Acoustic window and septum for imaging catheters

A catheter for diagnosing body interiors utilizing the transmission and receiving of ultrasonic waves generated therewith, said catheter having a distal and a proximal end, said catheter comprising:

• an elongated catheter sheath having a proximal end open to the atmosphere and an acoustic septum disposed at a distal end thereof, said septum comprising a flexible sheet or tube of foraminous thermoplastic material having thickness, the depths of the foramina being substantially equal to said thickness and at a predetermined ratio relative to their diameters;
• a hydrophilic coating disposed on said sheet or tube, said coating covering at least the edges of said foramina and allowing the passage of liquid therethrough to fill said sheath, said coating being absorbent of said liquid to close said foramina and prevent the passage of liquids in either direction;
• means for generating and receiving ultrasonic waves disposed within the distal end of said catheter, said means being in an operating relationship with said septum whereby to enable said means to be bathed in said fluid and enable sonic transmissions.

A method for diagnosing body interiors utilizing the transmission and receiving of ultrasonic waves generated therewith, said catheter having a distal and a proximal end, said method comprising:

• disposing said catheter adjacent a body part to be examined, said catheter having a catheter sheath with a proximal end open to the atmosphere and an acoustic septum disposed at a distal end thereof, said septum comprising a flexible sheet or tube of foraminous thermoplastic material having thickness, the depths of the foramina being substantially equal to said said thickness and at a predetermined ratio relative to their diameters, said septum having a hydrophilic coating disposed thereon, said coating covering at least the edges of said foramina and allowing the passage of liquid therethrough to fill said sheath, said coating being absorbent of said liquid to close said foramina and prevent the passage of liquids in either direction;
• generating and receiving ultrasonic waves from a transmitter-receiver disposed within the distal end of said catheter through said septum whereby to enable said transmitter/receiver to be bathed in said fluid and enable sonic transmissions.