Carotid Artery and Aortic Stiffness Evaluation in Aortic 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.

Importance of Increased Arterial Resistance in Risk Prediction in Patients with Cardiovascular Risk Factors and Degenerative Aortic Stenosis

Background: Cardiovascular disease is a leading cause of heart failure (HF) and major adverse cardiac and cerebral events (MACCE). Objective: To evaluate impact of vascular resistance on HF and MACCE incidence in subjects with cardiovascular risk factors (CRF) and degenerative aortic valve stenosis (DAS). Methods: From January 2016 to December 2018, in 404 patients with cardiovascular disease, including 267 patients with moderate-to-severe DAS and 137 patients with CRF, mean values of resistive index (RI) and pulsatile index (PI) were obtained from carotid and vertebral arteries. Patients were followed-up for 2.5 years, for primary outcome of HF and MACCE episodes. Results: RI and PI values in patients with DAS compared to CRF were significantly higher, with optimal cut-offs discriminating arterial resistance of ≥0.7 for RI (sensitivity: 80.5%, specificity: 78.8%) and ≥1.3 for PI (sensitivity: 81.3%, specificity: 79.6%). Age, female gender, diabetes, and DAS were all independently associated with increased resistance. During the follow-up period, 68 (16.8%) episodes of HF-MACCE occurred. High RI (odds ratio 1.25, 95% CI 1.13–1.37) and PI (odds ratio 1.21, 95% CI 1.10–1.34) were associated with risk of HF-MACCE. Conclusions: An accurate assessment of vascular resistance may be used for HF-MACCE risk stratification in patients with DAS.

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.

The Progress of Advanced Ultrasonography in Assessing Aortic Stiffness and the Application Discrepancy between Humans and Rodents

Aortic stiffening is a fundamental pathological alteration of atherosclerosis and other various aging-associated vascular diseases, and it is also an independent risk factor of cardiovascular morbidity and mortality. Ultrasonography is a critical non-invasive method widely used in assessing aortic structure, function, and hemodynamics in humans, playing a crucial role in predicting the pathogenesis and adverse outcomes of vascular diseases. However, its applications in rodent models remain relatively limited, hindering the progress of the research. Here, we summarized the progress of the advanced ultrasonographic techniques applied in evaluating aortic stiffness. With multiple illustrative images, we mainly characterized various ultrasound techniques in assessing aortic stiffness based on the alterations of aortic structure, hemodynamics, and tissue motion. We also discussed the discrepancy of their applications in humans and rodents and explored the potential optimized strategies in the experimental research with animal models. This updated information would help to better understand the nature of ultrasound techniques and provide a valuable prospect for their applications in assessing aortic stiffness in basic science research, particularly with small animals.

Short-term changes of blood pressure and aortic stiffness in older patients after transcatheter aortic valve implantation

Background

Both aortic valve stenosis and aortic stiffness are moderators of arterio ventricular coupling and independent predictors of cardiovascular morbidity and mortality. Studies on the effect of transcatheter aortic valve implantation (TAVI) on aortic functional properties are limited. We performed a study to investigate the possible short-term changes in aortic stiffness and other aortic functional properties after TAVI in older patients.

Methods

TAVI Care&Cure is an observational ongoing study including consecutive patients undergoing a TAVI procedure. Central and peripheral hemodynamic measurements were measured non invasively 1 day before (T-1) and 1 day after (T+1) TAVI using a validated oscillometric method using a brachial cuff (Mobil-O-Graph).

Results

40 patients were included. Mean aortic valve area at baseline was 0.76±0.24 cm². Indices of severity of aortic valve stenosis improved significantly. Systolic blood pressure (SBP) dropped by 8.5%, from 130.3±22.9 mmHg to 119.5±15.8 mmHg (p=0.005). Diastolic blood pressure (DBP) dropped by 13.1% from 74.8±14.5 mmHg to 65.0±11.3 mmHg (p<0.001). The arterial pulse wave velocity (aPWV) decreased from 12.05±1.99 m/s to 11.6±1.56 m/s (p=0.006). Patients with high aPWV at baseline showed a significantly larger reduction in SBP in comparison to patients with low aPWV: – 20.3 mmHg (−14.1%) vs – 3.1 mmHg (−2.6%), respectively (p=0.033). The same trend was found for the DBP: −16.2 (−20.4%) vs −4.5 mmHg (−6.3%) for high vs low aPWV at baseline (p=0.037).

Conclusion

We found short-term changes in blood pressure and aortic stiffness after TAVI. The amplitude of the changes was the largest in patients with elevated aortic stiffness at baseline.

The role of ventricular-arterial coupling in cardiac disease and heart failure: assessment, clinical implications and therapeutic interventions. A consensus document of the European Society of Cardiology Working Group on Aorta & Peripheral Vascular Diseases, European Association of Cardiovascular Imaging, and Heart Failure Association

Ventricular-arterial coupling (VAC) plays a major role in the physiology of cardiac and aortic mechanics, as well as in the pathophysiology of cardiac disease. VAC assessment possesses independent diagnostic and prognostic value and may be used to refine riskstratification and monitor therapeutic interventions. Traditionally, VAC is assessed by the non-invasive measurement of the ratio of arterial (Ea) to ventricular end-systolic elastance (Ees). With disease progression, both Ea and Ees may become abnormal and the Ea/Ees ratio may approximate its normal values. Therefore, the measurement of each component of this ratio or of novel more sensitive markers of myocardial (e.g. global longitudinal strain) and arterial function (e.g. pulse wave velocity) may better characterize VAC. In valvular heart disease, systemic arterial compliance and valvulo-arterial impedance have an established diagnostic and prognostic value and may monitor the effects of valve replacement on vascular and cardiac function. Treatment guided to improve VAC through improvement of both or each one of its components may delay incidence of heart failure and possibly improve prognosis in heart failure. In this consensus document, we describe the pathophysiology, the methods of assessment as well as the clinical implications of VAC in cardiac diseases and heart failure. Finally, we focus on interventions that may improve VAC and thus modify prognosis.

Changes in Aortic Pulse Wave Velocity and the Predictors of Improvement in Arterial Stiffness Following Aortic Valve Replacement

BACKGROUND

The interaction between valvular aortic stenosis (AS) and arterial stiffness, as well as the impact of aortic valve replacement (AVR) on arterial stiffness, remains unclear. In this study, we aimed to evaluate the degree of AS severity on non-invasive pulse wave velocity (PWV) measurements. We also searched whether the AVR procedure favorably affects PWV.

METHODS

In all, 38 patients undergoing AVR for chronic AS were included. The degree of aortic stiffness was measured with PWV at both baseline and 6 months after AVR. Improvement in aortic stiffness was defined as the absolute decrease in PWV at 6 months compared to the baseline value.

RESULTS

The study population had a mean age of 59 ± 16 years, mean aortic gradient of 47.1 ± 6.4 mmHg, and mean aortic valve area (AVA) index of 0.45 ± 0.11 cm² /m² . Baseline PWV values correlated positively with the mean aortic gradient (r = 0.350, p = 0.031) and negatively with the AVA index (r = -0.512, p = 0.001). The mean PWV improved in 20 patients (53%) and worsened in 18 patients (47%). The baseline New York Heart Association (NYHA) class (odds ratio [OR] = 1.023, 95% confidence interval [CI] = 1.005-1.041, p = 0.041) and AVA index (OR = 1.040, 96% CI = 1.023-1.057, p = 0.028) emerged as the independent predictors of improvement in PWV following AVR.

CONCLUSION

The severity of AS was significantly associated with baseline PWV. In general, the mean PWV did not change with AVR. Baseline NYHA class and the AVA index independently predicted PWV improvement following AVR. Since the change in PWV after AVR was polarized based on the patients' characteristics, such as preoperative NYHA functional class or AVA index, further studies are needed to confirm clinical significance of PWV change following AVR in severe AS patients.

Determinants and Prognostic Significance of Symptomatic Status in Patients with Moderately Dysfunctional Bicuspid Aortic Valves

Background

We aimed to identify the clinical and echocardiographic determinants of symptoms and their prognostic implications in patients with moderately dysfunctional bicuspid aortic valves (BAVs).

Methods

Among 1,019 subjects in the BAV registry treated in a single tertiary care center, the records of 127 patients (85 men, age 58±13 years) with moderately dysfunctional BAVs were comprehensively reviewed. The patients were divided into two groups based on symptom status: asymptomatic (n = 80) vs. symptomatic (n = 47). The primary end-point was defined as a composite of aortic valve surgery, hospitalization for heart failure, and any cause of death.

Results

The symptomatic group had a higher proportion of females, hypertension, aortic stenosis, and aortopathy than did the asymptomatic group. The symptomatic group showed lower e′ (5.5±1.7 vs. 6.5±2.2 cm/s, p = 0.003), higher E/e′ (13.3 ± 4.9 vs. 10.9±3.7, p = 0.002), and larger left atrial volume index (29.9±11.4 vs. 24.6±9.1 ml/m², p = 0.006) than did the asymptomatic group. In multivariate logistic regression analysis, female gender (odds ratio [OR] 2.84, 95% confidence interval [CI] 1.10–7.36, p = 0.031), hypertension (OR 3.07, 95% CI 1.20–7.82, p = 0.019), moderate aortic stenosis (OR 5.33 5.78, 95% CI 1.99–16.83, p = 0.001), E/e′ >15 (OR 3.82, 95% CI 1.03–11.19, p = 0.015), and aortopathy (OR 2.76, 95% CI 1.07–7.10, p = 0.035) were independently correlated with symptom status. The symptomatic group showed a significantly lower rate of event-free survival during the 8-year follow-up period (54±9% vs. 68±10%, p = 0.001).

Conclusions

In patients with moderately dysfunctional BAVs, the presence of moderate aortic stenosis, aortopathy, and diastolic dysfunction determines symptom status, along with female gender and hypertension. Symptom status was associated with clinical outcomes.

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.

Impact of Valvuloarterial Impedance on Concentric Remodeling in Aortic Stenosis and Its Regression after Valve Replacement

Background

Left ventricle (LV) in patients with aortic stenosis (AS) faces a double hemodynamic load incorporating both valvular stenosis and reduced systemic arterial compliance (SAC). This study aimed to evaluate the impact of global LV afterload on LV hypertrophy (LVH) before and after aortic valve replacement (AVR).

Methods

The study cohort included 453 patients (247 males; mean age, 64 ± 11 years) who underwent AVR. Pre- and post-AVR echocardiographic examinations were retrospectively analyzed including an index of valvuloarterial impedance (Z_VA) and LV mass index/LV end-diastolic volume index (LVMI/LVEDVI) as a parameter of LVH.

Results

Pre-AVR LVMI/LVEDVI was 2.7 ± 0.9 g/mL with an aortic valve area (AVA) of 0.6 ± 0.2 cm². Z_VA was 5.9 ± 1.9 mm Hg/mL/m² and showed a stronger correlation (β = 0.601, p < 0.001) with pre-AVR LVMI/LVEDVI than indexed AVA (β = 0.061, p = 0.19), transvalvular peak velocity (β = 0.211, p < 0.001). During a median follow-up of 3.5 years, patients had a 18.8 ± 10.4% decrease in the LV geometry index with a decrease in SAC from 1.20 ± 0.48 to 1.00 ± 0.38 mL/m²/mm Hg (p < 0.001). Pre-AVR LV ejection fraction (r = 0.284, p < 0.001) and Z_VA (r = 0.523, p < 0.001) were independent factors associated with LVH regression in 322 patients with follow-up duration >1 year after AVR.

Conclusion

Z_VA is a major determinant of concentric remodeling in AS before AVR and LVH regression after AVR, which should be incorporated in routine evaluation of AS.

A non-contact approach for PWV detection: application in a clinical setting

A need for screening methods for arteriosclerosis led to the development of several approaches to measure pulse wave velocity (PWV) being indicative of arterial stiffness. Carotid-femoral PWV (cfPWV) can be measured between common carotid artery (CCA) and femoral artery (FA) displaying the physiologically important stiffness of the conduit arteries. However, this measurement approach has several disadvantages, and a local PWV-measurement of CCA-stiffness has been proposed as an alternative in the past. In the presented pilot study, laser Doppler vibrometry (LDV) is used to measure PWV locally in the CCA (PWVLDV) in 48 patients aged between 48 and 70, with known atherosclerotic arterial disease: stabilized coronary artery disease (CAD), cerebro-vascular disease (CVD) or peripheral artery disease (PAD). Additionally, cfPWV, CCA distensibility coefficient (DC), CCA intima-media thickness (IMT), blood pressure (BP) and age were evaluated. LDV is a valid method for local PWV-measurement. The method is potentially easy to use, and causes no discomfort to the patient. PWVLDV correlates with age (R  =  0.432; p  =  0.002) as reported in related studies using other techniques, and measured values lay between 2.5 and 5.8 m s(-1), which is well in line with literature measures of local PWV in the CCA. In conclusion, PWVLDV potentially is a marker for arterial health, but more research in a larger and more homogeneous patient population is mandatory. In future studies, blood velocity measurements should be incorporated, as well as a reference method such as pulse wave imaging (PWI) or magnetic resonance imaging (MRI).

The left ventricle in aortic stenosis--imaging assessment and clinical implications

Aortic stenosis has an increasing prevalence in the context of aging population. In these patients non-invasive imaging allows not only the grading of valve stenosis severity, but also the assessment of left ventricular function. These two goals play a key role in clinical decision-making. Although left ventricular ejection fraction is currently the only left ventricular function parameter that guides intervention, current imaging techniques are able to detect early changes in LV structure and function even in asymptomatic patients with significant aortic stenosis and preserved ejection fraction. Moreover, new imaging parameters emerged as predictors of disease progression in patients with aortic stenosis. Although proper standardization and confirmatory data from large prospective studies are needed, these novel parameters have the potential of becoming useful tools in guiding intervention in asymptomatic patients with aortic stenosis and stratify risk in symptomatic patients undergoing aortic valve replacement.

This review focuses on the mechanisms of transition from compensatory left ventricular hypertrophy to left ventricular dysfunction and heart failure in aortic stenosis and the role of non-invasive imaging assessment of the left ventricular geometry and function in these patients.