Resistive and pulsatile arterial hemodynamics and cardiovascular events: the Multiethnic Study of Atherosclerosis

Variations of arterial compliance and vascular resistance due to plaque or infarct in a single vascular territory of the middle cerebral artery

Background

Arterial compliance (AC) and vascular resistance (VR) are crucial for the regulation capacity of the vascular system. However, alterations of these features and hemodynamics due to atherosclerosis in a single intracranial artery territory have not been extensively investigated. Thus this study aimed to examine the AC, VR, and hemodynamic variations due to plaque and infarction in the middle cerebral artery (MCA).

Methods

Patients with symptomatic MCA atherosclerosis were recruited. Both sides of the MCA were assessed and then classified according to the following scheme: group 0, without plaque; group 1, with plaque but without infarct; group 2, with plaque and infarct in the supplying territories. Data on AC, VR, blood flow, and pulsatility index (PI) were obtained based on 4D flow magnetic resonance imaging (MRI) and the Windkessel model.

Results

A total of 63 patients were recruited. After 17 MCAs were excluded (occlusion, n=6; poor image quality, n=11), datasets on 109 MCAs were finally collected and classified into group 0 (n=39), group 1 (n=40), and group 2 (n=30). From groups 0 to 2, there was a decrease in AC (0.0060±0.0031 vs. 0.0052±0.0029 vs. 0.0026±0.0020 mL/mmHg) and an increase in VR [28.65±16.11 vs. 42.59±27.53 vs. 63.21±40.37 mmHg/(mL/s)]. Compared to group 1, group 2 had significantly decreased AC (0.0052±0.0029 vs. 0.0026±0.0020 mL/mmHg; P=0.003) and increased VR [42.59±27.53 vs. 63.21±40.37 mmHg/(mL/s); P=0.021]. From group 0 to group 2, there was a decrease in blood flow (179.29±73.57 vs. 125.11±59.04 vs. 92.05±48.79 mL/min; P<0.001). The PI varied significantly among the 3 groups (0.86±0.20 vs. 1.12±0.50 vs. 0.79±0.16; P<0.001), with group 1 having the highest PI.

Conclusions

With the occurrence of plaque and infarct, AC and blood flow progressively decrease while VR increases. The PI was the highest in the group with plaque and without infarct. Assessments of vascular function and hemodynamics in a single artery territory can clarify comprehensive alterations in the cerebral vascular system (CVS).

Estimated pulse wave velocity and incident heart failure and its subtypes: Findings from the multi-ethnic study of atherosclerosis

Age-associated increase in aortic stiffness, measured as carotid-femoral pulse wave velocity (PWV), is an important effector of cardiac damage and heart failure (HF). Pulse wave velocity estimated from age and blood pressure (ePWV) is emerging as a useful proxy of vascular aging and subsequent cardiovascular disease risk. We examined the association of ePWV with incident HF and its subtypes in a large community sample of 6814 middle-aged and older adults from the Multi-Ethnic Study of Atherosclerosis (MESA).

METHODS

Participants with an ejection fraction ≤40 % were classified as HF with reduced ejection fraction (HFrEF) while those with an ejection fraction ≥50 % were classified as HF with preserved ejection fraction (HFpEF). Cox proportional hazards regression models were used to calculate hazard ratios (HR) and 95 % confidence intervals (CI).

RESULTS

Over a mean follow-up period of 12.5 years, incident HF was diagnosed in 339 participants: 165 were classified as HFrEF and 138 as HFpEF. In fully adjusted models, the highest quartile of ePWV was significantly associated with an increased risk of overall HF (HR 4.79, 95 % CI 2.43-9.45) compared with the lowest quartile (reference). When exploring HF subtypes, the highest quartile of ePWV was associated with HFrEF (HR 8.37, 95 % CI 4.24-16.52) and HFpEF (HR 3.94, 95 % CI 1.39-11.17).

CONCLUSIONS

Higher ePWV values were associated with higher rates of incident HF and its subtypes in a large, diverse cohort of men and women.

Ventricular-arterial coupling: definition, pathophysiology and therapeutic targets in cardiovascular disease

INTRODUCTION

The heart and arterial system are equally affected by arteriosclerosis/atherosclerosis. There is a constant interaction between the left ventricular (LV) function and the arterial system, termed ventricular-arterial coupling (VAC), which reflects the global cardiovascular efficiency. VAC is traditionally assessed by echocardiography as the ratio of effective arterial elastance (E_a) over end-systolic elastance (E_es) (E_a/E_es). However, the concept of VAC is evolving and new methods have been proposed such as the ratio of pulse wave velocity (PWV) to global longitudinal strain (GLS) and myocardial work index.

AREA COVERED

This clinical review presents the hemodynamic background of VAC, its clinical implications and the impact of therapeutic interventions to normalize VAC. The review also summarizes the detrimental effects of cardio-metabolic risk factors on the aorta and LV, and provides an update on arterial load and its impact on LV function. The narrative review is based upon a systemic search of the bibliographic database PubMed for publications on VAC.

EXPERT OPINION

Newer methods such as PWV/GLS-ratio may be a superior marker of VAC than the traditional echocardiographic E_a/E_es in predicting target organ damage and its association with clinical outcomes. Novel anti-diabetic drugs and optimal antihypertensive treatment may normalize VAC in high-risk patients.

Pulmonary and systemic hemodynamics are associated with myocardial injury in the acute respiratory distress syndrome

Background

Whether right and left heart hemodynamics are associated with myocardial injury in the acute respiratory distress syndrome (ARDS) is not known.

Methods

We performed a retrospective cohort study of subjects who had right heart catheterization within the ALVEOLI trial and Fluid and Catheter Treatment Trial. Myocardial injury was assessed using a highly sensitive troponin assay (hsTn; Abbot ARCHITECT). Hemodynamic variables included right atrial pressure, pulmonary artery wedge pressure, cardiac index and stroke volume, pulmonary vascular resistance, pulmonary arterial compliance, and pulmonary effective arterial elastance. We performed linear, logistic, and Cox regression to determine the association of hemodynamic variables with myocardial injury and to determine if hemodynamics mediated the association between myocardial injury and death.

Results

Among 252 ARDS patients, median day 0 troponin was 65.4 (13.8–397.8) ng/L. Lower cardiac index (β −0.23 SE 0.10; P < 0.001) and stroke volume (β −0.26 SE 0.005; P < 0.001), higher pulmonary vascular resistance (β 0.22 SE 0.11; P < 0.001), lower pulmonary arterial compliance (β −0.24 SE 0.06; P < 0.001), and higher arterial elastance (β 0.27 SE 0.43; P < 0.001) were associated with greater myocardial injury in univariable and adjusted models. Changes in stroke volume, cardiac index, pulmonary arterial compliance, pulmonary vascular resistance, and arterial elastance were all associated with progressive myocardial injury over three days. hsTn levels were associated with mortality; however, the association was attenuated after adjustment for each of stroke volume, pulmonary vascular resistance, pulmonary arterial compliance, and arterial elastance.

Conclusion

Pulmonary vascular hemodynamics are associated with myocardial injury in ARDS, while filling pressures are not. Pulmonary vascular disease may represent a treatable contributor to myocardial injury in ARDS.

Chronic Obstructive Pulmonary Disease as a Predictor of Cardiovascular Risk: A Case-Control Study

Chronic obstructive pulmonary disease (COPD) is a complex multi-morbid disorder with significant cardiac mortality. Current cardiovascular risk prediction models do not include COPD. We investigated whether COPD modifies future cardiovascular risk to determine if it should be considered in risk prediction models.Case-control study using baseline data from two randomized controlled trials performed between 2012 and 2015. Of the 90 eligible subjects, 26 COPD patients with lung hyperinflation were propensity matched for 10-year global cardiovascular risk score (QRISK2) with 26 controls having normal lung function. Patients underwent cardiac magnetic resonance imaging, arterial stiffness and lung function measurements. Differences in pulse wave velocity (PWV), total arterial compliance (TAC) and aortic distensibility were main outcome measures.PWV (mean difference 1.0 m/s, 95% CI 0.02-1.92; p = 0.033) and TAC (mean difference -0.27 mL/m²/mmHg, 95% CI 0.39-0.15; p < 0.001) were adversely affected in COPD compared to the control group. The PWV difference equates to an age, sex and risk-factor adjusted increase in relative risk of cardiovascular events and mortality of 14% and 15%, respectively.There were no differences in aortic distensibility. In the whole cohort (n = 90) QRISK2 (β = 0.045, p = 0.005) was associated with PWV in multivariate analysis. The relationship between QRISK2 and PWV were modified by COPD, where the interaction term reached significance (p = 0.014). FEV1 (β = 0.055 (0.027), p = 0.041) and pulse (B = -0.006 (0.002), p = 0.003) were associated with TAC in multivariate analysis.Markers of cardiovascular outcomes are adversely affected in COPD patients with lung hyperinflation compared to controls matched for global cardiovascular risk. Cardiovascular risk algorithms may benefit from the addition of a COPD variable to improve risk prediction and guide management.HAPPY London ClinicalTrials.gov: NCT01911910 and HZC116601; ClinicalTrials.gov: NCT01691885.

Low systemic arterial compliance is associated with increased cardiovascular morbidity and mortality in aortic valve stenosis

Objective

Lower systemic arterial compliance (SAC) is associated with increased cardiovascular morbidity and mortality in hypertension, but this has not been assessed in a prospective study in aortic valve stenosis (AS).

Methods

Data from 1641 patients (38% women) with initially asymptomatic mild-moderate AS enrolled in the Simvastatin and Ezetimibe in Aortic Stenosis study was used. Median follow-up was 4.3 years. SAC was assessed from Doppler stroke volume index to central pulse pressure ratio and considered low if ≤0.64 mL/m², corresponding to the lower tertile in the population. The association of SAC with outcome was assessed in Cox regression analysis and reported as HR and 95% CI.

Results

Low SAC at baseline was characterised by older age, female sex, hypertension, obesity, presence of a small aortic root, lower mean aortic gradient and more severe AS by effective aortic valve area (all p<0.01). In Cox regression analysis adjusting for factors, low SAC was associated with higher HRs for cardiovascular death (HR 2.13(95% CI 1.34 to 3.40) and all-cause mortality (HR 1.71(95% CI 1.23 to 2.38)), both p=0.001). The results did not change when systolic or diastolic blood pressure, other measures of AS severity or presence of discordantly graded AS were included in subsequent models. Presence of low SAC did not improve mortality prediction in reclassification analysis.

Conclusions

In patients with AS without diabetes and known cardiovascular disease, but a high prevalence of hypertension, low SAC was associated with higher cardiovascular and all-cause mortality independent of well-known prognosticators.

Trial registration number

NCT00092677; Post-results.

Living Arrangement: a Contributor to Vascular Disease in Asymptomatic African American Women

BACKGROUND

Diminished social support lias shown to lead to worse cardiovascular outcomes and since cardiovascular disease (CVD) is the leading cause of death in the United States (U.S.), it is critical to non-invasively study its precursor- vascular disease (VD). Assessing the impact social support lias on vascular outcomes can unveil potential CVD susceptibilities in at-risk populations. African American women exhibit the greatest burden of CVD morbidity and mortality; therefore, the purpose of tins study is to examine the association between living arrangement/social support and impaired vascular function in asymptomatic African American women.

METHODS

Vascular function was assessed by a non-invasive screening tool, HDI/PulseWave CR-2000, during screenings at community outreach events on participants clinically free of CVD. Vascular disease was defined as abnormal/impaired vascular function. Living arrangement, a binary variable (living with someone/living alone), was determined by survey responses (N=67) and represented social support. Multivariable analyses were used to estimate adjusted odds ratios (AORs) and 95% confidence intervals (95% CIs) to determine the association between living arrangement and vascular disease after controlling for confounders. Analyses were conducted using SAS 9.2.

RESULTS

Of those who lived alone, 82% had vascular disease (p=0.03). After adjusting for family CVD, and other CVD risk factors, those who lived with a spouse/partner or relative were 78% (p=0.04) less likely to develop vascular disease (AOR=0.22; 95% 0=0.05, 0.98).

CONCLUSIONS

Our study provides preliminary evidence to suggest that among African American women, clinically free of CVD, living arrangement is associated with vascular disease. While living alone may place individuals at an increased risk of CVD because of the association, living with a spouse/partner or relative may act as a protective factor against vascular disease and reduce the risk of CVD. Public health practitioners may use individuals' living arrangement as preventive measure for CVD risk.

Arterial properties in adults with long-lasting active juvenile idiopathic arthritis compared to healthy controls

BACKGROUND

The data on cardiovascular risk and systemic arterial properties in patients with long-lasting juvenile idiopathic arthritis (JIA) is limited. The objective of this study was to describe systemic arterial properties including characteristic impedance (Z₀), total arterial compliance (C), and peripheral vascular resistance (R) in patients with long-lasting active JIA compared with matched controls, and to assess the relation to JIA disease variables and traditional cardiovascular risk factors.

FINDINGS

Methods: Eighty-one JIA patients (median age 38.6) with at least 15 years of active disease were reexamined after median 29 years of disease duration and compared to 41 healthy controls. With use of echocardiography and calibrated right common carotid artery tonometric pulse traces, noninvasive estimates of pressure and blood flow from the aortic root were obtained and used to estimate the systemic arterial parameters Z₀, C and R.

RESULTS

The patients had higher Z₀ as assessed by Windkessel model (mean ± SD 65.0 ± 30.1 versus 53.4 ± 18.8 10^- 3 mmHg/ml/s, p = 0.027), lower C as assessed by either Windkessel model or ratio of stroke volume and pulse pressure (1.57 ± 0.46 versus 1.80 ± 0.65 ml/mmHg, p = 0.030, 1.29 ± 0.37 versus 1.43 ± 0.34 ml/mmHg, p = 0.038), and similar R compared to the controls. Years on daily prednisolone and insulin resistance were the most important correlates of Z_0. Metotrexat use, polyarticular disease course and erythrocyte sedimentation rate were also associated with a higher Z_0. CONCLUSION: Our results indicate that JIA patients had altered arterial properties as compared to controls. Years on daily prednisolone and insulin resistance were the most important correlates of altered arterial properties.

Hemodynamic Patterns Identified by Impedance Cardiography Predict Mortality in the General Population: The PREVENCION Study

Background Blood pressure is determined by the interactions between the heart and arterial properties, and subjects with identical blood pressure may have substantially different hemodynamic determinants. Whether arterial hemodynamic indices quantified by impedance cardiography ( ICG ), a simple operator-independent office procedure, independently predict all-cause mortality in adults from the general population, and specifically among those who do not meet criteria for American College of Cardiology/American Heart Association stage 2 hypertension, is currently unknown. Methods and Results We studied 1639 adults aged 18 to 80 years from the general population. We used ICG to measure hemodynamic parameters and metrics of cardiac function. We assessed the relationship between hemodynamic parameters measured at baseline and all-cause mortality over a mean follow-up of 10.9 years. Several ICG parameters predicted death. The strongest predictors were total arterial compliance index (standardized hazard ratio=0.38; 95% confidence interval=0.31-0.46; P<0.0001) and indices of cardiac contractility: velocity index (standardized hazard ratio=0.45; 95% confidence interval=0.37-0.55; P<0.0001) and acceleration index (standardized hazard ratio=0.44; 95% confidence interval=0.35-0.55; P<0.0001). These remained independently predictive of death after adjustment for multiple confounders, as well as systolic and diastolic blood pressure. Among subjects without stage 2 hypertension (n=1563), indices of cardiac contractility were independently predictive of death and identified a subpopulation (25% of non-stage-2 hypertensives) that demonstrated a high 10-year mortality risk, equivalent to that of stage 2 hypertensives. Conclusions Hemodynamic patterns identified by ICG independently predict mortality in the general population. The predictive value of ICG applies even in the absence of American College of Cardiology/American Heart Association stage 2 hypertension and identifies higher-risk individuals who are in earlier stages of the hypertension continuum.

Systemic arteriosclerosis is associated with left ventricular remodeling but not atherosclerosis: a TASCFORCE study

BACKGROUND

Arteriosclerosis (arterial stiffening) is associated with future cardiovascular events, with this effect postulated to be due to its effect on cardiac afterload, atherosclerosis (plaque formation) progression or both, but with limited evidence examining these early in disease formation. The aim of the current study is to examine the association between arteriosclerosis, atherosclerosis and ventricular remodelling in a population at low-intermediate cardiovascular risk.

METHODS

One thousand six hundred fifty-one subjects free of clinical cardiovascular disease and with a < 20% 10 year cardiovascular risk score underwent a cardiovascular magnetic resonance (CMR) study and whole body CMR angiogram. Arteriosclerosis was measured using total arterial compliance (TAC) - calculated as the indexed stroke volume divided by the pulse pressure. Atherosclerosis was quantified using a standardised atheroma score (SAS) which was calculated by scoring 30 arterial segments within the body based on the degree of stenosis, summating these scores and normalising it to the number of assessable segments. Left ventricular remodelling was measured using left ventricular mass to volume ratio (LVMVR).

RESULTS

One thousand five hundred fifteen (38% male, 53.8 ± 8.2 years old) completed the study. On univariate analysis TAC was associated with SAS but this was lost after accounting for cardiovascular risk factors in both males (B = - 0.001 (- 0.004-0.002),p = 0.62) and females (B = 0.000(95%CI -0.002--0.002),p = 0.78). In contrast compliance correlated with LVMVR after accounting for cardiovascular risk factors (B = - 0.12(95%CI -0.16--0.091),p < 0.001 in males; B = - 0.12(95%CI -0.15--0.086),p < 0.001 in females).

CONCLUSION

Systemic arteriosclerosis is associated with left ventricular remodelling but not atherosclerosis. Future efforts in cardiovascular risk prevention should thus seek to address both arteriosclerosis and atherosclerosis individually.

Elevated Pulse Pressure Levels Are Associated With Increased In-Hospital Mortality in Acute Spontaneous Intracerebral Hemorrhage

OBJECTIVES

Clinical outcome after intracerebral hemorrhage (ICH) remains poor. Definitive phase-3 trials in ICH have failed to demonstrate improved outcomes with intensive systolic blood pressure (SBP) lowering. We sought to determine whether other BP parameters-diastolic BP (DBP), pulse pressure (PP), and mean arterial pressure (MAP)-showed an association with clinical outcome in ICH.

METHODS

We retrospectively analyzed a prospective cohort of 672 patients with spontaneous ICH and documented demographic characteristics, stroke severity, and neuroimaging parameters. Consecutive hourly BP recordings allowed for computation of SBP, DBP, PP, and MAP. Threshold BP values that transitioned patients from survival to death were determined from ROC curves. Using in-hospital mortality as outcome, BP parameters were evaluated with multivariable logistic regression analysis.

RESULTS

Patients who died during hospitalization had higher mean PP compared to survivors (68.5 ± 16.4 mm Hg vs. 65.4 ± 12.4 mm Hg; P = 0.032). The following admission variables were associated with significantly higher in-hospital mortality (P < 0.001): poorer admission clinical condition, intraventricular hemorrhage, and increased admission normalized hematoma volume. ROC analysis showed that mean PP dichotomized at 72.17 mm Hg, provided a transition point that maximized sensitivity and specific for mortality. The association of this increased dichotomized PP with higher in-hospital mortality was maintained in multivariable logistic regression analysis (odds ratio, 3.0; 95% confidence interval, 1.7-5.3; P < 0.001) adjusting for potential confounders.

CONCLUSION

Widened PP may be an independent predictor for higher mortality in ICH. This association requires further study.

Aortic flow conditions predict ejection efficiency in the NHLBI-Sponsored Women's Ischemia Syndrome Evaluation (WISE)

BACKGROUND

The Windkessel model of the cardiovascular system, both in its original wind-chamber and flow-pipe form, and in its electrical circuit analog has been used for over a century to modeled left ventricular ejection conditions. Using parameters obtained from aortic flow we formed a Flow Index that is proportional to the impedance of such a "circuit". We show that the impedance varies with ejection fraction (EF) in a manner characteristic of a resonant circuit with multiple resonance points, with each resonance point centrally located in a small range of EF values, i.e., corresponding to multiple contiguous EF bands.

METHODS

Two target populations were used: (I) a development group comprising male and female subjects (n=112) undergoing cardiovascular magnetic resonance (CMR) imaging for a variety of cardiac conditions. The Flow Index was developed using aortic flow data and its relationship to left ventricular EF was shown. (II) An illustration group comprised of female subjects from the Women's Ischemia Syndrome Evaluation (WISE) (n=201) followed for 5 years for occurrence of major adverse cardiovascular events (MACE). Flow data was not available in this group but since the Flow Index was related to the EF we noted the MACE rate with respect to EF.

RESULTS

The EFs of the development population covered a wide range (9%-76%) traversing six Flow Index resonance bands. Within each Flow Index resonance band the impedance varied from highly capacitive at the lower range of EF through minimal impedance at resonance, to highly inductive at the higher range of EF, which is characteristic of a resonant circuit. When transitioning from one EF band to a higher band, the Flow Index made a sudden transition from highly inductive to capacitive impedance modes. MACE occurred in 26 (13%) of the WISE (illustration) population. Distance in EF units (Delta_center) from the central location between peaks of MACE activity was derived from EF data and was predictive of MACE rate with an area under the receiver operator curve of 0.73. Of special interest, Delta_center was highly predictive of MACE in the sub-set of women with EF >60% (AUC 0.79) while EF was no more predictive than random chance (AUC 0.48).

CONCLUSIONS

A Flow Index that describes impedance conditions of left ventricular ejection can be calculated using data obtained completely from the ascending aorta. The Flow Index exhibits a periodic variation with EF, and in a separate illustration population the occurrence of MACE was observed to exhibit a similar periodic variation with EF, even in cases of normal EF.