| 摘要 |
An improved system and method for detecting dislodgement of an implantable medical device (IMD) such as a catheter or lead is disclosed. The system includes means for generating multiple, orthogonally-related signals within a body. For example, three current signals having a current path substantially oriented in the X, Y, and Z directions may be generated within the body. The invention further includes an IMD having an affixation device such as a helix at a distal tip for attachment to body tissue, and at least two sensing devices to sense the signals generated within the body. The difference in signal levels between two of the sensing devices may be measured. For example, a voltage potential difference created by the currents within the body may be measured between two electrodes. This measured signal level has components in the X, Y, and Z directions, and may therefore be used to define a directional vector in three-dimensional space. This vector is indicative of the orientation of the IMD. By comparing a directional vector indicative of a current IMD position with a vector indicative of a reference orientation, dislodgement of the IMD may be detected. In one embodiment, the reference orientation may be associated with a position wherein the IMD distal end is substantially perpendicular to the tissue. The comparison between the reference orientation and a subsequent IMD orientation may be performed by calculating the angle between the two associated vectors. If the angle exceeds a predetermined maximum angle, dislodgement is indicated.
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