Regional aortic distensibility and its relationship with age and aortic stenosis: a computed tomography study

Predictive value of reduced pulmonary arterial elasticity in acute pulmonary embolism for right ventricular dysfunction

BACKGROUND

Computed tomography pulmonary angiography (CTPA) yields indices, such as the right ventricular/left ventricular (RV/LV) ratio > 1.0, which are commonly used for risk stratification of patients with acute pulmonary embolism (APE). Although pulmonary artery elasticity (PAE) has been previously described, its relationship with right ventricular dysfunction (RVD) has not been explored. Here, we investigated whether PAE, measured using CTPA, is associated with RVD.

METHODS

Patients who underwent retrospective electrocardiogram-gated CTPA and had a definitive diagnosis of APE were included in the study. The subjects were classified into RVD and non-RVD groups according to the RVD on echocardiography. PAE, involving aortic distensibility (AD), aortic compliance (AC), and aortic stiffness (ASI), and right heart function indices were compared between the two groups, and their correlations were examined. Receiver operating characteristic (ROC) curves were generated to evaluate the specificity and sensitivity of the RVD prediction.

RESULTS

Thirty-five patients with APE were enrolled in the study (RVD: 18, non-RVD: 17). The groups showed no significant differences in age, sex, number of patients receiving thrombolysis, and number of high-risk conditions (P > 0.05). Regarding PAE parameters, AD was significantly reduced in the RVD group compared to that in the non-RVD group (P < 0.05), whereas AC and ASI were not statistically different (P > 0.05). The ratio of the maximum cross-sectional area of PA and AA (PA/AAmax),the ratio of the minimum cross-sectional area of PA and AA(PA/AAmin), diameter of the coronary sinus, RV/LV diameter, RV/Lvarea, the ratio of the end-diastolic volume of right ventricular and left ventricular (RV/LVDV), the ratio of the end-systolic volume of right ventricular and left ventricular (RV/LVSV) were significantly greater in the RVD group than in the non-RVD group (P < 0.05). Correlation analysis of AD and right heart function parameters showed that AD was negatively correlated with PA/AAmax, PA/AAmin, RV/LV diameter, RV/LVDV, and PAE measured by ultrasound, with correlation coefficients ranging from - 0.336 to - 0.580 (P < 0.05). The ROC curves of AD and RV/LVdiameter to predict RVD had areas under the curve of 0.748 and 0.712, sensitivities of 82.35% and 70.59%, specificities of 66.67% and 72.22%, and cutoff values of 4.9433 and 1.1105, respectively.

CONCLUSION

AD obtained by retrospective ECG-gated CTPA may be helpful in assessing RVD in patients with APE while accurately diagnosing APE. It contributes to timely diagnosis and treatment and improves the prognosis of patients with APE.

Dynamic aortic changes during the cardiac cycle in patients with aortic valve disease analyzed by computed tomography combined with PhyZiodynamics software

BACKGROUND

Endovascular therapy for the ascending aorta is expected in the future, but the dynamic changes in the ascending aorta are unclear.

PURPOSE

The purpose of the present study was to evaluate dynamic changes in the aortic cross-sectional area and examine related determinants.

METHODS

The subjects included 75 patients (aortic regurgitation [AR] in 18 patients, aortic stenosis [AS] in 46 patients, and 11 controls) who underwent dynamic computed tomography (CT) prior to cardiac treatment. According to the centerline method, the cross-sectional areas of the ascending and descending aortas at the same level were analyzed. The rate of change from the minimum value to the maximum value in one heartbeat and peak rate of change in cross-sectional area (peak area change) were measured.

RESULTS

The rates of change of the ascending and descending aortas were 4.4% and 6.4% (P < 0.05) and the peak area change was 0.3 mm2/msec vs. 0.2 mm2/msec (P < 0.05), respectively. In both the ascending and descending aortas, the rate of change and the peak area change were significantly greater in the AR group than in the AS and control groups. Results of the multiple regression analysis showed that greater stroke volumes (SVs) were associated with greater change in the ascending aorta and a faster momentary expansion rate. Furthermore, it was observed that the momentary expansion rate declined with age.

CONCLUSION

The ascending aortic diameter changes significantly in one heartbeat and differs depending on AR, age, and SV.

TRIAL REGISTRATION NUMBER

17 - 006.

DATE OF REGISTRATION

May 29, 2017 Retrospectively registered.

Arterial biomarkers in the evaluation, management and prognosis of aortic stenosis

Degenerative aortic valve stenosis is the most common primary valve disease and a significant cause of cardiovascular morbidity and mortality. In an era when new techniques for the management of aortic stenosis are gaining ground, the understanding of this disease is more important than ever to optimize treatment. So far, the focus has been placed on the assessment of the valve itself. However, the role that the arterial system plays in the pathogenesis and natural history of the disease needs to be further elucidated. Arteriosclerosis, when it coexists with a stenotic valve, augments the load posed on the left ventricle contributing to greater impairment of cardiovascular function. Arterial stiffness, a well-established predictor for cardiovascular disease and all-cause mortality, could play a role in the prognosis and quality of life of this population. Several studies using a variety of indices to assess arterial stiffness have tried to address the potential utility of arterial function assessment in the case of aortic stenosis. Importantly, reliable data identify a prognostic role of arterial biomarkers in aortic stenosis and stress their possible use to optimize timing and method of treatment. This review aims at summarizing the existing knowledge on the interplay between the heart and the vessels in the presence of degenerative aortic stenosis, prior, upon and after interventional management. Further, it discusses the evidence supporting the potential clinical application of arterial biomarkers for the assessment of progression, severity, management and prognosis of aortic stenosis.

Towards a Clinical Implementation of Measuring the Elastic Modulus of the Aorta from Cardiac Computed Tomography Images

OBJECTIVE

The elasticity of the aortic wall varies depending on age, vessel location, and the presence of aortic diseases. Noninvasive measurement will be a powerful tool to understand the mechanical state of the aorta in a living human body. This study aimed to determine the elastic modulus of the aorta using computed tomography images.

METHODS

We constructed our original formulae based on mechanics of materials. Then, we performed computed tomography scans of a silicon rubber tube by applying four pressure conditions to the lumen. The segment elastic modulus was calculated from the scanned images using our formulae. The actual modulus was measured using a tensile loading test for comparison.

RESULTS

The segment moduli of elasticity from the images were 0.525 [0.524, 0.527], 0.524 [0.520, 0.524], 0.520 [0.515, 0.523], and 0.522 [0.516, 0.532] (unit: MPa, median [25%, 75% quantiles]) for the four pressure conditions, respectively. The corresponding measurements in the tensile test were 0.548 [0.539, 0.566], 0.535 [0.528, 0.553], 0.526 [0.513, 0.543], and 0.523 [0.508, 0.530], respectively. These results indicated errors of 4.2%, 2.1%, 1.1%, and 0.2%, respectively.

CONCLUSION

Our formulae provided good estimations of the segment elastic moduli of a silicon rubber tube under physiological pressure conditions using the computed tomography images.

SIGNIFICANCE

In addition to the elasticity, the formulae provide the strain energy as well. These properties can be better predictors of aortic diseases. The formulae consist of clinical parameters commonly used in medical settings (pressure, diameter, and wall thickness).

Unique hemoglobin dynamics in female Tibetan highlanders

BACKGROUND

Tibetan highlanders have adapted to hypoxic environments through the development of unique mechanisms that suppress an increase in hemoglobin (Hb) concentration even in high-altitude areas. Hb concentrations generally decrease with increasing age. However, in the highlands, chronic altitude sickness is known to occur in the elderly population. To investigate how aging in a hypoxic environment affects Hb levels in Tibetan highlanders, we focused on the Mustang people, who live above 3500 m. We tried to clarify the pure relationship between aging and Hb levels in a hypoxic environment.

RESULTS

We found that the Hb concentration increased with increasing age in females but not in males. Multivariate analysis showed that age, pulse pressure, the poverty index, and vascular diameter were strongly correlated with the Hb concentration.

CONCLUSIONS

We found unique Hb dynamics among female Tibetan highlanders. As seen in these Hb dynamics, there may be sex-based differences in the adaptive mechanism in Tibetan highlanders.

Aortic distensibility in alkaptonuria

INTRODUCTION

Alkaptonuria (AKU) is a rare inherited disorder of tyrosine metabolism resulting in an accumulation of homogentisic acid oxidation products in the joints and cardiovascular system. Aortic distensibility may be a non-invasive indicator of cardiovascular complications. Descending thoracic aortic distensibility in alkaptonuria has not been studied.

METHODS

Patients diagnosed with alkaptonuria underwent Magnetic Resonance Imaging (MRI) and gated non-contrast and contrast-enhanced cardiovascular computed tomography. Using MRI cine images, aortic distensibility of the descending thoracic aorta was determined.

RESULTS

Seventy-six patients with alkaptonuria were imaged. When compared to literature normal values, aortic distensibility in AKU was impaired (5.2 vs 6.2 × 10^-3, p < .001). Aortic distensibility was inversely related to age (r = -0.6, p = .0001). Hypertensive patients with alkaptonuria had impaired distensibility compared to normotensive patients with alkaptonuria (4.6 vs 5.6 × 10^-3, p = .03), and hyperlipidemic patients with alkaptonuria had impaired distensibility compared to non-hyperlipidemic patients with alkaptonuria (4.1 vs 6.0 × 10^-3, p = .001). Male hypertensive patients with alkaptonuria had greater distensibility than their female counterparts (5.3 vs 2.9 × 10^-3, p = .02). Similarly, male hyperlipidemic patients with alkaptonuria had greater distensibility than their female counterparts (4.8 vs 2.5 × 10^-3, p < .01). Of patients with alkaptonuria, those with a coronary artery calcium (CAC) score greater than 100 had more impaired distensibility than those with a CAC score less than 100 (3.5 vs 5.1 × 10^-3, p = .01) and those with aortic calcium score greater than 100 had impaired distensibility compared to those with an aortic calcium score less than 100 (3.2 vs 4.9 × 10^-3, p = .02). Univariate analysis revealed age, aortic calcification, and hyperlipidemia to be significant factors of distensibility, and multiple regression analysis showed age as the only significant risk factor of distensibility.

CONCLUSIONS

Patients with alkaptonuria have impaired aortic distensibility, which is likely an early marker for reduced cardiovascular health. Variables such as age, hypertension, hyperlipidemia, and aortic and coronary calcification were associated with impaired distensibility.

Ascending aortic distensibility and target organ damage in primary hypertension without diabetes

To investigate the relationship between ascending aortic distensibility (AAD) and hypertensive target organ damage (TOD) and its potential value in prediction. One hundred and sixty seven primary hypertension inpatients who underwent coronary CTA examination were enrolled into our study. Retrospective ECG-triggering scanning mode were applied and the images were reconstructed every 5% phase in the entire R-R interval. Maximum and minimum ascending aortic areas as well as the AAD value were calculated on the interested slice. AAD (P < 0.001) and brachial-ankle pulse wave velocity (baPWV, P < 0.05) were changed significantly as the deterioration of TOD. Multivariate logistic regression analysis between TOD and its possible influence factors indicated that AAD was the only independent risk factor for the presence and severity of TOD. One standard deviation decrease on AAD would increase the risk of TOD significantly: TOD1 (odds ratio 0.45, P < 0.05), TOD2 (odds ratio 0.23, P < 0.05), and TOD3 (odds ratio 0.01, P < 0.05). The odds ratio of TOD in the third tertile group was found 5.47 times higher than that in the second tertile group, and the second tertile group TOD odds ratio was 6.4 times higher than that in the first tertile group. Decline of AAD can be taken as the independent predict factor for TOD in primary hypertension patients, superior to baPWV method and other conventional predictors. Without additional contrast media consumption and radiation dose, AAD derived from coronary CTA may provide early detection for hypertensive TOD.

Ascending Aortic Elasticity and Related Risk Factors Study on Prehypertension Patients

BACKGROUND

A new feature of coronary computed tomography angiography (CTA) is to estimate ascending aortic elasticity without additional cost, but its applicable benefit for prehypertension patients is still unclear. The aim of this study is to discuss the characteristic of ascending aortic elasticity for specific prehypertension patients and its risk factors.

METHODS

Coronary CTA examinations of 398 participants were performed using a 128 slicer CT scanner. The differences of 3 ascending aortic elasticity related indices, including aortic distensibility (AD), aortic compliance (AC), and aortic stiffness (ASI), and anatomical measurements were analyzed among the normal, prehypertension, and primary hypertension groups.

RESULTS

No difference was found for normalized minimum cross-sectional diameter and area for the ascending aorta between prehypertension and normal groups. AD, AC, and ASI were significantly different in 3 groups. Between prehypertension and normal groups, AD and AC were found much smaller but no difference were found for ASI; while between prehypertension and hypertension groups, significant differences were found in AD and ASI, and AC was found to a lesser extent. Risk factor study for prehypertension patients indicated that age and systolic pressure were the independent risk factors for AD decline.

CONCLUSION

As a byproduct, coronary CTA can provide multiple aortic elasticity related indices for the prehypertension patients, without additional contrast media consumption and radiation dose. It is proofed that the early detection of ascending aortic elasticity index changes, especially for AD are essential for identifying the high-risk individuals in the prehypertension populations.

CLINICAL TRIALS REGISTRATION

Our public trials registry number ChiCTR-RIC-15007482.