Fig. 6.

Abnormal conduction and arrhythmias in ODDD mutant mice. (A) Representative signal-averaged surface electrocardiograms (lead II) from a wild-type (WT) and an ODDD mutant mouse. Note the diminished QRS amplitude in the mutant. (B) Optical mapping of the left ventricular surface of a representative wild-type heart and three individual ODDD mutant hearts. The temporal and spatial scales are indicated and are identical for all images. Conduction velocity, determined from pixels between 1 and 3 mm from the site of stimulation, is significantly slowed in the ODDD hearts, as indicated by closer spacing of isochrones (1 ms apart). (C) Programmed electrical stimulation showing examples of return of sinus rhythm in a wild-type heart (Left), induction of sustained VT in an ODDD heart (Center), and spontaneous VT in an ODDD heart (Right). Tracings each include 2 sec of recordings.