Whole-Hearted Revolution in Cardiac Care: The New Leadless Pacemakers

The newest innovations in the cardiac rhythm management (CRM) market are about to electrify (forgive pun)  heart surgery and the medical world. Potentially, leadless pacemakers can reduce surgical complications and recovery times. Cardiac pacemakers have been around for almost six decades, but their design has gone through little if any changes down through time.

 Traditional cardiac pacemakers

Conventional devices have experienced particular problems over the years concerning the thin wires known as leads that are inserted through a vein and then stretched from the pulse generator to the heart. Constructed from polyurethane and silicone, these leads can break over time and the insulation surrounding them can also crack .Replacing fallen or broken leads has always been difficult and time-consuming. There have been, especially in the last decade in particular, several high profile recalls of pacemakers for this very reason.

 

Traditional Cardiac Pacemaker: Source:heartrhythmsfla1Traditional Cardiac Pacemaker: Source:heartrhythmsfla1

 

The two new leadless pacemakers

The two new single-chamber leadless pacemakers are St. Jude Medical's Nanostim, which obtained a CE mark  last year, and Medtonic's Micra Trans-Catheter Pacing System, which is targeting a CE Mark by the end of 2015. (These marks are the legal requirement to place a medical device on the market within the European Union.) Both look promising at the moment and can hold their own against traditional devices in terms of functionality and longevity. 

However, according to Reinoud Knops, a cardiologist at the Academic Medical Center in Amsterdam: "These are devices that we currently know how to put in, but we don't know if we will be able to get them out in a couple of years if the battery gets depleted."

The Nanostim leadless pacemaker

The design and intent of this pacemaker is the same as for all devices of this type.The difference lies in the implanting process. In the case of a standard pacemaker, the doctor creates a surgical pocket to implant the device and then attaches leads to the pacemaker and runs them to the heart where they pace its beats. Nanostim, St.Jude's leadless pacemaker, requires neither a surgical incision nor leads. It lies in the center of the heart where it creates a normal beat by sending small pulses of electricity when needed. The pacemaker battery life is equivalent to that found in standard pacemakers.

 

St. Jude's Nanostim Leadless Pacemaker: Source: SlideShareSt. Jude's Nanostim Leadless Pacemaker: Source: SlideShare

Nanostim gained regulatory approval in 2013  and is available for use in Europe. Data was very promising  as two centers submitted figures indicating a freedom from complications rate of 94%. Since approval, however, two death soccurred, causing a re-evaluation of the pacemaker. Study has resumed and is still in progress.

Medtronic's Micra-trans-catheter pacing system

The Micra leadless pacemaker is similar in concept to its rival and their difference lies in terms of how they are impanted into the heart. In the case of Nanostim, the device is fixed via a helix. According to Dr. Werner Jung, head of the Department of Cardiology, Schwarzwald-Baar Klinikum Villingen-Schwenningen, Germany, the Micra device includes fixation tines that actively attach into the tissue that holds the pacemaker's place in the heart.

Medtronic's Micra Leadless Pacemaker: Source: MedtronicsMedtronic's Micra Leadless Pacemaker: Source: Medtronics

Both pacemakers  utilize an introducer sheath and fixation approach, but Nanostim uses a smaller sheath, which is important because according to some experts, the sheath can impede the speed to access the source of bleeding after the surgical procedure. According to Mike Hess of Medtronics, "it's size offers an advantage .. Our design goal was to have more flexibility in where you place the device, and so by having it much shorter it can be placed in more locations in the apex or the septum or the ventricle...There is a way that allows physicians to snare the device and pull it back into the delivery system, and then it will remove the tines from the heart and let them position it somewhere else."

The future of leadless pacemakers

Despite the fact that battery life and power management remain among the most significant challenges facing leadless pacemakers, there seems little doubt they offer hope and promise to streamlining and improving  future cardiac care. As manufacturing continues and issues are identified and addressed, the benefits of these leadless devices are certian to outweigh whatever difficulties they currently present.

Closing thoughts on pacemakers:

The doctor must have put my pacemaker in  wrong. Every time my husband kisses me, the garage door opens up. ~ Minnie Pearl

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