Letter to the Editor

DOI: 10.19102/icrm.2012.030302

Mark D. Carlson, MD

In the article titled “External Insulation Breach Near the Tip of a Single Ventricular Pacing Lead,” published in the February issue of The Journal of Innovations in Cardiac Rhythm Management, Dr. Ernest Lau states, “After eliminating all the possible causes, “inside-out” abrasion appears as the most plausible explanation [of the observed outer insulation abrasion]”. This is not the case. Laboratory analysis of the returned lead (model 1788) revealed outer insulation damage between 4.0 and 4.8 cm from the lead tip due to external (not inside-out) abrasion.

The lead was examined using both optical and scanning electron microscopy. Optical microscopy revealed a polished, shiny surface on the lead’s outer insulation surrounding the insulation breach (Figure 1). Optical and scanning electron microscopy revealed longitudinal abrasion marks on the outer surface of the silicone insulation adjacent to the insulation breach (Figures 2 and 3). All of these findings are typical for cases of external abrasion and confirm that external abrasion caused the insulation breach. A very rare event, insulation breach from any cause in model 1788 leads has been confirmed to occur at a rate of only 0.04%, as documented in the St. Jude Medical Product Performance Report.

Figure 1: Polished (shiny) surfaces adjacent to the insulation breach confirm external abrasion processes.

Figure 2: Longitudinal abrasion marks on the outer surface of adjacent silicone confirms external abrasion processes.

Figure 3: Scanning electron microscopy showing longitudinal wear marks on the adjacent silicone insulation confirms external abrasion processes.

While communicating clinical findings is important to make physicians aware of product complications, it is equally important to ensure the information has been thoroughly investigated before conclusions are drawn. The lead discussed in this article was extracted on November 22, 2011 and was received by St. Jude Medical on December 9, 2011. The manuscript was received by the journal on December 19, 2011 and accepted for publication on January 3, 2012. Laboratory analysis of the lead was completed on January 16, 2012, and communicated to the author on January 17, 2012.

This case highlights the importance of appropriate laboratory analysis by experts in determining the root cause of lead damage. Visual inspection alone can result in incorrect conclusions. We encourage physicians to report any case of lead failure to us for further inspection and analysis.

Mark D. Carlson, MD
mcarlson@sjm.com
Chief Medical Officer and Senior Vice President
Research and Clinical Affairs
Cardiac Rhythm Management Division
St. Jude Medical
Sylmar, CA