An interventional medical device is provided that incorporates a forward-directed ultrasound imaging system integrated into a single device. The medical device can be in the form of sheaths, catheters, and interventional devices, particularly those suitable for minimally invasive procedures in the human or other mammalian body. The imaging system comprises one or more small ultrasound transducers that can be permanently integrated into the device or integrated into an interchangeable ultrasound transducer that can be inserted into and removed from the device to customize the device for a particular use. An ultrasound system can be provided in the device either alone or in combination with fiber optic imaging to provide a range of imaging and therapeutic capabilities of the device.