| 摘要 |
<p>A parameter indicative of the condition of a cardiac valve is determined by monitoring blood flow, and/or velocity in a vessel that is coupled to the cardiac valve or in a chamber adjacent to an artificial cardiac valve. One or more ultrasonic transducers (174A, 174B) are provided either in a wall or a cuff (302) disposed about a cardiac vessel (304) to monitor the parameter in regard to a natural or artificial cardiac valve, or in a support sewing ring of an artificial cardiac valve. A conformal array transducer or a tilted element is used to monitor fluid flow or velocity based on the effect of the blood on ultrasonic waves produced by the transducers. The conformal array transducer comprises a plurality of elements that are excited with an input signal provided by an implanted electronics circuit producing ultrasonic waves.</p> |
