His bundle electrocardiography in a patient with a digitalis induced bidirectional tachycardia revealed absence of His spike preceding earliest onset of ventricular activation during the bidirectional tachycardia. However, His potential preceded ventricular activation of normal complexes at a constant H V interval of 35 msec. The presence of fusion QRS complexes, capture QRS complexes, the analysis of of cycle lengths, and response to carotid sinus massage all favor a ventricular origin for this tachycardia in the patient presented.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
- Physiology (medical)