In this feature interview, Dr. Cooper discusses his use of Medtronic’s PEAK® PlasmaBlade, which offers the precision of a scalpel and the bleeding control of traditional electrosurgery without the extensive collateral tissue damage. Dr. Cooper is the Director of the Cardiac Electrophysiology Program at Temple University Hospital.
Tell us about the PEAK PlasmaBlade. How is it different from traditional electrosurgical instruments?
Electrocautery is used during pacemaker and defibrillator implantations as well as during procedures to replace the generator or to add or replace leads in an existing pacemaker or ICD system. The electrocautery unit is used for tissue dissection as well as hemostasis.
With standard unipolar electrocautery, a great amount of heat is generated where the metal blade of the handheld probe comes into contact with tissue, producing temperatures in the 250-350°C range. While this may be desirable from a blood coagulation or tissue-cutting standpoint, there may be unintended harmful effects if there are indwelling leads in place. The hot local temperature generated during cautery use may exceed the melting point of a lead’s outer insulation, resulting in permanent physical lead damage with impairment or complete loss of electrical function. Sometimes leads with insulation damage can be repaired, but frequently the lead will need to be replaced, which may completely change the nature and risk of the procedure being performed. In contrast to standard electrocautery, the PEAK PlasmaBlade system uses pulsed radiofrequency energy and also incorporates a thermal protective shield on the blade tip. The combination of these two features results in a significantly lower temperature at the tip of the PlasmaBlade, typically in the 40-100°C range, which tends to be below the melting temperature for lead insulation materials. Use of the PlasmaBlade therefore imparts a lower risk for damaging indwelling leads when compared to standard unipolar electrocautery.
The two most common insulating materials on pacemaker and ICD leads are silicone rubber and polyurethane. Silicone is very heat resistant and is much less likely to sustain thermal injury from either type of cautery. Polyurethane insulation, however, is more heat sensitive, with a melting temperature in the 185-225°C range, and that temperature is almost always exceeded by standard cautery, but usually not with the PlasmaBlade.
What does the PEAK PlasmaBlade technology consist of?
With each type of cautery system, there is a radiofrequency generator unit that is plugged into a standard wall outlet, and it is usually mounted on a wheeled stand to facilitate positioning in the electrophysiology laboratory. For unipolar cautery, a large adherent grounding pad is affixed to the patient’s skin, usually on the thigh or flank, and an electrical cord from this pad is plugged into the RF generator. The cautery delivery tool used by the electrophysiologist is a disposable pen-sized device that also plugs into the RF generator. There are typically two buttons on the tool, which allow the operator to deliver different types of energy through the electrode tip. The “cut” function is used for tissue dissection, with a higher power density delivered through the electrode. The “coagulation” function uses a lower average power to create thermal coagulum when tissue surface hemostasis is desired. With the PEAK PlasmaBlade, both cut and coagulation modes operate at lower temperatures than with standard cautery, but in particular, the cut feature with the PlasmaBlade generates significantly lower temperatures than other energy delivery. To minimize the risk of thermal injury to indwelling leads, the PlasmaBlade “cut” mode should be used when dissecting each lead free from pocket capsule tissue, and electrocautery energy in a device pocket should always be delivered for as short a duration as possible when working near leads.
So can the device also be used for the skin incision?
Yes, because of the low operating temperature at the tip of the PlasmaBlade in its “cut” mode, this tool can be used to make a skin incision with similar wound healing to an incision made by a surgical scalpel. Tissue histology of healing incisions made with the PlasmaBlade versus standard electrocautery show a clean blade-like appearance with the former, but much more thermal injury and local inflammation with the latter. That said, in most device cases, indwelling leads are not that close to the skin surface and a surgical scalpel can safely and effectively be used to make the skin incision.
In which of your cases do you use the PEAK PlasmaBlade? What are some of the biggest areas of risk when performing generator changes?
I tend to use the PlasmaBlade whenever I do a device procedure where there are leads in place that I wish to preserve. For new device implants, I tend to use a standard electrocautery system, as the majority of cautery use occurs prior to the introduction of leads to the pocket environment when there is no risk for lead insulation injury. Similarly, if I am performing a lead extraction procedure for a device infection, then all existing leads will be fully removed and there is minimal consequence if an indwelling lead were inadvertently damaged prior to its extraction. In contrast, during pacemaker or ICD generator changes and during device “upgrades” or procedures where supplemental leads are being implanted, I tend to use the PlasmaBlade in order to reduce the risk of damaging functional indwelling leads. If a functioning lead is accidentally injured during such a procedure, a new replacement lead might need to be implanted as a replacement. Especially if there is a stenosis or occlusion of the subclavian vein, the spur-of-the-moment need to implant additional leads can completely change the nature, risk, duration, and expense of the device procedure. In some situations, the operator may not even be able to salvage the device system and a second procedure may be needed, particularly if lead extraction techniques are required to add an additional lead and/or remove the one that was rendered non-functional. It is important to educate patients as part of the informed consent process of the possible risk of lead injury and the potential need for repair or replacement of indwelling leads, even during a “routine” generator change. From a health care cost perspective, there is a significant increase in expense associated with the more complex procedure and the potential increased hospital stay when there is an unanticipated need to replace leads that were injured by electrocautery use. Regardless of whether the PlasmaBlade or standard cautery is used, great care and meticulous attention to detail must be exercised when dissection is performed in a device pocket in order to minimize the risk of lead injury.
How do you determine if you have damaged a lead? How easy is it to repair or replace damaged leads with the PlasmaBlade?
A lead can be damaged either physically (e.g., a physical cut or abrasion made in the insulation with the tools being used, with silicone being more prone to abrasion than polyurethane) or thermally (e.g., melting of the insulation, with polyurethane being much more likely to melt than silicone). If the lead is closely inspected, the insulation defect can usually be seen, with the underlying metal or inner insulation layer being directly visible through the cut or hole. The lead should also be palpated, as the irregular edge of a small defect can frequently be felt if the lead is slid between the forefinger and thumb. Lastly, if tissue fluid or blood is seen under the outer insulation, this is a sign that there is likely a new breach in the outer insulation layer. Lead repair kits are generally intended for use on silicone insulation. A layer of silicone gel adhesive is spread over the defect and allowed to cure for 10 to 15 minutes. A silicone sleeve may additionally be placed on the lead, spanning the covered defect, with closely spaced suture ties used to secure the sleeve to the lead. More silicone gel adhesive can then be used to seal the ends and longitudinal seam of this sleeve. Because the silicone adhesive bonds to silicone insulation but not well to polyurethane, this repair technique is not as reliable for repairing polyurethane-covered leads. In either instance, if lead performance is critical to a patient’s well being (e.g., a right ventricular lead in a pacemaker-dependent patient), then I would not be satisfied with repairing that lead and using it chronically in a patient whose life depends on its proper function.
What are the clinical benefits that the PEAK PlasmaBlade offers to the physician?
We discussed earlier whether the PEAK PlasmaBlade can be used to make a skin incision, and certainly it can. Typically, however, most operators who implant devices will use a standard surgical scalpel to make the skin incision, which is my practice as well. There may be some circumstances where there is minimal subcutaneous adipose tissue and the indwelling leads may lie just under the skin surface, posing a risk for inadvertently cutting into the leads with a surgical blade. In these instances, the PEAK PlasmaBlade would provide a way to create a skin incision with less risk for injuring the nearby leads. But the main benefit of using the PlasmaBlade during device procedures is the lower risk of suddenly making a procedure more complex by inadvertently damaging the insulation of a functioning lead during a generator change or device “upgrade” procedure. If there is the unanticipated need to add a new lead, the procedure becomes longer, more expensive, and additional risks are introduced. Moreover, the patient may not have been made aware of the possibility of a new lead implantation, which may have implications for the duration of hospital stay and the need to impose post-operative arm range of motion restrictions for several weeks. Lastly, if there is a subclavian vein occlusion, then there may be a need for either an additional procedure involving lead extraction techniques, or a contralateral lead or device system implantation. The best way to avoid all these consequences is to minimize the risk of inadvertent lead injury in the first place.
What are the benefits to the patient as well?
At some point, most patients with pacemakers or defibrillators will need at least one generator change or potentially some type of alteration to their implanted device system. In each instance, that procedure will be safer for the patient if dissection in the pocket environment is done in a manner to reduce the risk of injury to the existing functioning leads. If a lead were damaged mechanically or by electrocautery during a generator change and a satisfactory lead repair could not be performed, a new lead would need to be implanted. Additional risks associated with new lead implantation would then be introduced, including the small risks of pneumothorax, lead dislodgement, pericardial tamponade, and arm swelling from venous thrombosis, stenosis or occlusion. The patient would likely be admitted overnight to the hospital rather than being discharged on the same day, and there would be additional arm movement restrictions imposed for several weeks to permit the new lead to heal in place. Both patients and physicians see benefits when procedure-related complications are minimized.
Is there anything else you’d like to add?
There is increasing attention these days to the concept of lead management. The weakest link in any pacemaker or defibrillator system is the lead component, and any practice that improves the durability of leads and reduces the likelihood for lead failure should be considered and adopted. Because of the increased expense and patient risk associated with having to extract and/or replace damaged leads, all device implanters should make use of all available techniques that are known to improve outcomes both at the time of initial implantation, as well as at each generator change.
One additional factor to consider is that the presence of an abandoned lead precludes that patient from having an MRI performed. Capped leads will generate greater heat in the MRI environment compared to leads that are attached to a pulse generator, posing a greater risk of myocardial thermal injury at the electrode tip. For this reason, even at centers where MRIs are performed on a variety of device patients, the presence of an abandoned/capped lead is seen as an absolute contraindication for performing MRI imaging on any part of the body. Because most indwelling leads that sustain inadvertent injury have been in place for years, they typically can only be removed from the body with lead extraction techniques that are not at the disposal of most implanting physicians. Even if the operator does perform lead extractions, there are anticipatory safety steps that are taken before a planned extraction, such as general anesthesia, a full chest sterile field prep, femoral vein and artery sheath placement, arranging cardiac surgical backup, and obtaining cross-matched blood for the patient, none of which will have been arranged before a generator change. Converting a simple device procedure to a lead extraction procedure is therefore typically inadvisable, which leaves the options of either abandoning the damaged lead or bringing the patient back to the EP lab for a second procedure on another day.
In summary, use of the PEAK PlasmaBlade system, with its lower operating temperature and lower risk for thermal injury to indwelling leads, may play a role in reducing the risk to existing leads when device upgrades or generator changes are performed. A lower lead complication rate will directly result in lower overall costs to the health care system and improved safety for patients.
Disclosures: Outside the submitted work, Dr. Cooper reports consultancy with Spectranetics (for product design), and honoraria from Boston Scientific (for educational lecture).