Ventricular tachycardia: noninvasive differentiation from supraventricular tachycardia.

The paramount importance of differentiating the wide-QRS tachycardias is stressed, and the alarming frequency of errors made by practicing physicians and cardiovascular nurses is documented. The most common causes of error are outlined, of which the most important is ignorance of diagnostically helpful QRS morphology in the electrocardiogram (EKG). The QRS contours and polarity that are useful in diagnosis are described in detail and illustrated. Finally, certain compromises in electrode placement that may be necessary in the operating room are suggested.