An inhomogeneous anisotropic model of the human torso for electrocardiographic studies

TLDR: A twice-life-size analogue model which mimics the resistive properties of heart muscle, heart-blood cavities, great vessels, lung, liver, fat, anisotropic skeletal muscle, ribs and spine is described.

Abstract: A method which can account for body tissue resistivity and anisotropy in studies of the heart-lead relation has long been desired. This paper describes a twice-life-size analogue model which mimics the resistive properties of heart muscle, heart-blood cavities, great vessels, lung, liver, fat, anisotropic skeletal muscle, ribs and spine. Although designed for electrocardiographic studies, its use for impedance plethysmographic investigation is equally suitable. The exterior boundary can be employed with or without the internal analogue structure to emphasize effects specifically associated with the inhomogeneities and anisotropies of the thoracic tissues. The technique for model construction combines two established methods of field investigation; the electrolytic tank and the resistive network. A matrix of interlocking plastic rods immersed in the conducting fluid constrains the current flow so as to create the desired resistor network within the electrolytic tank. The electrical instrumentation, which consists of a pulsed bridge with a storage-oscilloscope null detector, has several advantages over conventional measurement techniques and is also described in the paper.