The state of body surface mapping in Japan

In Japan, body surface mapping (BSM) started in 1974. A huge amount of data has been accumulated regarding basic researches and clinical applications. Recent work on BSM in Japan is summarized here, with the goals of establishing a normal database and diagnostic criteria by using the standardized mapping system. The standard systems used in Japan are the HPM-7100 and the VCM-3000, manufactured by Fukuda-Denshi (Tokyo, Japan) under the supervision of a committee of the Japanese Circulation Society. The number of leads in this system is 87 (59 on front, 28 on back). As a basic study, a computer simulation was carried out on bundle branch block with myocardial infarction (MI), on late potentials in MI, and finally, on the solution of the inverse problem. The database of 606 normal subjects was established regarding age and sex, and a "departure index" (the grade of deviation from normal: the difference between a patient's data the normal mean divided by the normal SD) was proposed. Using the departure index, diagnostic criteria were proposed for the ischemic site, MI site, hypertrophic site of the ventricle, etc. The origin of the ventricular premature contractions was determined by the site of minima and maxima of the QRS and QRST isointegral maps. The site of accessory pathways was determined by the site of minimum less than -0.15 mV on the BSM. For the prediction of patients prone to ventricular tachycardia (VT), several approaches were tried such as multipolar patterns of QRST isointegral maps, Wigner distribution, late potentials with relation to endo- or epicardial delayed potentials, body surface distribution of specific frequency band (25-50 Hz) obtained from fast Fourier transform analysis, and nondipolarity of the QRST isointegral map. To improve the ablation procedure of VT, the author developed a technique to determine the precise location of the VT focus in pace mapping using a correlation matrix between VT and pace maps. To ensure the longevity of the BSM, a reduction of the number of leads has been proposed. The usefulness of BSM has been confirmed and the technique accepted in Japan for daily clinical diagnosis.