SVEC III誘導法によるorthogonalベクトル心電圖の臨床的研究(第1報) : 正常スカラー心電圖

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The SVEC III lead system propoesd by Schmitt in 1955 has been shown to yield orthogonal components of the equivalent heart dipole with an accuracy of relative transfer impedances of ±5.8 per cent in angle and ±10.2 per cent in length, for a group of 9 source-dipole positions located at the corners and center of the cube having a volume of 8 cubic inches which surrounds the heart center of a torso model. By making use of this corrected lead system. scalar recordings of its component leads, X, Y, and Z were obtained for 303 healthy adult male subjects who were selected by proper sampling and strict screening tests. The material consisted of 182 aged American Caucasians (mean age : 58.1,range : 54 to 64), and 121 young Japanese (mean age : 24.2,range : 18 to 29).The range of normal variation of the deflections in each lead was determined as well as the mean spatial QRS and T vectors constructed from the X, Y, Z leads in order to examine the characteristics of performance of this lead system with relation to the human body as a basis for studies on pathologic series. Further, analyses of the effects of the differences in age, race and body build are briefly presented.Amplitudes of the QRS and T of Leads X, Y and Z, and the distribution of positive, diphasic and negative deflections in each lead were statistically observed. The QRS of Lead X was predominantly positive (91.8 per cent in the younger group); that of Lead Y, predominantly negative (93.5 per cent) and that of Lead Z showing an RS pattern with the S usually being greater than the R. The lower limit of the R/S ratio in Lead X was 1.3. The R/S ratio of Lead Z revealed a correlation with the azimuthal angle of mean spatial QRS vector (QRS-H°) which is perpendicular to the position of the QRS transitional zone in the conventional precordial leads, indicating that the R/S ratio tends to be smaller in the clockwise rotation of the QRS transition.The T wave of Lead X was always positive; that of Lead Y, always negative; and that of Lead Z was almost always positive-rarely plus-minus diphasic, but if a diphasic wave occurred it always showed a minimal negative comonent.The frontal QRS axis calculated from Leads X and Y showed a correlation with the Einthoven QRS axis (r : 0.678), although the normal range of the former item (mean : 49.8,S.D. : ±18.2) was narrower and more horizontal than that of the latter (mean : 64.3,S.D. : ±21.2).Mean spatial QRS and T vectors were constructed from the component leads X, Y and Z as a most convenient method of vector analysis without recording the VCG. The means, standard deviations and expected normal range limits for each vectorial item are presented.The elevational angle QRS-V° showed a correlation with the Einthoven QRS axis and its normal range was narromer than that of the latter, as was the SVSC III frontal QRS axis. The arc of the azimuthal angle QRS-H° was large, ranging from +43° to -77°. The mean of T-H° in the older group was 51.4°, while that in the younger group was 40.1°, indicating that the T vector points more anteriorly in the aged than in the young.The elevational and azimuthal angles in both the QRS and T vector were independent of each other.The mean spatial QRS magnitude was somewhat greater, with a statistical significance, in the younger Japanese (mean : 1.15 mV) than in the aged Americans (mean : 1.03 mV). It is a notable finding that the variation of this item in different age and positional groups was less than in the other items.The mean spatial T magnitude was the one that showed the highest age trend and racial difference; the mean of the younger Japanese being 0.53 mV, while that of the aged Americans was 0.35 mV.The results on human subjects indicate that the SVEC III lead system proved to be corrected more or less in length and angle, as the range of normal variation of the SVEC III mean spatial vectors was narrower in some of the items than in the ones of the mean spatial vectors derived from conventional leads. The ranges, however, are still too wide to attribute the variations solely to the heart itself. It cannot be denied entirely that these variations possibly are due partly to the contribution of some uncorrected factors and/or shortcomings in the method of analysis. On the other hand, the results suggest that comparison between the groups with different biological characteristics may be an excellent method to test the performance of any of the theoretically-derived corrected lead systems. The adjustable elastic vest employed in this study permits quick and convenient placement of the ten electrodes on the chest in a single motion, as all the electrodes are attached to the vest. The use of the scalar recordings of X, Y and Z leads for clinical routine as well as for mass-survey purposes seems very promising and it yields information comparable to or in a sense rather superior to the conventional 12 leads.
社団法人日本循環器学会の論文
1959-08-20

SVEC III誘導法によるorthogonalベクトル心電圖の臨床的研究(第1報) : 正常スカラー心電圖

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