IMPLANTABLE ANASTOMOSIS POTENCY MONITOR

SMALL DOPPLER ULTRASONIC CATHETERS, 1-2 MM IN DIAMETER, PREVIOUSLY DEVELOPED BY THE INVESTIGATIVE TEAM WILL BE USED TO MEASURE BLOOD FLOW IN VESSELS, 1-5 MM IN DIAMETER, TO DETECT VESSEL PATENCY AFTER MICROSURGERY. THE PRESENT PHASEWILL DEFINE BEST POSITIONING SITE FOR CATHETER TO VESSEL, DEVELOP APPROPRIATE SENSING AND DATA ANALYSIS ELECTRONICS, AND INVESTIGATIVE QUANTITATION METHODS FOR MAKING MEASURE- MENTS OF STENOSIS IN MONITORING VESSELS. EXIT THE INVESTIGATORS HAVE EXPERIENCE WITH THE USE OF 2MM DIAMETER CATHETERS WHICH CONTAIN AS MANY AS SEVEN TRANSDUCING ELEMENTS. BLOOD VESSEL CROSS-SECTIONAL AREA IS TO BE MEASURED WITH SIX OF THESE ELEMENTS AND THE SEVENTH WILL MEASURE BLOOD VELOCITY. TOTAL BLOOD FLOW IS DETERMINEDBY MULTIPLYING THE CROSS-SECTIONAL AREA OF THE VESSEL BY THEBLOOD VELOCITY. TOTAL BLOOD FLOW IS DETERMINED BY MULTI- PLYING THE CROSS-SECTIONAL AREA OF THE VESSEL BY BLOOD VELOCITY. SUCH CATHETERS WILL BE UTILIZED TO MEASURE BLOOD FLOW IN FREE FLAP TRANSPLANTS AND REPLANTED DIGITS (VESSELS 1-2 MM IN DIAMETER). THREE TYPES OF CRYSTAL GEOMETRIES WILLBE STUDIED -- THIN SECTOR, WIDE SECTOR, AND A DUAL TRANS- DUCER WITH TWO ELEMENTS IN OPPOSITION (APPROXIMATELY 120 DEGREES). CRYSTAL LENGTH WILL ALSO BE SUCH AS TO GUARANTEE COMPLETE ISONIFICATION OF THE VESSEL (1-2 MM LONG). USING THESE APPROACHES, IT SHOULD BE POSIBLE TO DETERMINE FACTORS WHICH MAY ACCOUNT FOR TISSUE ATTENUATION DUE TO THE DISTANCEOF PROBE TO VESSEL WALL, ALLOW FOR CALCULATION OF VESSEL CROOS-SECTIONAL AREA AND APPROXIMATE ROTATIONAL ANGLE BETWEEN VESSEL AND TRANSDUCER. SIGNALS WILL BE OBTAINED FROM A TRANSDUCER INPULSED DOPPLER MODE AND PROCESSED TO DETECT POWER OF SIDEBANDS, POWER OF CARRIER AND FOR ARC IMPLEMENTATION OF RANGE GATED SIGNALS. STENOSIS QUANTITATION WILL BE DERIVED FROM ANALYSIS OF PEAK FREQUENCY AND SPECTRAL BROADENING OF RECEIVED SIGNALS. USE OF DUAL ELEMENT CATHETER CONFIGURATIONS ARE CONSIDERED MOST PROMISING FOR PROVIDING QUANTATIVE INFORMATION. WHEN USED IN HUMAN SUBJECTS, THE CATHETER WILL BE IMPLANTED WITH DISSOLVABLE SUTURES AT THE TIME OF SURGERY AND CATHETER ATTACHED TO THE BODY WITH TAPE. THE PROBE WILL BE LEFT IN PLACE FOR 3-4 DAYS UNTIL THE SUTURES DISSOLVE. MEASUREMENTS WILL BE MADE INTERMITTENTLY FOR PERIODS RANGING FROM 1/2 TO 3 HOURS. EVIDENCE OF ALTERED FLOW WILL BE COMPARED AGAINST PRESENTLY AVAILABLE METHODOLOGIES WITH THE OBJECTIVE OF CHANGING THERAPY OR REOPERATION AS NEEDED.