Systems and methods for examining the electrical characteristic of cardiac tissue

A system for examining tissue within the heart comprising

• a three dimensional array of spaced apart electrodes for contacting endocardial tissue in a selected position,
• means for transmitting electrical current from the spaced apart electrodes in multiple paths through a region of heart tissue without altering the position of the array, and
• processing means for deriving an electrical characteristic of tissue lying in the multiple paths based, at least in part, by sensing tissue impedances in the multiple paths.

A method for examining tissue within the heart comprising the steps of

• transmitting electrical current in a first path through a region of tissue between a first pair of electrodes, at least one of which is located within the heart in contact with endocardial tissue,
• transmitting electrical current in a second path through tissue in the region between a second pair of the electrodes, at least one of which is located within the heart in contact with endocardial tissue, without substantially altering the position of the first pair of electrodes, and
• deriving the electrical characteristics of tissue lying in the first and second paths based, at least in part, upon sensing the impedances in the first and second paths.

A method for examining tissue within the heart comprising the steps of

• positioning a array of spaced apart electrodes in contact with a region of endocardial tissue in a desired position,
• transmitting electrical current from the spaced apart electrodes in multiple paths through a region of heart tissue without altering the position of the array, and
• deriving the electrical characteristics of tissue lying in the multiple paths based, at least in part, to sensing tissue impedances in the multiple paths.