HEART-RATE-VARIABILITY BEFORE THE OCCURRENCE OF SILENT-MYOCARDIAL-ISCHEMIA DURING AMBULATORY MONITORING

Citation
Y. Goseki et al., HEART-RATE-VARIABILITY BEFORE THE OCCURRENCE OF SILENT-MYOCARDIAL-ISCHEMIA DURING AMBULATORY MONITORING, The American journal of cardiology, 73(12), 1994, pp. 845-849
Citations number
29
Categorie Soggetti
Cardiac & Cardiovascular System
ISSN journal
00029149
Volume
73
Issue
12
Year of publication
1994
Pages
845 - 849
Database
ISI
SICI code
0002-9149(1994)73:12<845:HBTOOS>2.0.ZU;2-5
Abstract
Thirty-three ischemic episodes in 19 patients with stable coronary art ery disease were studied to clarify changing autonomic nervous system activity during daily life before the occurrence of myocardial ischemi a. Nonischemic points were studied for comparison of control data with ischemic episodes. These were defined as (1) patient showing no ische mic ST-T change while having the same heart rate with onset of ischemi c episodes, and (2) presence within 1 to 2 hours before or after onset of ischemic episodes in the same patient. We analyzed heart rate (HR) variability during the 30 minute period before the onset and after th e end of ischemic episodes during 24-hour monitoring. The period of 30 to 40 minutes before Ischemia was regarded as the baseline, and HR va riability was analyzed at 10-minute intervals before each ischemic epi sode and nonischemic point. HR variability was quantified on the band of 2 components: low frequency (0.04 to 0.15 Hz; 19) and high frequenc y (0.15 to 0.40 Hz; HF). Of the 33 episodes, 24 (73%) had a greater LF /HF value during the 30-minute period before ischemia than that before the nonischemic points. Distribution of the number of the 24 episodes demonstrated circadian rhythm with a peak from 8 to 10 A.M. HF power began to decrease from the last 10 minutes before ischemia, compared w ith baseline. A significant decrease in HF power with a background of greater value of LF/HF may explain the reduced ischemic threshold for ischemia during daily life.