\nThe next follow-up examination should take place 2-3 months after pacemaker implantation. This is the period during which both the pacing threshold and the sensing of spontaneous cardiac electrical signals stabilise. In addition to a physical examination and an ECG, the pacing and sensing thresholds should be measured, and the values obtained should be used to programme the pulse energy (amplitude and width) and the sensitivity of the atrial and\/or ventricular channel.<\/p>\n
Programming the pulse energy conservatively (usually 200-300% of the pacing threshold) can extend the pacemaker’s battery life, sometimes by several years beyond the average operating life predicted by the manufacturer. Appropriate sensitivity programming (within 1\/2\u20132\/3 of the absolute sensing threshold
\nvalues) prevents undersensing (failure to sense) and the associated sensing disturbances on the one hand, while counteracting all effects caused by oversensing on the other. In ventricular systems (VVI), T-wave oversensing involves incorrectly interpreting the T wave as a QRS complex, while in atrial or dual-chamber systems, far-field
\nsensing means incorrectly interpreting the R wave as another P wave. In ventricular or atrial unipolar systems, muscle potentials can temporarily inhibit pacing; in dual-chamber systems, myopotentials detected in the atrial channel cause ventricular pacing at the upper tracking rate (UTR).<\/p>\n
LONG-TERM FOLLOW-UP EXAMINATIONS<\/strong> During the final year of the pacemaker battery’s expected life (which also depends on any previous reduction in pacing pulse energy), follow-up examinations should be more frequent, on average every 2-3 months.<\/p>\n We can assess the condition of the pacemaker battery either directly, using a telemetry reading from the programmer, or indirectly, by analysing the pulse rate on an ECG recording or using an oscillosynchroscope. In the early stages of pacemaker battery depletion, the elective replacement indicator is activated, initially as a reduction in the test
\nPatients with an AAI(R) pacemaker implanted for sinus node dysfunction or chronotropic incompetence may have checks every 6 months;
\npatients with bradycardia\u2013tachycardia syndrome require much more frequent checks.
\nPatients with a dual-chamber pacemaker (DDD\/\/DDDR) implanted for acquired or congenital atrioventricular (AV) block may have checks every 6 months. However, the same type of pacemaker implanted for bradycardia\u2013tachycardia syndrome, or for other less typical indications (such as vasovagal syndrome, long QT syndrome or carotid sinus hypersensitivity syndrome), requires frequent follow-up examinations.
\nParticularly frequent checks (every 2-3 months, sometimes even every month) are required for patients with a dual-chamber pacemaker implanted for bradycardia\u2013tachycardia syndrome, because they experience supraventricular arrhythmias that present certain diagnostic (ECG interpretation) and therapeutic difficulties.
\nMore frequent follow-up examinations are required when taking
\nantiarrhythmic medicines (class Ia, Ic), which modify the pacing and sensing thresholds and AV conduction, and when it is necessary to assess the effectiveness of the relevant antiarrhythmic programmes in DDD pacemakers.<\/p>\n
\n(magnet) rate, followed by a reduction in the pacemaker’s basic pulse rate.
\nA sign of substantial battery depletion is an automatic change in pacing mode from dual-chamber to single-chamber (e.g. from DDD to VDD or VVI), or from demand pacing to a fixed-rate mode (e.g. from VVI to VOO). In most pacemakers, 6-12 months elapse between activation and display of the ERI indicator and complete battery depletion (end of life, EOL; end of service, EOS). In people who are completely dependent on their pacemaker
\n(patients with third-degree AV block, IIIo, without an intrinsic escape rhythm), elective replacement should be carried out as soon as the signs of battery depletion described above appear (elective replacement time, ERT). In other patients with a satisfactory escape rhythm, follow-up examinations should be performed more frequently between ERT and EOL (EOS), e.g. every month, and replacement should take place before the battery is depleted. Another sign that may prompt an earlier decision on possible
\npacemaker replacement is an unexpected change in its battery impedance.<\/p>\n
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