The clinical application and limitation of electrocardiography

Electrocardiography (EGG) is one of the most useful methods for diagnosis of the heart diseases, including ischemic heart disease, cardiomegaly and arrhythmias. However, image methods such as echocardiography, CT-scan and MRI for diagnosis of heart diseases developed in the recent several years gave rise to some conflictions between the findings obtained by ECG and the imaging methods. Therefore, the diagnostic criteria of ECG had to be re-examined. The body Surface Map (MAP) with 87 leads on the body surface revealed more circumstantial electric phenomena of the heart than the standard 12-lead ECG and vectorcardiography. However, the MAP needs a lot of time for recording and diagnosis because of its many electrodes. Computer diagnosis adequately developed, and simplification and abbreviation of recording are required. Morphologic disorders of the heart can be diagnosed more adequately by imaging methods such as echocardiography and CT-scan than ECGs. However for the study of arrhythmias, ECGs including standard 12-lead, vector and Holter electrocardiographies, and MAP are almost the only methods now available. Each method of ECG has different characteristics and is widely accepted not only for clinical diagnosis but also research of arrhythmias. In the near future, noninvasive examination from the body surface to reveal a minute electric change of the heart will be expected instead of invasive examinations as His-bundle ECGs.