Volumetrically illustrating a structure

A method of illustrating a selected path on a display, comprising:

• positioning a mapping instrument in a volume of a heart of a patient;
• moving a first position element in the volume with the mapping instrument;
• determining a plurality of positions of the first position element in the volume;
• generating a plurality of map data points of the volume based on the determined plurality of positions of the first position element;
• displaying a map including the plurality of map data points on a display device to illustrate an interior surface of the volume;
• selecting an implantation position at a first time with the first position element for a lead electrode in the heart;
• withdrawing the mapping instrument from the selected implantation position along a selected pathway;
• determining a plurality of pathway positions of the first position element along the pathway as the mapping instrument is being withdrawn;
• illustrating the plurality of determined pathway positions superimposed on the displayed map as a pathway icon, and illustrating the selected implantation position superimposed on the displayed map as a landmark icon;
• tracking a second instrument having a lead electrode in the volume at a second time later than the first time;
• displaying a second instrument icon representing a location of the lead electrode relative to the pathway icon and the landmark icon;
• and
• guiding the second instrument along the pathway towards the landmark icon at least based on the displayed position of the lead electrode relative to the pathway icon and the landmark icon.

A system for illustrating a selected path on a display, comprising:

• a mapping instrument having a first position element affixed to a portion of the instrument arranged to be inserted into a volume of a patient, the first position element arranged to sense an electrical property of the volume;
• a position sensing unit having a set of axis generation electrodes for injecting current into the patient, the axis generation electrodes adapted to be positioned on an outer surface of the patient and establish an axis via a conductive path therebetween, the injected current generating a voltage gradient in the patient between the set of electrodes;
• a processor coupled to the position sensing unit, the first position element and a display device, the processor operable to execute instructions to determine a plurality of positions of the first position element using only the position sensing unit and the first position element, and to display a map of the plurality of determined positions on the display device to illustrate an interior surface of the volume, the processor further operable to determine a plurality of positions along a selected pathway using only the position sensing unit and the first position element as the mapping instrument is being withdrawn from the volume, and to illustrate the determined plurality of pathway positions on the display device superimposed on the displayed map as a pathway icon;
• and
• a second instrument having a second position element, the second instrument arranged to be inserted into the volume, wherein the processor is operable to determine a position of the second position element using only the position sensing unit and display a second instrument icon on the displayed map representative of a location of the second instrument relative to the pathway icon.