Circumferential strain by velocity vector imaging and speckle-tracking echocardiography: validation against sonomicrometry in an aortic phantom

Biomechanical properties of the ascending aorta in patients with arterial hypertension by velocity vector imaging

Aortic stiffness is an important risk factor for cardiovascular events and morbidity. Increased aortic stiffness is associated with an increase in cardiac and vascular hypertension-related organ damage. To evaluate the biomechanical properties of the ascending aorta (AA) in patients with arterial hypertension (AH) by velocity vector imaging (VVI). Ninety-five patients with AH and 53 normal healthy control participants were prospectively enrolled. AA biomechanical properties, i.e., ascending aortic global longitudinal strain (ALS), ascending aortic global circumferential strain (ACS), and fractional area change (FAC), were evaluated by VVI. Relative wall thickness (RWT) and left ventricular mass (LVM) were calculated. Pulsed Doppler early transmitral peak flow velocity (E), early diastolic mitral annular velocity (e'), left ventricular global longitudinal strain (GLS), distensibility (D) and stiffness index (SI) of AA were also obtained. The ALS, ACS and FAC were significantly lower in the AH patients, especially in those with ascending aorta dilatation (AAD), than in the normal healthy control subjects. The patients with AAD had a higher E/e' ratio, RWT, LVM and SI and a lower GLS and D than patients without AAD and normal healthy volunteers (p < 0.05). There were significant associations between biomechanical properties and D, SI, E/e' and GLS (ALS and D: r = 0.606, ALS and SI: r = - 0.645, ALS and E/e': r = - 0.489, ALS and GLS: r = 0.466, ACS and D: r = 0.564, ACS and SI: r = - 0.567, ACS and E/e': r = - 0.313, ACS and GLS: r = 0.320, FAC and D: r = 0.649, FAC and SI: r = - 0.601, FAC and E/e': r = - 0.504, FAC and GLS: r = 0.524, respectively, p < 0.05). The biomechanical properties of AA were impaired in patients with AH, especially patients with ascending aorta dilatation. Hypertension is associated with a high prevalence of diastolic and systolic dysfunction and increased arterial stiffness. Further study is needed to evaluate the clinical application of AA biomechanical properties by VVI.

Structural and Functional Disturbances of the Thoracic Aorta in Atherosclerosis of Various Gradations

Aim      To study global aortic circumferential strain in normal conditions and in atherosclerosis of various grades and to determine its role in prediction of structural and functional disorders of the thoracic aorta (TA) and coronary atherosclerosis using 2D speckle-tracking transesophageal echocardiography.Material and methods  182 patients with typical or probable angina were examined. The control group consisted of 11 healthy volunteers. TA was visualized along its entire length. The height of each atheroma was measured, and the total number of plaques in the TA was determined. Five stages of TA atherosclerosis were identified. In the descending TA, the global peak systolic circumferential strain (GCS, %) and the global peak systolic circumferential strain normalized to pulse arterial pressure (PAP) (GCS / PAP∙100) were calculated. All patients underwent coronary angiography. The number of coronary arteries (CAs) with >50 % stenosis was determined, and the SYNTAX Score was calculated.Results TA atherosclerosis was not detected in the control group. Among 182 patients, stage 1-5 TA atherosclerosis was found in 23 (12.6 %), 103 (56.6 %), 43 (23.6 %), 7 (3.8 %), and 6 (3.4 %) cases respectively. GCS and GCS / PAD decreased as the ultrasound stage of TA atherosclerosis increased as compared with the control group: 9.2 % and 15.3 for the control group; stage 1, 5.6 % and 8.9 (p<0.001); stage 2, 4.1 % and 5.9 (p<0.001); stage 3, 4 % and 5.8 (p<0.001); stage 4, 3.7 % and 4.9 (p<0.01); and stage 5, 2.6 % and 3.3 (p<0.01), respectively. ROC analysis showed that GCS ≥5.9 % (area under the curve, AUC, 0.94±0.03; p<0.001) and GCS / PAD ≥11.4 (AUC, 0.97±0.02; p <0.001) were predictors of intact TA. Also, GCS ≤4.85 % (AUC, 0.82±0.04; p<0.001) and GCS / PAD ≤8.06 (AUC, 0.87±0.03; p<0.001) were predictors of hemodynamically significant TA atherosclerosis (stages 3-5). GCS ≤4.05 % (AUC, 0.62±0.04; p=0.007) and GCS / PAD ≤5.95 (AUC, 0.61±0.04; p=0.018) were predictors of hemodynamically significant (>50 %) stenosing atherosclerosis of at least one CA. Furthermore, GCS ≤3.75 % (AUC, 0.67±0.07; p=0.039) and GCS / PAD ≤5.15 (AUC, 0.64±0.07; p=0.045) were predictors of severe and advanced coronary atherosclerosis (SYNTAX Score ≥22).Conclusion      GCS and GCS / PAD are new diagnostic markers of structural and functional disorders of TA in atherosclerosis of various grades. GCS and GCS / PAD are independent predictors of high-grade TA atherosclerosis (stages 3-5) with GCS / PAD demonstrating the highest level of significance. GCS and GCS / PAD are non-invasive predictors of severe and advanced CA atherosclerosis.

A preliminary study of changes in carotid artery elasticity in type 2 diabetes mellitus

BACKGROUND

Carotid stiffening is found to be present in patients with type 2 diabetes mellitus (T2DM) together with endothelial dysfunction and it remains unclear about the role of carotid elasticity in the development of diabetic vascular damage. The aim of the study was to investigate changes and significance of carotid artery elasticity in diabetic patients with or without microvascular complications using velocity vector imaging (VVI) analysis.

METHODS

Fifty participants were enrolled and divided into health Control group, the uncomplicated DM (uDM) group and the complicated DM (cDM) group. All of them underwent carotid ultrasound examinations. VVI was used to evaluate the common carotid artery (CCA) elasticity and intima-media thickness (IMT) was also measured. Flow-mediated dilation (FMD) was performed to detect the vascular endothelial function. Then differences and correlations of variables between three groups were compared and analyzed.

RESULTS

CCA elasticity measured by VVI decreased significantly between three groups (p < 0.05), while FMD decreased significantly only in cDM group (p < 0.01) and only IMT in cDM group was significantly thicker than that of Control group (p < 0.05). Representative VVI variables were independently, negatively related to the known duration and microalbuminuria (p < 0.05). All VVI variables were significantly correlated with FMD (0.5 ≤ |r | <0.8, p < 0.001), and just a small part of VVI variables were significantly correlated with IMT (0.3 ≤ |r | <0.5, p < 0.05).

CONCLUSION

Compared with FMD, CCA elasticity measured by VVI showed more obvious changes in diabetic patients with different levels of vascular damage and may be considered as an alternative indicator in evaluating arterial status of T2DM.

Subjects Conceived through Assisted Reproductive Technologies Display Normal Arterial Stiffness

Multiple studies reported signs of vascular dysfunction in subjects conceived through assisted reproductive technologies (ART). The assessment of arterial stiffness in this cohort seems beneficial for risk stratification. Regional arterial stiffness of the abdominal aorta (AAO) and the common carotid arteries (CCA) was evaluated sonographically using two-dimensional speckle tracking in subjects conceived through ART and spontaneously conceived peers. Global arterial stiffness was assessed utilizing an oscillometric blood pressure device. The cohorts of 67 ART subjects and 86 spontaneously conceived peers (11.31 (8.10-18.20) years vs. 11.85 (8.72-18.27) years, p = 0.43) did not differ significantly in parameters of regional and global arterial stiffness. In the sub-analysis of study participants ≥10 years of age, markers of arterial stiffness did not display significant differences between both groups. However, a higher tendency of brachial systolic blood pressure was demonstrated in the ART cohort compared to the control group (120.18 ± 9.57 mmHg vs. 116.55 ± 8.05 mmHg, p = 0.050). The present study displayed no significant differences in arterial stiffness between ART subjects and spontaneously conceived peers. Moreover, this study suggests that arterial stiffness does not elevate more profoundly in ART subjects with increasing age. Further studies are required for a more detailed cardiovascular risk stratification of the ART cohort.

The Evaluation of Longitudinal Strain of Large and Small Abdominal Aortic Aneurysm by Two-Dimensional Speckle-Tracking Ultrasound

OBJECTIVES

Abdominal aortic aneurysm (AAA) is a dangerous and lethal vascular disease. Non-invasive two-dimensional speckle-tracking imaging (2D STI) plays an important role in assessing aortic biomechanical properties. Our study aimed to evaluate the alterations of biomechanical characteristics using 2D STI in 91 AAA patients with different size.

METHODS

Aneurysm strain, elastic modulus, stiffness index β, and aortic distensibility determined by M-Mode ultrasound (US), and longitudinal strain (LS) derived from 2D STI were compared in 40 large AAA patients (diameter ≥ 55 mm) and 51 small AAA patients (diameter < 55 mm).

RESULTS

Compared with small AAA group, anterior wall longitudinal strain (ALS) and posterior wall longitudinal strain (PLS) were significantly decreased in large AAA group (all P < .05) and not affected by age, symptom, hypertension, and thrombus. Meanwhile, ALS and PLS correlated negatively with maximal aneurysm diameters (r = -0.628 and -0.469, respectively, all P < .001). And only ALS was associated with M-Mode US parameters (all P < .05). Based on receiver operating characteristic (ROC) analysis, ALS and PLS had strong diagnostic values for large AAA with the area under the curve (AUC) of 0.82 and 0.72, and cut-off points of 1.71 and 1.64% with a sensitivity of 78 and 72%, and a specificity of 75 and 70%, respectively.

CONCLUSIONS

LS measured by 2D STI could evaluate the biomechanical properties of aneurysm wall with different size, and add additional diagnostic value in distinguishing between small and large AAA.

Assessment of the Global and Regional Circumferential Strain of Abdominal Aortic Aneurysm with Different Size by Speckle-Tracking Echocardiography

OBJECTIVES

We aimed to use speckle-tracking echocardiography (STE) to quantify circumferential aortic strain of abdominal aortic aneurysms (AAA) with different size.

METHODS

A total of 87 AAA patients were included. The morphological variables, including aortic maximum diameter (MD), end systolic area (ESA), end diastolic area (EDA), and thickness and area of intraluminal thrombus (ILT), were measured by ultrasound. STE was applied to calculate circumferential strain (CS) at 6 equally divided segments of the aorta at MD. We evaluated the mean value of peak strain along the 6 segments as global circumferential strain (GCS).

RESULTS

Large AAA (≥5.5 cm) patients had higher MD, ESA, EDA, AAA length, ILT thickness, and area, but lower fractional area change, GCS, and segmental CSs than small AAA (<5.5 cm) subjects (all P < .05). Compared with AAA <4.5 cm group, AAA patients ≥4.5 cm possessed increased MD, ESA, EDA, AAA length, ILT thickness, and area, which results were also reflected in the comparison between AAA <6.5 and ≥6.5 cm group. In small AAA patients, GCS and regional strains in CS1, CS3, and CS5 segments were lower in AAA subjects ≥4.5 cm than those <4.5 cm (all P<.05). However, no significant differences in the GCS and regional CS between ≥6.5 and <6.5 cm group were found. Correlation analysis revealed a significant negative association of GCS with MD, ESA, and EDA, even after adjusting the potential confounding factors (all P < .05).

CONCLUSIONS

Our findings may yield insight into the structural strain characteristics of AAA wall with different size, which adds the benefit of using simple echocardiography-derived biomechanics to stratify AAA patients.

In Vitro Validation of Regional Circumferential Strain Assessment in a Phantom Aortic Model Using Cine Displacement Encoding With Stimulated Echoes MRI

BACKGROUND

A novel application of cine Displacement ENcoding with Stimulated Echoes Magnetic Resonance Imaging (DENSE MRI) has recently been described to assess regional heterogeneities in circumferential strain around the aortic wall in vivo; however, validation is first required for successful clinical translation.

PURPOSE

To validate the quantification of regional circumferential strain around the wall of an aortic phantom using DENSE MRI.

STUDY TYPE

In vitro phantom study.

POPULATION

Three polyvinyl alcohol aortic phantoms with eight axially oriented nitinol wires embedded evenly around the walls.

FIELD STRENGTH/SEQUENCE

3 T; gradient-echo aortic DENSE MRI with spiral cine readout, gradient-echo phase-contrast MRI (PCMR) with Cartesian cine readout.

ASSESSMENT

Phantoms were connected to a pulsatile flow loop and peak DENSE-derived regional circumferential Green strains at 16 equally spaced sectors around the wall were assessed according to previously published algorithms. "True" regional circumferential strains were calculated by manually tracking displacements of the nitinol wires by two independent observers. Normalized circumferential strains (NCS) were calculated by dividing regional strains by the mean strain. Finally, DENSE-derived regional strain was corrected by multiplying regional DENSE NCS by the mean strain calculated from the diameter change on the PCMR.

STATISTICAL TESTS

One-sample t-test, Paired-sample t-test, and analysis of variance with Bonferroni correction, coefficient of variation (CoV), Bland-Altman analysis; P < 0.05 was considered statistically significant.

RESULTS

Aortic DENSE MRI significantly overestimated circumferential strain compared to the wire-tracking method (mean difference and SD 0.030 ± 0.014, CoV 0.31). However, NCS demonstrated good agreement between DENSE and wire-tracking data (mean difference 0.000 ± 0.172, CoV 0.15). After correcting the DENSE-derived regional strain, the mean difference in regional circumferential strain between DENSE and wire-tracking was significantly reduced to 0.006 ± 0.008, and the CoV was reduced to 0.18.

DATA CONCLUSION

For aortic phantoms with mild spatial heterogeneity in circumferential strain, the previously published aortic DENSE MRI technique successfully assessed the regional NCS distribution but overestimated the mean strain. This overestimation is correctable by computing a more accurate mean circumferential strain using a separate cine scan.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 2.

Velocity vector imaging for the assessment of segmental ventricular function in children with a single right ventricle after cavopulmonary anastomosis

OBJECTIVE

Ventricular function assessment is very important for the treatment and prognostic classification of children with a single right ventricle (SRV) after cavopulmonary anastomosis (CPA). However, unusual ventricular shapes can result in inaccurate measurements. The aim of this study was to evaluate velocity vector imaging (VVI) for assessing segmental ventricular function in children with SRV after CPA.

METHODS

Twenty-one children with SRV after CPA and 21 age- and sex-matched children with normal biventricular anatomy and function were included. The longitudinal velocity, displacement, strain and strain rate were measured in the two groups in six segments by VVI. The velocity, displacement, strain and strain rate of the SRVs were compared with max(dp/dt) measured during simultaneous cardiac catheterization in the SRV subjects.

RESULTS

The control group consisted of 13 males and 8 females (69% males) with a mean age of 6.7 ± 3.5 years and mean weight of 20.5 ± 6.5 kg, and the study group consisted of 13 males and 8 females with a mean age 6.7 ± 3.7 years and mean weight of 20.6 ± 6.8 kg. Age, weight and sex distribution were similar between the groups (all, p > .05). Strain and strain rate values in all six segments were significantly lower in the study group than in the control group (all, p < .05). The max(dp/dt) of the SRV was 522.84 ± 158.32 mmHg/s, and the strain rate of the basal segment at the rudimentary chamber correlated best with max(dp/dt) (r = 0.74, p < .01).

CONCLUSIONS

Segmental ventricular dysfunction was present in children with SRV after CPA, and it could be assessed using VVI.