Increased arterial wave reflections predict severe cardiovascular events in patients undergoing percutaneous coronary interventions

Study Protocol of a Prospective, Monocentric, Single-Arm Study Investigating the Correlation of Endograft Properties with Aortic Stiffness in Abdominal Aortic Aneurysm Patients Subjected to Endovascular Aortic Repair

The number of endovascular aortic repairs (EVARs) has surpassed the number of open surgical repairs of abdominal aortic aneurysms (AAAs) worldwide. The available commercial endoprostheses are composed of materials that are stiffer than the native aortic wall. As a consequence, the implantation of stent-graft endoprostheses during EVAR increases aortic rigidity and thus aortic stiffness, resulting in a decrease in abdominal aorta compliance. EVAR has been found to have a possibly harmful effect not only on heart functions but also on other vascular beds, including kidney function, due to the decrease in aortic compliance that it causes. Aortic stiffness is measured by various hemodynamic indices like the pulse wave velocity (PWV), the central aortic pressure (CAP), and the augmentation index (AIx). In the literature, there are increasing numbers of studies investigating the properties of endografts, which are strongly related to increases in aortic stiffness. However, there is a lack of data on whether there is a correlation between the length of various endografts implanted during EVAR and the increase in the PWV, CAP, and AIx postoperatively compared to the preoperative values. The aim of this prospective, observational, monocentric, single-arm study is to investigate the correlation between endograft length and the postoperative increase in the PWV, CAP, and AIx in patients subjected to EVAR. Additionally, this study intends to identify other endograft properties related to increases in the PWV, CAP, and AIx. Other endpoints to be studied are the existence of immediate postoperative myocardial and kidney injury after EVAR. The prediction of cardiovascular events caused by endograft-related increased aortic stiffness could contribute to the improvement of various endograft properties so that the impact of endografts on the native aortic wall can be minimized.

Arterial Stiffness and its Impact on Cardiovascular Health

PURPOSE OF REVIEW

Cardiovascular diseases are the leading cause of mortality globally. Identifying patients at risk is important to initiate preventive strategies. Over the last few decades, the role of the endothelium and its impact on arterial stiffness have been recognised as playing a pivotal role in cardiovascular disease. This review will focus on the effect of arterial stiffness in different patient cohorts with regard to cardiovascular morbidity and mortality, as well as its use in clinical practice.

RECENT FINDINGS

Arterial stiffness is associated with a range of cardiovascular risk factors and is an independent predictor of cardiovascular mortality. The gold standard for evaluating arterial stiffness is pulse wave velocity. Recently, cardio-ankle vascular index has been implemented as an easy and highly reproducible measure of arterial stiffness. Moreover, certain pharmacologic agents may modify arterial stiffness and alter progression of cardiovascular disease. The endothelium plays an important role in cardiovascular disease. Implementing assessment of arterial stiffness in clinical practice will improve stratification of patients at risk of cardiovascular disease and help modify disease progression.

The effect of exercise training level on arterial stiffness after clinically significant weight loss

Arterial stiffness is improved by weight loss. However, no data exist on the impact of aerobic exercise levels on arterial stiffness during weight maintenance. Adults who were  overweight or with obesity (N = 39) participated in a 10-week weight loss program. Participants who achieved ≥7% weight loss were randomized to aerobic training at the minimum physical activity guidelines (PA-REC, 550 MET min/week) or weight maintenance guidelines (WM-REC, 970 MET min/week) for 18 additional weeks. Arterial stiffness (carotid-to-femoral pulse wave velocity [cfPWV], augmentation index normalized for 75 beats/min [AIX75]) and blood pressure [aortic and brachial]) were assessed at baseline, the end of the weight loss phase (week 10), and follow-up (week 28). There was a reduction in cfPWV in participants who met the weight loss goal (-0.34 m/s, p = .02) and approached significance for the entire sample (p = .051). Similarly, there were reductions in AIX75, brachial blood pressure, and aortic blood pressure (p < .05) in the full sample. In the weight maintenance phase, no differences were observed between the PA-REC and the WM-REC groups for change in arterial stiffness or blood pressure (p > .05). However, changes in cfPWV were independently associated with changes in LDL (r2 : 0.45, p = .004) and exercise intensity (r2 : 0.17, p = .033). Aerobic exercise level at the minimum physical activity guidelines or weight maintenance guidelines does not affect the change in PWV or the change in cfPWV after clinically significant weight loss. However, interventions which limit increases in LDL cholesterol and promote high-intensity aerobic exercise may prevent increases in stiffness during weight maintenance.

Aortic blood pressure and pulse wave indices responses to exercise in peripheral artery disease

Peripheral artery disease (PAD) refers to obstructed blood flow in peripheral arteries typically due to atherosclerotic plaques. How PAD alters aortic blood pressure and pressure wave propagation during exercise is unclear. Thus, this study examined central blood pressure responses to plantar flexion exercise by investigating aortic pulse wave properties in PAD. Thirteen subjects with PAD and 13 healthy [age-, sex-, body mass index (BMI) matched] subjects performed rhythmic plantar flexion for 14 min or until fatigue (20 contractions/min; started at 2 kg with 1 kg/min increment up to 12 kg). Brachial (oscillometric cuff) and radial (SphygmoCor) blood pressure and derived-aortic waveforms were analyzed during supine rest and plantar flexion exercise. At rest, baseline augmentation index (P = 0.0263) and cardiac wasted energy (P = 0.0321) were greater in PAD due to earlier arrival of the reflected wave (P = 0.0289). During exercise, aortic blood pressure (aMAP) and aortic pulse pressure showed significant interaction effects (P = 0.0041 and P = 0.0109, respectively). In particular, PAD had a greater aMAP increase at peak exercise (P = 0.0147). Moreover, the tension time index was greater during exercise in PAD (P = 0.0173), especially at peak exercise (P = 0.0173), whereas the diastolic time index (P = 0.0685) was not different between the two groups. Hence, during exercise, the subendocardial viability ratio was lower in PAD (P = 0.0164), especially at peak exercise (P = 0.0164). The results suggest that in PAD, the aortic blood pressure responses and myocardial oxygen demand during exercise are increased compared with healthy controls.

Vascular ageing: moving from bench towards bedside

Prevention of cardiovascular disease (CVD) remains one of the largest public health challenges of our time. Identifying individuals at increased cardiovascular risk at an asymptomatic, sub-clinical stage is of paramount importance for minimizing disease progression as well as the substantial health and economic burden associated with overt CVD. Vascular ageing (VA) involves the deterioration in vascular structure and function over time and ultimately leads to damage in the heart, brain, kidney, and other organs. Vascular ageing encompasses the cumulative effect of all cardiovascular risk factors on the arterial wall over the life course and thus may help identify those at elevated cardiovascular risk, early in disease development. Although the concept of VA is gaining interest clinically, it is seldom measured in routine clinical practice due to lack of consensus on how to characterize VA as physiological vs. pathological and various practical issues. In this state-of-the-art review and as a network of scientists, clinicians, engineers, and industry partners with expertise in VA, we address six questions related to VA in an attempt to increase knowledge among the broader medical community and move the routine measurement of VA a little closer from bench towards bedside.

Prognostic value of central blood pressure on the outcomes of embolic stroke of undetermined source

We investigated the prognostic impact of central blood pressure (BP) on outcomes in patients with embolic stroke of undetermined source (ESUS). The prognostic value of central BP according to ESUS subtype was also evaluated. We recruited patients with ESUS and data on their central BP parameters (central systolic BP [SBP], central diastolic BP [DBP], central pulse pressure [PP], augmentation pressure [AP], and augmentation index [AIx]) during admission. ESUS subtype classification was arteriogenic embolism, minor cardioembolism, two or more causes, and no cause. Major adverse cardiovascular event (MACE) was defined as recurrent stroke, acute coronary syndrome, hospitalization for heart failure, or death. Over a median of 45.8 months, 746 patients with ESUS were enrolled and followed up. Patients had a mean age of 62.8 years, and 62.2% were male. Multivariable Cox regression analysis showed that central SBP and PP were associated with MACE. All-cause mortality was independently associated with AIx. In patients with no cause ESUS, central SBP and PP, AP, and AIx were independently associated with MACE. AP and AIx were independently associated with all-cause mortality (all p < 0.05). We demonstrated that central BP can predict poor long-term prognosis in patients with ESUS, especially those with the no cause ESUS subtype.

Association between Serum Soluble Urokinase-Type Plasminogen Activator Receptor Level and Arterial Stiffness in Chronic Hemodialysis Patients

Cardiovascular diseases (CVDs) remain a significant cause of death in hemodialysis (HD) patients. To explore their associations, we examine the role of soluble urokinase-type plasminogen activator receptor (suPAR) in arterial stiffness in chronic HD patients. From June to August 2020, we recruited 135 chronic HD patients. The arterial stiffness group included patients with a carotid–femoral pulse-wave velocity (cfPWV) of >10 m/s. Fifty-five HD patients (40.7%) were in the arterial stiffness group. They had a higher prevalence of diabetes (p = 0.001) and hypertension (p = 0.039), were older (p = 0.007) and had higher aortic systolic blood pressure (p = 0.034), brachial systolic blood pressure (p = 0.025), glucose (p = 0.019), C-reactive protein (p = 0.039), and AIx75 (p = 0.003) and suPAR (p < 0.001) levels than the control group. After we performed multivariable logistic regression analysis, except age and glucose, serum suPAR (odds ratio [OR]: 2.05; 95% confidence interval [CI]: 1.48–2.70, p < 0.001) was independently associated with arterial stiffness in chronic HD patients. In the multivariable linear regression analysis, suPAR positively correlated with cfPWV (β = 0.475, p < 0.001) and could serve as a biomarker for arterial stiffness development in patients undergoing HD.

Viewpoint: The Case for Non-Invasive Central Aortic Pressure Monitoring in the Management of Hypertension

Elevated central aortic pressure indices (e.g., systolic pressure and pulse pressure) predict cardiovascular (CV) events and mortality in addition to structural changes (e.g., left ventricular hypertrophy, carotid intima-media thickness and reduced glomerular filtration rate). These elevated risks have been shown in multiple studies to be superior to, and in others, at least as high as that associated with brachial pressures. Threshold values for the diagnosis of elevated central arterial pressures have been defined and can be considered target goals of treatment. Measurements of central arterial pressures can be incorporated into the current approaches to hypertension management utilizing currently available non-invasive devices that measure central pressures during the measurement of brachial BP. The objective of this review is to outline the rationale and evidence supporting incorporation of central aortic pressure monitoring into the care of patients with hypertension.

Vascular Aging and Arterial Stiffness

O envelhecimento biológico é reflexo da interação entre genética, idade cronológica e fatores externos; é a base para novos conceitos em envelhecimento vascular, cuja progressão é determinada pela diferença entre idade biológica e cronológica. Do ponto de vista estrutural, os efeitos do envelhecimento vascular são mais evidentes na camada média das grandes artérias elásticas e resultam em aumento da rigidez arterial, da dilatação do lúmen e da espessura da parede. Esses efeitos são descritos no continuum de envelhecimento cardiovascular (proposto por Dzau em 2010) em que as etapas progressivas de lesões da microvasculatura de coração, rins e cérebro, têm início a partir do processo de envelhecimento. O aumento da rigidez arterial pode ser verificado de forma não invasiva por vários métodos. Os eventos cardiovasculares têm sido tradicionalmente previstos utilizando escores que combinam fatores de risco convencionais para aterosclerose. No continuum cardiovascular clássico (Dzau, 2006), é desafiador avaliar o peso exato da contribuição de cada fator de risco; entretanto, por refletir o dano precoce e cumulativo desses fatores de riscos cardiovascular, a rigidez arterial reflete o verdadeiro dano à parede arterial. Este artigo fornece uma visão geral dos mecanismos da fisiopatogenia, alterações estruturais das artérias e consequências hemodinâmicas do envelhecimento arterial; métodos não invasivos para a avaliação da rigidez arterial e da medida central da pressão arterial; o continuum de envelhecimento cardiovascular, e aplicação do conceito de rigidez arterial na estratificação de risco cardiovascular.

Arterial Wave Reflection and Aortic Valve Stenosis: Diagnostic Challenges and Prognostic Significance

Introduction

Arterial wave reflection is an important component of the left ventricular afterload, affecting both pressure and flow to the aorta. The aim of the present study was to evaluate the impact of wave reflection on transvalvular pressure gradients (TPG), a key parameter for the evaluation of aortic valve stenosis (AS), as well as its prognostic significance in patients with AS undergoing a transcatheter aortic valve replacement (TAVR).

Materials and Methods

The study population consisted of 351 patients with AS (mean age 84 ± 6 years, 43% males) who underwent a complete hemodynamic evaluation before the TAVR. The baseline assessment included right and left heart catheterization, transthoracic echocardiography, and a thorough evaluation of the left ventricular afterload by means of wave separation analysis. The cohort was divided into quartiles according to the transit time of the backward pressure wave (BWTT). Primary endpoint was all-cause mortality at 1 year.

Results

Early arrival of the backward pressure wave was related to lower cardiac output (Q1: 3.7 ± 0.9 lt/min vs Q4: 4.4 ± 1.0 lt/min, p &lt; 0.001) and higher aortic systolic blood pressure (Q1: 132 ± 26 mmHg vs Q4: 117 ± 26 mmHg, p &lt; 0.001). TPG was significantly related to the BWTT, patients in the arrival group exhibiting the lowest TPG (mean TPG, Q1: 37.6 ± 12.7 mmHg vs Q4: 44.8 ± 14.7 mmHg, p = 0.005) for the same aortic valve area (AVA) (Q1: 0.58 ± 0.35 cm2 vs 0.61 ± 0.22 cm2, p = 0.303). In multivariate analysis, BWTT remained an independent determinant of mean TPG (beta 0.3, p = 0.002). Moreover, the prevalence of low-flow, low-gradient AS with preserved ejection fraction was higher in patients with early arterial reflection arrival (Q1: 33.3% vs Q4: 14.9%, p = 0.033). Finally, patients with early arrival of the reflected wave (Q1) exhibited higher all-cause mortality at 1 year after the TAVR (unadjusted HR: 2.33, 95% CI: 1.17–4.65, p = 0.016).

Conclusion

Early reflected wave arrival to the aortic root is associated with poor prognosis and significant aortic hemodynamic alterations in patients undergoing a TAVR for AS. This is related to a significant decrease in TPG for a given AVA, leading to a possible underestimation of the AS severity.

Twenty-Four-Hour Pulsatile Hemodynamics Predict Brachial Blood Pressure Response to Renal Denervation in the SPYRAL HTN-OFF MED Trial

Renal denervation (RDN) lowers blood pressure (BP), but BP response is variable in individual patients. We investigated whether measures of pulsatile hemodynamics, obtained during 24-hour ambulatory BP monitoring, predict BP drop following RDN.

Relationships between muscle sympathetic nerve activity and novel indices of arterial stiffness using single oscillometric cuff in patients with hypertension

The arterial velocity pulse index (AVI) and arterial pressure-volume index (API) have been proposed as new arterial stiffness indices that can be measured using an oscillometric cuff. Sympathetic nerve activity (SNA) contributes to arterial stiffness via increasing vascular smooth muscle tone. However, the associations between SNA and the AVI or API are not understood. The purpose of this study was to evaluate the relationships between muscle sympathetic nerve activity (MSNA) and the AVI or API in healthy individuals and patients with hypertension (HT). Forty healthy individuals (40.1 ± 15.2 years, 8 females) (healthy group) and 40 patients with HT (60.2 ± 13.6, 18 females) (HT group) were included in this study. The AVI, API, MSNA, beat-by-beat blood pressure, and heart rate were recorded simultaneously. The AVI and API were higher in the HT group than in the healthy group (AVI, 26.1 ± 7.6 vs. 16.5 ± 4.0, p < 0.001; API, 31.2 ± 8.6 vs. 25.5 ± 7.2, p = 0.002). MSNA in the HT group was also higher than in the healthy group (p < 0.001). MSNA was correlated with the AVI, but not with the API, in both the healthy group (R = 0.52, p = 0.001) and HT group (R = 0.57, p < 0.001). MSNA was independently correlated with the AVI in multivariate analysis (ß = 0.34, p = 0.001). In conclusion, AVI, obtained by a simple and less user-dependent method, was related to the MSNA in healthy individuals and patients with HT.

Non-Invasive Assessment of Arterial Stiffness: Pulse Wave Velocity, Pulse Wave Analysis and Carotid Cross-Sectional Distensibility: Comparison between Methods

Background: The stiffening of large elastic arteries is currently estimated in research and clinical practice by propagative and non-propagative models, as well as parameters derived from aortic pulse waveform analysis. Methods: Common carotid compliance and distensibility were measured by simultaneously recording the diameter and pressure changes during the cardiac cycle. The aortic and upper arm arterial distensibility was estimated by measuring carotid−femoral and carotid−radial pulse wave velocity (PWV), respectively. The augmentation index and blood pressure amplification were derived from the analysis of central pulse waveforms, recorded by applanation tonometry directly from the common carotid artery. Results: 75 volunteers were enrolled in this study (50 females, average age 53.5 years). A significant inverse correlation was found between carotid distensibility and carotid−femoral PWV (r = −0.75; p < 0.001), augmentation index (r = −0.63; p < 0.001) and central pulse pressure (r = −0.59; p < 0.001). A strong correlation was found also between the total slope of the diameter/pressure rate carotid curves and aortic distensibility, quantified from the inverse of the square of carotid−femoral PWV (r = 0.67). No correlation was found between carotid distensibility and carotid−radial PWV. Conclusions: This study showed a close correlation between carotid−femoral PWV, evaluating aortic stiffness by using the propagative method, and local carotid cross-sectional distensibility.

Hemodynamic variations in arterial wave reflection associated with the application of increasing levels of PEEP in healthy subjects

Positive end-expiratory pressure (PEEP) may affect arterial wave propagation and reflection, thus influencing ventricular loading conditions. The aim of the study was to investigate the hemodynamic variations in arterial wave reflection (i.e., wave reflection time, augmentation index, left ventricular ejection time, diastolic time, SEVR) associated with the application of increasing levels of PEEP in healthy subjects. We conducted a prospective observational study. Study population was selected from students and staff. Pulse contour wave analysis was performed from the right carotid artery during stepwise increase in PEEP levels (from 0 cmH₂O, 5 cmH₂0, 10 cmH₂O) with applanation tonometry. Sixty-two healthy volunteers were recruited. There were no significant changes in heart rate, augmentation index (AIx), left ventricular ejection time, Diastolic time (DT) among all of the different steps. A significant increase of time to the inflection point (Ti) was observed during all steps of the study. Diastolic area under the curve (AUC) divided by systolic-AUC (SEVR) increased from baseline to PEEP = 5 cmH₂O, and from baseline to PEEP = 10 cmH₂O. AIx and Ti were significantly correlated (directly) at the baseline and during PEEP = 10 cmH₂O. Ti and DT were significantly correlated at the baseline and during PEEP = 5 cmH₂O. In our preliminary results, low levels of PEEP played a role in the interaction between the heart and the vascular system, apparently mediated by a prolongation of the diastolic phase and a reduction in the systolic work of the heart.

Clinical trials registration number: NCT03294928, 19/09/2017.

Central versus ambulatory blood pressure for predicting mortality and cardiovascular events in hemodialysis patients: a multicenter cohort study

OBJECTIVE

Studies in the general population suggest that central blood pressure (BP) may be superior to peripheral BP in risk assessment. Although ambulatory brachial BP is recognized as the most reliable BP measurement in the dialysis population, there is no comparison of office central BP with ambulatory BP regarding risk stratification in these patients.

METHODS

In a multicenter prospective study of dialysis patients, central BP was measured noninvasively on a midweek nondialysis day, with interdialytic ambulatory BP and predialysis BP also collected. The primary outcomes were a composite of major adverse cardiovascular events (MACE) and all-cause mortality. Agreement between central and ambulatory BP was assessed using Cohen's Kappa index and Bland--Altman plot. Linear and nonlinear Cox regression models were used to determine the association of BP parameters with outcomes.

RESULTS

A total of 368 patients were recruited and 366 underwent central BP measurement. Central BP had a moderate agreement with ambulatory BP in defining hypertension (κ = 0.42) with wide limits of agreement in Bland--Altman analysis. After a median follow-up of 51.5 months, central pulse pressure, ambulatory SBP and ambulatory pulse pressure were associated with all-cause mortality, whereas all BP parameters, except for predialysis DBP, were significant predictors of MACE. However, whenever evaluated in a stepwise variable selection Cox model, only ambulatory pulse pressure, but not any central BP, was determined as the best candidate for prediction of both all-cause mortality and MACE. Nonlinear Cox models revealed no significant nonlinear trend of the association between central BP and outcomes.

CONCLUSION

Central BP is predictive of all-cause mortality and cardiovascular events in dialysis patients but its prognostic value does not outperform ambulatory peripheral BP. Our data support the superiority of ambulatory BP in the dialysis population.

Infrared sauna as exercise-mimetic? Physiological responses to infrared sauna vs exercise in healthy women: A randomized controlled crossover trial

BACKGROUND

Passive heat therapies have been reported to have similar effects on the cardiovascular system as exercise. Studies supporting these findings in healthy populations have predominantly been done with men using warm water immersions or traditional saunas, rather than newer infrared-based saunas.

OBJECTIVE

To explore short-term thermal and cardiovascular responses in women using an infrared sauna as compared to moderate-intensity exercise.

STUDY DESIGN

Randomized controlled crossover trial with balanced allocations.

SETTING

Brisbane, Australia (August 2019 - March 2020) PARTICIPANTS: Ten healthy women (36 ± 9 years) INTERVENTIONS: 45 min of resting, infrared sauna or indoor bicycling PRIMARY OUTCOME MEASURES: tympanic/skin temperatures; respiratory rate; blood pressure; arterial stiffness; heart rate variability RESULTS: Tympanic temperatures were elevated during infrared sauna as compared to both control (mean diff = +1.05 ^oC ± SEM 0.12 ^oC, 95% C.I.: 0.73 - 1.36, p < 0.0005) and exercise (mean diff = +0.79 ^oC ± SEM 0.12 ^oC, 95% C.I.: 0.49 - 1.08, p < 0.0005). Respiratory rates were higher during exercise as compared to both control (mean diff = +7.66 ± SEM 1.37, 95% C.I.: 4.09 - 11.23, p < 0.0005) and infrared sauna (mean diff = +6.66 ± SEM 1.33, 95% C.I.: 3.20 - 10.11, p < 0.0005). No significant differences in non-invasive measures of blood pressure, arterial stiffness or heart rate variability were detected between any of the interventions.

CONCLUSIONS

These findings suggest the physiological effects of infrared sauna bathing are underpinned by thermoregulatory-induced responses, more so than exercise-mimetic cardiorespiratory or cardiovascular activations.

Aortic Stiffness: Epidemiology, Risk Factors, and Relevant Biomarkers

Aortic stiffness (AoS) is a maladaptive response to hemodynamic stress and both modifiable and non-modifiable risk factors, and elevated AoS increases afterload for the heart. AoS is a non-invasive marker of cardiovascular health and metabolic dysfunction. Implementing AoS as a diagnostic tool is challenging as it increases with age and varies amongst races. AoS is associated with lifestyle factors such as alcohol and smoking, as well as hypertension and comorbid conditions including metabolic syndrome and its components. Multiple studies have investigated various biomarkers associated with increased AoS, and this area is of particular interest given that these markers can highlight pathophysiologic pathways and specific therapeutic targets in the future. These biomarkers include those involved in the inflammatory cascade, anti-aging genes, and the renin-angiotensin aldosterone system. In the future, targeting AoS rather than blood pressure itself may be the key to improving vascular health and outcomes. In this review, we will discuss the current understanding of AoS, measurement of AoS and the challenges in interpretation, associated biomarkers, and possible therapeutic avenues for modulation of AoS.

Arterial Stiffness in Renal Transplant Recipients: 5-Year Follow-up

BACKGROUND

Chronic kidney disease is a risk factor for cardiovascular diseases. After renal transplant, some traditional and chronic kidney disease-specific risk factors vanish, but new risk factors emerge. This retrospective study aimed to define the long-term impact of renal transplant and diabetes mellitus on arterial stiffness, evaluated by measuring pulse wave velocity (PWV) and augmentation index (AI) and on myocardial perfusion, evaluated by subendocardial viability ratio (SEVR).

METHODS

PWV, AI, and SEVR were evaluated noninvasively by applanation tonometry using SphygmoCor in the first 4 weeks after kidney transplant and 4 to 5 years thereafter.

RESULTS

A total of 48 graft recipients (18 women, 30 men; mean ± standard deviation age, 47.9 ± 11.8 years) were included. The follow-up period was 57.4 ± 8.0 months. PWV did not change significantly during the follow-up period (9.1 ± 1.8m/s and 8.7 ± 1.8m/s, respectively; P = .137). In the subgroup of patients without diabetes mellitus, we observed a trend of PWV reduction, whereas in the subgroup of patients with diabetes we observed the trend of PWV increase. The duration of smoking before transplant correlated significantly with PWV (P = .012). AI in the whole group increased significantly during the study period (from 18.3% ±10.3% to 25.9% ±9.4%; P < .01) as well as SEVR (from 134.9 ± 23.1 to 155.4 ± 28.6; P = .001).

CONCLUSIONS

PWV, reflecting the central vessel stiffness, did not change significantly in the whole group during the follow-up period. The AI, which indicates systemic stiffness, increased significantly within 5 years after transplant, indicating the progression of vascular processes of elastic and muscular arteries. Significant increases in the SEVR values in both diabetics and nondiabetics indicate the long-term favorable effect of kidney transplant on myocardial perfusion.

Evaluation of Vascular Pulse Contour Indices over the Physiological Blood Pressure Ranges in an Anesthetized Porcine Model

A series of physiological measures can be assessed from the arterial pulse waveform, which is beneficial for cardiovascular health diagnosis, monitoring, and decision making. In this work, we have investigated the variations in regional pulse wave velocity (PWVR) and other pulse waveform indexes such as reflected wave transit time (RWTT), augmentation index (Alx), ejection duration index (ED), and subendocardial viability ratio (SEVR) with blood pressure (BP) parameters and heartrate on a vasoconstrictor drug-induced porcine model. Two healthy female (nulliparous and non-pregnant) Sus scrofa swine (~ 80 kg) was used for the experimental study. The measurement system consists of a catheter-based system with two highly accurate pressure catheters placed via the sheath at the femoral and carotid artery for acquiring and recording the pressure waveforms. The pulse waveform indexes were extracted from these recorded waveforms. Results from the pulse contour analysis of these waveforms demonstrated that Phenylephrine, as a post-synaptic alpha-adrenergic receptor agonist that causes vasoconstriction, produced a significant increment in the carotid BP parameters and heartrate. Due to the drug's effect, the PWVR and SEVR were significantly increased, whereas the RWTT, AIx index and ED index significantly decreased.Clinical Relevance- This experimental study provides the usefulness of the pulse contour analysis and estimation of various pulse waveform indexes for cardiovascular health screening and diagnosis.

Pulsatile Hemodynamics and Coronary Artery Disease

Coronary artery disease (CAD) is the leading cause of human death and has a high prevalence throughout the world. Therefore, it is important to detect CAD early and to apply individualized therapy according to the patients' risk. There is an increasing interest in pulsatile arterial hemodynamics in the cardiovascular area. Widely used measurements of arterial pulsatile hemodynamics include pulse pressure, pulse wave velocity and augmentation index. Here, we will review underlying pathophysiology linking the association of arterial pulsatile hemodynamics with CAD, and the usefulness of the measurements of pulsatile hemodynamics in the prediction of future cardiovascular events of CAD patients. Clinical and therapeutic implications will be also addressed.

Lower Lean Mass Is Associated with Greater Arterial Stiffness in Patients with Lower Extremity Artery Disease

Background: Arterial stiffness is independently associated with lower extremity artery disease (LEAD). Although obesity is already known as an independent cardiovascular risk factor, it was found that, paradoxically, in patients diagnosed with cardiovascular disease, an increase in body mass index (BMI) was associated with a decrease in mortality. However, the underlying mechanism of this paradoxical association remain uncertain. In this study, we firstly hypothesize that arterial stiffness correlates with body mass; secondly, the underlying mechanism of the association for patients with LEAD is individual body composition, in particular, lean mass. Methods: The present study was performed as a single-center, prospective, observational analysis. A total of 412 patients with current or previously diagnosed LEAD (Rutherford Classification 2–4) were included, the cfPWV and AIx were measured as indices of arterial stiffness, and a body composition assessment was performed. Results: In male patients, there was a significantly negative correlation between the AIx and lean mass coefficient (p = 0.004, 95% CI: −0.28 (−0.48–0.09)). Conclusion: For patients with peripheral arterial disease, our data show that lower lean mass in male patients is associated with increased arterial stiffness as measured by the AIx. Therefore, progressive resistance training may be beneficial for the reduction in arterial stiffness in PAD patients in secondary prevention.

Limited value of pulse wave analysis in assessing arterial wave reflection and stiffness in the pulmonary artery

We explored the use of the augmentation index (AI) based on pulse wave analysis (PWA) in the pulmonary circulation as a measure of wave reflection and arterial stiffness in individuals with and without pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Right heart catheterization was performed using a pressure and Doppler flow sensor-tipped catheter to obtain simultaneous pressure and flow velocity measurements in the pulmonary artery in 10 controls, 11 PAH patients, and 11 CTEPH patients. PWA was applied to the measured pressure, while wave intensity analysis (WIA) and wave separation analysis (WSA) were performed using both the pressure and velocity to determine the magnitudes and timings of reflected waves. Type C (AI < 0) pressure waveform dominated in controls and type A (AI > 12%) waveform dominated in PAH patients, while there was a mixture of types A, B, and C among CTEPH patients. AI was greater and the inflection time shorter in CTEPH compared to PAH patients. There was a poor correlation between AI and arterial wave speed as well as measures of wave reflection derived from WIA and WSA. The infection point did not match the timing of the backward compression wave in ~50% of the cases. In patients with type C waveforms, the inflection time correlated well to the timing of the late systolic forward decompression wave caused by ventricular relaxation. In conclusion quantifying pulmonary arterial wave reflection and stiffness using AI based on PWA may be inaccurate and should therefore be discouraged.

Augmentation index predicts mortality in patients with aortic stenosis: an echo-tracking study

Aortic valve stenosis (AS) shares similarities with the atherosclerotic process but little is known about the effect of the mechanical properties of large arteries on outcome in patients with AS. The aims of this study were (1) to determine the relationship between indexes of carotid stiffness/compliance and the severity of AS and (2) to identify whether local arterial stiffness is independently associated with mortality. 133 patients with moderate to severe isolated AS and preserved LV ejection fraction (LVEF) were included. All underwent transthoracic echocardiography and local carotid stiffness evaluation by means of high-definition echo-tracking ultrasound with the calculation of stiffness/compliance parameters included augmentation index (AIx). None of the carotid stiffness parameters were significantly associated with AS severity parameters. During a mean follow-up of 51.6 ± 39.4 months, 70 patients received aortic valve replacement, 45 died and 18 were alive with no surgery. Who died were older (79.2 ± 6.9 vs. 73 ± 8.8 years, p < 0.0001), had higher carotid AIx (21.3 ± 14 vs. 16 ± 12%, p = 0.028). In multivariate Cox regression analysis AIx was independently associated with mortality (HR 1.048, 95% CI 1.01-1.07, p = 0.001), also after inclusion of age and creatinine. There was a significant association between the level of AIx and mortality in those patients who did not have surgery (p = 0.016). In severe AS and a normal LVEF, carotid AIx measured by echo-tracking system was independently associated with death. No relationship between AS severity and local carotid stiffness was found. These data emphasize the importance of arterial stiffness has a hallmark of long-term atherosclerotic burden and impaired prognosis.

Prediction of all-cause and cardiovascular mortality using central hemodynamic indices among elderly people: systematic review and meta-analysis

BACKGROUND

Despite widespread usage of central blood pressure assessment its predictive value among elderly people remains unclear.

OBJECTIVE

To ascertain the capacity of central hemodynamic indices for predicting future all-cause and cardiovascular hard outcomes among elderly people.

DESIGN AND SETTING

Systematic review and meta-analysis developed at the Del Cuore cardiology clinic, in Antonio Prado, Rio Grande do Sul, Brazil.

METHODS

312 full-text articles were analyzed, from which 35 studies were included for systematic review. The studies included needed to report at least one central hemodynamic index among patients aged 60 years or over.

RESULTS

For all-cause mortality, aortic pulse wave velocity (aPWV) and central systolic blood pressure (SBP) were significant, respectively with standardized mean difference (SMD) 0.85 (95% confidence interval, CI 0.69-1.01; I2 96%; P < 0.001); and SMD 0.27 (95% CI 0.15-0.39; I2 77%; P 0.012). For cardiovascular mortality brachial-ankle PWV (baPWV), central SBP and carotid-femoral PWV (cfPWV) were significant, respectively SMD 0.67 (95% CI 0.40-0.93; I2 0%; P 0.610); SMD 0.65 (95% CI 0.48- 0.82; I2 80%; P 0.023); and SMD 0.51 (95% CI 0.32-0.69; I2 85%; P 0.010).

CONCLUSIONS

The meta-analysis results showed that aPWV was promising for predicting all-cause mortality, while baPWV and central SBP demonstrated consistent results in evaluating cardiovascular mortality outcomes. Thus, the findings support usage of central blood pressure as a risk predictor for hard outcomes among elderly people.

REGISTRATION NUMBER IN PROSPERO

RD42018085264.

Sex modification of the association of the radial augmentation index and incident hypertension in a Chinese community-based population

BACKGROUND

Arterial stiffness, as assessed by aortic ultrasound and pulse wave velocity, is associated with incident hypertension. However, there is still no consensus on whether the augmentation index (AI) affects new onset of hypertension. This study investigated the relationship of radial AI (rAI) and incident hypertension in a Chinese community-based population without hypertension at baseline.

METHOD

A total of 1,615 Chinese non-hypertensive participants from an atherosclerosis cohort in Beijing, China were included in our analysis. Baseline rAI normalized to heart rate of 75 beats/min (rAIp75) was obtained using HEM-9000AI. New-onset hypertension was defined as blood pressure ≥ 140/90 mmHg or self-reported hypertension or taking anti-hypertensive medications at the follow up survey. Multivariate regression models were used to evaluate the impact of rAIp75 on the risk of new-onset hypertension.

RESULTS

After a mean 2.35-year follow-up, 213 (13.19%) participants developed incident hypertension. No significant relation between rAIp75 and incident hypertension was observed in the whole population after adjustment for possible confounders (adjusted odds ratio (OR) and 95% confidence interval (CI): 1.09 [0.95-1.27];P = 0.2260). However, rAIp75 was significantly associated with incident hypertension in women, but not in men (adjusted OR and 95% CI: 1.29 [1.06-1.56],P = 0.0113 for women; 0.91 [0.72-1.15],P = 0.4244 for men; P for interaction = 0.0133).

CONCLUSIONS

Sex modified the effect of the rAI on incident hypertension in a Chinese, community-based, non-hypertensive population. Screening of the rAI could be considered in women with a high risk of hypertension for the purpose of primary intervention.

Aortic Pulse Wave Velocity Predicts Cardiovascular Events and Mortality in Patients Undergoing Coronary Angiography: A Comparison of Invasive Measurements and Noninvasive Estimates

Aortic pulse wave velocity (PWV) is directly related to arterial stiffness. Different methods for the determination of PWV coexist. The aim of this prospective study was to evaluate the prognostic value of PWV in high-risk patients with suspected coronary artery disease undergoing invasive angiography and to compare 3 different methods for assessing PWV. In 1040 patients, invasive PWV (iPWV) was measured during catheter pullback. Additionally, PWV was estimated with a model incorporating age, central systolic blood pressure, and pulse waveform characteristics obtained from noninvasive measurements (estimated PWV). As a third method, PWV was calculated with a formula solely based on age and blood pressure (formula-based PWV). Survival analysis was based on continuous PWV as well as using cutoff values. After a median follow-up duration of 1565 days, 24% of the patients reached the combined end point (cardiovascular events or mortality). Cox proportional hazard ratios per 1 SD were 1.35 for iPWV, 1.37 for estimated PWV, and 1.28 for formula-based PWV (P<0.0001 for all 3 methods) in univariate analysis, remaining statistically significant after comprehensive multivariable adjustments. In a model including a modified risk score for coronary artery disease, iPWV and estimated PWV remained borderline significant. The net reclassification improvement was significant for iPWV (0.173), formula-based PWV (0.181), and estimated PWV (0.230). All 3 methods for the determination of PWV predicted cardiovascular events and mortality in patients with suspected coronary artery disease. This indicates that iPWV as well as both noninvasive estimation methods are suitable for the assessment of arterial stiffness, bearing in mind their individual characteristics.

Association of arterial stiffness with the histological severity of nonalcoholic fatty liver disease

BACKGROUND

Although arterial stiffness has been reported to be associated with nonalcoholic fatty liver disease (NAFLD), previous studies have relied only on noninvasive assessments for the diagnosis of NAFLD. This study attempted to investigate the association of arterial stiffness with the histological severity of NAFLD.

METHODS

We analyzed data from a biopsy-proven prospective NAFLD cohort. Augmentation index corrected for a heart rate of 75 bpm (AI@75) was obtained using applanation tonometry of the radial artery.

RESULTS

A total of 154 patients (mean age 55.2 years; females 55.8%) with biopsy-proven NAFLD were analyzed. Patients with higher AI@75 (≥ 76%) showed more severe grades of lobular and portal inflammation and hepatocellular ballooning, and more advanced stages of fibrosis compared to those with lower AI@75 (< 76%) (p < 0.05 for each). The presence of nonalcoholic steatohepatitis (NASH) (adjusted odds ratio [aOR] 2.48; 95% confidence interval [CI] 1.31-6.16; p = 0.008), lobular inflammation (aOR 2.03; 95% CI 1.09-3.78; p = 0.025) hepatocellular ballooning (aOR 2.82; 95% CI 1.23-6.43; p = 0.014), and significant fibrosis (≥ F2) (aOR 3.42; 95% CI 1.50-7.79; p = 0.003) were independently associated with higher AI@75 (≥ 76%) even after adjustment for confounders.

CONCLUSION

Arterial stiffness as indicated by higher AI@75 was associated with more severe NAFLD histology. This adds to the evidence for the association between increased arterial stiffness and NAFLD.

Respiratory and Cardiovascular Outcomes in Survivors of Extremely Preterm Birth at 19 Years

Rationale: Growth and development during adolescence may modify the respiratory and vascular differences seen among extremely preterm (EP) individuals in childhood and early adolescence.Objectives: To assess the trajectory of respiratory and cardiovascular outcomes during transition to adulthood in a national longitudinal cohort study of births before 26 weeks of gestation in the United Kingdom and Ireland.Methods: A total of 129 EP participants and 65 control subjects attended for a center-based evaluation at 19 years of age. Standardized measures of spirometry, hemodynamics, functional capacity, and markers of inflammation were obtained from EP subjects with and without neonatal bronchopulmonary dysplasia and term-born control subjects at 19 years of age and compared with previous assessments.Measurements and Main Results: Compared with the control group, the EP group was significantly impaired on all spirometric parameters (mean FEV₁ z-score, -1.08 SD [95% confidence interval, -1.40 to -0.77]) and had lower fractional exhaled nitric oxide concentrations (13.9 vs. 24.4 ppb; P < 0.001) despite a higher proportion with bronchodilator reversibility (27% vs. 6%). The EP group had significantly impaired exercise capacity. All respiratory parameters were worse after neonatal bronchopulmonary dysplasia, and respiratory function differences were similar at 11 and 19 years. The augmentation index was 6% higher in the EP group and associated with increased total peripheral resistance (difference in means, 96.4 [95% confidence interval, 26.6-166.2] dyne/s/cm^-5) and elevation in central, but not peripheral, blood pressure. Central systolic and diastolic blood pressures increased more quickly during adolescence in the EP group than in the control group.Conclusions: Clinicians should address both cardiovascular and respiratory risks in adult survivors of extremely preterm birth.

Relationship between arterial stiffness and variability of home blood pressure monitoring

Variability of blood pressure (BP) is known as a prognostic value for the subsequent target organ damage in hypertensive patients. Arterial stiffness is a risk factor for cardiovascular morbidity and mortality. The relationship between the arterial stiffness and the BP variability has been controversial. The objective of the present study was to investigate the relationship between arterial stiffness and home BP variability in patients with high normal BP and new onset hypertension (HTN).Four hundred sixty three patients (252 males, 49 ± 12 year-old) with high normal BP or HTN were enrolled. Using radial applanation tonometry, pulse wave analysis (PWA) was performed for evaluation of systemic arterial stiffness. All patients underwent both home BP monitoring (HBPM) and PWA. Home BP variability was calculated as the standard deviation (SD) of 7 measurements of HBPM. Multiple linear regression analysis was performed to estimate and test the independent effects of home BP variability on the arterial stiffness.Mutivariate analysis showed that both systolic and diastolic morning BP variabilities were correlated with arterial stiffness expressed as augmentation pressure (AP, β-coefficient = 1.622, P = .01 and β-coefficient = 1.07, P = .035). The SDs of systolic and diastolic BP of evening were also associated with AP (β-coefficient = 1.843, P = .001 and β-coefficient = 1.088, P = .036). The SDs of morning and evening systolic BP were associated with augmentation index (AI, β-coefficient = 1.583, P = .02 and β-coefficient = 1.792, P = .001) and heart rate (75 bpm) adjusted AI (β-coefficient = 1.592, P = .001 and β-coefficient = 1.792, P = .001).In present study, the variability of systolic BP was closely related with arterial stiffness. The home BP variability might be important indicator of arterial stiffness.

Association of obesity with arterial stiffness: The Multi-Ethnic Study of Atherosclerosis (MESA)

Arterial stiffness (AS) and obesity are recognized as important risk factors of cardiovascular disease (CVD). The purpose of this study was to investigate the relationship between AS and obesity. AS was defined as high augmentation index (AIx) and low elasticity (C1, large artery elasticity; C2, small artery elasticity) in participants enrolled in the Multi-Ethnic Study of Atherosclerosis at baseline. We compared AIx, C1, and C2 by body mass index (BMI) (< 25, 25-29.9, 30-39.9, ⩾ 40 kg/m²) and waist-hip ratio (WHR) (< 0.85, 0.85-0.99, ⩾ 1). The obesity-AS association was tested across 10-year age intervals. Among 6177 participants (62 ± 10 years old, 52% female), a significant inverse relationship was observed between obesity and AS. After adjustments for CVD risk factors, participants with a BMI > 40 kg/m² had 5.4% lower AIx (mean difference [Δ] = -0.82%; 95% CI: -1.10, -0.53), 15.4% higher C1 (Δ = 1.66 mL/mmHg ×10; 95% CI: 1.00, 2.33), and 40.2% higher C2 (Δ = 1.49 mL/mmHg ×100; 95% CI: 1.15, 1.83) compared to those with a BMI < 25 kg/m² (all p for trend < 0.001). Participants with a WHR ⩾ 1 had 5.6% higher C1 (∆ = 0.92 mL/mmHg ×10; 95% CI: 0.47, 1.37) compared to those with a WHR < 0.85. The WHR had a significant interaction with age on AIx and C2, but not with BMI; the inverse relationships of the WHR with AIx and C2 were observed only in participants < 55 years between the normal (WHR < 0.85) and the overweight (0.85 ⩽ WHR < 0.99) groups. Different associations of WHR and BMI with arterial stiffness among older adults should be further investigated.

Noninvasive vascular function tests for the future prediction of primary cardiovascular diseases

OBJECTIVES

Cardiovascular diseases (CVDs) still remain the main causes of death and disability in the US and worldwide, and the prediction for their future incidence is not well established. The utilization of the new cardiovascular risk score (CVRS) developed by the new ACC/AHA blood pressure treatment guidelines has improved the 10-year prediction of CVDs. However, its predictive value could be further increased with the addition of other risk factors identified with the use of several noninvasive vascular tests. These tests include, the older tests such as flow-mediated dilation (FMD), pulse wave velocity (PWV), pulse pressure (PP), and the newly developed noninvasive vascular tests of, reactive hyperemia-peripheral arterial tonometry (RH-PAT), cardio-ankle vascular index (CAVI), and the inter-arm/inter-leg pressure difference (IAPD/ILPD).

METHODS

In order to get a current perspective regarding the usefulness of these new noninvasive vascular tests for the future prediction of CVDs, a Medline search of the English language literature was conducted between 2014 and 2019 using the terms cardiovascular disease, coronary heart disease, noninvasive vascular tests, risk factors, and 26 pertinent papers were retrieved.

RESULTS

The analysis of results from these papers showed that these noninvasive vascular tests have an independent predictive value for the future incidence of CVDs and hypertension. However, their long-term predictive value is not well established, since there are no currently, available data from long-term clinical outcome studies.

CONCLUSION

The analysis of data from the retrieved papers demonstrated that the new noninvasive vascular tests have an independent predictive value for the future incidence of CVDs and hypertension. However, their long-term predictive value is not established as yet for the lack of long-term outcome studies. When the currently ongoing long-term trials are completed, it is quite possible that the data from these tests added to CVRS could enhance its predictive value.

Assessment of Arterial Stiffness in Patients With Resistant Hypertension: Additional Insights Into the Pathophysiology of This Condition?

BACKGROUND

Good understanding of the pathophysiological mechanism(s) of resistant hypertension (RH) and the relationship to vascular dysfunction is important for optimal blood pressure control.

METHODS AND RESULTS

The aim of this review article is to summarize the available data on the methods of arterial stiffness assessment, and their usefulness in RH. Several studies that provide information on the noninvasive methods of evaluation of arterial stiffness have been discussed; specifically, pulse wave velocity (PWV) and augmentation index (AIx) tests. Increased arterial stiffness, elevated AIx, and impaired endothelial function all act as indicators and predictors of cardiovascular events in patients with hypertension (HTN).

CONCLUSION

Our review suggests that PWV and AIx are impaired in patients with severe HTN. Early assessment of these characteristics can potentially be of value in patients with RH.

Aortic blood pressure and arterial stiffness in patients with controlled resistant and non-resistant hypertension

The purpose of the current study was to determine whether aortic blood pressure (BP) and arterial stiffness are greater in patients with controlled resistant hypertension (RHTN) than controlled non-resistant hypertension (non-RHTN) despite similar clinic BP level. Participants were recruited from University of Alabama at Birmingham (UAB) Hypertension Clinic. Controlled hypertension was defined as automated office BP measurement with BP < 135/85 mm Hg. A total of 141 participants were evaluated by pulse wave analysis (PWA) and carotid-femoral pulse wave velocity (cf-PWV). Among them, 75 patients had controlled RHTN with use of 4 or more antihypertensive medications and 56 patients had controlled non-RHTN with use of 3 or less antihypertensive medications. Compared to patients with controlled non-RHTN, those with controlled RHTN were more likely to be African American and had a higher prevalence of diabetes mellitus and congestive heart failure. The mean number of antihypertensive medications was greater in patients with controlled RHTN (4.4 ± 0.8 vs 2.3 ± 0.7, P < .001). Clinic brachial BP, aortic BP, augmentation pressure (AP), augmentation index normalized for heart rate of 75 beats per minute (AIx@75) and cf-PWV were similar in both groups. In summary, there was no significant difference in central BP or arterial stiffness between patients with controlled RHTN and controlled non-RHTN. These findings suggest that the higher residual cardiovascular risk observed in patients with RHTN after achieving BP control compared to patients with more easily controlled hypertension is not likely attributable to persistent differences in central BP and arterial stiffness.

Central blood pressure for the management of hypertension: Is it a practical clinical tool in current practice?

Since noninvasive central blood pressure (BP) measuring devices are readily available, central BP has gained growing attention regarding its clinical application in the management of hypertension. The disagreement between central and peripheral BP has long been recognized. Some previous studies showed that noninvasive central BP may be better than the conventional brachial BP in association with target organ damages and long-term cardiovascular outcomes. Recent studies further suggest that the central BP strategy for confirming a diagnosis of hypertension may be more cost-effective than the conventional strategy, and guidance of hypertension management with central BP may result in less use of medications to achieve BP control. Despite the use of central BP being promising, more randomized controlled studies comparing central BP-guided therapeutic strategies with conventional care for cardiovascular events reduction are required because noninvasive central and brachial BP measures are conveniently available. In this brief review, the rationale supporting the utility of central BP in clinical practice and relating challenges are summarized.

Estimation of wave reflection in aorta from radial pulse waveform by artificial neural network: a numerical study

BACKGROUND AND OBJECTIVE

Wave reflection in aorta has been shown to have incremental value for predicting cardiovascular events. However, its estimation by wave separation analysis (WSA) is complex.

METHODS

In this study, a novel method was proposed based on a cascade artificial neural network (ANN) for wave reflection estimation by the frequency features of radial pressure waveform alone. The simulation database of 4000 samples was generated by a 55-segment transmission line model of human arterial tree and was used for evaluating the ANN with 10-fold cross validation for the estimation of reflection magnitude (RM_ANN) and reflection index (RI_ANN) of wave reflection in aorta. RM and RI also were estimated by the WSA with a triangle waveform of aortic flow (RM_WSA and RI_WSA) and with a real aortic flow waveform (RM_Ref and RI_Ref) as reference values.

RESULTS

The results showed the correlation coefficient and mean difference between RM_ANN and RM_Ref (R² = 0.92, mean ± standard deviation (SD) = 0.0 ± 0.02) and those between RI_ANN and RI_Ref (R² = 0.91, mean ± SD = 0.0 ± 0.01) were better than those between RM_WSA and RM_Ref (R² = 0.51, mean ± SD = 0.01 ± 0.07) and those between RI_WSA and RI_Ref (R² = 0.50, mean ± SD = 0.0 ± 0.02). As the sample diversity in the simulation database was increased but the total number of samples keeps constant, the advantage of the ANN, though decreased slightly, became more significant than those of WSA (RM_ANN VS. RM_Ref and RI_ANN VS. RI_Ref: R² = 0.88 and 0.88, mean ± SD = 0.0 ± 0.05 and 0.0 ± 0.05; RM_WSA VS. RM_Ref and RI_WSA VS. RI_Ref: R² = 0.24 and 0.24, mean ± SD = 0.07 ± 0.24 and 0.02 ± 0.08, respectively). In addition, the ANN can achieve better results than the traditional method WSA even only two hidden neurons are used.

CONCLUSIONS

ANN is a potential method for the estimation of wave reflection in aorta by a single radial pulse waveform, but further validation of this method in clinic trials is needed.

On the importance of the nonuniform aortic stiffening in the hemodynamics of physiological aging

Mathematical models of the arterial tree constitute a valuable tool to investigate the hemodynamics of aging and pathology. Rendering such models as patient specific could allow for the assessment of central hemodynamic variables of clinical interest. However, this task is challenging, particularly with respect to the tuning of the local area compliance that varies significantly along the arterial tree. Accordingly, in this study, we demonstrate the importance of taking into account the differential effects of aging on the stiffness of central and peripheral arteries when simulating a person’s hemodynamic profile. More specifically, we propose a simple method for effectively adapting the properties of a generic one-dimensional model of the arterial tree based on the subject’s age and noninvasive measurements of aortic flow and brachial pressure. A key element for the success of the method is the implementation of different mechanisms of arterial stiffening for young and old individuals. The designed methodology was tested and validated against in vivo data from a population of n = 20 adults. Carotid-to-femoral pulse wave velocity was accurately predicted by the model (mean error = 0.14 m/s, SD = 0.77 m/s), with the greatest deviations being observed for older subjects. In regard to aortic pressure, model-derived systolic blood pressure and augmentation index were both in good agreement (mean difference of 2.3 mmHg and 4.25%, respectively) with the predictions of a widely used commercial device (Mobil-O-Graph). These preliminary results encourage us to further validate the method in larger samples and consider its potential as a noninvasive tool for hemodynamic monitoring.

NEW & NOTEWORTHY We propose a technique for adapting the parameters of a validated one-dimensional model of the arterial tree using noninvasive measurements of aortic flow and brachial pressure. Emphasis is given on the adjustment of the arterial tree distensibility, which incorporates the nonuniform effects of aging on central and peripheral vessel elasticity. Our method could find application in the derivation of important hemodynamic indices, paving the way for novel diagnostic tools.

Association of Pulse Pressure With Clinical Outcomes in Patients Under Different Antiplatelet Strategies After Percutaneous Coronary Intervention: Analysis of GLOBAL LEADERS

BACKGROUND

We evaluated the association of pulse pressure (PP) and different antiplatelet regimes with clinical and safety outcomes in an all-comers percutaneous coronary intervention (PCI) population.

METHODS

In this analysis of GLOBAL LEADERS (n = 15,936) we compared the experimental therapy of 23 months of ticagrelor after 1 month of dual-antiplatelet therapy (DAPT) vs standard DAPT for 12 months followed by aspirin monotherapy in subjects who underwent PCI and were divided into 2 groups according to the median PP (60 mm Hg). The primary end point (all-cause death or new Q-wave myocardial infarction) and the composite end points: patient-oriented composite end points (POCE), Bleeding Academic Research Consortium (BARC) 3 or 5, and net adverse clinical events (NACE) were evaluated.

RESULTS

At 2 years, subjects in the high-PP group (n = 7971) had similar rates of the primary end point (4.3% vs 3.9%; P = 0.058), POCE (14.9% vs 12.7%; P = 0.051), and BARC 3 or 5 (2.5% vs 1.7%; P = 0.355) and higher rates of NACE (16.4% vs 13.7%; P = 0.037) compared with the low-PP group (n = 7965). Among patients with PP < 60 mm Hg, the primary end point (3.4% vs 4.4%, adjusted hazard ratio [aHR] 0.77, 95% confidence interval [CI] 0.61-0.96), POCE (11.8% vs 13.5%, aHR 0.86, 95% CI 0.76-0.98), NACE (12.8% vs 14.7%, aHR 0.85, 95% CI 0.76-0.96), and BARC 3 or 5 (1.4% vs 2.1%, aHR 0.69, 95% CI 0.49-0.97) were lower with ticagrelor monotherapy compared with DAPT. The only significant interaction was for BARC 3 or 5 (P = 0.008).

CONCLUSIONS

After contemporary PCI, subjects with high PP levels experienced high rates of NACE at 2 years. In those with low PP, ticagrelor monotherapy led to a lower risk of bleeding events compared with standard DAPT.

Augmentation index in the assessment of wave reflections and systolic loading

BACKGROUND

Augmentation index (AI_x) is used to quantify the augmented systolic aortic pressure that impedes ventricular ejection. Its use as an index of wave reflections is questionable. We hypothesize that AI_x is quantitatively different from the reflection coefficient under varied physiological conditions.

METHODS

42 datasets of aortic pressure and flow waveforms were obtained during induced hypertension (methoxamine infusion) and vasodilation (nitroprusside infusion) in our mongrel dog experiments (n = 5) and from Mendeley data during various interventions (vasoconstrictors, vasodilators, pacing, stimulation, hemorrhage and hemodilution). Wave reflections and principal components of reflection coefficients were computed for comparison to AI_x and heart rate normalized AI_x. RESULTS: Principal reflection coefficient, Γ₁, increased in hypertension and decreased in vasodilation, hemorrhage and hemodilution. AI_x followed the trend in many cases but was consistently lower than Γ₁ in almost all the subjects. The Bland-Altman analysis also showed that both AI_x and normalized AI_x underestimated Γ₁. The relationship between augmentation index and reflection coefficient was explained by a linear regression model (r² = 0.23, p < 0.01) in which AI_x followed directional changes in Γ₁ and the normalization of AI_x resulted in a linear model that explained less variation in the relationship between AI_x and Γ₁.

CONCLUSION

AI_x is a reasonable clinical trend indicator, albeit not an accurate surrogate measure of the amount of wave reflections.

Association between central haemodynamics and risk of all-cause mortality and cardiovascular disease: a systematic review and meta-analysis

The aim of this meta-analysis of longitudinal studies was to obtain a valid and cogent assessment of predictive value of central haemodynamic variables for cardiovascular outcomes and all-cause mortality. We searched for eligible articles using MEDLINE, CINAHL, EMBASE and Web of Science between 1 January 1969 and 31 December 2017. We finally included 24 prospective cohort studies, comprising 146,986 individuals for this analysis. Adjusted pooled hazard ratio of total cardiovascular events was 1.10 (95% confidence interval [CI] 1.04-1.16) for a 10 mmHg increase of central systolic pressure, 1.12 (95% CI 1.05-1.19) for a 10 mmHg increase of central pulse pressure and 1.18 (95% CI 1.09-1.27) for a 10% increase of central augmentation index. Furthermore, pooled hazard ratio of all-cause mortality was 1.22 (95% CI 1.14-1.31) for a 10 mmHg increase of central pulse pressure and 1.19 (95% CI 1.05-1.34) for a 10% increase of central augmentation index. Central haemodynamic variables are independent predictors of cardiovascular disease and all-cause mortality. This finding supports the notion that central pressure components and indices could be suitably implemented in clinical practice.

B-type natriuretic peptide trumps other prognostic markers in patients assessed for coronary disease

BACKGROUND

Risk prediction for patients with suspected coronary artery disease is complex due to the common occurrence of prior cardiovascular disease and extensive risk modification in primary care. Numerous markers have the potential to predict prognosis and guide management, but we currently lack robust 'real-world' evidence for their use.

METHODS

Prospective, multicentre observational study of consecutive patients referred for elective coronary angiography. Clinicians were blinded to all risk assessments, consisting of conventional factors, radial artery pulse wave analysis, 5-minute heart rate variability, high-sensitivity C-reactive protein and B-type natriuretic peptide (BNP). Blinded, independent adjudication was performed for all-cause mortality and the composite of death, myocardial infarction or stroke, analysed with Cox proportional hazards regression.

RESULTS

Five hundred twenty-two patients were assessed with median age 66 years and 21% prior revascularization. Median baseline left ventricular ejection fraction was 64%, and 62% had ≥ 50% stenosis on angiography. During 5.0 years median follow-up, 30% underwent percutaneous and 16% surgical revascularization. In multivariate analysis, only age and BNP were independently associated with outcomes. The adjusted hazard ratio per log unit increase in BNP was 2.15 for mortality (95% CI 1.45-3.19; p = 0.0001) and 1.27 for composite events (1.04-1.54; p = 0.018). Patients with baseline BNP > 100 pg/mL had substantially higher mortality and composite events (20.9% and 32.2%) than those with BNP ≤ 100 pg/mL (5.6% and 15.5%). BNP improved both classification and discrimination of outcomes (p ≤ 0.003), regardless of left ventricular systolic function. Conversely, high-sensitivity C-reactive protein, pulse wave analysis and heart rate variability were unrelated to prognosis at 5 years after risk modification and treatment of coronary disease.

CONCLUSIONS

Conventional risk factors and other markers of arterial compliance, inflammation and autonomic function have limited value for prediction of outcomes in risk-modified patients assessed for coronary disease. BNP can independently identify patients with subtle impairment of cardiac function that might benefit from more intensive management.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT00403351 Registered on 22 November 2006.

Transcutaneous Carbon Dioxide Treatment Is Capable of Reducing Peripheral Vascular Resistance in Hypertensive Patients

AIM

We aimed to investigate the effects of a single carbon dioxide (CO₂) treatment on arterial stiffness by monitoring the changes of aortic pulse-wave velocity (PWV) and aortic augmentation index (AIXao), which are indicators of arterial stiffness.

PATIENTS AND METHODS

PWV and AIXao were measured by an invasively validated oscillometric device. The measurements of stiffness parameters were performed before the CO₂ treatment, and at 1, 4 and 8 h after the first treatment.

RESULTS

Thirty-one patients were included. No significant changes were found in PWV. AIXao decreased significantly 1 h and 4 h after CO₂ treatment compared to baseline values (p=0.034 and p<0.001). AIXao increased 8 h after the CO₂ treatment, but remained significantly lower than baseline AIXao values (p=0.016).

CONCLUSION

CO₂ treatment is capable of reducing peripheral vascular resistance. We hypothesize that CO₂ is not only a temporal vasodilator but is also capable of activating vasodilation pathways.

Comparsion of central aortic pressure to brachial artery pressure in hypertensive patients on drug treatment: An observational study

BACKGROUND

High brachial blood pressure (BP) is an important cardiovascular risk factor. However major differences in central systolic BP can occur among people with similar brachial systolic BP. It is known that central aortic pressure responses to antihypertensive therapy can differ substantially from brachial BP responses, such that true treatment effects cannot be gauged from conventional brachial BP.

OBJECTIVE

The purpose of this study was to examine if adequate control of brachial BP was concordant with central BP control in treated hypertensive subjects.

METHODS

Non-invasive acquisition of brachial and central pressures and wave forms was obtained from 100 subjects with systemic arterial hypertension on drug therapy and 50 healthy individuals. After all necessary precautions according to the guidelines, brachial and central pressures and wave forms were measured 3 times at 5 min intervals using an upper arm cuff (AGEDIO K900 HDP Stolberg, Germany). The mean of the last two measurements of each was recorded as representative of brachial and central aortic pressures and wave forms.

RESULTS

In 45 of 50 healthy subjects with normotension (41 male, 9 female, mean age 38 years), central systolic BP was <120 mmHg. Five healthy subjects (10%) had falsely normal brachial systolic BP, but raised central systolic BP. Out of 100 patients with known hypertension and on various anti-hypertensive drug combinations, 9 had uncontrolled hypertension (defined as brachial BP of >140/90 mmHg and central systolic BP > 120 mmHg). Ninety-one patients had controlled hypertension as estimated by brachial BP of whom, 37 patients had uncontrolled central BP (systolic BP > 120 mmHg). Thus, brachial BP estimation over-estimated control of hypertension in 41% patients (p < 0.01). Central systolic BP control was inadequate in 9 out of 41 patients (22%) on angiotensin receptor blocking therapy versus 27 out of 31 (87%) patients on beta-blocking therapy (p < 0.05). Thus, there was a marked mismatch with regard to control of hypertension between central and peripheral measurements.

CONCLUSION

Central BP measurement provides important information on true prevalence of uncontrolled hypertension in the outpatient setting which is higher than current estimates from brachial BP measurement. Optimal BP control by central BP is far less than observed from peripheral pressure measurement. Residual cardiovascular risk despite adequate control of brachial BP can also be explained by the substantial frequency of uncontrolled hypertension as determined by the central BP in patients with apparently controlled hypertension. Both these conclusions have significant impact on prevalence of uncontrolled hypertension and its proper management. Further studies are required to confirm the current data and to provide evidence that treatment decisions based on measurements of central BP result in better outcomes.

Irreversible effects of long-term chronic smoking on arterial stiffness: An analysis focusing on ex-smokers among otherwise healthy middle-aged men

Objective: Smoking is a modifiable cardiovascular risk factor closely related to arterial stiffness (AS). However, data are lacking regarding the chronic effects of smoking on AS, especially in ex-smoker (ES) who faces remnant cardiovascular risk when compared to never-smokers (NS).Methods: Among 1722 health screening participants, we retrospectively evaluated 652 healthy men with different smoking history [240 current smoker (CS) vs. 228 ES vs. 184 NS]. To assess AS, augmentation index (AIx), pulse pressure amplification (PPamp), and carotid-femoral pulse wave velocity (cfPWV) were measured and compared.Results: Baseline characteristics were similar except age and triglyceride level. AIx was lowest in NS, followed by ES, and was highest in CS. PPamp was highest in NS, lowest in CS, and ES was of intermediate level. The differences were more robust after adjustment for baseline covariates (AIx, p = 0.005; PPamp: p = 0.001). On the other hand, no significant intergroup difference was observed for cfPWV in our middle-aged population. With the regression analyses revealing an independent association between smoking duration and AS in ES, subgroup analysis demonstrated that long-term ES (smoking duration ≥20 years) had significantly higher AS than short-term ES (<20 years) and NS, approaching levels comparable to CS (AIx and PPamp: p < 0.0001).Conclusions: Our study demonstrated impaired arterial elastic properties in long-term ES, suggesting that AS caused by chronic smoking might be irreversible even after smoking cessation. Further longitudinal studies are warranted to determine the impacts of past smoking on AS and its clinical relevance.

Pulse wave reflection responses to bench press with and without practical blood flow restriction

Resistance exercise is recommended to increase muscular strength but may also increase pulse wave reflection. The effect of resistance exercise combined with practical blood flow restriction (pBFR) on pulse wave reflection is unknown. The purpose of this study was to evaluate the differences in pulse wave reflection characteristics between bench press with pBFR and traditional high-load bench press in resistance-trained men. Sixteen resistance-trained men participated in the study. Pulse wave reflection characteristics were assessed before and after low-load bench press with pBFR (LL-pBFR), traditional high-load bench press (HL), and a control (CON). A repeated-measures ANOVA was used to evaluate differences in pulse wave reflection characteristics among the conditions across time. There were significant (p ≤ 0.05) interactions for heart rate, augmentation index, augmentation index normalized at 75 bpm, augmentation pressure, time-tension index, and wasted left ventricular energy such that they were increased after LL-pBFR and HL compared with rest and CON, with no differences between LL-pBFR and HL. Aortic pulse pressure (p < 0.001) was elevated only after LL-pBFR compared with rest. In addition, there was a significant (p ≤ 0.05) interaction for aortic diastolic blood pressure (BP) such that it was decreased after LL-pBFR compared with rest and CON but not HL. The subendocardial viability ratio and diastolic pressure-time index were significantly different between LL-pBFR and HL compared with rest and CON. There were no significant interactions for brachial systolic or diastolic BP, aortic systolic BP, or time of the reflected wave. In conclusion, acute bench press resistance exercise significantly altered pulse wave reflection characteristics without differences between LL-pBFR and HL.

Carotid Arterial Pulse Waveform Measurements Using Fiber Bragg Grating Pulse Probe

Arterial pulse is an established source of information for the clinical assessment of cardiovascular health. The central aortic pressure is known to be a better predictor of cardiovascular status than the peripheral pressure. The carotid arterial pulse is considered to be the best indicator of the central aortic pressure. The present work deals with the development of a novel noninvasive probe based on fiber Bragg grating (FBG) sensor for the real-time acquisition of the pulse waveform in the carotid arterial site. The fiber Bragg grating pulse probe (FBGPP) developed is used to obtain the carotid arterial pulse waveform (CAPW) of individual subjects, in the form of beat-to-beat carotid pulse. The FBGPP developed comprises of an elastic rubber diaphragm that comes into contact with the skin below, which the carotid artery is pulsating, creating strain variations over it. Effectively, the carotid arterial pulse is tranduced into the strain variations over a rubber diaphragm, which is acquired by the FBG sensor bonded over it. The FBGPP is designed such that the positioning and the access for the device to the carotid arterial site can be carried out with ease. Furthermore, the recorded CAPW is subjected to the pulse wave analysis in order to evaluate vital cardiovascular parameters like heart rate, left ventricular ejection time, carotid augmentation index, and ejection duration index, which are indicators of the cardiac health of the subject and the performance of the heart. Also, the linearity between these cardiovascular parameters is explored for a sample size of 55.