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Monday, September 27, 2010

Technology Assessment for Electrocautery used in Conjunction with Pacemakers

Recommendation:
By utilizing emerging technology regarding electrocautery devices, and making modifications to that technology, an electrocautery device can be constructed that is safe for use on patients with pacemakers.

Introduction:
This report examines the both the existing technology as well as emerging technology regarding use of electrocauteries on patients with pacemakers. By comparing the technologies, recommendations can be made for the construction and implementation of an improved electrocautery safe to use on patients with pacemakers.
There is a medical need involving the inability to effectively use electrocautery devices on patients with pacemakers. Over three million people worldwide have pacemakers implanted into their body to regulate the rhythm of their heart [1]. The pacemaker produces a periodic electrical signal to stimulate the heart to keep its rhythm constant [2]. Because of the sensitivity of the pacemaker, it is susceptible to electromagnetic interference [2]. Electrocautery devices act by using high frequency electrical current through an electrode to cut through tissue, or seal blood vessels [3]. The issue at hand is that the signals from the electrocautery device can interfere with the pacemaker, causing problems with the patient such as: skipped beats, asystole, drained battery, pacemaker reprogramming, and fibrillation [3, 4, 5]. Thus, if a device were to be constructed that allows electrocautery without restriction on patients with pacemakers, many people could benefit.

Existing Technologies:
There are currently several existing ways to deal with electrosurgical devices when used on patients with pacemakers. These ways include only using electrocautery with bipolar signals [6, 7], not using electrocautery devices within a close proximity to the pacemaker location (about 15 cm) [6, 8], only using the device for short bursts, and not an extended period of time [6, 7], placing a magnet over the pacemaker to reset it and keep it in asynchronous mode [7, 8], and using an ultrasonic scalpel instead of a cautery for patients with pacemakers [6, 9]. A patent search also reveals a 1977 cautery protection circuit that was designed to be connected to the output of the pacemaker, absorbing induced electrical signals from electrocautery devices and protecting the pacemaker [10]. The alternative to any of the above ways of dealing with electrocauteries and pacemakers would be to not use electrocautery devices at all on patients implanted with pacemakers.

Emerging Technologies:
There are also two emerging new technologies that will be considered in this report, and compared to the existing technologies.
The first of these is described in a patent application as a device that is used in conjunction with an electrocautery device to protect tissue outside of the target area [11]. This device includes a stent implanted in nearby tissue, supplied with electrical power, which detects electrical fields generated by the cautery to the surrounding tissue. This stent then produces a signal that feeds back to the cautery probe, and regulates the electrical power supplied to the electrocautery, preventing the signal from being strong enough to get past the stent into surrounding tissue [11]. This is described in the flowchart Figure 1, taken from the patent application.




Figure 1: Flowchart of the operation of the stent and electrocautery probe [11].

The second new emerging technology that can be applied as a possible solution to this medical need is described in a 2004 patent. This device is a cardiac rhythm management system that includes a mode specific to electrosurgery [12]. This device is essentially a pacemaker that includes specific programming to counteract the effects of the electromagnetic interference caused by electrocauteries. This program can be activated from outside the body prior to surgery. When the program is activated, parameters such as the pacing of the heart, the AV delay, pulse, and amplitudes can all be controlled [12]. The program also filters out any electromagnetic interference that may be caused by the electrocautery device, making the device immune to electrosurgical interference [12]. A flow chart describing the electrosurgical mode is below, copied from the patent.

Figure 2: Flow chart illustrating electrosurgery mode of the pacemaker program [12].

Decision Criteria:
To best satisfy the medical need described above, the new solution should meet certain criteria. One criterion is that the solution should also not affect the function or operation of the pacemaker. The solution should work on all persons with pacemakers. Another criterion is that the solution should not be prohibitively expensive. The solution should also allow electrocautery in close proximity to the pacemaker without disrupting its function. Finally, the solution should allow electrocautery for an extended period of time on a patient. All of these decision criteria are shortcomings of the current solutions to this medical need, so if the alternatives satisfy these needs they are better equipped for this application.

Analysis of Alternatives:
Based on the above decision criteria, the alternative solutions can be evaluated as follows:
Electric field detecting stent:
Pros:
• Prevents electrical interference from traveling outside the target area, preventing pacemaker interference
• Can be used without resetting the pacemaker or changing pacemaker settings
• Circuitry could be simplified to be made inexpensive
• Would allow the cautery to be used within close proximity of the pacemaker, as long as the stent was there to prevent electrical signals from traveling
• The device could be used for an extended period of time, as long as the stent remains in place
Cons:
• The stent may be bulky and get in the way during surgery
• The device was not designed for use with pacemakers, so modification may be necessary
• If the stent were to fall out of place, signals from the cautery could travel to the pacemaker
• Increased complexity during procedures makes more room for error

Pacemaker with electrosurgery programming:
Pros:
• Prevents electromagnetic interference from disrupting the pacemaker function
• Allows electrocautery to be performed on any person with the programming in their pacemaker
• Would allow electrocautery for an extended period of time
• Would allow the cautery to be used within close proximity to the pacemaker
Cons:
• Would require either a new pacemaker, or a pacemaker modification, so it would not be ready to go on any person with a pacemaker
• Requires modification to the pacemaker program prior to surgery
• Expensive to replace a pacemaker with a modified version

Based on the analyses above, the electrical field detecting stent used in conjunction with the electrocautery satisfies the most criteria, and thus shows itself to be a good candidate to meet this medical need. The pacemaker with electrosurgery programming could meet future needs, but will not work on current pacemakers, and thus it is not as fit to satisfy this current need.

Conclusion:
The electrical field detecting stent combined with the electrocautery looks promising for allowing electrocauteries to be used on patients with pacemakers. However, further analysis and possible modification must be performed to test this device and its compatibility with pacemakers. Overall, this device shows vast improvements over the current technology, and could prove to be an important step forward in electrosurgery.

Actions Required
The cautery-stent apparatus was not designed specifically for use with pacemakers. For this reason, it must be vigorously tested to see if it is sufficient to block electrical signals from reaching and interfering with the pacemaker. Modification to the design of the device may also be necessary to improve the blocking of electromagnetic interference. Overall, it is recommended that this device be analyzed further as the most reasonable solution to this medical need.


References

[2]: DiFrancesco, D. Pacemaker Mechanisms in Cardiac Tissue. Annual Review of Physiology. 55: 455-472, 1993.

[5]: El-Gamal, H. M., R. G. Dufresne, and K. Saddler. Electrosurgery, pacemakers and ICDs: a survey of precautions and complications experienced by cutaneous surgeons. Dermatologic Surgery. 4: 385-390, 2001.

[9]: Epstein, Michael, J. E. Mayer, and B. W. Duncan. Use of an Ultrasonic Scalpel as an Alternative to Electrocautery in Patients With Pacemakers . The Annals of Thoracic Surgery. 65: 1802-1804, 1998.

[12]: Gilkerson, James O., et al. Cardiac Rhythm management System With Electrosurgical Mode. Cardiac Pacemakers, Inc., assignee. Patent 6,678,560. 13 Jan. 2004.

[11]: Kefer, John. Apparatus and method for protecting nontarget tissue of a patient during electrocautery surgery. The Cleveland Clinic Foundation, assignee. Patent Application: 11/502,700. 15 Feb. 2007.

[4]: Mangar, D., G M Atlas, and P B Kane. Electrocautery-induced pacemaker malfunction during surgery. Canadian Journal of Anesthesiology. 38: 616-618, 1991.

[6]: Okan, Erdogan. Electromagnetic Interference on Pacemakers. Indian Pacing Electrophysiology. 2: 74-78, 2002.

[8]: Petersen BT, Hussain N, Marine JE, Trohman RG, Carpenter S, Chuttani R, Croffie J, Disario J, Chotiprasidhi P, Liu J, Somogyi L, Technology Assessment Committee. Endoscopy in patients with implanted electronic devices. Gastrointest Endosc. 65(4):561-8, 2007.

[1]: Rozner, Marc A. The patient with a cardiac pacemaker or implanted defibrillator and management during anaesthesia. Current Opinion in Anaesthesiology. 20: 261-268, 2007.

[10]: Thompson, David L. Cautery protection circuit for a heart pacemaker. Medtronic, Inc., assignee. Patent 4,038,990. 12 Aug. 1977.

[3]: Tobias, Joseph D. Issues in Pediatric and Adult Outpatient Care. Audio-Digest Anesthesiology. 49.13: 1-5, 2007.

[7]: Wilson, Shurea, Steven Neustein, and Jorge Camunas. Rapid Ventricular Pacing due to Electrocautery: A Case Report and Review. The Mount Sinai Journal of Medicine. 73: 880-883, 2006.

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