Ino-Oka E, Takahashi T, Sagawa K, Inooka H
Ohizumi Memorial Hospital, Miyagi Preferecture, Japan.
Clin Cardiol. 1996 Jun;19(6):467-72. doi: 10.1002/clc.4960190605.
It has been suggested that episodes of silent myocardial ischemia (SMI) might influence the prognosis of patients with ischemic heart disease, as its consequences are similar to those of myocardial ischemia accompanied by pain. Ambulatory electrocardiogram (ECG) is generally employed in diagnosis as well as in evaluation of clinical efficacy in patients with SMI, but problems related to its application remain because of the difficulty in differentiating between nonischemic and ischemic ST-segment depressions and because of the absence of data concerning body movement.
We developed a method for simultaneously recording onto magnetic tape both the ECG chart and pedometer count, as well as a program which enables semi-automatic analysis of the heart rate (HR)-ST relationship. This new method was employed to record ambulatory ECG along with pedometer count for a total of 70 patients, consisting of 53 with coronary heart disease who were shown to have ischemic heart disease, and 17 with various heart diseases in whom coronary angiography revealed no coronary stenosis. The HR-ST relationship was assessed for periods during which steps were recorded by the pedometer, that is, when patients were confirmed to have been under exertion effort. Patients demonstrating the following findings were diagnosed as true positive for SMI: the ST segment level did not decline until HR increased to a certain threshold, and the rate of change in the ST-segment level noted thereafter was -0.025 mm/beats/min or lower; or the ST-segment depression induced by effort continued even after discontinuation of exercise, after which time HR began to decrease, and the HR-ST loop consequently described a counterclockwise rotation. Evaluation of the HR-ST relationship based on these criteria revealed excellent results, as demonstrated by values of 79.2% for sensitivity and 94% for specificity.
Our newly developed method of assessment of the HR-ST relationship via analysis of simultaneous data from an ambulatory ECG and a pedometer appears to be time saving, highly objective, and useful with regard to the diagnosis of SMI and evaluation of the therapeutic effect of drugs in patients with ischemic heart disease.
有研究表明，无症状心肌缺血（SMI）发作可能会影响缺血性心脏病患者的预后，因为其后果与伴有疼痛的心肌缺血相似。动态心电图（ECG）通常用于SMI患者的诊断以及临床疗效评估，但由于难以区分非缺血性和缺血性ST段压低，且缺乏有关身体活动的数据，其应用仍存在问题。
我们开发了一种将心电图图表和计步器计数同时记录到磁带上的方法，以及一个能够对心率（HR）-ST关系进行半自动分析的程序。采用这种新方法对70例患者进行动态心电图记录并同时记录计步器计数，其中53例冠心病患者经证实患有缺血性心脏病，17例患有各种心脏病，冠状动脉造影显示无冠状动脉狭窄。在计步器记录到步数的时间段内，即确认患者处于运动状态时，评估HR-ST关系。出现以下情况的患者被诊断为SMI真阳性：ST段水平在HR升高到一定阈值之前未下降，此后记录到的ST段水平变化率为-0.025 mm/次心跳/分钟或更低；或者运动诱发的ST段压低在运动停止后仍持续存在，此后HR开始下降，HR-ST环因此呈逆时针旋转。基于这些标准对HR-ST关系进行评估，结果显示敏感性为79.2%，特异性为94%，效果良好。
我们新开发的通过分析动态心电图和计步器的同步数据来评估HR-ST关系的方法，在诊断SMI以及评估缺血性心脏病患者的药物治疗效果方面，似乎节省时间且高度客观，具有实用性。
