Aortic Augmentation Index is Dependent on Bodyside in Healthy Young Subjects.

Introduction: Aortic augmentation index (AIx) is a commonly used measure to evaluate the arterial stiffness of large elastic arteries. It has been used as an indicator for cardiovascular risk in clinical practice.

Aim: To evaluate the difference in the aortic AIx assessed from the left and the right hand in a group of healthy young adults using SphygmoCor and Arteriograph devices.

Pulse wave velocity and its gender-related associations with cardiovascular risk factors in a high cardiovascular risk population.

Introduction: Associations found between pulse wave velocity (PWV) and cardiovascular risk factors (CVrF) are diverse. We aimed to evaluate whether differences in PWV and its associations with CVrF in a high cardiovascular risk population exist between genders and between the whole population (WHgr) and groups of apparently healthy (AHgr) and those of hypertensive, obese or diabetics (Rgr).

Material And Methods: Pulse wave velocity measured by Arteriograph was investigated in 805 adults aged 20-65, randomly selected from the Tallinn Population Register.

QT interval variability index and QT interval duration during different sleep stages in patients with obstructive sleep apnea.

Objectives: The aim of the study was to investigate the impact of obstructive sleep apnea (OSA) on the QT interval variability and duration in patients during different sleep stages.

Methods: Polysomnographic recordings of 28 (13 male, 15 female) patients with OSA and 30 (15 male, 15 female) patients without OSA were analyzed. The QT interval variability index (QTVI) and the corrected QT interval (QTc) analyses were performed using two awake, 3-4 non-rapid eye movement (NREM) and three rapid eye movement (REM) sleep episodes (each 300 s).

Influence of gender on the QT interval variability and duration in different wake-sleep stages in non-sleep apneic individuals: Analysis of polysomnographic recordings.

Introduction: The aim of the study was to determine the influence of gender and sleep stages, especially rapid eye movement sleep (REM), on QT interval variability and duration in normal subjects.

Methods: Polysomnographic recordings of 24 male and 24 female patients without obstructive sleep apnea were analyzed. In each patient, the QT interval variability index (QTVI) and the corrected QT interval (QTc) values were calculated as means of 2 awake, 4 non-rapid eye movement sleep (NREM) and 3 REM episodes, 300s each.

Pulse wave registration from radial artery using photoplethysmographic method.

This pilot study was aimed to investigate the possibilities to use the photoplethysmographic (PPG) method for the pulse wave registration from radial artery. The PPG sensor with different separation distances between light emitting diodes (LED) and photodiode was built. The PPG signal registration was carried out at the locations with two different depths of artery and at the locations without large blood vessels under the sensor.

QT Interval Variability Index and QT Interval Duration in Different Sleep Stages: Analysis of Polysomnographic Recordings in Nonapneic Male Patients.

The aim of the study was to determine whether different sleep stages, especially REM sleep, affect QT interval duration and variability in male patients without obstructive sleep apnea (OSA). Polysomnographic recordings of 30 patients were analyzed. Beat-to-beat QT interval variability was calculated using QTV index (QTVI) formula.

The effect of local cold and warm exposure on index finger photoplethysmographic signal waveform.

The study was carried out in order to analyse the changes in photoplethysmographic (PPG) signal waveform, which are caused by cold and warm stimulation. The study was carried out on 7 subjects. The right hand was immersed in cold and warm water up to the wrist during the experiment.

New photoplethysmographic signal analysis algorithm for arterial stiffness estimation.

The ability to identify premature arterial stiffening is of considerable value in the prevention of cardiovascular diseases. The "ageing index" (AGI), which is calculated from the second derivative photoplethysmographic (SDPPG) waveform, has been used as one method for arterial stiffness estimation and the evaluation of cardiovascular ageing. In this study, the new SDPPG analysis algorithm is proposed with optimal filtering and signal normalization in time.

An experimental measurement complex for probable estimation of arterial stiffness.

Current work is a part of long term research, which aim is to study the possibilities to diagnose the atherosclerosis in early stadium by using pulse wave velocity and its waveform analysis. The mobile experimental measurement complex is built and technically tested for the long term study in hospital. Measurement complex consists of ten physiological signal recording channels and reference devices: Sphygmocor, Arteriograph, Finapres.

Adjustment of adaptive sum comb filter for PPG signals.

AC component of photoplethysmography signal carries important information for diagnostics. Registered signal may be affected by noises, which are sharing the same bandwidth. Adaptive comb filter is used for the AC component extraction.

Adaptive impulse correlated filter (AICF) improvement for photoplethysmographic signals.

Measured PPG signals are often contaminated with different noises and artifacts. For clinical diagnostics, it is important to have accurate signals. Removing noises and motion artifacts from PPG signal has been actual also in previous studies.

Assessment of Pulse Wave Velocity and Augmentation Index in different arteries in patients with severe coronary heart disease.

The aim of this study was to assess pulse wave velocity (PWV) and augmentation index in different arteries in patients with severe coronary heart disease (CHD). Signal measurements were obtained from 28 subjects. Severe coronary heart disease was confirmed by coronary angiography.

Analogue step-by-step DC component eliminator for 24-hour PPG signal monitoring.

For applications where PPG signal AC component needs to be measured without disturbances in its shape and recorded digitally with high digitalization accuracy, the step-by-step DC component eliminator is developed. This paper describes step-by-step DC component eliminator, which is utilized with analogue comparator and operational amplifier. It allows to record PPG signal without disturbances in its shape in 24-hours PPG signal monitoring system.

Echocardiographic assessment of the different left ventricular geometric patterns in middle-aged men and women in Tallinn.

The aim of this study was to determine the association of left ventricular (LV) geometry with sex, age, arterial hypertension and obesity in Tallinn. In a framework of a population study for cardiovascular risk factors, echocardiography was carried out in 325 men and 398 women (69.3% of all 1043 participants aged 35-59) in 1999-2001.

Self-mixing in a diode laser as a method for cardiovascular diagnostics.

Our aim is the development of a simple optical method for pulse wave profile, pulse wave delay time, and blood flow measurement. The method is based on recording the Doppler frequency shift related to a moving target--blood vessel walls or small particles. The Doppler signal is detected using the self-mixing that occurs in the diode laser cavity when radiation scatters back from the moving target into the laser and interferes with the field inside.