Acute Changes in Carotid-Femoral Pulse-Wave Velocity Are Tracked by Heart-Femoral Pulse-Wave Velocity

The 24-h activity cycle and cardiovascular outcomes: establishing biological plausibility using arterial stiffness as an intermediate outcome

This review proposes a biologically plausible working model for the relationship between the 24-h activity cycle (24-HAC) and cardiovascular disease. The 24-HAC encompasses moderate-to-vigorous physical activity (MVPA), light physical activity, sedentary behavior (SB), and sleep. MVPA confers the greatest relative cardioprotective effect, when considering MVPA represents just 2% of the day if physical activity guidelines (30 min/day) are met. While we have well-established guidelines for MVPA, those for the remaining activity behaviors are vague. The vague guidelines are attributable to our limited mechanistic understanding of the independent and additive effects of these behaviors on the cardiovascular system. Our proposed biological model places arterial stiffness, a measure of vascular aging, as the key intermediate outcome. Starting with prolonged exposure to SB or static standing, we propose that the reported transient increases in arterial stiffness are driven by a cascade of negative hemodynamic effects following venous pooling. The subsequent autonomic, metabolic, and hormonal changes further impair vascular function. Vascular dysfunction can be offset by using mechanistic-informed interruption strategies and by engaging in protective behaviors throughout the day. Physical activity, especially MVPA, can confer protection by chronically improving endothelial function and associated protective mechanisms. Conversely, poor sleep, especially in duration and quality, negatively affects hormonal, metabolic, autonomic, and hemodynamic variables that can confound the physiological responses to next-day activity behaviors. Our hope is that the proposed biologically plausible working model will assist in furthering our understanding of the effects of these complex, interrelated activity behaviors on the cardiovascular system.

Vascular effects of biologic and targeted synthetic antirheumatic drugs approved for rheumatoid arthritis: a systematic review

BACKGROUND

Rheumatoid arthritis (RA) increases the risk of cardiovascular disease (CVD), with inflammation playing a key role. Biologic and targeted synthetic drugs used to treat RA can induce systemic immunomodulation and may have pleiotropic effects on vascular function, making it crucial to investigate their impact on CVD risk in RA patients.

METHODS

A systematic review of the literature was conducted to investigate the impact of biologic and targeted synthetic treatments approved for RA on various cardiovascular markers, including endothelial function, arterial stiffness, and subclinical atherosclerosis. Our analysis included a search of the MedLine (via PubMed) and Web of Science databases using a pre-determined search strategy. We conducted a narrative synthesis of the included studies due to heterogeneity in study design and outcome measures.

RESULTS

From an initial pool of 647 records, we excluded 327 studies based on their titles and abstracts, and we selected 182 studies for final examination. Ultimately, 58 articles met our inclusion criteria and were included in our systematic review. Our analysis of these studies revealed a positive effect of biologic and targeted synthetic therapies on vascular dysfunction associated with RA. However, the impact of these treatments on subclinical atherosclerosis was inconsistent.

CONCLUSION

Overall, our systematic review provides important insights into the potential cardiovascular benefits of biologic and targeted synthetic treatments for RA by a still unknown mechanism. These findings can inform clinical practice and contribute to our understanding of their possible effects on early vascular pathology. Key Points • Great heterogeneity of methods are used to evaluate the endothelial function and arterial stiffness in patients with RA on biologic and targeted synthetic antirheumatic drugs. • Most studies have shown a considerable improvement in endothelial function and arterial stiffness with TNFi, despite some studies reporting only transient or no improvement. • Anakinra and tocilizumab may have a beneficial effect on vascular function and endothelial injury, as indicated by increased FMD, coronary flow reserve, and reduced levels of biomarkers of endothelial function, while the overall impact of JAKi and rituximab remains inconclusive based on the reviewed studies. • To fully comprehend the distinctions between biologic therapies, more long-term, well-designed clinical trials are necessary using a homogeneous methodology.

One Step Back from Bedside to the Bench-How Do Different Arterial Stiffness Parameters Behave in Relation to Peripheral Resistance?

The investigation of arterial stiffening is a promising approach to estimating cardiovascular risk. Despite the widespread use of different methods, the dynamic nature of measured and calculated stiffness parameters is marginally investigated. We aimed to determine the stability of large artery elasticity parameters assessed via commonly used, ultrasound-based and oscillometric methods in relation to peripheral resistance modulation. A human experimental environment was composed, and fifteen young males were investigated at rest after extremity heating and external compression. Functional vascular parameters were monitored in each session, and several arterial stiffness parameters were analysed. The distensibility coefficient (DC) did not show significant changes during heat provocation and extremity compression, while DC's stability seemed to be acceptable. The same stability of carotid-femoral pulse wave velocity (PWV) was detected with ultrasound measurement (5.43 ± 0.79, 5.32 ± 0.86 and 5.28 ± 0.77, with p = 0.38, p = 0.27 and p = 0.76, respectively) with excellent intersession variability (intraclass correlation coefficient of 0.90, 0.88 and 0.91, respectively). However, the oscillometric PWV (oPWV) did change significantly between the heating and outer compression phase of the study (7.46 ± 1.37, 7.10 ± 1.18 and 7.60 ± 1.21, with p = 0.05, p = 0.68 and p < 0.001, respectively), the alteration of which is closely related to wave reflection, represented by the changes in reflection time. Our results indicate the good stability of directly measured elastic parameters such as DC and PWV, despite the extreme modulation of peripheral resistance. However, the oscillometric, indirectly detected PWV might be altered by physical interventions, which depend on wave reflection. The effective modulation of wave reflection was characterized by changes in the augmentation index, detected using both oscillometry and applanation tonometry. Thus, the environment during oscillometric measurement should be rigorously standardized. Furthermore, our results suggest the dynamic nature of the reflection point, rather than being a fixed anatomical point, proposed previously as aortic bifurcation.

Loss of hepatic PPARα in mice causes hypertension and cardiovascular disease

The leading cause of death in patients with nonalcoholic fatty liver disease (NAFLD) is cardiovascular disease (CVD). However, the mechanisms are unknown. Mice deficient in hepatocyte proliferator-activated receptor-α (PPARα) (PparaHepKO) exhibit hepatic steatosis on a regular chow diet, making them prone to manifesting NAFLD. We hypothesized that the PparaHepKO mice might be predisposed to poorer cardiovascular phenotypes due to increased liver fat content. Therefore, we used PparaHepKO and littermate control mice fed a regular chow diet to avoid complications with a high-fat diet, such as insulin resistance and increased adiposity. After 30 wk on a standard diet, male PparaHepKO mice exhibited elevated hepatic fat content compared with littermates as measured by Echo MRI (11.95 ± 1.4 vs. 3.74 ± 1.4%, P < 0.05), hepatic triglycerides (1.4 ± 0.10 vs. 0.3 ± 0.01 mM, P < 0.05), and Oil Red O staining, despite body weight, fasting blood glucose, and insulin levels being the same as controls. The PparaHepKO mice also displayed elevated mean arterial blood pressure (121 ± 4 vs. 108 ± 2 mmHg, P < 0.05), impaired diastolic function, cardiac remodeling, and enhanced vascular stiffness. To determine mechanisms controlling the increase in stiffness in the aorta, we used state-of-the-art PamGene technology to measure kinase activity in this tissue. Our data suggest that the loss of hepatic PPARα induces alterations in the aortas that reduce the kinase activity of tropomyosin receptor kinases and p70S6K kinase, which might contribute to the pathogenesis of NAFLD-induced CVD. These data indicate that hepatic PPARα protects the cardiovascular system through some as-of-yet undefined mechanism.

Pulse-wave velocity assessments derived from a simple photoplethysmography device: Agreement with a referent device

Objective

Pulse-wave velocity (PWV), a common measure of arterial stiffness, can be measured continuously and across multiple body sites using photoplethysmography (PPG). The objective was to determine whether a simple photoplethysmography PPG PWV method agrees with a referent device.

Approach

Photoplethysmography heart-finger PWV (hfPWV) and heart-toe PWV (htPWV) were compared to oscillometric carotid-wrist PWV (cwPWV) and carotid-ankle PWV (caPWV) referent measurements, respectively. In 30 adults (24.6 ± 4.8 years, body mass index 25.2 ± 5.9 kg/m², 18 female), three measurements were made: two supine baseline measurements (Base 1, Base 2) and one measurement (Tilt) 5 min after a modified head-up tilt test (mHUTT). Overall agreement and repeated measures agreement (change in PPG PWV from Base to Tilt vs. change in referent PWV from Base to Tilt) were calculated using linear mixed models. Agreement estimates were expressed as intra-class correlation coefficients (ICC).

Main results

For hfPWV there was strong overall agreement (ICC: 0.77, 95%CI: 0.67-0.85), but negligible and non-significant repeated measures agreement (ICC: 0.10, 95%CI: -0.18 to 0.36). For htPWV, there was moderate overall agreement (ICC:0.50, 95%CI: 0.31-0.65) and strong repeated measures agreement (ICC: 0.81, 95%CI: 0.69-0.89).

Significance

Photoplethysmography can continuously measure PWV at multiple arterial segments with moderate-strong overall agreement. While further work with upper-limb PPG PWV is needed, PPG can adequately capture acute changes in lower-limb PWV.

Mental stress augments central artery stiffness in young individuals of both sexes

Mental stress is a daily stimulus that can acutely activate the sympathetic nervous system. Whether sympathetic stimulation can augment central artery stiffness (CAS) has not yet been well documented. Moreover, sex differences in sympathetic neurovascular transduction have been reported. We assessed whether mental stress augments CAS in both sexes and whether any CAS increase is blunted in women compared with men. The hf-PWV (heart-femoral pulse wave velocity; index of CAS), MAP (mean arterial pressure), PP (pulse pressure), TPR (total peripheral resistance), and HR (heart rate) were measured in 26 young individuals (13 men, 13 women) at rest and throughout a 10-minute bout of stress induced by mental arithmetic. Data over the mental stress period were compared to the preceding baseline values and between sexes. Mental stress increased hf-PWV, MAP, PP, and HR from baseline throughout the entire stimulation period (p < .005). TPR diminished in the first minute of stimulation (p < .001) in both sexes and increased in the last minutes in women only (p < .005). Hf-PWV was lower in women than men (p < .001) at rest and during mental stress, but the changes from baseline were similar in both sexes. There were sex differences in the PP and TPR changes, which were evident at different times of stimulation. Mental stress increased CAS in both sexes throughout the stimulation period. Although values of CAS were lower in women both at rest and during mental stress, the CAS increase due to mental stress was similar in both sexes.

Multimodal Finger Pulse Wave Sensing: Comparison of Forcecardiography and Photoplethysmography Sensors

Pulse waves (PWs) are mechanical waves that propagate from the ventricles through the whole vascular system as brisk enlargements of the blood vessels' lumens, caused by sudden increases in local blood pressure. Photoplethysmography (PPG) is one of the most widespread techniques employed for PW sensing due to its ability to measure blood oxygen saturation. Other sensors and techniques have been proposed to record PWs, and include applanation tonometers, piezoelectric sensors, force sensors of different kinds, and accelerometers. The performances of these sensors have been analyzed individually, and their results have been found not to be in good agreement (e.g., in terms of PW morphology and the physiological parameters extracted). Such a comparison has led to a deeper comprehension of their strengths and weaknesses, and ultimately, to the consideration that a multimodal approach accomplished via sensor fusion would lead to a more robust, reliable, and potentially more informative methodology for PW monitoring. However, apart from various multichannel and multi-site systems proposed in the literature, no true multimodal sensors for PW recording have been proposed yet that acquire PW signals simultaneously from the same measurement site. In this study, a true multimodal PW sensor is presented, which was obtained by integrating a piezoelectric forcecardiography (FCG) sensor and a PPG sensor, thus enabling simultaneous mechanical-optical measurements of PWs from the same site on the body. The novel sensor performance was assessed by measuring the finger PWs of five healthy subjects at rest. The preliminary results of this study showed, for the first time, that a delay exists between the PWs recorded simultaneously by the PPG and FCG sensors. Despite such a delay, the pulse waveforms acquired by the PPG and FCG sensors, along with their first and second derivatives, had very high normalized cross-correlation indices in excess of 0.98. Six well-established morphological parameters of the PWs were compared via linear regression, correlation, and Bland-Altman analyses, which showed that some of these parameters were not in good agreement for all subjects. The preliminary results of this proof-of-concept study must be confirmed in a much larger cohort of subjects. Further investigation is also necessary to shed light on the physical origin of the observed delay between optical and mechanical PW signals. This research paves the way for the development of true multimodal, wearable, integrated sensors and for potential sensor fusion approaches to improve the performance of PW monitoring at various body sites.

A Primer on Repeated Sitting Exposure and the Cardiovascular System: Considerations for Study Design, Analysis, Interpretation, and Translation

Sedentary behavior, particularly sitting, is ubiquitous in many contemporary societies. This is a major societal concern considering the evidence for a strong association between sitting behavior and cardiovascular disease morbidity and mortality. Unsurprisingly, leading public health agencies have begun to advocate “reduction” in sitting behavior. Though, the guidelines are typically vague and non-specific. The lack of specific guidelines for prolonged sitting is attributable to the absence of available evidence to facilitate guideline development. To inform policy, well-designed randomized controlled trials are required to test the efficacy of specific and translatable sitting reduction strategies. To guide the design of randomized controlled trials, this review postulates that several gaps in the literature first need to be filled. Following a general discussion of the importance of sitting behavior to contemporary societies, each of the following are discussed: (i) acute sitting exposure and systems physiology; (ii) recommendations for a systems physiology toolbox; (iii) study design considerations for acute sitting exposure; and (iv) translation of sitting-focused research.