频率应答功能ppt课件.ppt

Acceleration detection circuit Activity sensor signal frequency band The activity sensor signal frequency band is from 1Hz to 10Hz. The accelerometer sensing element mechanically dampens frequencies above 45 Hz, which makes the sensor system less sensitive to false positive responses. Acceleration detection circuit The acceleration detection circuit converts physical motion into an electrical signal proportional to the level of movement. A count is generated each time the activity sensor signal exceeds a user-programmable (positive) activity threshold level and subsequently returns to below the negative threshold level (see for a more detailed description of the threshold: Programming the sensor – Activity Threshold). Vibration vs. acceleration 压电晶体的传感器在起搏器外壳的内侧，外界的任何压力都能使它做出反应。非常的不准确。 加速度计感知器在起搏器的内部，对外界的压力不敏感，收集到的信息与活动度有较好的相关性，相当较精确 Vibration sensor (Piezoelectric Crystal) The piezoelectric sensor is bonded to the inside surface of the pacemaker case. Mechanical forces are transmitted by the surrounding connective tissue, fatty tissue, and muscles. The extent of contact and the coupling mass of the mechanical forces can vary considerably. Accelerometer sensor The accelerometer is mounted on the pacemaker’s hybrid circuitry. Therefore, measured accelerations are independent of surrounding tissue and patients physical properties. Studies Studies have shown that measurement of acceleration provides a better correlation with the level of exertion than does measurement of the frequency of activity signals (Connelly 1993, Sharp et al, 1997). Mode Rate response becomes active by programming the sensor to a rate responsive mode (XXXR) Increased tidal volume and rate increase transthoracic impedance, which increases the pacing rate. １、原理 每分钟通气量传感器通过测量电极导线顶端电极与脉冲发生器之间的经胸阻抗，测得潮气量和呼吸频率，然后计算出每分钟通气量，并与安静状态的基础值相比较，经脉冲发生器的内设算法自动调节起搏输出频率。每分钟通气量传感器需要特殊的双极电极导线。 ２、临床应用 此类传感器的最大优点为起搏频率的改变与活动量变化的相关性比较好，因此在临床上应用比较广泛。如Ela Talent、Medtronic Kapp400、Guidant Insignia Plus;Guidant Pulsar