Is it VT? Deciphering Wide Complex Tachycardia

Stacey EP NP

As a nurse on the cardiac step-down unit, you have been trained to pay attention to the loud, ever-sounding "ding, ding, ding" of the telemetry (tele) monitor. Sometimes it can be heard as many times as a call light bell on a 30-bed unit over the span of a 12hr day shift. So much so that you begin to drown out the sound, but don't let it be you ignoring the tele alarm when your co-worker yells out, "Your patient is in VT!” and everyone rushes to the room with a crash cart in tow. It is not uncommon to witness this scenario when caring for cardiac patients but don't call the cardiologist just yet.

Wide complex tachycardia (WCT) is an umbrella term, defined as a wide QRS>120ms, with a heart rate >100bpm indicating tachycardia. Ventricular tachycardia (VT) is not the only reason you may see a wide complex fast rhythm on the tele monitor. Thus, determining true VT from other rhythms is a necessary skill for the prudent cardiac nurse, as this determination will direct the immediate actions of care staff and further clinical course, as well as outcomes for the patient.

What To Do First

As soon as there is any indication that your patient may be in sustained VT, the first thing you, as the registered nurse, must do is evaluate your patient!

Are they alert and talking to you?
Are they breathing?
Do they have a pulse?
Stable (baseline blood pressure and oxygen level) vs unstable (hypotension and hypoxia)

Get an EKG (electrocardiogram) to give more in-depth and detailed information on the arrhythmia. Further details found on the EKG are analyzed by the physician or cardiologist to determine the etiology of the rhythm.

SVT (supraventricular tachycardia) with Aberrancy

Differentiating whether the WCT stems from the upper chambers (atria) vs that of the lower chambers (ventricles) of the heart proves to be a difficult, yet critical determinant in the selection of appropriate interventions for patient evaluation and care. SVT with aberrancy is a tachyarrhythmia that stems from the atria and demonstrates a wide QRS but is NOT true VT. Aberrant conduction patterns are often "representative of typical right and left bundle" configurations (JAHA, 2020). Useful clues to indicate a likely diagnosis of SVT with aberrancy rather than true VT are provided by EKG as well as patient history and are as follows:

Presence of prior tachyarrhythmia (atrial tachycardia, atrial fibrillation/flutter, or Wolf Parkinson White)
In the case of Afib RVR (rapid ventricular rate) with aberrancy, the rhythm remains irregular in contrast to true VT, in which the pattern is inherently regular
Baseline left or right bundle branch block, as seen on previous EKG, with identical morphology to the WCT
Terminated by Adenosine and/or vagal maneuvers

Another possible though uncommon cause of tachycardia with evidence of QRS widening is Pacemaker mediated tachycardia (PMT). Sometimes a patient's pacemaker will increase the ventricular rate in an attempt to track an intrinsic atrial arrhythmia. To identify if the tachycardia is pacemaker mediated, first assess; does my patient have a pacemaker or other implanted cardiac device? Are there pacer spikes? If unsure, obtain EKG and device interrogation.

Artifact

Often appears as random and irregular, unexplainable 'junk' on the tele monitor. When you check on your patient, you find them returning from the bathroom and shuffling the covers on their bed, causing interference with monitor signals; meanwhile, the patient denies any acute symptoms. Artifact often only affects one tele lead with the other leads reading the patient's baseline rhythm. No intervention is required unless the artifact is persistent, indicating the need for tele lead adjustment or reattachment with new stickers.

True Ventricular Tachycardia

Staying true to its nomenclature, VT stems from the ventricle and is classified as either sustained (>30 seconds) or non-sustained (<30 seconds). Key signs of true VT (see image¹) include a monomorphic, (identical or uniform) very wide QRS complex (160ms+) seen in all 6 precordial leads (V1–V6) on EKG that change deflection (above or below axis) from baseline rhythm with heart rate (HR) at least 140-180 beats per minute. Characteristic AV dissociation, P and QRS complexes at different rates, is commonly noted in fast VT as well as slow VT, which encompasses all classic criteria though at an unusually slow HR. True VT should be suspected in patients with the following:

Age >35 yr.
Coronary artery disease
Cardiomyopathy
Existing arrhythmias (atrial fibrillation, premature ventricular conduction, etc.)
Family history of sudden cardiac death
Structural heart problems (Valve disorders)
Electrolyte imbalances; particularly potassium or magnesium

EKG strip

Sustained VT with an extremely elevated HR can lead to impaired cardiac output and resultant:

Hypotension
Syncope and collapse
Loss of pulse

VT can progress to sustained ventricular fibrillation (VF) and result in sudden cardiac death therefore, the nurse must quickly determine if the patient is stable vs unstable and act accordingly. Immediate treatment for a patient in sustained VT or VF with no pulse is to initiate CPR, then defibrillate from either the crash cart or an automated external defibrillator (AED). Initiation of anti-arrhythmic medications, such as amiodarone or lidocaine, is indicated in confirmed VT or VF. If the patient is found to be stable, then you still must take action and contact the physician with anticipation of expert (cardiology) consultation.

Making the Decision

In the end, it is not solely your responsibility as the bedside nurse to differentiate all of the complex arrhythmias that your patient may have, but it is your responsibility to know when to act emergently and when to keep calm in order to protect your patient. When it comes to wide complex tachycardia, always be alert, and before anything else, evaluate your patient! Especially in patients with known risk factors for VT, you can safely assume that the majority of the time, it is true VT. A prudent rule of thumb to follow is "If in doubt, treat as VT!”². Determine if it is sustained or non-sustained and if your patient is stable or unstable to guide your next moves. Always look for possible reversible causes such as electrolyte imbalances or drug use, particularly cocaine or methamphetamine, indicative of toxic‐metabolic etiology. The tele monitor will continue to ding whether it is a true emergency or not ... that's its job; it's your job to know what to do with the information provided.

References/Resources

1 Ventricular Tachycardia – Monomorphic VT (image): Life in the Fast Lane

2 VT versus SVT (Robert Buttner and ED Burns): Life in the Fast Lane

Wide Complex Tachycardia Differentiation: A Reappraisal of the State‐of‐the‐Art: Journal of the American Heart Association

Monomorphic Ventricular Tachycardia: Cleveland Clinic

Wide Complex Tachycardia – Diagnosis: CARDIOGUIDE

Wide Complex Tachycardia: Management: CARDIOGUIDE

Ventricular Tachycardia: Mayo Clinic