Intrinsic Properties of Uncorrected and Highly Corrected Leads

Abstract

An improved experimental method was employed to determine the dipolar and nondipolar sensing characteristics of various lead connections in an electrically homogeneous human torso model. The intrinsic properties of the cube and tetrahedron leads were compared with those of an ideal vectorcardiographic system. The conventional precordial leads, V 1 through V 6 , were analyzed anatomically and electrically with respect to corresponding ideal unipolar leads, with similar treatment of the augmented unipolar extremity leads. Finally, methods of constructing highly corrected anteroposterior and transverse vectorcardiographic leads were developed. The study of the cube and tetrahedron systems confirms in strict quantitative terms that they are not suited for accurate vectorcardiographic registration. The defects of existing Z leads are greatly minimized by the use of a grid system in which the electrodes of the anteriorly applied array are individually weighted. An X lead of similar quality was achieved by a transverse grid in which the left-sided electrodes, including the arm connection, were also weighted individually. These two corrected leads, together with a previously described vertical connection, form a vectorcardiographic system whose inherent properties approach those of an ideal system. Analysis of the precordial unipolar leads demonstrates that they are in fact proximity electrodes and some of them are approximately unipolar in their behavior. Leads aV R and aV L are classed as semi-remote, and lead aV F as remote. Thoracic structures are not electrically homogeneous or isotropic. Nevertheless, lacking definitive information on the manner in which these factors influence the electrocardiographic transfer properties of the body, the study of electrolyte-filled models remains a valid experimental basis for lead analysis and synthesis.