The present invention provides a vascular catheter apparatus for temperature measurement of vascular tissue, comprising a flexible body, at least one resiliently biased projection depended from the body, a sensor carried by the projection and an electrical carrier for transmitting temperature data at the vascular wall from the sensor to a remote device. The electrical carrier may be coiled around the length of the projection to reduce the strain at critical points where it is necessary to maintain a seal and hence electrical isolation.