Ventricular Tachycardia

OVERVIEW

  • Ventricular Tachycardia = 3 or more VEB at a rate of > 130 beats/min
  • If > 30 seconds = sustained
  • can be monophoric or polymorphic

TYPES

Monomorphic

  • most common
  • associated with MI

Polymorphic

  • QRS at 200 beats/min or more which change amplitude and axis so they appear to twist around the baseline
  • -> treatment is the same for both

MECHANISMS

  • enhanced automaticity (ectopic pacemaker activity)
  • enhanced trigger activity
  • re-entry

PREDISPOSTING CONDITIONS

Channelopathies (Na+ and K+)

  • Lange-Neilsen syndrome (long QT + deafness)
  • Romano-Ward syndrome (long QT and no deafness)
  • Brugada syndrome

Other electrophysiology effects

Drugs that cause QT Prolongation

  • clarithromycin
  • erythromycin
  • metaclopramide
  • haloperidol
  • TCA
  • methadone
  • droperidol

Electrolytes

  • hypokalaemia
  • hyperkalaemia
  • hypomagnesaemia
  • hypocalcaemia

Hypothermia

Structural heart disease

  • LV dysfunction
  • coronary artery disease
  • MI
  • HOCM

DIFFERENTIATING VT FROM WIDE COMPLEX SVT

Criteria for diagnosis of VT using the 4-step Brugada algorithm:

(i) Is RS complex present in any lead? -> if NO the rhythm is VT
(ii) Is the RS duration >100ms in any lead? -> if YES then the rhythm is VT
(iii) Is there AV dissociation? (fusion or capture beats) -> if YES then the rhythm is VT
(iv) Is the rhythm morphologically consistent with SVT (looks like RBBB or LBBB)? -> if NO the rhythm is VT

-> fusion beats = complex looks half normal and half abnormal
-> capture beats = normal complex seen

MANAGEMENT

PULSELESS

  • ACLS protocol
  • Immediate unsynchronised defibrillation
  • CPR with minimal interruption (30:2, with 2 minute cycles)
  • Intubation
  • O2
  • IV access
  • Adrenaline 1mg Q3min
  • Amiodarone 300mg (following 3rd shock)
  • Exclude reversible causes (4 H’s and T’s)

CLINICALLY COMPROMISED

  • Haemodynamically unstable, chest pain, ischaemia, heart failure, VR > 150/min -> synchronised shock (x 3)
  • O2
  • IV access
  • Rapid exclusion of reversible factors (wire, PA catheter in RV, hypoK+ or Mg2+)
  • Amiodarone 5mg/kg -> infusion
  • Synchronised DC Shock (50J Bi, 100 Mono)
  • Consider:
    -> procainamide 50mg/min
    -> lignocaine 1mg/kg
    -> sotalol 1mg/kg
  • Repeat DC Shock (150 Bi, 360 Mono)
  • Overdrive pacing

CLINICALLY STABLE

  • controversial
  • debate between cardioversion and pharmacological treatment
  • still a medical emergency as can degenerate into unstable VT and VF
  • O2
  • Amiodarone or sotolol
  • Cardioversion if medical therapy fails (quickly) – will need sedation
  • Consider pacing if cardioversion no effective
  • Evaluation and treatment of cause (usually IHD)
  • If associated with long QT -> consider Mg2+

References and Links

litfl.com


CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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