The invention relates to an interventional system comprising an interventional device (11) for being inserted into a living being (7) and comprising an optical shape sensing fiber, wherein the optical shape sensing fiber is used for determining respiratory motion by monitoring a movement of a part of the interventional device, which moves in accordance with the respiratory motion. Thus, respiratory motion can be determined, without necessarily requiring a physician to handle with further devices like a respiratory belt, i.e. the same interventional device can be used for performing an interventional procedure and for determining the respiratory motion. The interventional procedure can therefore be less cumbersome for a physician. Moreover, since the determination of the respiratory motion is based on optical shape sensing, which is a very accurate position determination technique, the respiratory motion can be determined very accurately.
