What is the initial treatment of acute ventricular tachycardia (VT)?

Updated: Dec 05, 2017
  • Author: Steven J Compton, MD, FACC, FACP, FHRS; Chief Editor: Jeffrey N Rottman, MD  more...
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Answer

The acute emphasis in patients with ventricular tachycardia (VT) is on achieving an accurate diagnosis and conversion to sinus rhythm. VT associated with loss of consciousness or hypotension is a medical emergency necessitating immediate cardioversion. In a normal-sized adult, this is typically accomplished with a 100- to 200-J biphasic cardioversion shock administered according to standard Advanced cardiovascular life support (ACLS) protocols. [60, 61, 62]  Please refer to the most current ACLS guidelines, which are subject to periodic revision.

Reversible risk factors for VT should be addressed. Efforts should be made to correct hypokalemia and to withdraw any long-term medications associated with QT-interval prolongation.

When VT occurs in patients with ongoing myocardial ischemia, lidocaine is suggested as the primary antiarrhythmic medication, because the mechanism in these cases is thought to be abnormal automaticity rather than reentry. [63] Although intravenous (IV) lidocaine is effective at suppressing peri-infarction VT, it may increase the overall mortality risk. In situations involving torsade de pointes, magnesium sulfate may be effective if a long QT interval is present at baseline.

Synchronized cardioversion should be considered at an early stage if medical therapy fails to stabilize the rhythm. The initial shock energy should be 100 J (monophasic), followed by higher shock energies if the response is inadequate.

Occasionally, patients present with wide QRS complex tachycardia of unknown mechanism. In the absence of pacing, the differential diagnosis includes VT and aberrantly conducted supraventricular tachycardia (SVT) (see the images below). If hemodynamic compromise is present or if any doubt exists about the rhythm diagnosis, the safest strategy is to treat the rhythm as VT.

Supraventricular tachycardia with aberrancy. This Supraventricular tachycardia with aberrancy. This tracing is from a patient with a structurally normal heart who has a normal resting electrocardiogram. This rhythm is orthodromic reciprocating tachycardia with rate-related left bundle-branch block. Note the relatively narrow RS intervals in the precordial leads.
This electrocardiogram is from a 48-year-old man w This electrocardiogram is from a 48-year-old man with wide-complex tachycardia during a treadmill stress test. Any wide-complex tachycardia tracing should raise the possibility of ventricular tachycardia, but closer scrutiny confirms left bundle-branch block conduction of a supraventricular rhythm. By Brugada criteria, RS complexes are apparent in the precordium (V2-V4), and the interval from R-wave onset to the deepest part of the S wave is shorter than 100 ms in each of these leads. Ventriculoatrial dissociation is not seen. Vereckei criteria are based solely upon lead aVR, which shows no R wave, an initial q wave width shorter than 40 ms, and no initial notching in the q wave. The last Vereckei criterion examines the slope of the initial 40 ms of the QRS versus the terminal 40 ms of the QRS complex in lead aVR. In this case, the initial downward deflection in lead aVR is steeper than the terminal upward deflection, yielding Vi/Vt ratio above 1. All of these criteria are consistent with an aberrantly conducted supraventricular tachycardia. Gradual rate changes during this patient's treadmill study (not shown here) were consistent with a sinus tachycardia mechanism.

If the clinical situation permits, a 12-lead electrocardiogram (ECG) should be obtained before conversion of the rhythm. The ECG criteria of Brugada et al [15] may be useful in differentiating the arrhythmia mechanism (see Workup).

Rarely, patients present with repetitive runs of nonsustained VT. Prolonged exposure to this (or any other) tachycardia may cause a tachycardia-induced cardiomyopathy, which typically improves with medical or ablative treatment of the VT. [19]


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