Clinical and research applications of ambulatory Holter ST-segment and heart rate monitoring.

Monitoring of the electrocardiogram during normal daily activity yields data regarding silent myocardial ischemia and its relation to heart rate in addition to the detection of cardiac arrhythmias. In recent years various techniques have been developed to quantify the frequency and duration of ischemic episodes in patients with ischemic heart disease. Of particular importance are the newer frequency-modulated recording techniques, which ensure adequate low frequency response, and the computerized digital analysis used to define the role of ST-segment monitoring in the clinical and research setting. The techniques used for acquiring artifact-free signals, the methods of data analysis and the clinical role of ambulatory Holter monitoring of ST-segment changes in the diagnosis of Prinzmetal's angina, in chronic stable angina and in the detection of calcium antagonist withdrawal syndrome in angina are discussed. The data indicate the particular utility of Holter monitoring to analyze the variability of heart rate in defining the effects of calcium-channel blockers, beta-adrenergic blocking agents and their combined use in pharmacologic therapy of ischemic myocardial syndromes.