Using specialized cardiac catheters for image acquisition, features of the heart 5 are readily identifiable on an ultrasound image, based on a previously generated electrical activation map of the heart. The electrical activation map is automatically registered with the ultrasound image using information obtained from position sensors in the catheters. Features identifiable on the electrical activation map, presented as points, tags, design lines, and textual identification, are projected into 10 the plane of the ultrasound fan and overlaid on the ultrasound image, thereby clarifying the features that are visible on the latter. 20/04/07,16524 specification,2 TO CATHETER TO CATHETER TO CATHETER MAPPING LOCATION ACOUSTIC TRANSDUCERS ELECTRODE SENSORS 58 36 39 56 MAPPING POSITIONING ULTRASOUND ULTRASOUND CIRCUITRY PROCESSOR DRIVER CIRCUITRY PROCESSOR- FUSER 6NPUT DISPLAY FIG. 3 FIG. 4 BEGIN '-66 DISPLAY S OF 76 ELECTRO -ANATOMIC 68 SELECT CHAMBERS 78 UTAOUD ZE 70 COMPUTE CHAMBER .80 ULTRASOUND IMAGE INTERSECTIONS WITH ULTRASOUND IMAGE SUPERIMPOSE MAP & ULTRASOUND IMAGE 72 DISPLAY OVERLAY 82 IDENTIFY ANATOMIC FEATURES ON 74 ADD TEXT LABELS 86 ULTRASOUND IMAGE
