Devices and methods for enhancing observability under ultrasound imaging of medical devices include temporal markers which are dynamic, producing a variable ultrasound image over time. Included are rotating markers which produce a Doppler shift visible through ultrasound imaging in a Doppler mode and which enhance visibility of the marker. Other devices and methods include alternating streams of fluid contrast agents and saline as well as destroying a fluid contrast agent stream with a high intensity ultrasound pulse.