Echo-tracking assessment of carotid artery stiffness in patients with aortic valve stenosis

Arterial stiffness in aortic stenosis - complex clinical and prognostic implications

Arterial stiffness and degenerative aortic stenosis (AoS) are frequently associated leading to a combined valvular and vascular load imposed on the left ventricle (LV). Vascular load consists of a pulsatile load represented by arterial stiffness and a steady load corresponding to vascular resistance. Increased vascular load in AoS has been associated with LV dysfunction and poor prognosis in pre-intervention state, as well as after aortic valve replacement (AVR), suggesting that the evaluation of arterial load in AoS may have clinical benefits. Nevertheless, studies that investigated arterial stiffness in AoS either before or after AVR used various methods of measurement and their results are conflicting. The aim of the present review was to summarize the main pathophysiological mechanisms which may explain the complex valvulo-arterial interplay in AoS and their consequences on LV structure and function on the patients' outcome. Future larger studies are needed to clarify the complex hemodynamic modifications produced by increased vascular load in AoS and its changes after AVR. Prospective evaluation is needed to confirm the prognostic value of arterial stiffness in patients with AoS. Simple, non-invasive, reliable methods which must be validated in AoS still remain to be established before implementing arterial stiffness measurement in patients with AoS in clinical practice.

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.

Carotid Occlusion Accentuates Aortic Stenosis and Cardiac Remodeling With Preserved Systolic Function in LDL Receptor-Deficient Mice

Background: Carotid atherosclerotic disease is associated with aortic stenosis and reduced cardiac function. The causality between carotid and cardiac pathologies is unknown. We aim to explore the effects of carotid stenosis or occlusion on cardiac pathology and function.

Methods and Results: We produced carotid obstruction or stenosis in 36 atherogenic mice with 150- or 300-μm tandem surgery or sham surgery. The structure and function of the heart were assessed by histology and animal ultrasound. The 150-μm group had larger plaque burden and thicker valve leaflets in the aortic root than did the control group. Also, the two surgery groups had a thicker left ventricular posterior wall and smaller internal diameter compared with controls. Increased myocardial fibrosis was also found in the 150-μm group compared with controls, although the surgery groups had preserved systolic function compared with that of controls.

Conclusions: In a mouse model, carotid occlusion accentuated the formation of aortic stenosis and promoted ventricular remodeling without impairing systolic function. Carotid atherosclerotic plaque may be a pathogenic factor for aortic stenosis and ventricular remodeling.

Healthy aging and carotid performance: strain measures and β-stiffness index

Arterial stiffness is related to the risk of cardiovascular disease (CVD) and increases with aging. Functional impairment of the arterial wall can occur before structural changes and can be detectable before CVD symptoms. The elastic properties of the carotid arterial wall during the cardiac cycle can be evaluated by standard 2-dimensional (2D) ultrasound longitudinal or circumferential imaging of vascular deformation (strain) using speckle tracking. The purpose of this study was to compare standard 2D ultrasound circumferential and longitudinal images of vascular tissue motion and strain using speckle tracking in young and older individuals. Participants underwent recording of 2D ultrasound circumferential and longitudinal images of the common carotid artery. Circumferential carotid strain (CS) and CS rate were obtained and analyzed via speckle tracking software. Following the strain analysis, the circumferential strain β-stiffness (C-β) was calculated. Conventional longitudinal β-stiffness (L-β) was calculated and non-invasive blood pressure measurements were obtained from carotid artery pressure measurements in a resting supine position using applanation tonometry. C-β was significantly higher than L-β, and the association with age was greater (r = .824 vs. r = .547). CS and CS rate were significantly higher in the young compared to the older group. L-β does not explain as much of the age-dependent differences in the carotid artery compared with C-β. This is possibly due to the inclusion of whole arterial wall motion and deformation observed in the CS image. The ability of C-β to accurately predict the future risk of CVD independent of age still needs further investigation.

Xuezhikang reduced arterial stiffness in patients with essential hypertension: a preliminary study

This study aimed to test the effects of xuezhikang, a cholestin extract that contains statin-like components, on arterial stiffness in patients with essential hypertension. One hundred hypertensive patients from the Chinese PLA General Hospital were randomly allocated to receive xuezhikang (1200 mg/day, orally) or placebo (same capsules containing only pharmaceutical excipients). Physical examination outcomes, lipid profile, high sensitivity C-reactive protein (hs-CRP) levels, matrix metalloproteinases-9 (MMP-9) levels, and arterial outcomes, including stiffness parameter (β), pressure-strain elasticity modulus (Ep), arterial compliance (AC), augmentation index (AI), and one-point pulse wave velocity (PWVβ) were obtained at baseline and after 6 months of the intervention. Xuezhikang significantly reduced β (8.4±3.1 vs 6.8±2.1, P=0.007), Ep (122.8±43.9 vs 100.7±33.2, P=0.009), PWVβ (6.7±1.2 vs 6.1±1.0, P=0.013), low-density lipoprotein cholesterol (3.4±0.6 vs 2.9±0.5, P=0.001), hs-CRP [2.1 (0.4-10.0) vs 1.4 (0.3-4.1), P=0.020], and MMP-9 (17.2±2.4 vs 12.7±3.8, P <0.001) compared to baseline. The placebo had no effect on these parameters. The changes of PWVβ in the xuezhikang group was significantly associated with the changes of hs-CRP and MMP-9 (r=0.144, P=0.043; r=0.278, P=0.030, respectively) but not with lipid profile changes. Our research showed xuezhikang can improve the parameters of arterial stiffness in hypertensive patients, and its effect was independent of lipid lowering.

A Review on Atherosclerotic Biology, Wall Stiffness, Physics of Elasticity, and Its Ultrasound-Based Measurement

Functional and structural changes in the common carotid artery are biomarkers for cardiovascular risk. Current methods for measuring functional changes include pulse wave velocity, compliance, distensibility, strain, stress, stiffness, and elasticity derived from arterial waveforms. The review is focused on the ultrasound-based carotid artery elasticity and stiffness measurements covering the physics of elasticity and linking it to biological evolution of arterial stiffness. The paper also presents evolution of plaque with a focus on the pathophysiologic cascade leading to arterial hardening. Using the concept of strain, and image-based elasticity, the paper then reviews the lumen diameter and carotid intima-media thickness measurements in combined temporal and spatial domains. Finally, the review presents the factors which influence the understanding of atherosclerotic disease formation and cardiovascular risk including arterial stiffness, tissue morphological characteristics, and image-based elasticity measurement.

Comparison of arterial stiffness/compliance in the ascending aorta and common carotid artery in healthy subjects and its impact on left ventricular structure and function

Arterial stiffness and compliance parameters from two adjacent elastic arteries [aorta and common carotid artery (CCA)] were compared and their relationship with left ventricular (LV) structure and function and clinical parameters was assessed. 584 healthy subjects were prospectively enrolled [mean age 47.8 ± 18.4 years, range 16-94; 318 (54.4%) men]. They underwent comprehensive transthoracic echocardiography; M-mode diameters were measured at the level of the ascending aorta in systole and diastole and by echo-tracking at the level of the left CCA. The β-stiffness, pressure-strain elastic modulus, arterial compliance and one-point pulse wave velocity were derived. A significant correlation was observed between aortic and CCA stiffness and compliance parameters (p < 0.0001 for all). At multiple regression analysis, CCA stiffness parameters were constantly correlated with age and systolic blood pressure, and accounted for up to 56% of the variability (vs. only 29% in aortic stiffness and compliance). CCA stiffness parameters were found to better predict LV structure, diastolic function than aortic stiffness parameters. Aortic and CCA stiffness and compliance were found to correlate with each other and with age, with the correlation being higher for CCA stiffness. At multiple regression analysis, CCA stiffness parameters were better predictors of LV structure and function than aortic stiffness.

How arterial stiffness may affect coronary blood flow: a challenging pathophysiological link

AIMS

A relationship between arterial stiffening and coronary flow abnormalities, although not fully elucidated, has been observed. The purpose of this study was to investigate the relationship among carotid stiffness, measured using echo-tracking, and Doppler parameters of coronary blood flow, sampled at the left anterior descending (LAD) artery.

METHODS

We studied 88 consecutive patients (49 men, mean age 51.2 ± 16.2 years) with cardiovascular risk factors but without history of cardiovascular diseases. Each patient underwent echocardiographic evaluation for measurement of the diastolic velocity time integral (DVTI) and calculation of the diastolic velocity time integral coronary index (DVTICI), the ratio between DVTI and total velocity time integral of LAD artery flow × 100, and carotid ultrasound for measurement of carotid intima media thickness (IMT) and stiffness parameters such as β index and elastic modulus (Ep).

RESULTS

DVTICI was significantly greater in men than in women (median 82, interquartile range 78-86 vs. median 80, interquartile range 73-83, respectively; P < 0.016). After correlating DVTICI with other variables, a significant inverse relation was obtained with β index (Rho = -0.449, P < 0.001), Ep (Rho = -0.478, P < 0.001), age (Rho = -0.52, P < 0.001), left ventricular mass index (Rho = -0.543, P < 0.001), E/E' (Rho = -0.411, P < 0.001), pulse pressure (Rho = -0.417, P < 0.001) and IMT (Rho = -0.480, P < 0.001). With linear multiple regression analysis, only β index (P < 0.001), Ep (P < 0.001), male sex (P < 0.001) and left ventricular mass index (P = 0.008) were independently associated with reduction of DVTICI.

CONCLUSION

Increased arterial stiffness, directly affecting coronary perfusion, is associated with reduced diastolic coronary flow. Echo-tracking for feasible measurement of carotid artery stiffness parameters may be valuable in more accurate cardiovascular risk stratification.

Correlation between Echo-Tracking Parameters and In Vitro Measurements of Arterial Contraction and Relaxation in Rats Fed a High-Cholesterol Diet

BACKGROUND

Echo-tracking (ET) is a new technique that allows the assessment of arterial function and stiffness. This study aimed to ascertain the utility of the echo-tracking (ET) technique to assess vascular stiffness in rats with hypercholesterolemia and atherosclerosis.

MATERIAL AND METHODS

ET was used to measure the arterial stiffness of the aorta in cholesterol-fed Sprague-Dawley rats (group T1, n=10, for 4 weeks; group T2, n=10, for 12 weeks) and normal control rats (group C1, n=10; group C2, n=10). In vitro isometric tension experiments were used to measure the maximum contractile tension (MCT) and maximum relaxation percentage (MRR%) of aortic rings. Indicators of arterial stiffness and aortic MCT and MRR% were compared between groups using linear regression analysis. Light microscopic evaluation was used to demonstrate atherosclerotic changes in the aorta.

RESULTS

The rat models were successfully induced; pathological examination of the aortas showed significant atherosclerosis in group T2, but not in groups C1, C2, or T1. The arterial stiffness parameters obtained using ET and aortic rings in vitro showed significant impairments in T1 and T2 rats compared with C1 and C2 controls (all P<0.05 vs. controls). In addition, these impairments were greater in the T2 group than in the T1 group (all P<0.05). Finally, MRR% correlated with the distensibility coefficient (r=0.396, P=0.012), arterial compliance (r=0.317, P=0.047), stiffness parameter b (r=-0.406, P=0.009) and one-point pulse wave β (r=-0.434, P=0.005).

CONCLUSIONS

These results suggest that ET could be used to evaluate the changes in arterial wall elasticity associated with atherosclerosis and hypercholesterolemia.

Quantifying subtle changes in cardiovascular mechanics in acromegaly: a Doppler myocardial imaging study

AIM OF THE STUDY

To describe morphological and functional cardiovascular changes in acromegaly (ACM) patients, as well as to investigate the ability of Doppler-based myocardial deformation imaging (DMI) to characterize subtle dysfunction in ACM.

METHODS

69 patients (pts) with ACM (mean age 47 ± 10 years, 27 men) and 31 controls (mean age 43 ± 16 years, matched for age and gender) were recruited. Standard echocardiography and DMI data were obtained for all patients. Peak systolic longitudinal strain values (S) were determined for the left and right ventricles. Radial S was measured at the level of the mid inferolateral segment. Using a high-resolution echo-tracking system, the main indices of arterial stiffness were measured.

RESULTS

Of the ACM subjects, 57 had active disease (group A), and 12 controlled ACM (group B). All pts with ACM presented structural changes: a higher LV indexed mass (112 ± 36, 118 ± 23 vs 74 ± 18 g/m(2), p < 0.001) and a higher relative wall thickness (0.45 ± 0.09, 0.50 ± 0.07 vs 0.40 ± 0.07, p = 0.003) compared to controls. Also, ACM pts had functional changes: reduced LV ejection fraction (57 ± 5, 55 ± 5 vs 64 ± 4%, p < 0.001) and altered diastolic function (E/A 1.0 ± 0.4, 1.1 ± 0.1 vs 1.3 ± 0.3, p = 0.005) compared to controls. Both longitudinal and radial LV S values were lower in ACM compared to controls: -16.5 ± 3.5, -16.8 ± 4.3 vs -21.5 ± 3.8%, p < 0.001 for longitudinal and 38.3 ± 12.3, 35.6 ± 11.8 vs 52.2 ± 11.7%, p = 0.002 for radial strain.

CONCLUSIONS

ACM pts present LV concentric hypertrophy and LV systolic and diastolic dysfunction, even in controlled disease. Altered global LV systolic function appears to be due both to longitudinal and radial dysfunction.

Comparison of aortic and carotid arterial stiffness parameters in patients with verified coronary artery disease

BACKGROUND

Arterial stiffness parameters are commonly used to determine the development of atherosclerotic disease. The independent predictive value of aortic stiffness has been demonstrated for coronary events.

HYPOTHESIS

The aim of our study was to compare regional and local arterial functional parameters measured by 2 different noninvasive methods in patients with verified coronary artery disease (CAD). We also compared and contrasted these stiffness parameters to the coronary SYNTAX score in patients who had undergone coronary angiography.

METHODS

In this study, 125 CAD patients were involved, and similar noninvasive measurements were performed on 125 healthy subjects. The regional velocity of the aortic pulse wave (PWVao) was measured by a novel oscillometric device, and the common carotid artery was studied by a Doppler echo-tracking system to determine the local carotid pulse wave velocity (PWVcar). The augmentation index (AIx), which varies proportionately with the resistance of the small arteries, was recorded simultaneously.

RESULTS

In the CAD group, the PWVao and aortic augmentation index (Alxao) values increased significantly (10.1 ± 2.3 m/sec and 34.2% ± 14.6%) compared to the control group (9.6 ± 1.5 m/sec and 30.9% ± 12%; P < 0.05). We observed similar significant increases in the local stiffness parameters (PWVcar and carotid augmentation index [Alxcar]) in patients with verified CAD. Further, we found a strong correlation for PWV and AIx values that were measured with the Arteriograph and those obtained using the echo-tracking method (r = 0.57, P < 0.001 for PWV; and r = 0.65, P < 0.001 for AIx values).

CONCLUSIONS

Our results indicate that local and regional arterial stiffness parameters provide similar information on impaired arterial stiffening in patients with verified CAD.

A brief journey into the history of the arterial pulse

Objective. This paper illustrates the evolution of our knowledge of the arterial pulse from ancient times to the present. Several techniques for arterial pulse evaluation throughout history are discussed. Methods. Using databases including Worldcat, Pubmed, and Emory University Libraries' Catalogue, the significance of the arterial pulse is discussed in three historical eras of medicine: ancient, medieval, and modern. Summary. Techniques used over time to analyze arterial pulse and its characteristics have advanced from simple evaluation by touch to complex methodologies such as ultrasonography and plethysmography. Today's understanding of the various characteristics of the arterial pulse relies on our ancestors' observations and experiments. The pursuit of science continues to lead to major advancements in our knowledge of the arterial pulse and its application in diagnosis of atherosclerotic disease.

[Functional vascular alterations associated with aortic valve stenosis]

Degenerative changes, atherosclerotic process and calcification of valvular leaflets are mostly responsible for valvular aortic valve stenosis, but congenital bicuspid aortic valve and rheumatic fever in history are also known predisposing factors. Aortic valve stenosis is frequently associated with different functional vascular alterations. The aim of this review is to demonstrate these vascular alterations evaluated by non-invasive methods and underlying physiologic and pathophysiologic processes.

Early Identification of Vascular Damage in Patients With Systemic Sclerosis

Vascular involvement in systemic sclerosis (SSc) plays a key role in the pathogenesis of fibrosis. We assessed arterial stiffness using a new echo-tracking technique in patients with SSc asymptomatic for cardiovascular diseases. We enrolled 22 patients (21 female, 63 ± 14 years) and 20 controls (12 female, 62 ± 3 years). Carotid intima-media thickness (IMT) was comparable between the 2 groups (1.1 ± 0.3 vs 1.0 ± 0.4 mm, P = ns), whereas the stiffness parameters were significantly increased in patients (β: 9.5 ± 4.2 vs 5.8 ± 1.1, P = .001; pulse wave velocity [PWV]: 6.5 ± 1.5 vs 5.2 ± 0.6 m/sec, P = .003). A correlation between stiffness parameters, anti-Scl-70 antibodies (β: r = .46, P = .03; PWV: r = .50, P = .02), and anticentromere antibodies (β: r = -.54, P = .020; PWV: r = -.53, P = .023) was found. Echo-tracking technique may be valuable in early identification of vascular involvement in patients with SSc.

Reproducibility of arterial stiffness indices in different vascular territories and between different observers

BACKGROUND

Increased arterial stiffness (AS) corresponds to an increase in cardiovascular risk. According to recent guidelines AS parameters can be measured on all superficial arteries.

OBJECTIVE

Proceeding from the assumption that viscoelastic properties differ along the arterial tree we set ourselves the task to study the reproducibility of AS indices measured at the common carotid, brachial and femoral arteries.

METHODS

The initial study population included 75 patients (40 ± 14.5 years, 45% males) with a variable distribution of cardiovascular risk factors and without clinical evidence of coronary artery disease. AS parameters were measured at the common carotid, brachial and femoral arteries in all patients using echo-tracking (ET) technique. In a subgroup of 36 patients we tested the interobserver variability in the three vascular territories.

RESULTS

We found that there was a significant correlation between AS indices measured at the common carotid and femoral artery (with the only exception for augmentation index) and that AS parameters measured at the brachial artery did correlate neither with common carotid nor with femoral artery indices. The interobserver variability of ET derived AS parameters was good when they were measured at the carotid or femoral artery. The values of AS indices at the brachial artery however showed considerably lower interobserver agreement.

CONCLUSION

The reproducibility of ET derived AS parameters was good when AS was measured at the common carotid or femoral arteries. On the basis of our results brachial artery is probably not a reliable site for AS measurement.

Increased carotid arterial stiffness in subclinical hypothyroidism

OBJECTIVE

Arterial stiffness is involved in the pathophysiology of cardiovascular disease, and subclinical hypothyroidism (SCH) is associated with increased risk of atherosclerosis. The present study was designed to examine whether SCH is associated with an increase in carotid arterial stiffness.

METHODS

The carotid arterial stiffness parameter in 93 patients with SCH and 90 sex- and age-matched euthyroid volunteers was evaluated using a color Doppler ultrasound machine implemented with a high-resolution echo-tracking system.

RESULTS

The participants with SCH had higher total cholesterol, LDL-cholesterol and highly sensitive C-reactive protein (hsCRP) levels than those who were euthyroid. Furthermore, carotid arterial stiffness β (β index) was significantly higher in SCH patients than in normal controls, and β index was significantly positively correlated with age, smoking index, diastolic blood pressure, systolic blood pressure, TSH and hsCRP and significantly negatively correlated with pulse rate in subclinical hypothyroid patients.

CONCLUSIONS

Subclinical hypothyroidism is associated with preclinical vascular alteration, characterized by increased carotid arterial stiffness values, which have been shown to be related to the hsCRP and TSH.

Pulse wave velocity and augmentation index, but not intima-media thickness, are early indicators of vascular damage in hypercholesterolemic children

BACKGROUND

Arterial stiffness is an important determinant of cardiovascular risk. It is associated with several cardiovascular risk factors, including hypertension, diabetes and cigarette smoking. However, there are conflicting data about the relationship between arterial stiffness and hypercholesterolemia. Furthermore, augmentation index (AIx), a measure of systemic arterial stiffness, has not been previously investigated in hypercholesterolemic (HCh) children. Aim of our study was to evaluate local and systemic arterial stiffness as well as carotid intima-media thickness (IMT) in HCh children and also to investigate the relation between serum cholesterol levels and arterial stiffness.

MATERIALS AND METHODS

We determined lipid profile, body mass index, blood pressure, heart rate, carotid IMT and several arterial stiffness parameters, as beta-index, elastic modulus (E(p)), arterial compliance (AC), pulse wave velocity (PWV) and AIx, in 44 untreated HCh children (mean age 10.7 +/- 2.8 years; 18 with familial hypercholesterolemia, FH, and 26 with primary hypercholesterolemia, PHC) and 18 age- and sex-matched controls. HCh children never received any medication, including antihypertensive and lipid lowering drugs.

RESULTS

Respect to controls and to PHC, FH had significantly higher (P < 0.001) beta-index (5.22 +/- 1.13 vs. 3.13 +/- 0.74 and 3.60 +/- 1.02), PWV (4.72 +/- 0.72 m s(-1) vs. 3.66 +/- 0.55 m s(-1) and 4.10 +/- 0.67 m s(-1)), AIx (3.55 +/- 3.97% vs. -4.43 +/- 4.09% and 0.61 +/- 2.39%) and E(p) (64.4 +/- 19.6 kPa vs. 36.2 +/- 11.3 kPa and 42.9 +/- 13.1), whereas AC (1.25 +/- 0.48 mm(2) kPa(-1) vs. 1.9 +/- 0.43 mm(2) kPa(-1) and 1.62 +/- 0.43 mm(2) kPa(-1)) was lower (P < 0.001). There was no significant difference in carotid IMT and blood pressure values between the groups. The multiple regression analysis showed a significant association of arterial stiffness values with plasma cholesterol levels (P < 0.0001).

CONCLUSION

Our findings show that local and systemic arterial stiffness are increased in asymptomatic, normotensive HCh children, suggesting that HCh plays a key role in arterial mechanical impairment since the paediatric age.