Wide Complex Tachycardias

Wide Complex Tachycardias & Ventricular Arrhythmias - Joseph Quintana

Background

  • Ask yourself, is this Ventricular Tachycardia (VT) or is it SVT with Aberrant conduction 
    • Aberrant conduction: supraventricular impulse whose QRS is > 110 ms and may resemble a BBB (right bundle more likely to be refractory)

Wide Complex Tachycardias

 

Evaluation

  • BMP, Mg lvl, troponin (if concerned for ischemia)
  • Quick and Accurate: AVR criteria
  • Ventricular Tachycardia is always regular (RR interval): irregular = AF with aberrancy
  • ECG features which increase likelihood of VT
    • Positive or negative concordance = lack of R wave progression on Precordial leads
    • Very broad complexes >160 ms
    • AV dissociation
      • Capture Beats: native QRS complexes making a cameo during the VT
      • Fusion Beats: QRS which appear like a signal average of VT and native complex
    • RsR’ complex with a taller left rabbit ear
    • Absence of typical BBB morphologies

 

Management

  • Unstable = SHOCK 
    • Midazolam: draw 2 mg (comes in 2 mg vials), give 1 mg (have more available)
    • Synchronized 100 J Biphasic if VT
    • Defibrillation if VF
    • Pacer Pads, talk to cards fellow, start medical work-up (labs, imaging, EKG, etc)
  • Stable
    • Medications
      • Acute antiarrhythmics: amiodarone, lidocaine, procainamide
    • Cardioversion
    • Treatment of underlying cause if identifiable
      • Ischemia, electrolyte disturbances, heart failure, drugs
  • Chronic
    • Medications: beta-blockers, amiodarone, mexiletine, sotalol
    • Radiofrequency ablation
    • ICD

 

Additional information

  • Definitions of Ventricular Arrhythmias  
    • Premature Ventricular Complex (PVC): early ventricular depolarization +/- mechanical contraction
        • PVC burden:  % of beats of ventricular origin / total beats over a  24- hour period
    • Sustained VT: continuous VT for 30 seconds, or shorter if it requires an intervention for termination
    • VT storm: three or more separate episodes of sustained VT within 24 hours
  • VT Morphologies
    • Monomorphic VT: a similar QRS configuration from beat to beat
        • Usually, 2/2 scar medicated VT from prior infarction
    • Polymorphic VT: a continuously changing QRS configuration from beat to beat
        • Ischemia until proven otherwise
    • Torsades de Pointes: a form of polymorphic VT with a continually varying QRS that appears to spiral around the baseline of the ECG in a sinusoidal pattern
        • SHORT – LONG – SHORT = refers to the R-R interval activation sequence
        • PVC (Short) followed by compensatory pause (Long) -> results in heterogenous repolarization -> PVC ( R on T phenomena) -> VT
    • VF: chaotic rhythm characterized by undulations that are irregular in timing and morphology, without discrete QRS complexes

 

Premature Ventricular Complexes (PVCs)

Background

  • PVCs are common: Up to 80% of apparently healthy people have PVCs 
    • Normal number of PVCs in an adult is <500 in 24 hrs 
  • Causes 
    • Re-entry: patient with structural heart disease like in post infarction (scars)
    • Abnormal Automaticity: electrolyte abnormalities or acute ischemia (Purkinje fibers)
    • Triggered Activity: early and late after depolarizations which occur because of Hypokalemia, ischemia, infracts, excess calcium and drug toxicity  
  • Etiologies
    • HTN with LVH, HF, myocarditis, ARVC, HCM, idiopathic VT, OSA, pHTN, COPD, thyroid disease, substance use (EtOH, nicotine, stimulants, caffeine)

Work Up

  • Inpatient Evaluation:  
    • 12 lead EKG: conduction disease, long QT syndrome, Brugada syndrome, ARVC
    • Labs: K and Mg, TSH, drug screen
    • Evaluate Burden on Tele
    • Evaluate for QT prolonging agents: Longer QT // risk of Torsades
       
  • Outpatient Evaluation: 
    • 12 Lead EKG
    • Labs: BMP, CBC, TSH, Drug screen, BNP if c/f congestion, Dig level if applicable
    • If exertional symptoms: exercise treadmill testing
    • Ambulatory Heart Monitoring to evaluate burden

 

Management

  • Treat correctable causes discovered on laboratory testing
  • First line therapy for distressing, symptomatic PVCs = beta blockers 
    • Diltiazem is a reasonable consideration although avoid in CHF patients
  • Patients with 10% or higher PVC burden should be evaluated by echocardiography due to development of PVC induced cardiomyopathy and benefit from catheter ablation