Comparison of cardiac-induced endogenous fields and power frequency induced exogenous fields in an anatomical model of the human body.

Physics in medicine and biology · 1998 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 5380

Study snapshot

PublicationPhysics in medicine and biology · 1998

Study typeengineering

Reported directionUnclear

Evidence ratingInsufficient

Abstract

Time-domain potentials measured at 64 points on the surface of a large canine heart, considered comparable with those of a human heart, were used to calculate the electric fields and current densities within various organs of the human body. A heterogeneous volume conductor model of an adult male with a resolution of approximately 6 mm3 and 30 segmented tissue types was used along with the admittance method and successive over-relaxation to calculate the voltage distribution throughout the torso and head as a function of time. From this time-domain voltage description, values of [E(t)] and [J(t)] were obtained, allowing for maximum values to be found within the given tissues of interest. Frequency analysis was then used to solve for [E(f)] and [J(f)] in the various organs, so that average, minimum and maximum values within specific bandwidths (0-40, 40-70 and 70-100 Hz) could be analysed. A comparison was made between the computed results and measured data from both EKG waveforms and isopotential surface maps for validation, with good agreement in both amplitude and shape between the computed and measured results. These computed endogenous fields were then compared with exogenous fields induced in the body from a 60 Hz high-voltage power line and a 60 Hz uniform magnetic field of 1 mT directed from the front to the back of the body. The high-voltage power line EMFs and 1 mT magnetic field were used as 'bench' marks for comparison with several safety guidelines for power frequency (50/60 Hz) EMF exposures. The endogenous electric fields and current densities in most of the tissues (except for organs in close proximity to the heart, for example lungs, liver, etc) in the frequency band 40-70 Hz were found to be considerably smaller, between 5% and 10%, than those induced in the human body by the electric and magnetic fields generated by the 60 Hz sources described above.

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AI evidence extraction

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Study typeengineering

Effect directionunclear

PopulationAnatomical model of an adult male human body; cardiac potentials measured on a large canine heart (considered comparable with those of a human heart)

Sample sizeNot supplied

ExposureELF

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

A heterogeneous anatomical volume conductor model was used to compute endogenous electric fields and current densities from cardiac potentials, with computed results showing good agreement with measured EKG waveforms and isopotential surface maps. Endogenous electric fields and current densities in most tissues (except organs close to the heart such as lungs and liver) in the 40–70 Hz band were considerably smaller (about 5–10%) than fields induced by a 60 Hz high-voltage power line and by a 60 Hz uniform 1 mT magnetic field.

Outcomes measured

Computed endogenous electric fields E(t)/E(f) in organs
Computed endogenous current densities J(t)/J(f) in organs
Comparison of endogenous fields vs exogenous fields induced by 60 Hz sources
Validation against measured EKG waveforms and isopotential surface maps

Limitations

Model-based study using a canine heart dataset considered comparable to human heart potentials
Results depend on assumptions/parameters of the anatomical volume conductor model and computational methods
Exogenous exposure scenarios limited to a 60 Hz high-voltage power line and a 60 Hz uniform 1 mT magnetic field

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": "ELF",
    "source": "high-voltage power line; uniform magnetic field",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Anatomical model of an adult male human body; cardiac potentials measured on a large canine heart (considered comparable with those of a human heart)",
  "sample_size": null,
  "outcomes": [
    "Computed endogenous electric fields E(t)/E(f) in organs",
    "Computed endogenous current densities J(t)/J(f) in organs",
    "Comparison of endogenous fields vs exogenous fields induced by 60 Hz sources",
    "Validation against measured EKG waveforms and isopotential surface maps"
  ],
  "main_findings": "A heterogeneous anatomical volume conductor model was used to compute endogenous electric fields and current densities from cardiac potentials, with computed results showing good agreement with measured EKG waveforms and isopotential surface maps. Endogenous electric fields and current densities in most tissues (except organs close to the heart such as lungs and liver) in the 40–70 Hz band were considerably smaller (about 5–10%) than fields induced by a 60 Hz high-voltage power line and by a 60 Hz uniform 1 mT magnetic field.",
  "effect_direction": "unclear",
  "limitations": [
    "Model-based study using a canine heart dataset considered comparable to human heart potentials",
    "Results depend on assumptions/parameters of the anatomical volume conductor model and computational methods",
    "Exogenous exposure scenarios limited to a 60 Hz high-voltage power line and a 60 Hz uniform 1 mT magnetic field"
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "endogenous electric fields",
    "cardiac-induced fields",
    "current density",
    "volume conductor model",
    "admittance method",
    "successive over-relaxation",
    "EKG validation",
    "power frequency",
    "60 Hz",
    "high-voltage power line",
    "uniform magnetic field",
    "1 mT",
    "safety guidelines"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.42,
      "reason": "Compares induced fields from a 60 Hz high-voltage power line and a 1 mT 60 Hz magnetic field, relevant to power-frequency exposure contexts."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1088/0031-9155/43/10/027
PubMed: 9814536

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