Savard P, Cohen D, Lepeschkin E, Cuffin B N, Madias J E
Circ Res. 1983 Aug;53(2):264-73. doi: 10.1161/01.res.53.2.264.
The direct-current magnetocardiogram not only shows the features usually seen on the electrocardiogram, but also shows the T-Q (baseline) shift due to cardiac injury current. The first direct-current magnetocardiogram measurements of the human heart are presented here. The hypothesis tested is that there is no injury current associated with the S-T shift seen in two electrocardiogram abnormalities: early repolarization, and left bundle branch block. The data from three typical early repolarization subjects and one typical left bundle branch block patient are presented. It is found, in each case, that although there is appreciable S-T shift, there is essentially no baseline shift on the direct-current magnetocardiogram. The absence of baseline shift proves that the S-T shifts in these cases are not "apparent" shifts, caused by a dc injury current which is interrupted during the S-T interval; instead, these are "true" S-T shifts caused by a current flowing only during systole, presumably due to an altered repolarization of the ventricles. It is also found that the direct-current magnetocardiogram does not have routine clinical application because of a practical problem. This is the presence of false baseline shifts due to noncardiac currents, mostly in the gastrointestinal tract, which could be suppressed in only about one-third of the subjects. However, the direct-current magnetocardiogram may be useful as a research tool, for clarifying the cause of the S-T shift in selected subjects.
直流心磁图不仅显示出通常在心电图上可见的特征，还显示出由于心脏损伤电流导致的T-Q（基线）偏移。本文展示了对人体心脏的首次直流心磁图测量。所检验的假设是，在两种心电图异常情况：早期复极和左束支传导阻滞中，不存在与S-T段偏移相关的损伤电流。文中给出了来自三名典型早期复极受试者和一名典型左束支传导阻滞患者的数据。结果发现，在每种情况下，尽管存在明显的S-T段偏移，但直流心磁图上基本没有基线偏移。基线偏移的缺失证明，这些情况下的S-T段偏移并非由在S-T间期中断的直流损伤电流引起的 “表观 ”偏移；相反，这些是仅在收缩期流动的电流引起的 “真正 ”S-T段偏移，推测是由于心室复极改变所致。还发现，由于一个实际问题，直流心磁图没有常规临床应用价值。这个问题是存在由非心脏电流引起的假基线偏移，主要来自胃肠道，在大约三分之一的受试者中这种偏移可以被抑制。然而，直流心磁图作为一种研究工具，对于阐明特定受试者中S-T段偏移的原因可能是有用的。
