A novel device for measuring arterial stiffness using finger-toe pulse wave velocity: Validation study of the pOpmètre®

Arterial stiffness assessment by pulse wave velocity in postmenopausal women: comparison between noninvasive devices

OBJECTIVE

This study aimed to ascertain the accuracy of measure arterial stiffness using the HUAWEI GT 3 Pro smartwatch and pOpmètre device against the SphygmoCor (algorithms: intersect tangent and maximum of the second derivate).

METHODS

Twenty-three physically active postmenopausal women (age: 58.9 ± 3.2 years; body mass index: 26.3 ± 4.8 kg/m 2 ) were recruited. Carotid-femoral pulse wave velocity, finger-toe pulse wave velocity, and wrist-finger pulse wave velocity were obtained using SphygmoCor, pOpmètre and HUAWEI GT 3 Pro devices in a randomized order. Additionally, the pulse mean carotid-femoral and finger-toe pulse transit time was registered for SphygmoCor and pOpmètre, respectively.

RESULTS

Lower values of pulse wave velocity were recorded by HUAWEI in comparison with SphygmoCor with both algorithms, whereas no significant differences were detected between SphygmoCor and pOpmètre results. Pulse wave velocity values from SphygmoCor were positively correlated with pOpmètre results ( r = 0.464 and r = 0.451 using intersect tangent and second derivative algorithms), whereas this was not the case with those obtained from HUAWEI. Coefficients of bias of Lin's concordance coefficients close to 1 (0.832 and 0.831 for intersect tangent and second derivative algorithm, respectively) and mean bias close to 0 from Bland-Altman analysis suggested an acceptable agreement between pulse wave velocity obtained from SphygmoCor and pOpmètre.

CONCLUSIONS

Our results suggest an acceptable concordance of pulse wave velocity values recoded by SphygmoCor and pOpmètre, whereas this was not the case for data obtained from HUAWEI GT 3 Pro smartwatch. Therefore, the pOpmètre may be a viable alternative for assessing arterial stiffness, but measurement via the smartwatch device cannot be recommended.

Determinants of hand pulse wave velocity and hand pulse transit time in healthy adults

Arterial pulse wave velocity (PWV) is recognized as a convenient method to assess peripheral vascular stiffness. This study explored the clinical characteristics of hand PWV (hPWV) and hand pulse transit time (hPTT) in healthy adults (sixty males = 42.4 ± 13.9 yrs; sixty-four females = 42.8 ± 13.9 yrs) voluntarily participated in this study. The arterial pulse waveform and the anatomical distance from the radial styloid process to the tip of the middle finger of both hands were recorded in the sitting position. The hPWV was calculated as the traversed distance divided by hPTT between those two points. Male subjects showed significantly greater hPWV, systolic blood pressure, and pulse pressure than age-matched female subjects, while the hPTT was not significantly different between genders. Multiple linear regression analysis showed that gender is a common determinant of hPWV and hPTT, and that age and heart rate (HR) were negatively correlated with hPWV and hPTT, respectively. We conclude that male subjects have greater hPWV than female subjects. Ageing is associated with decreased hPWV, while increased HR is associated with a smaller hPTT. The hPWV and hPTT might be used as non-invasive indices to characterise the ageing and arterial stiffness of peripheral blood vessels.

Association between arterial stiffness and Loa loa microfilaremia in a rural area of the Republic of Congo: A population-based cross-sectional study (the MorLo project)

BACKGROUND

Loa loa filariasis (loiasis) is still considered a relatively benign disease. However, recent epidemiologic data suggest increased mortality and morbidity in L. loa infected individuals. We aimed to examine whether the density of L. loa microfilariae (mfs) in the blood is associated with cardiovascular disease.

METHODOLOGY

Using a point-of-care device (pOpmètre), we conducted a cross-sectional study to assess arterial stiffness and peripheral arterial disease (PAD) in 991 individuals living in a loiasis-endemic rural area in the Republic of the Congo. Microfilaremic individuals were matched for age, sex and village of residence with 2 amicrofilaremic subjects. We analyzed markers of arterial stiffness (Pulse-Wave Velocity, PWV), PAD (Ankle-Brachial Index, ABI) and cardiovascular health (Pulse Pressure, PP). The analysis considered parasitological results (L. loa microfilarial density [MFD], soil-transmitted helminths infection, asymptomatic malaria and onchocerciasis), sociodemographic characteristics and known cardiovascular risk factors (body mass index, smoking status, creatininemia, blood pressure).

PRINCIPAL FINDINGS

Among the individuals included in the analysis, 192/982 (19.5%) and 137/976 (14.0%) had a PWV or an ABI considered out of range, respectively. Out of range PWV was associated with younger age, high mean arterial pressure and high L. loa MFD. Compared to amicrofilaremic subjects, those with more than 10,000 mfs/mL were 2.17 times more likely to have an out of range PWV (p = 0.00). Factors significantly associated with PAD were older age, low pulse rate, low body mass index, smoking, and L. loa microfilaremia. Factors significantly associated with an elevation of PP were older age, female sex, high average blood pressure, low pulse rate and L. loa microfilaremia.

CONCLUSION

A potential link between high L. loa microfilaremia and cardiovascular health deterioration is suggested. Further studies are required to confirm and explore this association.

Noninvasive hemodynamic indices of vascular aging: an in silico assessment

Vascular aging (VA) involves structural and functional changes in blood vessels that contribute to cardiovascular disease. Several noninvasive pulse wave (PW) indices have been proposed to assess the arterial stiffness component of VA in the clinic and daily life. This study investigated 19 of these indices, identified in recent review articles on VA, by using a database comprising 3,837 virtual healthy subjects aged 25-75 yr, each with unique PW signals simulated under various levels of artificial noise to mimic real measurement errors. For each subject, VA indices were calculated from filtered PW signals and compared with the precise theoretical value of aortic Young's modulus (EAo). In silico PW indices showed age-related changes that align with in vivo population studies. The cardio-ankle vascular index (CAVI) and all pulse wave velocity (PWV) indices showed strong linear correlations with EAo (Pearson's rp > 0.95). Carotid distensibility showed a strong negative nonlinear correlation (Spearman's rs < -0.99). CAVI and distensibility exhibited greater resilience to noise compared with PWV indices. Blood pressure-related indices and photoplethysmography (PPG)-based indices showed weaker correlations with EAo (rp and rs < 0.89, |rp| and |rs| < 0.84, respectively). Overall, blood pressure-related indices were confounded by more cardiovascular properties (heart rate, stroke volume, duration of systole, large artery diameter, and/or peripheral vascular resistance) compared with other studied indices, and PPG-based indices were most affected by noise. In conclusion, carotid-femoral PWV, CAVI and carotid distensibility emerged as the superior clinical VA indicators, with a strong EAo correlation and noise resilience. PPG-based indices showed potential for daily VA monitoring under minimized noise disturbances.NEW & NOTEWORTHY For the first time, 19 noninvasive pulse wave indices for assessing vascular aging were examined together in a single database of nearly 4,000 subjects aged 25-75 yr. The dataset contained precise values of the aortic Young's modulus and other hemodynamic measures for each subject, which enabled us to test each index's ability to measure changes in aortic stiffness while accounting for confounding factors and measurement errors. The study provides freely available tools for analyzing these and additional indices.

Recent development of piezoelectric biosensors for physiological signal detection and machine learning assisted cardiovascular disease diagnosis

As cardiovascular disease stands as a global primary cause of mortality, there has been an urgent need for continuous and real-time heart monitoring to effectively identify irregular heart rhythms and to offer timely patient alerts. However, conventional cardiac monitoring systems encounter challenges due to inflexible interfaces and discomfort during prolonged monitoring. In this review article, we address these issues by emphasizing the recent development of the flexible, wearable, and comfortable piezoelectric passive sensor assisted by machine learning technology for diagnosis. This innovative device not only harmonizes with the dynamic mechanical properties of human skin but also facilitates continuous and real-time collection of physiological signals. Addressing identified challenges and constraints, this review provides insights into recent advances in piezoelectric cardiac sensors, from devices to circuit systems. Furthermore, this review delves into the integration of machine learning technologies, showcasing their pivotal role in facilitating continuous and real-time assessment of cardiac status. The synergistic combination of flexible piezoelectric sensor design and machine learning holds substantial potential in automating the detection of cardiac irregularities with minimal human intervention. This transformative approach has the power to revolutionize patient care paradigms.

Correlation analysis of human upper arm parameters to oscillometric signal in automatic blood pressure measurement

Cardiovascular diseases are the leading cause of global deaths, making cardiovascular health monitoring important. Measuring blood pressure using an automatic sphygmomanometer is the most widely used method to monitor cardiovascular health due to its accessibility, convenience, and strong correlation with cardiovascular diseases. In this work, in order to estimate brachial artery diameter, stiffness, or thickness using an automatic sphygmomanometer, the correlation between upper arm parameters and the oscillometric signal was intensively investigated through analytical, numerical, and experimental approaches. The parametric studies commonly revealed that the inner radius of the brachial artery is the most influential parameter in determining the amplitude of the oscillometric signal. The experimental results of using a cardiovascular simulator (a virtual patient) combined with upper arm phantoms with various inner radii of the brachial artery showed a 6.5% change in the oscillometric signal amplitude with a 10% artery radius variation. It was concluded that the oscillometric signal can be used to evaluate brachial artery diameter. Based on the clinical relationship between brachial artery diameter and cardiovascular risk factors such as hypertension, diabetes, and obesity, this study showed and verified a novel method to monitor brachial artery diameter and hence, cardiovascular risks while measuring blood pressure.

Acute and Long-Term Consequences of COVID-19 on Arterial Stiffness-A Narrative Review

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the ongoing global coronavirus (COVID-19) pandemic. Although initially viewed as an acute respiratory illness, COVID-19 is clearly a complex multisystemic disease with extensive cardiovascular involvement. Emerging evidence shows that the endothelium plays multiple roles in COVID-19 physiopathology, as both a target organ that can be directly infected by SARS-CoV-2 and a mediator in the subsequent inflammatory and thrombotic cascades. Arterial stiffness is an established marker of cardiovascular disease. The scope of this review is to summarize available data on the acute and long-term consequences of COVID-19 on vascular function. COVID-19 causes early vascular aging and arterial stiffness. Fast, noninvasive bedside assessment of arterial stiffness could optimize risk stratification in acute COVID-19, allowing for early escalation of treatment. Vascular physiology remains impaired at least 12 months after infection with SARS-CoV-2, even in otherwise healthy adults. This raises concerns regarding the extent of arterial remodeling in patients with preexisting vascular disease and the potential development of a persistent, chronic COVID-19 vasculopathy. Long-term follow up on larger cohorts is required to investigate the reversibility of COVID-19-induced vascular changes and their associated prognostic implications.

Differential prognostic burden of cardiovascular disease and lower-limb amputation on the risk of all-cause death in people with long-standing type 1 diabetes

Background

Cardiovascular disease (CVD) and nontraumatic lower-limb amputation (LLA) each results in reduced life expectancy in patients with type 1 diabetes, but the differential burden between these conditions is unknown. We compared the effects of CVD and LLA on the risk of mortality in people with type 1 diabetes.

Methods

We used pooled data from the SURGENE, GENEDIAB, and GENESIS prospective cohorts. Data were divided into: 1/absence of CVD (myocardial infarction and/or stroke) nor LLA, 2/history of CVD alone without LLA, 3/LLA alone without CVD or 4/both conditions at baseline. Participants with baseline history of peripheral artery disease were excluded from groups 1 and 2. The study endpoint was any death occurring during follow-up, regardless of the causes.

Results

Among 1169 participants (male 55%, age 40 ± 13 years, diabetes duration 23 ± 11 years), CVD, LLA or both were present at baseline in 49 (4.2%), 62 (5.3%) and 20 (1.7%) subjects, respectively. All-cause death occurred in 304 (26%) participants during 17-year follow-up, corresponding to 18,426 person-years and an incidence rate of 16 (95%CI, 15–18) per 1000 person-years. The risk of death increased in individuals with baseline history of CVD (adjusted HR 2.00 [95% CI 1.34–3.01], p = 0.0008) or LLA (2.26 [1.56–3.28], p < 0.0001), versus no condition, with an additive effect in people with both conditions (5.32 [3.14–9.00], p < 0.0001). No incremental risk of death was observed in people with CVD versus LLA (0.87 [0.54–1.41]). Compared with no condition, CVD and LLA were similarly associated with reduced life expectancy during follow-up: 2.79 (95% CI 1.26–4.32) and 3.38 (1.87–4.88) years, respectively. Combined conditions expose to 7.04 (4.76–9.31) less years of life expectancy (all p < 0.0001).

Conclusions

CVD and LLA conferred a similar burden regarding mortality in type 1 diabetes population. Our findings encourage a careful consideration of people with type 1 diabetes and LLA as usually recommended for those with CVD, in terms of management of risk factors, treatments and prevention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01487-8.

Assessing hemodynamics from the photoplethysmogram to gain insights into vascular age: A review from VascAgeNet

The photoplethysmogram (PPG) signal is widely measured by clinical and consumer devices, and it is emerging as a potential tool for assessing vascular age. The shape and timing of the PPG pulse wave are both influenced by normal vascular aging, changes in arterial stiffness and blood pressure, and atherosclerosis. This review summarizes research into assessing vascular age from the PPG. Three categories of approaches are described: 1) those which use a single PPG signal (based on pulse wave analysis), 2) those which use multiple PPG signals (such as pulse transit time measurement), and 3) those which use PPG and other signals (such as pulse arrival time measurement). Evidence is then presented on the performance, repeatability and reproducibility, and clinical utility of PPG-derived parameters of vascular age. Finally, the review outlines key directions for future research to realize the full potential of photoplethysmography for assessing vascular age.

Estimation of aortic pulse wave velocity based on waveform decomposition of central aortic pressure waveform

Objective.Aortic stiffness is associated with risk of cardiovascular events. Carotid-femoral pulse wave velocity (cfPWV) is the current noninvasive gold standard for assessing aortic stiffness. However, the cfPWV measurement is challenging, requiring simultaneous signals at the carotid and femoral sites.Approach.In this study, the aortic PWV is estimated using a single radial pressure waveform and compared with cfPWV. 111 subjects' aortic PWVs are estimated from the decomposition of the derived central aortic pressure waveform based on three types of reconstructed flow waveform: the peak of triangular flow waveform based on 30% ejection time (Q_30%tri), the peak of triangular flow waveform based on inflection point (Q_tri), and averaged flow waveform (Q_avg). The central aortic pressure waveform is derived from a radial pressure waveform via a validated transfer function.Main results.TheQ_avgis used for estimating aortic PWV without the determination of the peak point of the triangular flow waveforms. The estimated aortic PWV shows good agreement with cfPWV. The mean difference ± SD is 0.29 ± 1.50 m s^-1(r² = 0.29,p< 0.001) for theQ_30%tri; 0.27 ± 1.40 m s^-1(r² = 0.38,p < 0.001) for theQ_tri; 0.23 ± 1.39 m s^-1(r² = 0.40,p < 0.001) for theQ_avg. The correlation between estimated aortic PWV based onQ_30%triand measured cfPWV is weak. The results ofQ_triandQ_avgshow no obvious difference.Significance.The proposed method can be used as a less complex way than conventional measurement of cfPWV to further assess arterial stiffness and predict cardiovascular risks or events.

Non-Invasive Methods for PWV Measurement in Blood Vessel Stiffness Assessment

In recent years, statistical studies highlighted an increasing incidence of cardiovascular diseases (CVD) which reflected on additional costs on the healthcare systems worldwide. Pulse wave velocity (PWV) measurement is commonly considered a CVD predictor factor as well as a marker of Arterial Stiffness (AS), since it is closely related to the mechanical characteristics of the arterial wall. An increase in PWV is due to a more rigid arterial system. Because of the prevalence of the elastic component, in young people the PWV is lower than in the elderly. Nowadays, invasive and non-invasive methods for PWV assessment are employed: there is an increasing attention in the development of non-invasive devices which mostly perform a regional PWV measurement (over a long arterial portion) rather than local (over a short arterial portion). The accepted gold-standard for non-invasive AS measurement is the carotid-femoral PWV used to evaluate the arterial damage, the corresponding cardiovascular risk and to adapt the proper therapy. This review article considers the main commercially available devices underlining their operating principles in terms of sensors, execution mode, pulse waveform acquired, site of measurement, distance and time estimation methods, as well as their main limitations in clinical practice.

Relationship Between Diabetic Retinopathy Stages and Risk of Major Lower-Extremity Arterial Disease in Patients With Type 2 Diabetes

OBJECTIVE

We evaluated the association between diabetic retinopathy stages and lower-extremity arterial disease (LEAD), its prognostic value, and the influence of potential contributors to this relationship in a prospective cohort of patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Diabetic retinopathy was staged at baseline as absent, nonproliferative, or proliferative. A Cox regression model was fitted in order to compute the hazard ratio (HR) (95% CI) for major LEAD (lower-limb amputation or revascularization) during follow-up by baseline retinopathy stages. The retinopathy-LEAD association was assessed in subgroups by age, sex, diabetes duration, HbA_1c, systolic blood pressure, diabetic kidney disease, smoking, and macrovascular disease at baseline. The performance of retinopathy in stratifying LEAD risk was assessed by using the C statistic, integrated discrimination improvement (IDI), and net reclassification improvement (NRI).

RESULTS

Among 1,320 participants without a history of LEAD at baseline, 94 (7.1%) developed a major LEAD during a 7.1-year median follow-up (incidence rate 9.6 per 1,000 person-years [95% CI 7.8-11.7]). The LEAD incidence rate (per 1,000 person-years) increased as retinopathy worsened: it was 5.5 (95% CI 3.9-7.8) in participants in whom retinopathy was absent, 14.6 (11.1-19.3) in those with nonproliferative retinopathy, and 20.1 (11.1-36.3) in those with proliferative retinopathy. Nonproliferative retinopathy (adjusted HR 2.31 [95% CI 1.43-3.81], P = 0.0006) and proliferative retinopathy (3.14 [1.40-6.15], P = 0.007) remained associated with major LEAD. No heterogeneity was observed across subgroups. Retinopathy enhanced the C statistic (+0.023 [95% CI 0.003-0.044], P = 0.02), IDI (0.209 [0.130-0.321], P < 0.001), and NRI (0.562 [0.382-0.799], P < 0.001) values for risk of LEAD, beyond traditional risk factors.

CONCLUSIONS

An independent dose-response relationship was identified between diabetic retinopathy stages and major LEAD. Retinopathy yielded incremental prognostic information for stratifying risk of LEAD, suggesting its usefulness as a predictor of LEAD.

Current assessment of pulse wave velocity: comprehensive review of validation studies

OBJECTIVE

Carotid-femoral pulse wave velocity (PWV) is considered the gold standard for arterial stiffness assessment in clinical practice. A large number of devices to measure PWV have been developed and validated. We reviewed different validation studies of PWV estimation techniques and assessed their conformity to the Artery Society Guidelines and the American Heart Association recommendations.

METHODS

Pubmed and Medline (1995-2017) were searched to identify PWV validation studies. Of the 96 article retrieved, 26 met the inclusion criteria.

RESULTS

Several devices had been developed and validated to noninvasively measure arterial stiffness, using applanation tonometry (SphygmoCor, PulsePen), piezoelectric mechanotransducers (Complior), cuff-based oscillometry (Arteriograph, Vicorder and Mobil-O-Graph), photodiode sensors (pOpmètre) and devices assessing brachial-ankle pulse wave velocity and cardiac-ankle PWV. Ultrasound technique and MRI remain confined to clinical research. Good agreement was found with the Artery Society Guidelines. Two studies (Complior, SphygmoCor Xcel) showed best adherence with the guidelines. In Arteriograph, MRI, ultrasound and SphygmoCor Xcel validation studies sample size was smaller than the minimum suggested by the guidelines. High discrepancies between devices were shown in distance estimation: in two studies (Arteriograph, Complior) path length was estimated in conformity to the guidelines. Transit time was calculated using the intersecting tangent method, but in two studies (Vicorder, pOpmètre) best agreement was found using the maximum of the second derivative. Six studies reached the accuracy level 'excellent' defined in the Artery guidelines.

CONCLUSION

Method to assess transit time and path length need validation in larger populations. Further studies are required in different risk population to implement clinical applicability of every device.

How to Measure Arterial Stiffness in Humans

Despite the wide recognition of larger artery stiffness as a highly clinically relevant and independent prognostic biomarker, it has yet be incorporated into routine clinical practice and to take a more prominent position in clinical guidelines. An important reason may be the plethora of methods and devices claiming to measure arterial stiffness in humans. This brief review provides a concise overview of methods in use, indicating strengths and weaknesses. We classified and graded methods, highly weighing their scrutiny and purity in quantifying arterial stiffness, rather than focusing on their ease of application or the level at which methods have demonstrated their prognostic and diagnostic potential.

Standardization of a new non-invasive device for assessment of arterial stiffness in rats: Correlation with age-related arteries' structure

Pulse wave velocity (PWV) has become a gold standard index to quantify the stiffness of the aorta and is a predictor of cardiovascular events. A recent paper compared the pOpmètreⓇ, a device for measuring the finger-toe PWV, with other techniques and demonstrated its accuracy and validity. However, human devices do not allow the advancement of our knowledge on conditioning mechanisms. Based on its human validation, a new device, pOpetⓇ 1.0 system was designed for estimation of PWV in small animals and this present study aimed to standardize the pOpetⓇ 1.0 for estimation of arterial stiffness in rats, and to confirm its liability and stability as well as the reproducibility of assessments. Therefore several precautions were taken into consideration like as the correct position of the animal and photodiodes according to manufacturers' suggestions. Results indicated that estimation of PWV through the new pOpetⓇ 1.0 device exhibits good internal consistency, stability and objectivity in all tests performed between days and evaluators. Importantly, data suggest for the first time that this new device is able to detect changes in arterial stiffness that are conditioned by age and pressure-related arterial remodeling. • This new pOpetⓇ device is able to detect changes in vessel structure. • This new pOpetⓇ device exhibits good internal consistency, stability and objectivity in all tests performed • Correct position of the animal and photodiodes are crucial to obtain a very stable signal.

Simplified pulse wave velocity measurement in children: Is the pOpmètre valid?

In population exposed to cardiovascular risk, aortic stiffness is an important marker which is assessed by carotid-to-femoral pulse wave velocity (PWV). In childhood, the validated applanation tonometer SphygmoCor® can be used to measure PWV, but is limited in routine practice by the child's cooperation and operator's experience. An alternative device, the pOpmètre® is validated in adults and rapidly measures finger-to-toe PWV using 2 oxymeter-like sensors. The aim of this study is to validate the pOpmètre® device in children aged between 4 and 8 years. We compared simultaneous PWV measurements of the two devices, SphygmoCor® and pOpmètre®, in a training group, using the Bland-Altman method. Then we proposed an algorithm to correct pOpmètre® PWV (PWVpop). Finally, we validated this new algorithm in a validation group of children using the Bland-Altman method. This prospective study enrolled 26 children in the training group. Mean PWVpop was 3.919 ± 0.587 m/s and mean SphygmoCor® PWV was 4.280 ± 0.383 m/s, with a difference of -0.362(CI95%(-0.546;-0.178)) m/s. A new algorithm was defined using transit time (TTpop): corrected PWVpop (m/s) = 0.150/TTpop(s) + 1.381*Height(m) + 1.148. We enrolled 24 children in the validation group. Mean corrected PWVpop was 4.231 ± 0.189 m/s and mean SphygmoCor® PWV was 4.208 ± 0.296 m/s with a corrected difference of 0.023(CI95%(-0.086;0.131)) m/s. With this algorithm correction, we found an agreement between PWV measured by the SphygmoCor® and the pOpmètre®, with a difference of less than 10%. Using this algorithm, the pOpmètre® could be used in clinical or research practice in young children exposed to cardiovascular risk. (This study was registered as NCT02991703).

Improvement in arterial stiffness (pOpmètre®) after bariatric surgery. Results from a prospective study

BACKGROUND

Arterial stiffness (AS) is an independent predictor of cardiovascular risk, and could be used as a surrogate marker of improvement in cardiovascular risk following bariatric surgery. The aim of this study was to compare AS before and after surgery.

METHODS

One hundred and thirty-four patients undergoing bariatric surgery between May 2016 and January 2019 were prospectively included. AS was measured on pulse wave velocity (PWV) with the pOpmètre® device pre- and postoperatively. The main endpoint was change in PWV between baseline and 3 months post-surgery.

RESULTS

Overall, mean PWV was 6.87m/s preoperatively and 6.71m/s at 3 months (P=0.7148). Patients with pathologic PWV (>2 standard deviations from expected value for age) showed significant improvement at 3 months (31 patients; 10.1m/s preoperatively vs 7.5m/s at 3 months; P=0.007). These results did not correlate with improvement in other clinical or biological parameters following surgery (excess weight loss, mean blood pressure, fasting blood glucose, waist circumference, body composition).

CONCLUSION

These results suggest that pathological arterial stiffness may resolve following bariatric surgery independently of the other factors influencing cardiovascular risk in obesity.

Mapping the site-specific accuracy of loop-based local pulse wave velocity estimation and reflection magnitude: a 1D arterial network model analysis

OBJECTIVE

Local pulse wave velocity (PWV) can be estimated from the waterhammer equation and is an essential component of wave separation analysis. However, previous studies have demonstrated inaccuracies in the estimations of local PWV due to the presence of reflections. In this study we compared the estimates of local PWV from the PU-loop, ln(D)U-loop, QA-loop and ln(D)P-loop methods along the complete human arterial tree, and analyzed the impact of the estimations on subsequent wave separation analysis.

APPROACH

Estimated values were derived from the numerical outputs (pressure, flow, flow velocity, area and diameter waveforms) of a 1D model of the human circulation, and compared against a reference PWV obtained from the Bramwell-Hill equation in a reference configuration, and in a configuration with lower distensibility representing ageing.

MAIN RESULTS

When including all nodes, the overall performance of the methods was poor (correlations and mean differences of R ²  <  0.4 and 3.0  ±  4.1 m s^-1 for the PU-loop, R ²  <  0.07 and  -0.7  ±  2.3 m s^-1 for the ln(D)U-loop, and R ²  <  0.06 and  -0.4  ±  2.3 m s^-1 for the QA-loop). Focusing on specific sites, the ln(D)U- and QA-loop methods yielded acceptable results in the thoracic aorta and iliac arteries, while the PU-loop method was acceptable at the aortic arch. The reflection-insensitive ln(D)P-loop method performed well over the complete network (R ²  =  0.9 and 0.3  ±  0.3 m s^-1), as did a previously proposed reflection-correction method for most vascular sites. Large errors in PWV estimation are attenuated in subsequent wave separation analysis, but the errors are site-dependent.

SIGNIFICANCE

We conclude that the performances of the PU-loop, ln(D)U-loop and QA-loop methods are highly site-specific. The results should be interpreted with caution at all times.

The Predictive Value of Pulse Wave Velocity for Anastomotic Leakage After Colorectal Surgery

BACKGROUND

Arterial perfusion defects are a risk factor for anastomotic leakage (AL) following colorectal surgery. Measuring arterial stiffness using pulse wave velocity (PWV) is known to reflect the performance of the arterial network. The objective of this study was to assess the predictive value of PWV for AL after colorectal surgery.

METHODS

A prospective monocentric study was conducted on all consecutive patients who underwent colorectal surgery scheduled between March 1, 2016 and May 1, 2017. Patients were divided into two groups according to the PWV which was measured preoperatively using the pOpmètre^® device: PWV+ (PWV > 10 m/s) and PWV- (PWV ≤ 10 m/s). We then compared the PWV+ and PWV- groups. The primary endpoint was the AL rate.

RESULTS

A total of 96 patients were studied, including 60 in the PWV- group and 36 in the PWV+ group. Patients in the PWV+ group were more at risk of presenting with AL than those in the PWV- group (6.25 vs 0%) (p = 0.002). There was no difference in immediate postoperative complications between the two groups apart from the length of hospital stay. PWV predicted the appearance of AL with a sensitivity of and a negative predictive value of 100%.

CONCLUSION

Measuring PWV could be a used as a predictive examination in the early detection of AL after colorectal surgery.

Pulse wave velocity is lower in trained than in untrained sickle cell trait carriers

BACKGROUND

Sickle cell trait (SCT) is a benign condition of sickle cell disease. Nevertheless, previous reports showed that SCT carriers have increased blood viscosity and decreased vascular reactivity compared to non-SCT carrier. The benefit of regular exercise on vascular function has been well documented in the general population but no study focused on the SCT population.

PURPOSE

The aim of our study was to compare arterial stiffness and blood viscosity between trained and untrained SCT carriers, as well as a group of untrained non-SCT.

METHODS

Arterial stiffness (finger-toe pulse wave velocity) and blood viscosity were evaluated in untrained non-SCT carriers (n = 10), untrained SCT carriers (n = 23) and trained SCT carriers (n = 17) who reported at least 10 hours of physical exercise per week.

RESULTS

Untrained SCT carriers had higher pulse wave velocity (p = 0.032) and blood viscosity (p < 0.001) than their trained counterparts. In addition, untrained SCT carriers had higher blood viscosity (p < 0.001) than the untrained non-SCT group. A positive association was noted between blood viscosity and pulse wave velocity in the whole study population.

CONCLUSION

Our study suggests that regular exercise may be beneficial for the vascular function of SCT carriers.

Difference between ejection times measured at two different peripheral locations as a novel marker of vascular stiffness

Pulse wave velocity (PWV) has been recommended as an arterial damage assessment tool and a surrogate of arterial stiffness. However, the current technology does not allow to measure PWV both continuously and in real-time. We reported previously that peripherally measured ejection time (ET) overestimates ET measured centrally. This difference in ET is associated with the inherent vascular properties of the vessel. In the current study we examined ETs derived from plethysmography simultaneously at different peripheral locations and examined the influence of the underlying arterial properties on ET prolongation by changing the subject’s position. We calculated the ET difference between two peripheral locations (ΔET) and its corresponding PWV for the same heartbeat. The ΔET increased with a corresponding decrease in PWV. The difference between ΔET in the supine and standing (which we call ET index) was higher in young subjects with low mean arterial pressure and low PWV. These results suggest that the difference in ET between two peripheral locations in the supine vs standing positions represents the underlying vascular properties. We propose ΔET in the supine position as a potential novel real-time continuous and non-invasive parameter of vascular properties, and the ET index as a potential non-invasive parameter of vascular reactivity.

Numerical assessment and comparison of pulse wave velocity methods aiming at measuring aortic stiffness

Pulse waveform analyses have become established components of cardiovascular research. Recently several methods have been proposed as tools to measure aortic pulse wave velocity (aPWV). The carotid-femoral pulse wave velocity (cf-PWV), the current clinical gold standard method for the noninvasive assessment of aPWV, uses the carotid-to-femoral pulse transit time difference (cf-PTT) and an estimated path length to derive cf-PWV.

OBJECTIVE

The heart-ankle PWV (ha-PWV), brachial-ankle PWV (ba-PWV) and finger-toe (ft-PWV) are also methods presuming to approximate aPWV based on time delays between physiological cardiovascular signals at two locations (~heart-ankle PTT, ha-PTT; ~brachial-ankle PTT, ba-PTT; ~finger-toe PTT, ft-PTT) and a path length typically derived from the subject's height. To test the validity of these methods, we used a detailed 1D arterial network model (143 arterial segments) including the foot and hand circulation.

APPROACH

The arterial tree dimensions and properties were taken from the literature and completed with data from patient scans. We calculated PTTs with all the methods mentioned above. The calculated PTTs were compared with the aortic PTT (aPTT), which is considered as the absolute reference method in this study.

MAIN RESULTS

The correlation between methods and aPTT was good and significant, cf-PTT (R ²  =  0.97; P  <  0.001; mean difference 5  ±  2 ms), ha-PTT (R ²  =  0.96; P  <  0.001; 150  ±  23 ms), ba-PTT (R ²  =  0.96; P  <  0.001; 70  ±  13 ms) and ft-PTT (R ²  =  0.95; P  <  0.001; 14  ±  10 ms). Consequently, good correlation was also observed for the PWV values derived with the tested methods, but absolute values differed because of the different path lengths used.

SIGNIFICANCE

In conclusion, our computer model-based analyses demonstrate that for PWV methods based on peripheral signals, pulse transit time differences closely correlate with the aortic transit time, supporting the use of these methods in clinical practice.

Measurement of Aortic Pulse Wave Velocity With a Connected Bathroom Scale

BACKGROUND

Measurement of arterial stiffness should be more available. Our aim was to show that aortic pulse wave velocity can be reliably measured with a bathroom scale combining the principles of ballistocardiography (BCG) and impedance plethysmography on a single foot.

METHOD

The calibration of the bathroom scale was conducted on a group of 106 individuals. The aortic pulse wave velocity was measured with the SphygmoCor in the supine position. Three consecutive measurements were then performed on the Withings scale in the standing position. This aorta-leg pulse transit time (alPTT) was then converted into a velocity with the additional input of the height of the person. Agreement between the SphygmoCor and the bathroom scale so calibrated is assessed on a separate group of 86 individuals, following the same protocol.

RESULTS

The bias is 0.25 m·s⁻¹ and the SE 1.39 m·s⁻¹. This agreement with Sphygmocor is “acceptable” according to the ARTERY classification. The alPTT correlated well with cfPTT with (Spearman) R = 0.73 in pooled population (cal 0.79, val 0.66). The aorta-leg pulse wave velocity correlated with carotid-femoral pulse wave velocity with R = 0.76 (cal 0.80, val 0.70).

CONCLUSION

Estimation of the aortic pulse wave velocity is feasible with a bathroom scale. Further investigations are needed to improve the repeatability of measurements and to test their accuracy in different populations and conditions.

[Impact of sickle cell trait on arterial stiffness in African subjects]

Sickle cell trait (SCT) is the benign condition of sickle cell disease. Often asymptomatic, the carriers of the sickle cell trait have hemorheological disturbances with increased oxidative stress compared to healthy subjects. These disturbances can lead to structural and functional changes in large vessels. The aim of the study was to measure arterial stiffness, an independent marker of subclinical atherosclerosis, SCT carriers compared to sickle cell anemia (SCA) subjects. Nine SCT carriers aged 32±9 years (7 men) were compared to 14 SCA subjects aged 29±9 years (2 men) and 22 control subjects aged 34±9 years (11 men) recruited by the National blood transfusion center (CNTS) in Dakar (Senegal). Arterial stiffness was assessed by measurement of the finger-toe pulse wave velocity (PWVft) using pOpmètre^® (Axelife SAS-France). The cardiovascular risk (CVR) was assessed according to the Framingham Laurier score. The SCT carriers had a higher PWVft (m/s) than SCA subjects (8.2±2.2 vs 6.1±0.9m/s, P=0.004) but not different from that of healthy controls (8.2±2.2 vs 7.4±1.8m/s, P=0.33). Linear regression showed a positive relationship between PWVft and the pulse pressure (PP) (P˂0.001; r²=0.39; F=13.20). The results show that the SCT carriers have stiffer arteries than SCA subjects. Linear regressions adjusted for age, mean arterial pressure (MAP) and PP, showed that only age and PP were independently correlated with arterial stiffness in the entire population.

A novel signal acquisition platform of human cardiovascular information with noninvasive method

Cardiovascular diseases (CVDs) are considered the major cause of death worldwide, so more researchers pay more and more attention to the development of a non-invasive method to obtain as much cardiovascular information (CVI) as possible for early screening and diagnosing. It is known that considerable brain information could be probed by a variety of stimuli (such as video, light, and sound). Therefore, it is quite possible that much more CVI could be extracted via giving the human body some special interrelated stimulus. Based on this hypothesis, we designed a novel signal platform to acquire more CVI with a special stimulus, which is to give a gradual decrease and a different settable constant pressure to six air belts placed on two-side brachia, wrists, and ankles, respectively. During the stimulating process, the platform is able to collect 24-channel dynamic signals related with CVI synchronously. Moreover, to improve the measurement accuracy of signal acquisition, a high precision reference chip and a software correction are adopted in this platform. Additionally, we have also shown some collection instances and analysis results in this paper for its reliability. The results suggest that our platform can not only be applied on study in a deep-going way of relationship between collected signals and CVDs but can also serve as the basic tool for developing a new noninvasive cardiovascular function detection instrument and system that can be used both at home and in the hospital.

Outpatient measurement of arterial stiffness in patients with type 2 diabetes and obesity

BACKGROUND

Pulse wave velocity (PWV) is a marker of arterial stiffness. The aim of the present study was to compare PWV in patients with type 2 diabetes mellitus (T2DM) or obesity and healthy subjects in an outpatient setting.

METHODS

A cross-sectional study was conducted in patients with obesity without T2DM (n = 37), T2DM without obesity (n = 40), T2DM plus obesity (n = 43), and healthy controls (n = 114). Outpatient measurements of the finger-toe PWV (ftPWV) were made.

RESULTS

Mean (± SD) ftPWV was higher in men than in women (10.57 ± 5.02 vs 9.14 ± 3.68 m/s, respectively P = 0.006) and was positively correlated with age (r²  = 0.31, P < 0.0001), body mass index (r²  = 0.03, P = 0.01), systolic blood pressure (SBP; r²  = 0.06, P < 0.0001), and right (r²  = 0.03, P = 0.01) and left (r²  = 0.03, P = 0.01) ankle-brachial index (ABI). Age, SBP and ABI remained significantly correlated with ftPWV in the stepwise regression analysis. Mean ftPWV in controls and in patients with obesity, T2DM, and T2DM plus obesity was 8.32 ± 2.68, 9.50 ± 3.38, 11.29 ± 4.34, and 12.36 ± 6.67 m/s, respectively (P < 0.0001). These differences remained significant after adjustments for sex, age, SBP, and ABI (P = 0.008). Although ftPWV was higher in patients with than without macrovascular complications (13.11 ± 6.25 vs 10.40 ± 4.54 m/s, respectively; P = 0.006) in univariate analysis, this was not so in the multivariate-adjusted model.

CONCLUSIONS

Outpatient-measured ftPWV was correlated with age, SBP, and ABI. It was higher in patients with T2DM and obesity compared with healthy controls. The highest ftPWV was observed in patients with both T2DM and obesity.

A simplified measurement of pulse wave velocity is not inferior to standard measurement in young adults and children

The standard measurement of pulse wave velocity (PWV) is restricted by the need for simultaneous tonometry measurements requiring two technicians and expensive equipment, limiting this technique to well-resourced settings. In this preliminary study, we compared a simplified method of pulse wave detection from the finger and toe to pulse wave detection from the carotid and radial arteries using applanation tonometry in children and young adults. We hypothesized that the simplified method of PWV measurement would strongly correlate with the standard measurement in different age groups and oxygen conditions. Participants included (a) boys and girls aged 8-12 years and (b) men and women aged 18-40 years. Participants rested supine while carotid and radial artery pulse waves were measured using applanation tonometry and finger and toe pulse waves were simultaneously collected using a Finometer Midi and a piezo-electric pulse transducer, respectively. These measurements were repeated under hypoxic conditions. Finger-toe PWV measurements were strongly correlated to carotid-radial PWV in adults (R=0.58; P=0.011), but not in children (R=0.056; P=0.610). Finger-toe PWV was sensitive enough to show increases in PWV with age (P<0.0001) and hypoxia in children (P<0.0001) and adults (P=0.003). These results indicate that the simplified measurement of finger-toe PWV strongly correlates with the standard measurement of carotid-radial PWV in adults, but not in children. However, finger-toe PWV can be used in either population to determine changes with hypoxia.