Sasaki A, Takimiya A, Arai T, Song Y, Nakajima S, Muto K, Ibukiyama C
Second Department of Internal Medicine, Tokyo Medical College Hospital, Japan.
Jpn Heart J. 1996 Nov;37(6):879-89. doi: 10.1536/ihj.37.879.
The normal shape of the T wave on the standard 12-lead electrocardiogram (ECG) is asymmetrical. The spatial velocity electrocardiogram (SVECG) is a method of recording the slope of the wave of the ECG and makes it possible to quantify the symmetry of the ECG-T wave. The aim of this study was to diagnose resting effort angina pectoris not detectable by conventional resting ECG using SVECG. We studied SVECG-T waves in effort angina pectoris patients with significant coronary artery stenosis but with normal resting ECG (AP group: 50 subjects) and in an age- and sex-matched normal controls (N group: 30 subjects). The SVECG is depicted as a simple differential wave, and all SVECG-T waves had two peaks. The first peak of the SVECG-T wave was designated as the 'a' wave and the second peak as the 'c' wave. The heights (a wave-mag, c wave-mag) and c wave-mag/a wave-mag ratio (c/a ratio) were calculated. The c/a ratio was significantly decreased in the AP group (1.52 +/- 0.29 vs 1.87 +/- 0.27, p < 0.0001). In cases below the cut off c/a ratio of 1.7, the diagnostic sensitivity, specificity and accuracy for effort angina pectoris were retrospectively evaluated to be 82%, 70% and 78%, respectively. The heights of the 'a' and 'c' waves correspond to the maximum slope of the ascending and descending limbs of the T wave on ECG. The symmetrization of the T wave on ECG is considered to occur when the c/a ratio decreases and approaches 1.0. In conclusion, the c/a ratio of the SVECG-T wave is a useful index to diagnose effort angina pectoris at rest when the resting ECG is normal.
标准12导联心电图（ECG）上T波的正常形态是不对称的。空间速度心电图（SVECG）是一种记录心电图波形斜率的方法，能够对心电图T波的对称性进行量化。本研究的目的是使用SVECG诊断常规静息心电图无法检测到的静息性劳力型心绞痛。我们研究了冠状动脉严重狭窄但静息心电图正常的劳力型心绞痛患者（AP组：50名受试者）以及年龄和性别匹配的正常对照组（N组：30名受试者）的SVECG-T波。SVECG被描绘为一个简单的微分波，所有SVECG-T波都有两个峰值。SVECG-T波的第一个峰值被指定为“a”波，第二个峰值为“c”波。计算了高度（a波幅值、c波幅值）和c波幅值/a波幅值比值（c/a比值）。AP组的c/a比值显著降低（1.52±0.29 vs 1.87±0.27，p<0.0001）。在c/a比值低于1.7的情况下，对劳力型心绞痛的诊断敏感性、特异性和准确性进行回顾性评估，分别为82%、70%和78%。“a”波和“c”波的高度对应于心电图上T波上升支和下降支的最大斜率。当c/a比值降低并接近1.0时，心电图上的T波被认为发生了对称化。总之，当静息心电图正常时，SVECG-T波的c/a比值是诊断静息性劳力型心绞痛的有用指标。
