[Present and future of cardiac function tests: electrophysiologic tests]

Various electrocardiographic and physiologic tests have been developing for almost 100 years since Einthoven established the standard 12 lead electrocardiogram(ECG) system. Recently, interest has focused on the new developing parameters associated with cardiac ventricular repolarization, such as transmural dispersion of repolarization, T wave alternans and QT dispersion. QT dispersion, measured as interlead difference of QT interval, has been suggested to reflect regional variation of ventricular repolarization. However, still unsolved basic problems give difficulties for clinical acceptance of this parameter. On the other hand, it is generally accepted that heart rate variability obtained from Holter ECG is useful tool to assess the autonomic tone. Head-up tilt test is a valuable diagnostic tool to identify patients with neurally mediated syncope and also useful for assessment of reflex cardiac autonomic function, such as baroreflex sensitivity. The number of electrophysiologic study(EPS) dramatically increased together with increase of radiofrequency catheter ablation. A new three-dimensional nonfluoroscopic electroanatomical mapping system(CARTO) is an exciting development in catheter ablation treatment. Transtelephonic ECG and its computer-assisted answering system are also useful for diagnose and treatment in the patients of paroxysmal cardiac symptoms.