Apparatus for performing a medical procedure in the circulatory system

1. Apparatus for carrying out a medical procedure at a site in a patient's blood circulatory system, comprising:

a first assembly having an outer diameter and including a device to be implanted in the circulatory system;

a tubular sheath surrounding said first assembly and having a first diameter;

a hollow tube having a second diameter, distal and proximal ends, and an axial length between said distal and proximal ends, said hollow tube being open at both ends;

a pressure transducer disposed at said proximal end of said hollow tube for detecting the pressure in said tube; and

a filter that is collapsible into said sheath and expandable upon being deployed out of said sheath for blocking debris and passing blood in the circulatory system, at the site of the medical procedure, said filter having, when deployed, a radially expanded, generally conical or frustoconical form with a large diameter end, a small diameter end opposite to said large diameter end, and a side surface extending between said large diameter end and said small diameter end,

said filter:

comprising a flexible filter material covering said side surface and having pores dimensioned to prevent the passage of debris therethrough while allowing the passage of blood, and having a first opening at said large diameter end, a second opening at said small diameter end, and a third opening in the flexible filter material at said side surface, each said opening having a respective diameter and being free of filter material,

wherein:

the diameter of said second opening is substantially equal to the first diameter such that said second opening forms a seal with said sheath when said sheath extends into said filter through said second opening;

said hollow tube is insertable, via said distal end, into said filter through said third opening; and

the diameter of said third opening is substantially equal to the second diameter.

2. The apparatus of claim 1 , wherein said hollow tube is controllable to displace said distal end in directions transverse to said axial length of said hollow tube.

3. The apparatus of claim 2 , wherein said hollow tube is a steerable catheter.

4. The apparatus of claim 1 , wherein said first assembly is a transaortic valve implantation assembly and said device to be implanted in the circulatory system is a prosthetic valve.