Apparatus for carrying out a medical procedure at a site in a patients blood circulatory system, including a device to be implanted in the circulatory system, a sheath surrounding device and having a first diameter a hollow tube having a second diameter and having a pressure transducer at its proximal end, and a filter that is collapsible into the sheath and is expandable out of the sheath for blocking debris and passing blood in the circulatory system.
