Abstract: Conduction velocity information for a cardiac region can be used to map the cardiac muscle fiber orientation of that region. In particular, for a plurality of locations within the cardiac region, a relationship between a local conduction velocity, a maximum local conduction velocity within the region, and a minimum local conduction velocity within the region is used to determine the cardiac muscle fiber orientation at the respective location. Even more particularly, when the local conduction velocity at the respective location equals the maximum local conduction velocity, the cardiac muscle fiber orientation is parallel to a direction of a conduction velocity vector at the respective location, and when the local conduction velocity at the respective location equals the minimum local conduction velocity, the cardiac muscle fiber orientation is perpendicular to a direction of a conduction velocity vector at the respective location.

Abstract: Cardiac activation timing is mapped using a catheter-mounted roving electrode instead of a fixed (e.g., coronary sinus) electrode. The roving electrode is used to measure an initial electrophysiological signal at an initial cardiac location as a reference signal, which is defined as a reference signal. Local activation time(s) for other cardiac location(s), also measured using the catheter-mounted roving electrode, are determined relative to the reference signal. The stability of the reference signal can be monitored, such as by comparing activation rates or cycle lengths between an instantaneously-measured electrophysiological signal and the initial electrophysiological signal. Smaller differences between the two (e.g., less than about 5%) can be compensated for, while larger differences can result in redefining the reference signal.

Abstract: Conduction velocity information for a cardiac region can be used to map the cardiac muscle fiber orientation of that region. In particular, for a plurality of locations within the cardiac region, a relationship between a local conduction velocity, a maximum local conduction velocity within the region, and a minimum local conduction velocity within the region is used to determine the cardiac muscle fiber orientation at the respective location. Even more particularly, when the local conduction velocity at the respective location equals the maximum local conduction velocity, the cardiac muscle fiber orientation is parallel to a direction of a conduction velocity vector at the respective location, and when the local conduction velocity at the respective location equals the minimum local conduction velocity, the cardiac muscle fiber orientation is perpendicular to a direction of a conduction velocity vector at the respective location.

Abstract: Cardiac activation timing is mapped using a catheter-mounted roving electrode instead of a fixed (e.g., coronary sinus) electrode. The roving electrode is used to measure an initial electrophysiological signal at an initial cardiac location as a reference signal, which is defined as a reference signal. Local activation time(s) for other cardiac location(s), also measured using the catheter-mounted roving electrode, are determined relative to the reference signal. The stability of the reference signal can be monitored, such as by comparing activation rates or cycle lengths between an instantaneously-measured electrophysiological signal and the initial electrophysiological signal. Smaller differences between the two (e.g., less than about 5%) can be compensated for, while larger differences can result in redefining the reference signal.