Asymptomatic wide complex tachycardia: a case report
© Mukerji et al; licensee BioMed Central Ltd. 2009
Received: 13 October 2008
Accepted: 13 January 2009
Published: 13 January 2009
Wide complex tachycardias are a commonly encountered entity in coronary care units, intensive care units and emergency departments. Though, these arrhythmias are potentially fatal, they need to recognized first and treated appropriately. Associated physical signs are helpful in this. We present a case of a 54-year-old-female who recently underwent placement of an implantable cardioverter-defibrillator for cardiomyopathy and developed tachycardia.
Selected differential diagnosis of wide complex tachycardia
Ventricular tachycardia (VT)
Presence of AV dissociation with more ventricular than atrial events, QRS duration more than 140 ms, fusion beats, capture beats
Supraventricular tachycardia with aberrancy
QRS duration of not more than 140 ms 
Hemodynamically stable, normal QRS complexes, "precipitating" cause viz. movements
Presence of "delta wave", short PR interval
No apparent rate, fibrillatory waves, absent pulse, unrecordable BP
Characteristics in favor of EKG artifacts include:
Normal hemodynamic parameters during the event
Presence of normal QRS complexes (arrows in Figure 2)
Unstable baseline on the EKG
Associated body movements 
Krasnow et al showed that the most likely causes of EKG artifacts that mimic VT are body movements and a poor skin-electrode contact. 
In our patient, the ICD implantation was done a day prior to this event. Routine device interrogation post-implantation did not reveal any abnormal events. In addition, the patient was noticed to have voluntary movements in the form of "shaking her leg" and examination revealed normal hemodynamic parameters. Serum electrolytes were within normal limits too. Hence, the presence of an asymptomatic patient with a normally functioning ICD not firing should alert the physician to the possibility of artifacts rather than an abnormal rhythm.
No treatment is indicated for this condition. Therefore, in modern day medicine it is imperative to differentiate artifacts from VT, and thus reduce health costs.
Ventricular tachycardia accounts for 80% of WCT. [4, 5] In such patients, a history of structural heart disease, particularly of coronary artery disease or prior myocardial infarction, strongly suggests a diagnosis of VT.
SVT with aberrancy accounts for a relatively small number of patients with WCT. This tachycardia typically originates in atrial tissue and/or AV junction and utilizes the normal atrioventricular (AV) conduction system for ventricular activation. Aberrance occurs when there is delay or block in the His-Purkinje system during antegrade conduction of impulses over the normal AV fascicles. Essentially, all types of SVT with aberrant conduction can present as a WCT. Atrial tachycardias, atrioventricular nodal reentrant tachycardias, orthodromic reciprocating tachycardias are some of the common SVTs which can be associated with aberrance. Termination of WCT by adenosine, digoxin, calcium-channel blockers, beta-blockers or vagal maneuvers is suggests SVT. Grubb, however, showed that VT too could be terminated with carotid sinus stimulation. 
In ventricular fibrillation multiple foci take over from the ventricles and produce a disorganized, chaotic rhythm. The patient is considered pulse-less, with no blood pressure, requiring immediate intervention. VF is secondary to coronary artery disease, myocardial ischemia, myocardial infarction, cardiomyopathy, cardiac trauma, drug toxicity, hypoxia, and electrolyte imbalance.
Preexcited tachycardias are conducted antegradely over an accessory pathway (AP). Evidence for the presence of an AP can be manifest of the surface electrocardiogram (EKG) which can show intermittent or continuous presence of a delta wave associated with a short PR interval. The delta wave represents the part of the ventricular myocardium that is depolarized through the AP.
Thus, it is imperative for a clinician to recognize an EKG artifact and differentiate it from other causes of WCT. This would prevent unwarranted interventions and minimize unnecessary procedures.
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
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