If the QRS in lead V6 is negative and wide, what does this possibly indicate?

A negative and wide QRS complex in lead V6 is strongly indicative of a ventricular conduction abnormality. Ventricular tachycardia (VT) typically produces a wide QRS complex due to the electrical impulse originating from the ventricles rather than the normal conduction pathway that begins at the atria. In VT, the rate of ventricular contraction can be elevated, and the morphology of the QRS complex can also be altered, making it appear wide and often negative in certain precordial leads, including V6.

The key features contributing to this interpretation include the width of the QRS complex, as a normal QRS duration is typically less than 120 milliseconds. A QRS complex measuring 120 milliseconds or more suggests significant delay in ventricular conduction, which is characteristic of certain arrhythmias, particularly VT. The negative polarity further implies that there may be an abnormal vector direction of depolarization, consistent with an ectopic origin in the ventricles.

Understanding the nature of the QRS morphology assists in differentiating VT from other conditions like atrial fibrillation, which does not typically result in wide QRS complexes. In contrast, bundle branch blocks may present a wide QRS complex but are usually not negative in V6 unless associated with additional