It is well-known that dysfunction of the autonomic control is linked to the development of cardiovascular diseases. Dysfunction of the autonomic control could be diagnosed using the spectral analysis of the finger photoplethysmographic (PPG) signals.

OBJECTIVE

To compare the normalized spectral indexes LF%, HF%, and LF/HF index estimated from the PPG signals of the healthy subjects, arterial hypertension (AH) patients, coronary heart disease (CHD) patients, and aortic stenosis patients age 20 to 60 in the context of cardiovascular disease screening. Age-related dynamics of the LF% index was also investigated.

MATERIAL AND METHODS

The study included 620 subjects: 53 healthy subjects, 500 AH patients, 54 stable CHD patients, and 13 pre-surgery patients with aortic stenosis. The subjects were divided into two subgroups according to their age: subgroup A — 20 to 40 years, and subgroup B — 40 to 60 years. All CHD patients were assigned to group B. For each subject, we recorded a 10-minute finger PPG signal recorded from the right middle finger. Each signal was recorded in the supine position. From the PPG signals we estimated the LF%, HF%, and LF/HF indexes.

RESULTS

The HF% index was higher in the AH patients, CHD patients, and aortic stenosis patients in relation to the healthy subjects in both groups: 4.5 times higher, 9 times higher, and 5 times higher, respectively. The LF% index was lower: 5.5 times lower, 17 times lower and 1.1 times lower, respectively. The LF/HF index also changed accordingly. The LF% index showed no significant age-related changes in both healthy subjects and cardiovascular patients. Results of the ROC analysis suggest that the diagnostics of AH, CHD, and aortic stenosis based on the spectral analysis has sufficient sensitivity and specificity.

CONCLUSION

Our results suggest the same pattern of vegetative dysfunction in AH patients, CHD patients, and aortic stenosis patients characterized by lower LF% index, higher HF% index, and decreased LF/HF index. It was also shown that aging has no significant effect on the distribution of the LF% index in both healthy subjects and cardiovascular patients, diagnostics based on this index also demonstrated sufficient sensitivity and specificity. These results illustrate the importance of this index for preventive medicine.