Such lead synthesis may be employed to extend the clinical value of a database containing digitized VCG signals. The concept of synthesized leads was first introduced to handle situations in which VCG leads were available but where analysis of the standard 12-lead ECG was desired. Leif Sörnmo, Pablo Laguna, in Bioelectrical Signal Processing in Cardiac and Neurological Applications, 2005 Synthesized leads Also the vector cardiograph is valuable for training purposes to obtain a better understanding of the spatial distribution of the electrical activity of the heart. For special diagnostic problems the vector cardiograph has some distinct advantages (e.g., the vector display of the QRS complex has a much better resolution than the narrow QRS waveform obtained with a standard 12-lead ECG). All doctors the world over are trained according to this tradition (the interpretation of EEG waveforms is another striking example of such a practice). The reason for these relationships may be unknown, and is not of great concern as long as the empirical procedure furnishes precise diagnostic results. From long experience, a clinical information bank has been assembled giving the relation between waveform and diagnosis. However, the problem for vector cardiography is that it is very difficult to throw overboard the long tradition of interpreting curves obtained with the old standardized electrode positions. In principle, the 12-channel registration is reduced to three even so, this 3D data set contains more information than the two-dimensional data set from leads I, II, and III. Three loci curves of the vector tip in the three planes are the basis for the doctor's description. The heart vector is calculated from the recorded lead voltages and projected into the three body planes. Five strategically positioned skin surface electrodes define the heart vector in the transversal plan, and two additional electrodes on the head and left leg take care of the vertical vector component. 3D vector-cardiography according to Frank is based upon the heart vector in a 3D Cartesian diagram. Sverre Grimnes, Ørjan G Martinsen, in Bioimpedance and Bioelectricity Basics (Third Edition), 2015 10.1.4 Vector Cardiographyįigure 10.6 actually shows a two-dimensional vector cardiogram in the frontal plane. Alarms can be activated when a preset threshold of ST segment deviation is surpassed. When such a capability is introduced in the ambulance or in the critical care unit (CCU), the map or compass will update continuously so that the medical staff may closely follow the progression or regression of ST deviations. These methods concentrate on clarifying for the reader the direction and magnitude of ST-J deviation in 3D space. Transforming ST-J measurements from the 12-lead ECG to an ST map and vectorcardiographic measurements to an ST compass as described previously are two ways of displaying ST measurements in a format that is easily taught to and understood by health care personnel. Results are presented in frontal and transverse plane displays, but contrary to the ST map approach, the Andersen display of the “ST compass” contains only arrows that indicate vector direction and vector magnitude in each plane. 8 ST vectors are derived using the ECG-to-VCG transformation approaches mentioned previously. 21 used these vectorcardiographic principles to develop an alternative to the frontal and transverse planar displays described by Nimmermark et al. These are not exact derivations a VCG can derive only an approximation of the 12-lead ECG, and a 12-lead ECG can derive only an approximation of the VCG.Īndersen et al. When the necessary resources for computer-based processing of ECG and VCG signals became available, several studies 18-20 described ways of mathematically deriving VCGs from 12-lead ECGs and vice versa. This ECG imaging method was developed in the mid-20th century and was used for several years as a complement to conventional 12-lead electrocardiography. Only three orthogonal leads, termed X, Y, and Z, are required, with X and Y providing the frontal plane image, X and Z the transverse plane, and Y and Z the sagittal plane. Vectorcardiography (VCG) is a method of developing two-dimensional (2D) images of cardiac electrical activity by displaying the spatial locations of ECG waveforms at each sequential time of their duration. Wagner, in Cardiac Electrophysiology: From Cell to Bedside (Sixth Edition), 2014 2D Imaging Based on Vectorcardiography
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