Lasers Med Sci DOI 10.1007/s10103-013-1470-7
BRIEF REPORT
Electromagnetic interference from lasers and intense light sources in the treatment of patients with artificial pacemakers and other implantable cardiac devices Tom Lister & Lindsay Grant & Siu-Man Lee & Richard P. Cole & Anthony Jones & Timothy Taylor & Angela Mayo & Philip A. Wright
Received: 22 July 2013 / Accepted: 13 October 2013 # Springer-Verlag London 2013
Abstract Measurements of the electric and magnetic field strengths surrounding six laser systems and one intense pulsed light system were carried out. The results were compared to exposure limits published by cardiac device manufacturers to assess the risk of electromagnetic interference to implantable cardiac devices such as pacemakers or implantable cardioverter defibrillators. The majority of lasers assessed in this study were found to produce electric and magnetic field strengths below the published exposure limits for cardiac devices. However, the low-frequency electric field and static magnetic field of both the CO2 laser and the ruby laser were found to exceed these limits. Ensuring that a small separation is maintained at all times between the laser unit and any patient with a pacemaker or implantable cardioverter defibrillator appears to be a sensible expedient in avoiding overexposure of an implantable cardiac device to electromagnetic interference. Due to the single-shot fast discharge nature of the intense pulsed light system, changes in electromagnetic field strength were too fast for some of the measuring equipment used in this study to register accurate readings during operation. T. Lister (*) : R. P. Cole : P. A. Wright Wessex Specialist Laser Centre, Salisbury District Hospital NHS Foundation Trust, Salisbury, Wiltshire SP2 8BJ, UK e-mail:
[email protected] L. Grant : S.150 KHz) Static magnetic field (DC)
6,000 V/m 80 A/m=100 μT 100 V/m 5 Gauss=0.5 mT
There appears to be no consensus amongst hospitals and other centres that use medical lasers with regard to their approach for patients with pacemakers or ICDs. This may be because there is very little published work regarding the potential for electromagnetic radiation from medical lasers to interact adversely with these devices [3, 4]. The work presented here aims to assist with the assessment of risk for patients with pacemakers and ICDs so that an informed decision may be made regarding their treatment. The data presented may also be used to inform an assessment of risk for individuals who are likely to work alongside medical lasers.
Method Manufacturers of pacemakers and ICDs publish maximum electromagnetic radiation exposure limits. These are values to which their devices are deemed safe. The exposure limits listed in Table 1 were used to assess the risk of electromagnetic interference from six laser systems and one intense pulsed light system considered in this study (Table 2). All measurements were taken in the same room and were performed both in the standby mode of the devices (armed but not firing) and whilst firing them. Worst case scenarios were considered using the highest available settings on each device and recording the greatest value of each measurement of electric or magnetic field
that could be found at each site. The sites chosen included each side of the laser or intense pulsed light system, the top of the unit, the user interface and the handpiece or beam delivery system. The equipment used to measure the electric and magnetic field strengths is detailed in Table 3.
Results The results of the study are presented in Tables 4 and 5. The measured low- and high-frequency electric field strengths and static magnetic field strengths were lower than those of the cardiac device manufacturer-published exposure limits for each of the lasers assessed in this study. The highest values of electric field strength were measured on the CO2 and neodymium:YAG lasers, and were found on the left-hand side and the front, respectively, of the laser units. Similar values were obtained whether these lasers were on standby or in operation. The CO2 laser was the only laser found to exceed the exposure limit for static magnetic field strength when in ‘standby’ mode, although a value equating to 94 % of this limit was measured on the ruby laser. Both lasers exceeded the exposure limit for static magnetic field strength when in operation. Both lasers also exceeded the low-frequency magnetic field strength limit when in operation, but not in standby mode. The highest values of magnetic field strength measured from the CO2 and the ruby laser units were measured on the left-hand side of the former and the righthand side of the latter. The measured electric and magnetic field strengths from the intense pulsed light system did not exceed those of the published exposure limits.
Discussion The CO2 and ruby lasers exhibited measured values of low frequency and static magnetic field strength which exceeded
Table 2 Summary of the lasers assessed Device
Manufacturer and model name
Energy (J)
Rate (HZ)
Pulse width
Other settings
Alexandrite laser CO2 laser Erbium:YAG laser Intense pulsed light Q-switched neodymium:YAG laser Pulsed dye laser Ruby laser
Cynosure Apogee Coherent Ultrapulse 2000 L Asclepion MCL30 Dermablate iPulse IFL i300 Cynosure Affinity Cynosure Cynergy Aesculap Rubistar
11 125 2.0 0.8 0.7 3.8 1.0 10
1 360 15 Single shot 10 2 1 1
20 ms CW 9 ns Not stated 6 ns 0.5 ms
