Site of Origin of Halothane–Epinephrine Arrhythmia Determined by Direct and Echocardiographic Recordings

A constantly coupled bigeminal arrhythmia was induced in dogs anesthetized with thiopental-halothane by infusion of epinephrine (1 microgram.kg-1.min-1). The site of origin of the abnormal beat was localized to the interventricular septum by bipolar recordings from the left and right ventricular epicardium and two sites in the septum. Simultaneous echocardiograms showed early movement of the septum with a pattern similar to that seen in the left bundle branch block. Simulation at the recording sites resulted in movement patterns which indicate that assessment of septal and posterior left ventricular motion can be helpful in localization of the origin of ventricular arrhythmias, although only with left ventricular arrhythmias is there potential for anatomic localization to a small area of muscle.