Detection of pressure waves transmitted through catheter/lead body

Abstract

In an implanted medical device, a method and apparatus for detecting pressure waves caused by movement of a body organ, muscle group, limb or the like and transmitted through a catheter or lead body to the implanted medical device employing a pressure wave transducer mounted in relation to the proximal end of the catheter or lead to detect the transmitted pressure waves. The system may also include a reference transducer having the same pressure wave response characteristics as the pressure wave transducer but isolated from the proximal connector end for providing a reference signal including common mode pressure wave noise that both transducers are simultaneously subjected to. The pressure wave signal and the reference signal are preferably amplified, bandpass filtered to the body pressure wave of interest and stored, telemetered out or used to trigger a device operation. The pressure and reference wave transducers preferably are piezoelectric crystal transducers or accelerometers in direct or indirect mechanical contact with the proximal connector end of the catheter and is encapsulated from the body within a device connector assembly. Preferably, the catheter is a lead extending into direct or indirect contact with the patient's heart. Cardiac pressure waves and respiration pressure waves are both transmitted proximally through the lead body to the pressure wave transducer. Pressure wave signals may be derived in parallel to detect particular characteristics of the cardiac and/or respiratory cycle to provide timing signal(s) for controlling the device operations.