Leadless pacemakers: a contemporary review.

Over one million cardiac pacemakers are implanted every year worldwide,[1] of which approximately 200,000 are implanted in the United States alone.[2] Combined with an aging population and increasing pacing indications, these numbers are expected to grow. Since the first pacemaker implantation in 1950s, cardiac pacemaker technology has rapidly advanced. Reduction in generator size, increased battery longevity, quality of pacemaker leads, algorithmic and rate responsive programming―all have revolutionized and transformed the implantation and management of transvenous cardiac pacemaker (TV-PPM). Despite these advances, the potential for complications and technical failure always necessitates consideration. Short-term complications, which have been reported to be as high as 12%,[3] are typically related to the presence of a transvenous lead and or subcutaneous pocket. These complications include pneumothorax, cardiac perforation, lead dislodgement, and pocket infection or hematoma. Long-term complications are also related primarily to the pacing lead and subcutaneous pocket, and include pocket infection, tricuspid regurgitation, venous obstruction, lead fractures and insulation failure. In addition, development of lead related endocarditis is a significant concern, with mortality rates reported between 12%–31%.[4]–[6] Some Studies have shown that long-term complications are primarily related to lead failure, identifying it as the weakest component of the current pacing system.[3],[7] Data obtained from the Truven MarkestScan database, which tracks Medicare and US health care claims, showed a 15%-16% complication rate at three years among 72,701 patients with TV-PPM, representing a significant economic burden to both the patient and healthcare system.[8] Leadless pacemakers were initially conceptualized in the 1970s[9] and successfully implanted in dogs using a mercury battery powered capsule. With advanced battery technology, communication capability, and catheter-based delivery systems leadless pacemakers became a reality. In this paper, we will discuss the current leadless pacing systems focusing on their pros and cons as compared to traditional TV-PPM.