II. Signs: Unstable
- Rapid Heart Rate
- Poor Perfusion
III. Differential Diagnosis
- Pulseless Electrical Activity
-
Narrow Complex Tachycardia
- Sinus Tachycardia
- Irregular Supraventicular Tachycardia
- Regular Supraventricular Tachycardia
- Sinus Tachycardia (rarely >150 in adults)
- Atrial Flutter
- Atrial rate: 300 bpm
- Ventricular rate most commonly 2:1 = 150 bpm
- Paroxysmal Supraventricular Tachycardia (PSVT)
- Atrioventricular Nodal Reentry (AVNRT)
- Signal down the slow AV nodal pathway and retrograde up the fast AV nodal pathway
- In 10% of cases, the signal reentry route is reversed
- Atrioventricular Reciprocating Tachycardia (AVRT)
- Includes Wolff-Parkinson-White Syndrome (characterized by delta wave)
- Accessory pathway outside the AV Node
- Atrial Tachycardia (AT)
- Junctional Ectopic Tachycardia
- Atrioventricular Nodal Reentry (AVNRT)
-
Wide Complex Tachycardia
- Ventricular Tachycardia (VT)
- Torsade De Pointes
-
Supraventricular Tachycardia (SVT) with aberrancy (e.g. Bundle Branch Block)
- Mistakenly managing Ventricular Tachycardia as SVT can be lethal (assume VT first)
- Even using established guidelines for wide SVT, will miss 10-40% of cases
- Findings consistent with Ventricular Tachycardia
- Lead V1 with taller R than R' (taller left rabbit ear)
- Lead V6 with R Wave < S Wave (RS upward deflection < downward deflection)
- Atrioventricular Dissociation
- Fusion complexes (Fusion Beats)
- Combined supraventricular and ventricular beats (e.g. QRS Complex merges into P Wave)
- References
- Mattu (2018) Crit Dec Emerg Med 32(5): 29
- Mistakenly managing Ventricular Tachycardia as SVT can be lethal (assume VT first)
IV. Management (Same initial approach for all ages)
- ABC Management
- Mnemonic: IV-O2-Monitor
- Obtain IV Access
- Oxygen Delivery
- Cardiopulmonary monitor
- Additional evaluation
- Vital Signs
- History
- Exam
- Electrocardiogram
- Chest XRay
- If signs of immediate failure present:
- Pulse Present and NOT Sinus Tachycardia
- Prepare for immediate Synchronized Cardioversion
- Brief trial of medications (e.g. Adenosine) if no delay
- Pulse Absent
- Pulse Present and NOT Sinus Tachycardia
- Assess QRS Duration
- If QRS Duration narrow (<0.09 sec in children or <0.12 sec in adults)
- If QRS Duration wide (>0.09 sec in children or >0.12 sec in adults)