Finite Element Stress-Strain Analysis of a Cardiac Pacemaker Casing under Controlled Compression

Objective To develop a device-specific finite element (FE) model of a cardiac pacemaker pulse generator casing and evaluate it against a controlled compression experiment within the approximately elastic loading regime. Methods A Guidant Contak Renewal TR-2 generator was compressed as an assembled device while force, crosshead displacement and pacing output were monitored. The subsequently opened housing, battery and polymer supports were manually measured and represented in MSC Patran for MD Nastran. The battery modulus was obtained from one destructive compression trace. The original experimental and computational documentation was revisited to restore omitted methods [26]. Results At 4000 N, archived measured and computed displacements were 0.45 and 0.52 mm, respectively (15.6% relative difference). The experimental response changed slope near 5000 N. Pacing amplitude decreased by approximately 40% at 5700 N and 1.69 mm; pacing impulses disappeared at 5920 N and an observed displacement of 1.74 mm. The previously reported 0.66 mm at 5920 N is an extrapolated elastic-equivalent value, not the measured displacement. The final refined model shows a maximum single-side displacement of 0.352 mm. Conclusions The model provides a device-specific description of deformation under one controlled bench configuration and suggests candidate load-transfer regions. Its elastic-material representation does not predict the observed plastic deformation or temporary functional loss at the highest load and cannot establish a clinical safety margin.