The missing waveform information in the orthogonal electrocardiogram (Frank leads). I. Where and how can this missing waveform information be retrieved?

SUMMARY The orthogonal electrocardiogram (Frank leads) is a reasonable compromise between the demands of practicability and diagnostic accuracy. The accuracy has been enhanced by the use of computerized multivariate statistical procedures. The work of the last two or three decades, however, has shown that these leads account for only part of the total available surface information. In this paper, the missing waveform information with respect to the Frank leads is quantitatively and systematically determined and a method of retrieval is worked out. The essence of this method rests on the empirical evidence obtained by testing each of the 126 surface electrocardiograms for the XYZ content. The results are analyzed by a least squares, best fit procedure. The poorly fitted curves are considered as additional waveform sources. The number and the sites of the additional information are determined on a test group of 207 patients. The "total" surface waveform information is found to be represented by nine surface leads. This set of waveforms is then tested on a control group consisting of 205 patients. An average re-synthesis coefficient of 96% is reached. No further resynthesis is looked for because of the estimated noise level. Although the waveforms recorded at these sites represent the minimum number of unique building blocks capable of synthesizing any waveform on the body surface, they cannot predict the surface potential distribution at all surface points. This information is "total" as far as statistical procedures performing discriminant analysis on time-functions-are concerned. This "total" wave-form information consists of a set of electrocardiograms recorded in each individual at nine well-defined anatomical locations. Additional Indexing Words: Multivariate analysis Curve-fitting Resynthesis surface maps Multiple surface leads Waveform information T HE RECORDING on the thoracic surface of the electrical activity of the heart remains one of the most useful tools in the diagnosis of heart conditions. The advent of powerful digital computers has enabled us to handle large numbers of ECG measurements and to submit them to complex statistical procedures. Early comparisons be-984 tween the conventional 12 lead ECG and the corrected orthogonal lead systems (e.g., the Frank leads) have shown that these systems were almost interchangeable as far as the clinical information provided is concerned.' 2, 8Subsequently, large-scale studies based on sophisticated statistical procedures were conducted by Pipberger et al. using Frank's XYZ leads.4 5 Considerable improvement in diagnostic accuracy was reported in the Frank lead system when compared with either descriptive …