Tachycardia

Aka: Tachycardia, Unstable Tachycardia, Unstable Tachyarrhythmia

1. See Also
   1. Cardiopulmonary Resuscitation
   2. Sinus Tachycardia
   3. Narrow Complex Tachycardia
   4. Wide Complex Tachycardia
2. Signs: Unstable
   1. Rapid Heart Rate
   2. Poor Perfusion
      1. Altered Level of Consciousness
      2. Hypotension
      3. Shock
3. Differential Diagnosis
   1. Pulseless Electrical Activity
   2. Narrow Complex Tachycardia
      1. Sinus Tachycardia
      2. Irregular Supraventicular Tachycardia
         1. Atrial Fibrillation
      3. Regular Supraventricular Tachycardia
         1. Sinus Tachycardia (rarely >150 in adults)
         2. Atrial Flutter
            1. Atrial rate: 300 bpm
            2. Ventricular rate most commonly 2:1 = 150 bpm
         3. Paroxysmal Supraventricular Tachycardia (PSVT)
            1. Atrioventricular Nodal Reentry (AVNRT)
               1. Signal down the slow AV nodal pathway and retrograde up the fast AV nodal pathway
               2. In 10% of cases, the signal reentry route is reversed
            2. Atrioventricular Reciprocating Tachycardia (AVRT)
               1. Includes Wolff-Parkinson-White Syndrome (characterized by delta wave)
               2. Accessory pathway outside the AV Node
                  1. Orthodromic (narrow complex): Signal down the AV Node and up the accessory path
                  2. Antidromic (wide complex): Signal down the accessory path and up the AV Node
            3. Atrial Tachycardia (AT)
               1. Abnormal focus of atrial automaticity (outside the SA Node)
               2. Unlike AVNRT and AVRT, no accessory pathway is involved
            4. Junctional Ectopic Tachycardia
   3. Wide Complex Tachycardia
      1. Ventricular Tachycardia (VT)
      2. Torsade De Pointes
      3. Supraventricular Tachycardia (SVT) with aberrancy (e.g. Bundle Branch Block)
         1. Mistakenly managing Ventricular Tachycardia as SVT can be lethal (assume VT first)
            1. Even using established guidelines for wide SVT, will miss 10-40% of cases
         2. Findings consistent with Ventricular Tachycardia
            1. Lead V1 with taller R than R' (taller left rabbit ear)
            2. Lead V6 with R Wave < S Wave (RS upward deflection < downward deflection)
            3. Atrioventricular Dissociation
            4. Fusion complexes (Fusion Beats)
               1. Combined supraventricular and ventricular beats (e.g. QRS Complex merges into P Wave)
         3. References
            1. Mattu (2018) Crit Dec Emerg Med 32(5): 29
4. Management (Same initial approach for all ages)
   1. ABC Management
   2. Mnemonic: IV-O2-Monitor
      1. Obtain IV Access
      2. Oxygen Delivery
      3. Cardiopulmonary monitor
   3. Additional evaluation
      1. Vital Signs
      2. History
      3. Exam
      4. Electrocardiogram
      5. Chest XRay
   4. If signs of immediate failure present:
      1. Pulse Present and NOT Sinus Tachycardia
         1. Prepare for immediate Synchronized Cardioversion
         2. Brief trial of medications (e.g. Adenosine) if no delay
      2. Pulse Absent
         1. Asystole
         2. Pulseless Electrical Activity
         3. Ventricular Tachycardia
         4. Ventricular Fibrillation
   5. Assess QRS Duration
      1. If QRS Duration narrow (<0.09 sec in children or <0.12 sec in adults)
         1. See Narrow Complex Tachycardia
         2. See Supraventricular Tachycardia Management in the Child
         3. See Supraventricular Tachycardia Management in the Adult
      2. If QRS Duration wide (>0.09 sec in children or >0.12 sec in adults)
         1. See Wide Complex Tachycardia
         2. See Ventricular Tachycardia Management in the Adult
         3. See Ventricular Tachycardia Management in the Child
5. References
   1. Cardiopulmonary Resuscitation Guidelines
      1. http://www.circulationaha.org
      2. (2010) Guidelines for CPR and ECC [PubMed]
      3. (2000) Circulation, 102(Suppl I):86-9 [PubMed]