tailieunhanh - HANDBOOK OF CARDIAC PACING – PART 3

ôi đã từng có một bác sĩ cho tôi biết "Tôi có sáu nam châm xếp chồng lên nhau trên đầu trang của máy tạo nhịp tim của anh chàng này và nó vẫn còn nhịp" Thực tế là hầu như tất cả các máy tạo nhịp tốc độ không đồng bộ | 24 Handbook of Cardiac Pacing 2 will turn it off. I once had a physician tell me I have six magnets stacked on top of this guy s pacemaker and it is still pacing The fact is that virtually all pacemakers will pace asynchronously sensing is disabled with the application of a magnet Fig. . The rate of pacing may change during the magnet application. It may be higher lower or equal to the programmed rate depending on the device. In addition be aware that in dual chamber devices the AV-interval and or the mode of pacing may change . DDD to VOO instead of the expected DOO . The magnet rate is one method used to determine the status of the battery. Application of the magnet elicits pacing at a specific rate as defined by the model and sometimes serial number . A change in this magnet rate according to the specification by the manufacturer will indicate an intensified follow-up period recommended replacement time RRT or end of device life EOL . Use of the magnet rate allows some determination of device status by simple transtelephonic transmission of a cardiac rhythm strip. Some devices allow the magnet response to be programmed On or Off. If the response is programmed off there will be NO response to magnet application. Fig. . A ring magnet is shown in proper position placed over a pacemaker to close the magnetic reed switch within the pacemaker. Fig. . Strip showing magnet response of a pacemaker. The device paces in an asynchronous manner no sensing of the underlying QRS or P waves . In this example due to 100 AV pacing this is ot readily seen. The clue to the change in this device is the shortening of the AVI which changes from 200 ms to 120 ms. The response of each manufacturer and model to the magnet may be unique. Basic Single Chamber Pacing Basic Pacing Single Chamber Additional II BASIC PACING SINGLE CHAMBER MODES In order to understand the basic timing of a pacemaker one must understand the terminology commonly used to .