V Tach vs. SVT

Assume ventricular tachycardia until proven otherwise

Background

• Ventricular tachycardia vs. supraventricular tachycardia

Evaluation

Monomorphic ventricular tachycardia

PSVT at ~180 bpm

Termination of PSVT following adenosine

Factor	V-Tach	SVT with Aberrancy
Age	>50	<35
History	MI, CHF, CABG, MVR	MVR, WPW
Cannon A Waves	Present	Absent
Arterial Pulse	Variation	No variation
First heart sound	Variable	Not variable
Fusion Beats	Present	Absent
AV dissociation	Present	Absent
QRS	>0.14sec	<0.14sec
Axis	Extreme LAD (< -30)	Normal or slightly abnormal
Vagal Maneuvers	No response	Slows or terminates
QRS morphology (RBBB-like pattern)	V1 - R or qR V6 - rS	V1 - rsR' V6 - R(slurredS)
QRS morphology (LBBB-like pattern)	V1 or V2 - Broad R wave (>40msec) V6 - Any Q or QS	V1 - rS or QS V6 - qRs

Diagnostic Algorithms

• Only for regular rhythms, if irregular consider a-fib with block
• Only for treatment decision if patient is stable
• Assume V-tach until proven otherwise

Brugada Algorithm

• Absence of an RS complex in all precordial leads?
  • If yes then VT
  • If no then continue
• RS interval >100ms in any precordial lead? (onset of R wave to deepest part of S wave)
  • If yes then VT
  • If no then continue
• AV dissociation?
  • If yes then VT
  • If no then continue
• Morphology criteria for v-tach present in both V1-2 and V6?
  • If yes then VT
  • If no then possibly SVT with aberrant conduction

aVR Algorithm

• In lead aVR:

• Presence of an initial R wave?
  • If yes then VT
  • If no then continue
• Presence of an initial r or q wave >40ms
  • If yes then VT
  • If no then continue
• Presence of a notch on descending limb of a negative onset, predominantly negative QRS?
  • If yes then VT
  • If no then continue
• Ventricular activation-velocity ratio (Vi/Vt) ≤1?
  • If yes then VT
  • If no then SVT

Niemann Algorithm

• Combination of the most specific aspects of the above two algorithms

Acronym: CARMA → Concordance → aVR →Regular → Morphology →AV dissociation

• Presence of an initial R wave in aVR?
  • If yes then VT
  • If no then continue
• Is there concordance (monophasic with same polarity) in all of the precordial leads?
  • If yes then VT
    

    Example of concordance in precordial leads
    

    Example of disconcordance in precordial leads
  • If no then continue
• Is there evidence of AV dissociation/Capture beats?
  

  Example of capture beat
  • If yes then VT
  • If no then continue
• Is the QRS morphology in V1 and V6 consistent with either LBBB or RBBB?
  • If no then VT
  • If yes then SVT with aberrancy

R-Wave Peak Time Method

• In lead II, if the TIME in (ms) it takes the R wave to go from the isoelectric line to its peak voltage is greater than 50ms, it is VT
• Positive Likelihood ratio of 34.8

Lesser Known Criteria

• Josephson's sign --- notching or slurring near the nadir of the S-wave is characteristic of V. Tach
  

  Josephson's Sign Vtach
• Rsr' sign --- A taller left R wave in v1-v2 is very specific for VT, as opposed in a RBBB where the second/right R-wave (R') is taller
• "Northwest" axis deviation -- Negative QRS complex in I, AVF and Positive QRS in AVR

See Also

• Tachycardia (Wide)
• SVT
• ACLS (Main)
• ACLS: Tachycardia
• PALS (Main)
• PALS: Tachycardia

References

Authors

Ross Donaldson, Jordan Swartz, Daniel Ostermayer, Peter Morris, Babak Missaghi, Neil Young, Michael Holtz