Mechanics of lumenless pacing lead strength during extraction procedures based on laboratory bench testing.

BACKGROUND: With the advent of conduction system pacing, use of the Medtronic SelectSecure Model 3830 lead has increased substantially. However, with this increased use, the potential need for lead extraction also will increase. Lumenless lead construction requires an understanding of both applicable tensile forces as well as lead preparation techniques that can influence consistent extraction. OBJECTIVE: The purpose of this study was to use bench testing methodologies to characterize the physical properties of lumenless leads and to describe related lead preparation methods that support known extraction techniques. METHODS: Multiple 3830 lead preparation techniques, commonly used in extraction practices, were compared on the bench to assess rail strength (RS) in simple traction and use conditions with simulated scar. Retention of the IS1 connector vs severing the lead body preparation techniques were compared. Distal snare and rotational extraction tools were evaluated. RESULTS: The retained connector method provided higher RS compared to the modified cut lead method: mean 11.42 lbf (9.85-12.73 lbf) vs 8.51 lbf (1.66-14.32 lbf), respectively. Snare use distally did not significantly affect RS: mean 11.05 lbf (8.58-13.95 lbf). Lead damage occurred with the TightRail extraction tool at angles ≥90°, which could occur with right-sided implants. CONCLUSIONS: When extracting SelectSecure leads, the retained connector method to maintain cable engagement benefits preservation of the extraction RS. Limiting traction force to <10 lbf (4.5 kgf) and avoiding poor lead preparation methods are critical to consistent extraction. Femoral snaring does not change RS when needed and offers a method to regain lead rail in cases of distal cable fracture.

In vitro modeling accurately predicts cardiac lead fracture at 10 years.

BACKGROUND: Development of a cardiac lead fracture model has the potential to differentiate well-performing lead designs from poor performing ones and could aid in future lead development. OBJECTIVE: The purpose of this study was to demonstrate a predictive model for lead fracture and validate the results generated by the model by comparing them to observed 10-year implantable cardioverter-defibrillator lead fracture-free survival. METHODS: The model presented here uses a combination of in vivo patient data, in vitro conductor fatigue test data, and statistical simulation to predict the fracture-free survival of cardiac leads. The model was validated by comparing the results to human clinical performance data from the Medtronic Sprint Fidelis (Minneapolis, MN) models 6931 (single coil, active fixation) and 6949 (dual coil, active fixation), as well as the Quattro model 6947 (dual coil, active fixation). RESULTS: Median patient age in the single coil Fidelis 6931 population (64 years) was less than in the dual coil Fidelis 6949 and Quattro populations (68 years). Modeled and observed fracture-free survival for Quattro (>97%) was superior to that for Fidelis (<94%). The modeled survival agreed with the observed fracture-free survival data. The average model error was 0.3% (SD 1.2%). CONCLUSION: This model for cardiac lead fracture-free survival using in vivo lead bending measurements and in vitro bench testing can be used to predict lead performance as observed by alignment with field survival data.