Among the most difficult set of arrhythmias to analyze, diagnose, and treat appropriately in the electrophysiology laboratory are wide QRS tachycardias. The reasons for this difficulty include the relatively rare occurrence of some of these conditions and the fact that the differential diagnosis for a wide QRS rhythm includes all the possibilities for a narrow QRS rhythm and, in addition, arrhythmias related to antegrade pathway conduction and ventricular tachycardia. This wide range of possibilities can be confusing even to experienced electrophysiologists, and a complex case may lead to inappropriate diagnoses and maneuvers, including a wrong ablation sequence. This chapter focuses on the overall approach to wide QRS tachycardias. A brief description of the clinical and electrocardiographic features is followed by an in-depth discussion of diagnostic maneuvers and approaches in the electrophysiology laboratory. Finally, representative electrograms and case studies follow to illustrate some of the more involved principles discussed in this chapter.
Belhassen Syndrome in Teenager Originating from Left Anterior Fascicle
