COMPARISON OF A VECTORCARDIOGRAPHICALLY DERIVED 12-LEAD ELECTROCARDIOGRAM WITH THE CONVENTIONAL ELECTROCARDIOGRAM DURING WIDE QRS COMPLEX TACHYCARDIA, AND ITS POTENTIAL APPLICATION FOR CONTINUOUS BEDSIDE MONITORING

Previous investigators published conflicting reports comparing a vectorcardiographically derived electrocardiogram (ECG(D)) with the conventional 12-lead one (ECG). Prior comparisons were obtained in adults during sinus rhythm, but never in patients with wide QRS complex tachycardia. The ECG(D) was evaluated during baseline rhythms in patients with varying cardiac diagnoses, and the diagnostic accuracy of the 2 methods was compared during 64 episodes of wide QRS complex tachycardia in 49 patients during cardiac electrophysiologic study. All leads of the 12-lead ECG(D) closely resembled the conventional ECG in baseline and tachycardia tracings, except leads V3 and V4. QRS voltages were less in the ECG(D), resulting in an inability to detect left ventricular hypertrophy in one third of patients with that diagnosis. There was excellent agreement between the ECG(D) and ECG in diagnosing prior myocardial infarction (92%), ventricular preexcitation patterns (100%), bundle branch and fascicular blocks (100%), and axis deviation. The ECG(D) was equally as valuable as the ECG in the diagnosis of wide QRS complex tachycardia. There was perfect agreement between the 2 lead systems in application of the morphologic criteria differentiating supraventricular tachycardia with aberration from ventricular tachycardia in leads V1, V2 and V6, and for criteria requiring axis determination and measurement of RS intervals in the precordial leads. The ECG(D) tracings contained less muscle artifact during body movements (e.g., after direct-current defibrillation). In conclusion, the ECG(D's) close correlation with the ECG, and its technical superiority and simple 5 torso-positioned electrode configuration make it worth pursuing as an option for continuous bedside monitoring.