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Ventricular Arrhythmias

Nonsustained Ventricular Tachycardia (NSVT)

  • ≥3-5 consecutive ventricular beats lasting <30s
    • Patient remains hemodynamically stable
    • 0-4% of ambulatory patients
    • Frequently asymptomatic
    • W/U: EKG ± CXR/TTE
    • Treatment
      • Admit if
        • High-Risk (Age >45, Symptomatic, Known SHD, Concerning FH)

Courtesy of Tom Fadial, https://ddxof.com/nonsustained-ventricular-tachycardia/

General

  • Patients with CHD and LV systolic dysfunction are at increased risk of ventricular arrythmias including VT and VF
    • 95% of wide complex tachycardias are VT in pts with SHD
    • Associated with
      • Dilated Cardiomyopathies, Brugada’s syndrome, HCM, Amyloidosis/Sarcoidosis, Duchenne Muscular Dystrophy, TOF, and myocarditis
  • Treatment in patients with Recurrent VT
    • 1) Stabilize
    • 2) Find underlying cause (electrolyte abnormalities)
      • Order Electrolyte panel and Digoxin level
      • Hypokalemia and hypomagnesemia (loop diuretics)
      • Digoxin ± Hypokalemia

Types

1) Fast Ventricular Tachycardias - Monomorphic VT (MVT) - Sustained Monomorphic VT (SMVT) - Polymorphic VT (PVT) 2) Slow Ventricular Tachycardias 3) Ventricular Fibrillation

Fast Ventricular Tachycardias

  • 3 consecutive premature ventricular beats (widened QRS)

    • Wide QRS complex tachycardia often w/ abnormal QRS complexes and T waves in the vector opposite of the QRS
    • Common, along with Vfib, post MI
    • Pulse or pulseless presentation

Monomorphic Ventricular Tachycardia (MVT)

  • Etiology
    • Rapid and repetitive firing of ≥3 premature ventricular complexes in a row with the same morphology
    • Macro re-entrant circuit with conduction through and around scar tissue, reentry of an ectopic ventricular depolarization
    • May be post MI (reentry)
  • QRS wide (>0.12), uniform and stable, rate between 100-250
  • AV dissociation may be apparent (regular rate between p waves)
    • Cannon A waves in the neck
    • Capture beats and fusion beats possible
  • Symptoms
    • Palpitations, dyspnea, lightheadedness, angina, or near-syncope, syncope, seizures
  • Treatment
    • Stable/Pulse: IV amiodarone, metoprolol, revascularization OR Synchronized cardioversion
    • Pulseless: CPR + Defibrillation ± Vasopressors

Sustained Monomorphic Ventricular Tachycardia (SMVT)

  • Wide complex tachycardia with 2 fusion beats
  • Fusion beats: capture of electrical signal though both the atrium and ventricle briefly
    • Hybrid of a normal and wide QRS complex (P waves precede fusion complex)
  • Treatment
    • Stable: IV Amiodarone > Procainamide, sotalol, lidocaine
    • Unstable: Synchronized Cardioversion

Polymorphic Ventricular Tachycardia (PVT)

  • Triggered tachycardia, >220 can cause Ventricular Fibrillation
  • Wide complex, rapid and unstable
  • QRSs vary in amplitude, size, and duration
    • Normal QTc = Coronary Ischemia (MI)
    • Prolonged QTc = Torsade De Pointes
      • Men >440ms, women >460ms
  • A) Torsade De Points (Polymorphic VT, TdP)
    • A rapid PVT with PVCs before T wave, may cause syncope
    • VT with constantly changing cycle length, axis, and morphology
      • Onset: prolongation/lengthening of the QT interval which can be initiated by a PAC/PVC
    • Causes: Hypokalemia, hypomagnesemia, genetic Long QT
      • Medications increasing QT interval via inhibition of the rapid components of the delayed rectifier potassium current (Ikr)
      • Meds: Chloroquine, hydroxychloroquine, azithromycin
      • RF for drug induced: QTc >500ms, QTc lengthening >60ms, female, age >65, bradycardia, hypokalemia, hypomagnesemia, hypocalcemia, HFrEF, ≥2 QT prolonging drugs, rapid IV admin
      • 30% have mutation in one of 5 QT syndrome genes
    • Goals
      • K >4, Mg >2, EKG q3-6m
      • Baseline then annually if on methadone, daily if >120mg
    • Treatment
      • Stable
        • IV Magnesium sulfate, avoid QT prolongation, lidocaine, increase HR (shortens QT)
          • Even if normal serum Mg
        • Temporary pacemaker, isoproterenol
      • Unstable: Defibrillation

General Management

  • Pulse + Stable and Sustained Monomorphic
    • IV Amiodarone > lidocaine
      • CI: Hypotension/unstable
    • Immediate Cardioversion if amiodarone fails
  • Pulse + Unstable and Sustained Monomorphic
    • Synchronized Cardioversion
      • Low energy shock to QRS complex that is timed
    • IV amiodarone to prevent VT/VF after Cardioversion
  • Pulseless
    • 1) Defibrillation (unsynchronized Cardioversion)
      • High energy shock at a random point, multiple attempts
    • 2) Epinephrine every 3-5 mins
    • 3) Amiodarone/Lidocaine
  • Chronic: ICD

Slow Ventricular Tachycardias(40-150 BPM)

Ventricular escape (3rd degree AV Block)

Accelerated Ventricular Rhythm

Idioventricular

Ventricular Fibrillation (VF)

  • Chaotic, irregular waveform of varying shapes and amplitude
  • No coordinated contractions, identifiable p waves, QRS, or T waves
  • Very rapid, irregular polymorphic rhythm
    • Disorganized electrical activity with multiple rapidly firing foci in the ventricles (Ventricles can’t produce CO)
    • Diffuse wide QRS segments
    • Pulseless tachyarrhythmia
  • Most begin with Vtach
  • RF: IHD, antiarrhythmics, Atrial fib w/RVR
    • Common in patients with MI
    • Most common cause of SCD during acute MI
  • Treatment
    • Immediate Defibrillation + CPR
      • IV Epinephrine or Vasopressin without interrupting CPR if 1st defibrillation doesn’t work
      • IV amiodarone