SIGNS AND SYMPTOMS 
History
Physical Exam
- Establish presence of pulses, mental status and vital sign abnormalities.
- Auscultation of heart will reveal tachycardia.
ESSENTIAL WORKUP
- EKG:
- Most important initial test to differentiate VT from SVT with aberrancy or LBBB
- VT definition:
- ≥3 consecutive QRS complexes with a ventricular rate over 100 bpm and a QRS duration > 120 msec
- Torsades de pointes:
- Polymorphic VT that rotates its axis every 10–20 beats
- Criteria to determine VT:
- Atrial ventricular (AV) dissociation (present in 60–75%)
- Fusion beats (P-wave partially activates ventricle in advance of next VT cycle), capture beats (P-wave totally activates ventricle)
- Uniform morphology (except in the case of torsades)
- Extreme axis deviation (–90° to +180°)
- QRS > 140 msec, with right bundle branch block (RBBB) morphology; or QRS > 160 msec, with LBBB morphology, but > 160 suggests VT regardless of bunch branch morphology
- QRS concordance in the precordial leads
- RBBB pattern V1 with R > R' is VT 50:1.
- LBBB pattern with Q or QS pattern in V 6 is VT 50:1.
- Brugada criteria defines VT in wide complex tachycardia:
- 99% sensitivity, 97% specificity
- Only need to meet 1 criterion
- AV dissociation
- R-S interval absent in all precordial leads
- QRS onset to the nadir of S > 100 msec in any precordial lead
- V1 R-wave > 30 msec; R-S interval > 70 msec, slurred, notched S
- Wide QRS with LBBB in precordium
- Indicators of SVT with aberrancy include:
- Normal-axis QRS < 140 msec
- Absence of Q-waves
- RBBB in V1 with rsR' triphasic pattern
- AV nodal blockade: Slowing of impulse conduction velocity seen with antiarrhythmic drugs is more pronounced at faster rates, so may result in wide complex SVT (SVT with aberrancy)
DIAGNOSIS TESTS & INTERPRETATION
Lab
- Cardiac enzymes
- Electrolytes, BUN, creatinine, glucose
- Magnesium level
- Calcium level
- Digoxin level if toxicity suspected
Imaging
CXR:
- Cardiomegaly or other cardiac anomalies may be apparent.
ECHO:
- Structural disease may be identified.
Diagnostic Procedures/Surgery
Esophageal pacing catheters:
- May be able to detect atrial activity to establish AV dissociation and therefore diagnose VT
- Catheters can then be used to overdrive pace if refractory to cardioversion/antiarrhythmics.
DIFFERENTIAL DIAGNOSIS
- SVT with aberrancy or baseline LBBB
- Proarrhythmia secondary to antidysrhythmia medications; suspect if:
- VT morphology is different than previous episodes of VT
- Medications have recently been started or changed
- QT interval is > 440 msec.
- Torsades de pointes
- If VT continues to recur after cardioversion
[Outline]
PRE-HOSPITAL
- Cautions:
- Transport stable patients suspected of being in VT without attempting to convert them.
- Synchronized cardioversion for unstable patients with a pulse
- Defibrillation for pulseless VT
- Controversies:
INITIAL STABILIZATION/THERAPY
Pulseless VT: Defibrillate immediately and follow the VF treatment plan.
ED TREATMENT/PROCEDURES
- Unstable patient:
- Definition:
- Initiate immediate synchronized cardioversion with 100 J, quickly progressing to 200 J, 300 J, and 360 J if no response.
- If the VT is polymorphic, begin cardioversion at 200 J.
- Sedate the patient before cardioversion if at all possible.
- If unable to terminate the VT, administer lidocaine and repeat the cardioversion.
- Antitachycardia overdrive pacing if torsades
- After successful return of sinus rhythm, begin amiodarone.
- Stable patient, monomorphic VT:
- Normal cardiac function at baseline:
- Procainamideor sotalol; may also consider amiodarone or lidocaine
- Avoid sotalol if evidence of prolonged QT or known long QT syndrome.
- Impaired cardiac function at baseline:
- Amiodarone bolus, then infusion or lidocaine, then synchronized cardioversion
- Stable patient, polymorphic VT:
- Normal QT interval at baseline:
- Correct electrolyte abnormalities.
- Treat ischemia if present.
- Then begin 1 of the following: b2-blockers, lidocaine, amiodarone, procainamide, or sotalol.
- Prolonged QT Torsades de pointes:
- Correct electrolytes.
- Magnesium sulfate or overdrive pacing or 1 of the following: Isoproterenol, phenytoin, lidocaine
- Isoproterenol is used to overdrive the tachycardia if the patient has no history of coronary artery disease or long QT syndrome.
- Temporizing measure until external pacing available
- Impaired cardiac function at baseline
- Amiodarone bolus or lidocaine bolus then synchronized cardioversion
Pediatric Considerations
- Primary cardiac arrest and VT are rare in children.
- Usually secondary to hypoxia and acidosis
- VT is tolerated for longer periods in children than adults and is less likely to degenerate to VF.
- Infants in VT most commonly present with CHF.
- VT in children results from:
- Cardiomyopathy
- Congenital structural heart disease
- Congenital prolonged QT syndromes
- Coronary artery disease secondary to vasculitis
- Toxins, poisons, drugs
- Severe electrolyte imbalances, especially of potassium
MEDICATION
First Line
- Procainamide: 3–6 mg/kg over 5 min, may repeat every 5–10 min to max. total dose of 15 mg/kg. Do not exceed 100 mg/dose or 500 mg in 30 min (peds: 15 mg/kg IV/IO over 30–60 min).
- Amiodarone: 150 mg IV bolus over 10 min, may repeat; arrest dose is 300 mg IV/IO max. cumulative dose 2.2 g IV/24 h; followed by 1 mg/min for 6 hr, then 0.5 mg/min for 18 hr. (peds: 5 mg/kg IV or IO over 20–60 min, max. 15 mg/kg/d)
- MgSO4: 2 g in D5W over 5–10 min followed by infusion of 0.5–1 g/h IV, titrate to control torsades (peds: 25–50 mg/kg IV/IO over 10 min, max. dose 2 g)
Second Line
- Lidocaine: 1–1.5 mg/kg bolus IV push 1st dose, 0.5–0.75 mg/kg 2nd dose, and q5–10min for a max. of 3 mg/kg; tracheal administration 2–4 mg/kg; maintenance infusion 1–4 mg/min if converted. Not recommended for ACS induced VT(peds: 1 mg/kg bolus with infusion 20–50 µg/kg/min)
- Adenosine: 6 mg IV push followed by 12 mg IV push if needed in 1–2 min (peds: 1 mg/kg, max. 6 mg). Note: Does not convert VT, do not use if unstable or irregular WCT.
- Isoproterenol: 2–10 µg/min, titrate to heart rate (peds: 0.1 µg/kg/min). Note: Do not give with epinephrine, may precipitate VT/VF (no longer part of ACLS protocol), do not give if prolonged QT.
- Sotalol: 100 mg IV over 5 min. (peds: Use not recommended for initial management). Note: Do not give if prolonged QT.
[Outline]
DISPOSITION
Admission Criteria
- Admit sustained VT to a critical care setting.
- Admit nonsustained VT and a history of MI or dilated cardiomyopathy for electrophysiologic studies.
Discharge Criteria
- Rare patients with nonsustained VT and a previous evaluation that revealed no structural heart disease can be discharged:
- Patients with automatic internal cardiac defibrillators that are well functioning can also be discharged.
Issues for Referral
All patients discharged with VT should be followed by a cardiologist within 48 hr.
FOLLOW-UP RECOMMENDATIONS
Patients should follow-up with a cardiologist.
[Outline]
ICD9
427.1 Paroxysmal ventricular tachycardia
ICD10
I47.2 Ventricular tachycardia
[Outline]
- Connolly SJ, Dorian P, Roberts RS, et al. Comparison of beta-blocker, amiodarone plus beta-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: The OPTIC Study: A randomized trial. JAMA. 2006;295:165–171.
- Pellegrini CN, Scheinman MM. Clinical management of ventricular tachycardia. Curr Probl Cardiol. 2010;35(9):453–504.
- Zipes DP, Camm AJ, Borggrefe M, et al. ACC/AHA ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death—executive summary. J Am Coll Cardiol. 2006;48:1064–1108.
Acknowledgments
Thank you to the prior authors of this chapter, Jennifer Audi and Shannon Straszewski
See Also (Topic, Algorithm, Electronic Media Element)
2010 AHA Guidelines for CPR and ECC
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