The first pacemaker follow-up appointment is critical, according to the Cleveland Clinic: The technician will make adjustments to prolong battery life, and discuss the importance and purpose of various pacemaker tests. Pacemaker tests not only indicate the functioning of the system; they can also assess overall cardiac well-being.
System and Diagnostic Testing
A comprehensive pacemaker test is typically performed in a physician's office by a qualified technician through a programmer capable of two-way communication with the device. At the beginning of a follow-up session, the device will conduct a series of automated tests. These initial tests provide an overview of the central pacemaker components, that is, the battery and the leads. Often referred to as "measured data," "initial interrogation," or simply, "interrogation," these tests check the resistance of the leads, and provide the pacemaker's battery status by measuring the current, voltage, and resistance of the battery cell encased in the device. In addition, the pacemaker will retrieve any stored recordings for further evaluation. Recordings will also be used to determine the need for customization in setting parameters that will trigger future recordings.
Sensitivity Testing
While some devices incorporate automated sensitivity tests, a thorough sensing test is manually performed in a clinic. Pacemakers operate on-demand; therefore, to work effectively, device settings need to ensure a balance: The device must be sensitive enough to operate when needed, but not so sensitive that it is picking up unrelated signals. A sensitivity threshold test measures these values allowing the technician to program the device to an appropriate setting.
Capture Threshold Testing
A pacemaker causes the heart to beat when it delivers a stimulus of adequate voltage to the heart tissue. Capture threshold testing determines the minimum voltage capable of evoking a heartbeat. Since capture thresholds can fluctuate for numerous reasons, clinicians typically set the permanent output voltage to be double the capture threshold voltage, which is called the "safety margin." Some devices feature automated capture testing capabilities, but a thorough capture threshold evaluation takes place manually in a clinic setting.
Remote Testing
Many practices provide small transmitters to be kept at home for the convenience of remote trans-telephonic monitoring, or in lay terms: telephone checks. The pacemaker performs a basic battery test triggered by placing a magnet over the device. According to MayoClinic.com, during a typical TTM session, a technician on the other end of the phone line checks the patient's heart rate and rhythm and evaluates the pacemaker's function and remaining battery life. Telephone checks, however, have limitations. In the Nov. 24, 2009, issue of the "Journal of the American College of Cardiology" researchers concluded that, other than determining battery status, TTM is of little clinical value. Device manufactures, however, continue to develop remote transmission capabilities, in the hope that remote technology will improve in the future.
References
- Cleveland Clinic: Pacemaker Homegoing Instructions
- "Current Opinion in Cardiology"; Troubleshooting Pacemakers and Implantable Cardioverter-Defibrillators; Scher; January 2004
- Chest Journal: Myopotential Inhibition of Demand Pacemakers
- MayoClinic.com: Pacemaker: What You Can Expect-After the Procedure
- "Journal of the American College of Cardiology"; Clinical Benefits of Remote Versus Transtelephonic Monitoring of Implanted Pacemakers; Crossley et al; November 2009
