Effects of an Innovative Head-Up Tilt Protocol on Blood Pressure and Arterial Stiffness Changes

Preclinical Orthostatic Abnormalities May Predict Early Increase in Vascular Stiffness in Different Age Groups: A Pilot Study

Clinical orthostatic hypotension (OH) and hypertension (OHT) are risk factors for arterial hypertension (AH) and cardiovascular diseases (CVD) and are associated with increased vascular stiffness. Preclinical OH and OHT are poorly understood. The main objective was to investigate preclinical orthostatic abnormalities and their association with increased vascular stiffness in different age groups of adults. A specially designed head-up tilt test standardized for hydrostatic column height was used to detect them. Three age groups of clinically healthy subjects were examined. In the group of young adults up to 30 years old, a significant predominance of orthostatic normotension (ONT) and an insignificant number of subjects with preclinical OH and OHT were found. In the age group over 45 years, compared to the group under 30 years, there was a twofold decrease in the proportion of individuals with ONT and a significant increase with preclinical OH and OHT. In all age groups, there was a significant orthostatic increase in vascular stiffness (as measured by the brachial-ankle pulse wave velocity (baPWV), which was recovered to the baseline level when returning to the supine position. Overall, subjects with preclinical OH and OHT had significantly higher baPWV values compared to those with ONT (p = 0.001 and p = 0.002, respectively), with all subjects having vascular stiffness values within normal age-related values.

Effects of trunk posture on cardiovascular and autonomic nervous systems: A pilot study

Objective: Although regular and moderate physical activity has been shown to improve the cardiovascular and autonomic nervous systems, little has been done to study the effects of postural changes in the movement on the heart and autonomic nervous system. To uncover changes in cardiac function and autonomic nerves induced by different underlying posture transitions and explore which trunk postures lead to chronic sympathetic activation. Therefore, this study investigated the effects of trunk posture on the cardiovascular and autonomic nervous systems. Methods: Twelve male subjects (age 24.7 ± 1.3) underwent this study. The non-invasive cardiac output NICOM monitoring equipment and the FIRSTBEAT system are used to dynamically monitor seven trunk postures in the sitting position simultaneously (neutral position, posterior extension, forward flexion, left lateral flexion, right lateral flexion, left rotation, right rotation). Each posture was maintained for 3 min, and the interval between each movement was 3 min to ensure that each index returned to the baseline level. Repeated analysis of variance test was used to compare and analyze the differences in human cardiac function, heart rate variability index, and respiratory rate under different postures. Results: Compared with the related indicators of cardiac output in a neutral trunk position: the cardiac index (CI) was significantly reduced in forwarding flexion and left rotation (3.48 ± 0.34 vs. 3.21 ± 0.50; 3.48 ± 0.34 vs. 3.21 ± 0.46, Δ L/(min/m2)) (p = 0.016, p = 0.013), cardiac output decreased significantly (6.49 ± 0.78 vs. 5.93 ± 0.90; 6.49 ± 0.78 vs. 6.00 ± 0.96, Δ L/min) (p = 0.006, p = 0.014), the stroke volume (stroke volume)decreased significantly (87.90 ± 15.10 vs. 81.04 ± 16.35; 87.90 ± 15.10 vs. 79.24 ± 16.83, Δ ml/beat) (p = 0.017, p = 0.0003); heart rate increased significantly in posterior extension (75.08 ± 10.43 vs. 78.42 ± 10.18, Δ beat/min) (p = 0.001); left rotation stroke volume index (SVI) decreased significantly (47.28 ± 7.97 vs. 46.14 ± 8.06, Δ ml/m2) (p = 0.0003); in the analysis of HRV-related indicators, compared with the neutral trunk position, the LF/HF of the posterior extension was significantly increased (1.90 ± 1.38 vs. 3.00 ± 1.17, p = 0.037), and the LF/HF of the forward flexion was significantly increased (1.90 ± 1.38 vs. 2.85 ± 1.41, p = 0.041), and the frequency-domain index LF/HF of right rotation was significantly increased (1.90 ± 1.38 vs. 4.06 ± 2.19, p = 0.008). There was no significant difference in respiratory rate (p > 0.05). Conclusion: A neutral trunk is the best resting position, and deviations from a neutral trunk position can affect the cardiovascular and autonomic nervous systems, resulting in decreased stroke volume, increased heart rate, and relative activation of sympathetic tone.

Detection of Preclinical Orthostatic Disorders in Young African and European Adults Using the Head-Up Tilt Test with a Standardized Hydrostatic Column Height: A Pilot Study

Arterial hypertension (AH) remains the most common disease. One possible way to improve the effectiveness of the primary prevention of AH is to identify and control the preclinical orthostatic disturbances that precede the development of AH. The aim of the study was to determine the feasibility of a new protocol for the head-up tilt test (HUTT) with a standardized hydrostatic column height for the detection of asymptomatic orthostatic circulatory disorders and their racial differences in young African and European adults. Methods. In total, 80 young healthy adults (40 African and 40 European) aged 20–23 years performed the HUTT with a standardized hydrostatic column height of 133 cm. The hemodynamic parameters were recorded using a Task Force Monitor (3040i). The cardio-ankle vascular index (CAVI) was measured using a VaSera VS-2000 volumetric sphygmograph. Results. The baseline and orthostatic hemodynamic changes in both racial groups were within normal limits. Orthostatic circulatory disturbances were not detected in 70% of the European participants and 65% of the African participants; however, preclinical orthostatic hypertension, which precedes AH, was detected using the new HUTT protocol in 32.5% of the African participants and 20% of the European participants. The baseline CAVI was higher in the European group compared to the African group. Conclusion. The results of this study showed the feasibility of the detection of preclinical orthostatic disturbances in young adults and the detection of their racial differences using the HUTT protocol, providing the use of a standard gravity load. Further study on the evolution of preclinical orthostatic disturbances and their relation to increased vascular stiffness is necessary among large samples.

Support Vector Machine-Based Classification of Vasovagal Syncope Using Head-Up Tilt Test

Syncope is the medical condition of loss of consciousness triggered by the momentary cessation of blood flow to the brain. Machine learning techniques have been established to be very effective way to address such problems, where a class label is predicted for given input data. This work presents a Support Vector Machine (SVM) based classification of neuro-mediated syncope evaluated using train-test-split and K-fold cross-validation methods using the patient's physiological data collected through the Head-up Tilt Test in pure clinical settings. The performance of the model has been analyzed over standard statistical performance indices. The experimental results prove the effectiveness of using SVM-based classification for the proactive diagnosis of syncope.

Autoimmune Rheumatic Diseases and Vascular Function: The Concept of Autoimmune Atherosclerosis

Autoimmune rheumatic diseases (AIRDs) with unknown etiology are increasing in incidence and prevalence. Up to 5% of the population is affected. AIRDs include rheumatoid arthritis, system lupus erythematosus, systemic sclerosis, and Sjögren's syndrome. In patients with autoimmune diseases, the immune system attacks structures of its own body, leading to widespread tissue and organ damage, which, in turn, is associated with increased morbidity and mortality. One third of the mortality associated with autoimmune diseases is due to cardiovascular diseases. Atherosclerosis is considered the main underlying cause of cardiovascular diseases. Currently, because of finding macrophages and lymphocytes at the atheroma, atherosclerosis is considered a chronic immune-inflammatory disease. In active inflammation, the liberation of inflammatory mediators such as tumor necrotic factor alpha (TNFa), interleukine-6 (IL-6), IL-1 and other factors like T and B cells, play a major role in the atheroma formation. In addition, antioxidized, low-density lipoprotein (LDL) antibodies, antinuclear antibodies (ANA), and rheumatoid factor (RF) are higher in the atherosclerotic patients. Traditional risk factors like gender, age, hypercholesterolemia, smoking, diabetes mellitus, and hypertension, however, do not alone explain the risk of atherosclerosis present in autoimmune diseases. This review examines the role of chronic inflammation in the etiology-and progression-of atherosclerosis in autoimmune rheumatic diseases. In addition, discussed here in detail are the possible effects of autoimmune rheumatic diseases that can affect vascular function. We present here the current findings from studies that assessed vascular function changes using state-of-the-art techniques and innovative endothelial function biomarkers.

Association of free fatty acid binding protein with central aortic stiffness, myocardial dysfunction and preserved ejection fraction heart failure

There is an established link between cardiometabolic abnormality, central arterial stiffness, and preserved ejection fraction heart failure (HFpEF). Adipocyte free fatty acid binding protein (a-FABP) has been shown to signal endothelial dysfunction through fatty acid toxicity, though its role in mediating ventricular-arterial dysfunction remains unclear. We prospectively examined the associations of a-FABP with central arterial pressure using non-invasive applanation tonometry (SphygmoCor) and cardiac structure/function (i.e., tissue Doppler imaging [TDI] and global longitudinal myocardial strain [GLS]) in patients with cardiometabolic (CM) risk (n = 150) and HFpEF (n = 50), with healthy volunteers (n = 49) serving as a control. We observed a graded increase of a-FABP across the healthy controls, CM individuals, and HFpEF groups (all paired p < 0.05). Higher a-FABP was independently associated with higher central systolic and diastolic blood pressures (CSP/CPP), increased arterial augmentation index (Aix), lower early myocardial relaxation velocity (TDI-e'), higher left ventricle (LV) filling (E/TDI-e') and worsened GLS (all p < 0.05). During a median of 3.85 years (interquartile range: 3.68-4.62 years) follow-up, higher a-FABP (cutoff: 24 ng/mL, adjusted hazard ratio: 1.01, 95% confidence interval: 1.001-1.02, p = 0.04) but not brain natriuretic peptide, and higher central hemodynamic indices were related to the incidence of heart failure (HF) in fully adjusted Cox models. Furthermore, a-FABP improved the HF risk classification over central hemodynamic information. We found a mechanistic pathophysiological link between a-FABP, central arterial stiffness, and myocardial dysfunction. In a population with a high metabolic risk, higher a-FABP accompanied by worsened ventricular-arterial coupling may confer more unfavorable outcomes in HFpEF.