An emergency transection intervention device has an elongated catheter (4) with a movable nose cone dilator (8) temporarily closing off the first end of the elongate catheter, a haemostatic seal (6) on a second end of the catheter and closing off the second end of the elongate catheter. First and second inflatable balloons (12, 14) are spaced apart on the elongate catheter, and there is an aperture (16) in the elongate catheter between the balloons and the haemostatic seal. The emergency transection intervention device can be deployed into a blood vessel of the human or animal body, during an emergency procedure for instance, with the balloons positioned either side of a damaged portion of the vessel and the balloons inflated such that a region of the vessel between the balloons is isolated. The nose cone dilator can then be advanced to allow blood flow through the elongate catheter and exit through the aperture in the elongate catheter to bypass the damaged portion of the vessel during repair.