Pacemaker-generated stress fracture of the second rib: a case report.

Background: Pocket-related complications following the implantation of cardiovascular implantable electronic devices primarily include pocket hematoma, infection, skin erosion or decubitus, device migration, and Twiddler's syndrome, with other pathologies such as nerve impairment or bone lesions being extremely rarely encountered. We report a case of a 20-year old asthenic, non-athlete female patient presenting with a device-generated fracture of the second rib several months after sub-muscular permanent pacemaker implantation due to repeated bilateral pre-pectoral pocket infections.
Case Presentation: A 20-year old female patient was readmitted to our institution 9 months following sub-pectoral implantation of a permanent pacemaker, complaining of severe pocket-related pain, which arose spontaneously in the absence of direct trauma, intense physical activity or vigorous coughing, and was associated with normal day-to-day activity. To rule out a pacemaker re-infection, a native computed tomography and a positron emission tomography-computed tomography of the thorax were performed. Both modalities excluded an infection but showed a healing fracture and a focus of enhanced metabolic activity in the anterolateral part of the right second rib, indicating a non-traumatic or stress fracture of the bone. Consequently, a complete extraction of the pulse generator and both leads was performed and the smallest available single-chamber pulse generator with a single atrial electrode was implanted in the sub-fascial, pre-muscular pocket in the now recovered and uninfected left subclavicular region, alleviating patient's severe pain symptoms and significantly enhancing her quality of life.
Conclusions: In the absence of direct trauma, intense physical activity or vigorous coughing, we assume that in this asthenic girl a normal day-to-day motion of the right shoulder has persistently forced the sub-muscularly placed pulse generator toward thoracic wall, putting increased repetitive pressure force on the underlying bones, finally causing a fatigue stress fracture of the second rib. In asthenic phenotype patients with small thorax and short subclavicular distance, a sub-muscular pacemaker implantation can potentially cause unique and unexpected pocket-related adverse events necessitating advanced diagnostics and timely treatment.