The check itself takes between 15 and 45 minutes depending on the type of device implanted, and involves lying on a couch with ECG electrodes attached to the wrists and ankles, and a programmer placed over the site of the device. The technician will be looking at five main aspects, namely:

1. Its ability to sense, i.e. to detect when the heart is beating abnormally and kick in at that stage, but leave the heart alone when it is functioning normally;

2. The lead thresholds, to ensure that the minimum amount of energy necessary is being delivered from the generator to the leads in the chambers of the heart, so that pacing is consistent and battery life is maximised;

3. The programming of the device, so that the parameters set within the pacemaker correspond to the patient’s daily routine;

4. Any changes in heart rhythm and, in the case of ICDs, whether any shocks have been delivered to terminate dangerous heart rhythms such as VF (ventricular fibrillation) and VT (ventricular tachycardia);

5. The remaining battery life.

Most pacemaker batteries last between five and ten years, depending on how much the pacemaker is used; patients who are pacing dependent, i.e. where the pacemaker is pacing the heart 100% of the time, should expect to require a generator change earlier than someone whose pacemaker only “kicks in” intermittently. During a pacemaker check, the technician will be able to give an estimate about how long the battery is due to last, and a generator replacement will be arranged accordingly; for this a patient will be admitted to hospital for a few hours and the battery will be replaced under a local anaesthetic – the pacing leads themselves stay in position, provided they are still functioning normally.