The effect of radar on cardiac pacemakers.

Abstract

The susceptibility of 16 noncompetitive cardiac pacemakers to radiation from a powerful radar system was investigated in the laboratory and in the vicinity of its prototype. From comparative in vitro tests in air, fat, water, and saline it was concluded that only tests in fat or air represent the worst case condition after implantation. In air all pacemakers showed signs of interference at pulse power densities between 0.025 mW/cm2 and 62.5 mW/CM2. Three of six implanted pacemakers were triggered or inhibited depending on their mode of operation when tested at a location 1.2 km away from the radar station by the radar beam occurring every 5.5 sec. Because interfering radiation can enter the pacemaker circuitry directly along the electrode, acting as an antenna, metal encapsulation of the pulse generator does not provide sufficient shielding against microwave radiation. However, pacemakers modified by metal encapsulation and a low-pass filter at the electrode remained undistrubed at pulse power densities of greater than 10 W/cm2 when tested under worst case condition in air.

AI evidence extraction

Main findings

In laboratory tests in air, all 16 pacemakers showed signs of interference at pulse power densities between 0.025 mW/cm2 and 62.5 mW/cm2. In field testing 1.2 km from the radar station, 3 of 6 implanted pacemakers were triggered or inhibited depending on mode of operation. Pacemakers modified with metal encapsulation plus a low-pass filter at the electrode reportedly remained undisturbed at pulse power densities greater than 10 W/cm2 under worst-case conditions in air.

Outcomes measured

• pacemaker electromagnetic interference (triggering/inhibition)
• susceptibility under different test media (air, fat, water, saline)
• effect of shielding/modifications (metal encapsulation, low-pass filter)

Limitations

• Frequency of the radar signal not reported in the abstract.
• Exposure characterization is primarily in terms of pulse power density; other metrics (e.g., SAR) not provided.
• Small number of implanted pacemakers tested in the field (6).
• Laboratory conditions (air/fat/water/saline) may not fully represent in vivo implantation conditions.

Suggested hubs

• occupational-exposure (0.35)
  Radar exposure context may relate to occupational/operational environments where radar systems are present.

{
    "study_type": "other",
    "exposure": {
        "band": "microwave",
        "source": "radar",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": null,
    "sample_size": 16,
    "outcomes": [
        "pacemaker electromagnetic interference (triggering/inhibition)",
        "susceptibility under different test media (air, fat, water, saline)",
        "effect of shielding/modifications (metal encapsulation, low-pass filter)"
    ],
    "main_findings": "In laboratory tests in air, all 16 pacemakers showed signs of interference at pulse power densities between 0.025 mW/cm2 and 62.5 mW/cm2. In field testing 1.2 km from the radar station, 3 of 6 implanted pacemakers were triggered or inhibited depending on mode of operation. Pacemakers modified with metal encapsulation plus a low-pass filter at the electrode reportedly remained undisturbed at pulse power densities greater than 10 W/cm2 under worst-case conditions in air.",
    "effect_direction": "harm",
    "limitations": [
        "Frequency of the radar signal not reported in the abstract.",
        "Exposure characterization is primarily in terms of pulse power density; other metrics (e.g., SAR) not provided.",
        "Small number of implanted pacemakers tested in the field (6).",
        "Laboratory conditions (air/fat/water/saline) may not fully represent in vivo implantation conditions."
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "radar",
        "microwave radiation",
        "cardiac pacemaker",
        "electromagnetic interference",
        "pulse power density",
        "shielding",
        "low-pass filter",
        "implantable medical device"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.34999999999999997779553950749686919152736663818359375,
            "reason": "Radar exposure context may relate to occupational/operational environments where radar systems are present."
        }
    ]
}

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