Background: Elective Unit replacement or generator change of pacemakers/Intra-cardiac defibrillators (ICD), is a routine procedure performed in the catheter lab, usually as a day case and is associated with a low complication rate. Common complications, mentioned in the consent form include, bleeding, infection and lead displacement. Other complications include pneumothorax, ventricular perforation and tamponade if lead revision is also performed during the procedure.
Objectives: The aim of the project was to evaluate the incidence of all complications associated with box changes at our institution.
Methods: A retrospective analysis of all box change procedures carried out between 2016 –2020 was performed. All complications were recorded, with attention paid particularly to any novel complications not necessarily mentioned in the consent paperwork. Patient records were obtained, and any repeat procedures performed up to a year post initial box change were included in the analysis.
Results: A total of 892 generator changes were carried out. These included single and dual chamber pacemakers (553/892 -62%), ICDs (205/892-23%), and CRT P (134/892 – 15%) devices. Sub cutaneous ICD box changes were excluded from the group. Mean age was 61 years +/- 20 years. Mean BMI of the patients was 26 +/- 9. In terms of complications, a total of 7 out of 892 (0.8%) patients required a new lead, either at the time of generator change (3/7) or within one year of the procedure (4/7). Six out of 896 (0.7%) patients were diagnosed with infections, 2/6 of these cases were treated with antibiotics alone, and 4/6 patients underwent extractions. Five out of 892 patients (0.6%) developed large haematomas, 2/5 of these patients required a further procedure (haematoma evacuation), the remaining 3/5 patients were managed conservatively. 1 patient developed a pneumothorax when access was being obtained for new lead insertion. 1 patient had leads plugged into the incorrect port needing a revision. Fifteen out of 892 (1.7%) patients undergoing box change underwent a wound revision within 1 year of the initial box change procedure. This was mainly to resite the device mainly because of patient discomfort because of the device position., 3/15 patients were on Anti coagulation (Warfarin/NOAC), which had been stopped 2 days prior to the procedure, 5/15 patients had box changes with like for like replacements, with the other 10/15 having devices implanted with different manufacturers at the time of box change. 10/15 (67%) devices were Dual chamber pacemakers, 3/15 (20%) were ICDs and 2/15 (13%) were a CRT. This was in keeping with the overall proportion of devices implanted in each category.
Conclusion: Elective unit replacement is associated with complications including, lead failure, infection, haematoma, pneumothorax, incorrect lead placement into pacing box, and wound revision. The cumulative complication rate was just under 4% over the course of 1 year. Clinicians performing these procedures need to be aware of these complications so they can take steps to minimise this. In particular there was a significant risk of wound revision within a year, and specific steps should be taken to address this, as this seems to be under recognised. These steps may include deeper burial of the device for some individuals, especially those with a low BMI, extending the pocket at time of box change, and using a like for like replacement.