597587 Disclosed is a system for of calculating a cross-sectional area of a body lumen at each of a plurality of locations within the body lumen using electrical conductance data. The system comprises a device having a proximal end and a distal end, the distal end of the device for placement into a body lumen, the device comprising a first electrode and a second electrode. When a processor is connected to the first and second electrodes of the device for collecting conductance data from the electrode, the processor is capable of collecting conductance data from the device to determine a profile of the body lumen. The profile is indicative of a change in relative cross-sectional area of the body lumen such that a junction between two lumina can be identified. The conductance data is collected at a plurality of locations over a distance within the body lumen and determined at each of the plurality of locations when the first and second electrodes are immersed in a fluid within the body lumen in use. The body lumen comprises at least a portion of an atrium, a pulmonary vein-atrial junction, a blood vessel, a biliary tract, an esophagus and the fluid comprises blood.
