Abstract
Wide QRS tachycardias represent one of the most challenging scenarios in the interpretation of the electrocardiogram, even among experienced professionals or specialists. The various existing diagnostic criteria are essential tools for the correct identification of the origin of tachycardia, however, the knowledge of the electrophysiological principles of cardiac depolarization is fundamental to understand them, thus allowing greater accuracy in the interpretation of the exam.
Highlights
Tachycardias that present with a wide QRS on the electrocardiogram are usually a cause for diagnostic uncertainty and can generate anxiety and insecurity in the conduct of the clinical case, since the differentiation between supraventricular or ventricular origin is not always simple and intuitive, despite being fundamental for the proper management of the patient, with etiologies, treatment and prognosis very different from each other
If we add to that the emergency character normally related to these cases, when decisions must be quick and there is less scope for errors, and the negative impact that incorrect diagnosis can have on clinical outcomes[1], we are facing a scenario that is most challenging for the doctor, and that puts his confidence to the test.An example of this is the high percentage of disagreement in the diagnosis of wide QRS tachycardias among observers in the emergency room, reaching values of 50% in some studies, and a diagnostic accuracy only moderate in that same context, around 70%2, even using established algorithms that have proven to improve these variables
Atrioventricular dissociation (AV) - lack of relationship between depolarization of the atria and ventricles, in that order - is an indirect sign of the ventricular origin of tachycardia and one of the most remembered among the diagnostic criteria in wide QRS tachycardias, due to the easy understanding of its physiological mechanism
Summary
Tachycardias that present with a wide QRS on the electrocardiogram (duration QRS≥120 ms) are usually a cause for diagnostic uncertainty and can generate anxiety and insecurity in the conduct of the clinical case, since the differentiation between supraventricular or ventricular origin is not always simple and intuitive, despite being fundamental for the proper management of the patient, with etiologies, treatment and prognosis very different from each other. Understanding the physiological mechanisms of cardiac activation that explain the most used criteria for differential diagnosis of wide QRS tachycardias, and being able to deduce them instead of just memorizing them, appears as a way to improve the electrocardiographic interpretation in doubtful cases
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