Over the last two years, since the disclosure of safety issues regarding heart defibrillators, device designers, manufacturers and the regulators have paid closer attention to tracking device performance once they reach the market.
Pacing leads, which connect pacemakers and defibrillators to the heart, have received particular attention from regulators and the media. These leads are intended to deliver an electric shock, when necessary, to stabilise a dangerously erratic heartbeat and as such are a major component to the set-up of a pacemaker or defibrillator.
In Europe over 750,000 leads to pacemakers and defibrillators are implanted into patients every year. Of these leads it is estimated that between 4 and 7 per cent will have to be removed at some point due to damage, infection or the inability to implant new leads due to the presence of existing ones.
Since the commercial introduction of implanted transvenous pacing leads, a wide variety of methods for removing leads have been developed and today the main lead extraction technologies are either laser powered or mechanical.
Evolving Technology and Techniques
In the years following the introduction of chronically implanted transvenous pacing leads, a variety of methods for lead removal were trialled, the simplest being traction, often also called the “drag through” technique. For patients with significant fibrous overgrowth, more aggressive methods had to be developed, including traction applied by weights and elastic bands among other methods.
Nonetheless, complications and difficulties encountered when using traction for lead removal led some investigators to surgical approaches, whereby the heart and great veins were exposed via sternotomy or thoracotomy allowing extraction of a lead via an incision in the atrium or ventricle. In greatly experienced hands, these techniques produced high success rates, but required highly specialized skills gained through years of training. In addition, these techniques were associated with morbidity and the heavy economic impact of open surgery.
The desire for safe and more economically viable extraction techniques led to the development of intravascular counter-pressure and counter-traction – using telescopic sheaths made of polymer and /or steel material, which would slide over the lead body. This technique removes the fibrotic tissue that develops over time and entraps the implanted lead in the veins. As the sheaths are advanced over leads to tear and peel away the encapsulating tissue they achieve a transvenous removal of leads with minimised risk to the patient compared with previous methods.
Today’s Choices
The procedure of lead removal has matured into a definable, teachable art with its own specific tools and techniques. Today’s technology offers two main technology options for surgeons performing extractions – laser and mechanical.
Laser extraction requires a 600 pound (250kg) stand alone unit to interface and power an SLS laser sheath, with each sheath requiring complex calibration before each use. Heavy machinery like this requires support by way of annual maintenance and biomedical inspection as well as the requirement to employ an on-site laser officer. Put simply, it’s bulky, costly both in terms of operation, training and maintenance.
The other option is to use a mechanical approach. This offers benefits in that it requires less surgical finesse and is more intuitive to use than laser powered systems. It is also designed to negotiate chronic, heavily fibrosed and calcified lesions without requiring the ‘brute strength’ of traction.
An enhanced mechanical extraction approach doesn’t have the forward depth of cut like laser extraction sheaths. With this in mind, mechanical extraction historically has had a lower adverse event rate than that experienced using powered sheaths.
Today’s mechanical lead extraction technology has been designed to be as intuitive as possible for the surgeon specialist during a procedure. Lead extraction, which goes a long way in addressing device-related complications, has progressed, particularly as clinicians are more aware of the risks and complications associated with some of the techniques previously used. Mechanical techniques allow for greater success rates, thus making the patient’s journey also a much safer and enjoyable one.
Devices like the EVOLUTION® Mechanical Dilator Sheath Set consists of a flexible rotating sheath that succinctly separates fibrous binding sites from the leads that need extracting. The inner, exotic braided polymer sheath, shielded by an outer telescoping polymer sheath, connects to a handle, or trigger, which rotates it mechanically. It’s this mechanical trigger that allows the user to better feel progress along the lead and through lesions, thereby maximising physician control.
While extraction of chronically implanted leads has been difficult in the past, this seems to have been addressed with mechanical techniques, which have been proven to remove the scar tissue along the vein that is often the primary reason for partial or failed removal of a lead.
An Exciting Evolution
Lead extraction device manufacturers have a responsibility to provide the best, most versatile devices that provide safe, timely and effective treatment for the patient, and are easy-to-use devices for surgeons. Additionally, the need to reduce the financial burden of acquiring the best possible technology on health organisations has to be reduced. It’s exciting to see the benefits that the lead extraction evolution will deliver to health providers, doctors and patients.
