarely exceeds 220 minus the age; a fixed rate near 150 suggests flutter or SVT. Pacing: confirm electrical capture on the monitor and mechanical capture by a pulse.
