AUTOMATED QUANTIFICATION OF SLEEP HEART RATE PATTERNS IN NORMAL SUBJECTS AND ANGINA PATIENTS

Automated procedures, including detection of QRS complexes and mathematical modeling involving Markov processes, were developed to quantify accurately and efficiently heart rate and heart rate variability patterns in normal human adults and in patients with a history of angina attacks. The patterns in the normal and patient populations were compared for various sleep stages throughout the night, in order to elucidate possible autonomic nervous system and higher brain centers influence on the precipitation of angina.; The night sleep EEG, EOG and ECG from eight normal subjects (NORMAL group) and ten patients with a history of angina (ANGINA group) were recorded. The angina patients were further divided into two groups of five patients each. Patients in the first group (MEDICINE) were on medication while patients in the second group (SURGERY) had undergone coronary bypass surgery for the management of angina attacks.; A simple, novel and efficient algorithm was developed to detect QRS complexes automatically from the recorded ECG data using a PDP11-70 minicomputer. This algorithm discriminates QRS complexes against various artifacts including the effect due to tape recorder amplifier saturation.; The mean heart rate and the coefficient of variation of the heart rate were used to quantify heart rate patterns in a global fashion. The mean heart rate patterns in sleep state 2 (SS-2) and sleep stage REM (SS-REM) were found to be different among the three groups. However, appropriately normalized mean heart rate patterns were shown to be similar. The coefficient of variation of heart rate in a given group did not change during the night, whereas the coefficient of variation for subjects in the ANGINA groups was lower than the one in the NORMAL group and no difference was found between the two ANGINA groups.; The change in heart rate during sleep stage transitions (SSTs) was found to be gradual when going either from SS-2 to SS-REM or from SS-REM to SS-2 in the NORMAL group. But the ANGINA groups did not show any significant difference in heart rate during these SSTs. Contrary to the trend in the NORMAL group, the transitions from SS-0 to SS-1 and from SS-1 to SS-2 in the ANGINA groups showed a significant difference in heart rate, and this change took place in a gradual manner. (Abstract shortened with permission of author.)...