Interaction between widening of diameter of abdominal aorta and cardiovascular risk factors and atherosclerosis burden

Two-dimensional echocardiographic and strain values of the proximal thoracic aorta in a normal sub-Saharan African population

BACKGROUND

There is limited data regarding reference ranges for aortic dimensions in African populations. This study aims to establish normal reference ranges for echocardiographic dimensions and circumferential strain (CS) of the proximal thoracic aorta in a healthy sub-Saharan African population.

METHODS

This was a secondary analysis of data from a prospective cross-sectional study of 88 participants conducted at Chris Hani Baragwanath Hospital (2017-2019). Aortic measurements were obtained as per the 2015 American Society of Echocardiography guidelines using a Philips iE33 system. Circumferential Strain was measured using Philips QLAB version 11.0 software offline semi-automated analysis of speckle-based strain 2-D speckle-tracking software (Amsterdam, The Netherlands).

RESULTS

Mean age was 37.22 ± 10.79 years (41% male). The mean diameter at the aortic annulus, sinuses, sino-tubular junction (STJ) and ascending aorta (AAO) were 19.11 ± 2.38 mm, 27.40 ± 6.11 mm, 25.32 ± 3.52 mm and 25.36 ± 3.38 mm, respectively. Males had larger absolute and indexed aortic diameters at all levels when compared to females. The mean aorta CS was 11.97 ± 5.05%. There was no significant difference in CS based on gender (12.19 ± 5.04% vs 11.51 ± 5.02%, P = 0.267). On multivariate linear regression analysis, male sex was the most significant predictor of increased diameter at the level of the aortic annulus (r = 0.17, P = 0.014), body surface area was the most significant predictor at the sinuses (r = 0.17, P = 0.014) and AAO (r = 0.30, P < 0.001), while age was the most significant predictor at the STJ (r = 0.27, P = 0.004). There was a negative correlation between age and aortic CS (r = - 0.12, P < 0.001). The most important predictor of aorta CS was age, on multivariate analysis (r = - 0.19, P = 0.024).

CONCLUSIONS

This study provides normal reference ranges for dimensions of the proximal aorta and circumferential strain (CS) in a sub-Saharan African population according to age, sex, and body habitus. It serves as a platform for future larger studies and allows for risk stratification of cardiovascular disease in an African population.

Potential influencing factors of aortic diameter at specific segments in population with cardiovascular risk

Background

Aortic diameter is a critical parameter for the diagnosis of aortic dilated diseases. Aortic dilation has some common risk factors with cardiovascular diseases. This study aimed to investigate potential influence of traditional cardiovascular risk factors and the measures of subclinical atherosclerosis on aortic diameter of specific segments among adults.

Methods

Four hundred and eight patients with cardiovascular risk factors were prospectively recruited in the observational study. Comprehensive transthoracic M-mode, 2-dimensional Doppler echocardiographic studies were performed using commercial and clinical diagnostic ultrasonography techniques. The aortic dimensions were assessed at different levels: (1) the annulus, (2) the mid-point of the sinuses of Valsalva, (3) the sinotubular junction, (4) the ascending aorta at the level of its largest diameter, (5) the transverse arch (including proximal arch, mid arch, distal arch), (6) the descending aorta posterior to the left atrium, and (7) the abdominal aorta just distal to the origin of the renal arteries. Multivariable linear regression analysis was used for evaluating aortic diameter-related risk factors, including common cardiovascular risk factors, co-morbidities, subclinical atherosclerosis, lipid profile, and hematological parameters.

Results

Significant univariate relations were found between aortic diameter of different levels and most traditional cardiovascular risk factors. Carotid intima-media thickness was significantly correlated with diameter of descending and abdominal aorta. Multivariate linear regression showed potential effects of age, sex, body surface area and some other cardiovascular risk factors on aortic diameter enlargement. Among them, high-density lipoprotein cholesterol had a significantly positive effect on the diameter of ascending and abdominal aorta. Diastolic blood pressure was observed for the positive associations with diameters of five thoracic aortic segments, while systolic blood pressure was only independently related to mid arch diameter.

Conclusion

Aortic segmental diameters were associated with diastolic blood pressure, high-density lipoprotein cholesterol, atherosclerosis diseases and other traditional cardiovascular risk factors, and some determinants still need to be clarified for a better understanding of aortic dilation diseases.

Relationship between the abdominal aortic diameter and carotid atherosclerosis in middle-aged patients without established atherosclerotic cardiovascular diseases

BACKGROUND

The purpose of our research was to study the relationship between the diameter of abdominal aorta (AA) and subclinical atherosclerosis in patients without established atherosclerotic cardiovascular diseases (ASCD) in the absence of pathological enlargement of AA.

METHODS

The study included 136 patients (52.9% male, 47.1% female), median age was 51.0 (45.5; 58.0) years. The maximum diameter of AA was measured in the infrarenal region at a level between the place of origin of the lower renal artery and bifurcation in cross section. Measurement of the anteroposterior diameter of AA was carried out from the outer-to-outer edge (OTO). Also, we determined the Aortic Size Index (ASI) with respect to body surface area (BSA), using the values of BSA obtained by five different formulas validated for use in clinical practice. All patients underwent carotid duplex ultrasound scanning with assessment of degree of carotid stenosis (according to ECST criteria).

RESULTS

An increase in the anteroposterior diameter of AA was directly correlated with maximum stenosis of carotid arteries (r=0.186; P=0.030). According to the results of a logistic regression analysis an increase in the diameter of AA by 1 mm was associated with an increase in the relative risk of carotid stenosis ≥50% by 1.37 times (95% CI: 1.01-1.85; P=0.041) after adjustment. Thus, an increase in diameter of AA of more than 1.75 cm with a sensitivity of 71.4% and a specificity of 73.0% made it possible to predict the presence of stenosis of the carotid arteries ≥50%. An increase in ASI<inf>Boyd</inf> (BSA was calculated using Boyd's formula) of more than 0.84 allowed predicting the presence of stenosis of the carotid arteries ≥50% with a sensitivity of 85.7% and a specificity of 65.6%.

CONCLUSIONS

In middle-aged patients without established ASCD, the diameter of AA and ASI directly correlated with the degree of carotid stenosis (according to ECST criteria). The diameter of AA and ASI demonstrated good sensitivity and specificity for the presence of asymptomatic carotid stenosis of ≥50%.

An unexpected paradox: wall shear stress in the aorta is less in patients with severe atherosclerosis regardless of obesity

BACKGROUND

Obesity is a widespread condition that is more prevalent in Western countries compared to others. Aortic atherosclerosis (AA) is a condition that frequently has been associated with obesity. An obesity paradox, where morbidly obese decedents had either no or minimal AA compared to nonobese decedents, recently has been described by some of us. The explanation for this almost counterintuitive paradox has yet to be determined, but a number of hypotheses were advanced, including hemodynamic factors producing aortic wall shear stress (WSS). The purpose of the present study was to determine if there was a relationship between AA and WSS, as determined by postmortem measurement of aortic wall diameters.

METHODS

Circumferences of the aorta at the levels of the ascending, thoracic and abdominal aorta were measured in 274 consecutive autopsies over 2-year period of time. AA was assessed using a previously described grading scale as either mild or severe. Circumferences were mathematically converted to diameters and WSS was calculated using the Hagen-Poiseuille formula. Two different methods to estimate cardiac output were used, both based on literature methods, one of which was body mass index (BMI) dependent, and the other BMI independent. Univariate and multivariable analyses of the relationship between WSS, age, BMI, gender, race and severity of AA were performed.

RESULTS

Of the 274 decedents, 140 had mild and 134 had moderate to severe AA. BMI <35 was associated with moderate to severe AA. WSS was inversely correlated with AA in all these segments of the aorta in each BMI subgroup with the exception of the ascending aorta for decedents with BMI ≤35 kg/m². Contrary to what we had hypothesized, WSS was not a determinant of the obesity paradox. However, among all the variables analyzed, a history of hypertension, diabetes mellitus and age were significant factors for developing AA (relative risk [RR] 0.35, P = .039; RR 1.51, P = .0006, RR 1.19, P = .0001, respectively).

CONCLUSIONS

Our data demonstrate that WSS was unexpectedly lower in decedents with moderate and severe AA as compared to those with mild AA. This observation, which requires further investigations, was seen in all BMI ranges and was confirmed by 2 methods to calculate WSS.

No association between the abdominal aorta diameter and cervicocephalic atherosclerosis-Potential non-atherosclerotic origins of abdominal aorta aneurysms?

The atherosclerotic origin of abdominal aorta (AA) aneurysms is controversial. Using the Atahualpa Project Cohort, we aimed to assess the relationship between the AA diameter and two surrogates of cervicocephalic atherosclerosis, including the carotid intima-media thickness (cIMT) and the presence of carotid siphon calcifications (CSC). Atahualpa residents aged ≥60 years undergoing ultrasound examinations of the abdominal aorta and the carotid arteries (to calculate the AA diameter and the cIMT), and head CT (to assess CSC severity) were included. Associations between AA diameter and cIMT and CSC severity were assessed by generalized linear models, after adjusting for relevant confounders. Of 256 participants, 64 (25%) had an increased cIMT and 85 (33%) had high calcium content in the carotid siphons. In univariate analysis, being male (p < 0.001) and having total cholesterol blood levels <240 mg/dL (p = 0.022) were associated with a higher AA diameter. Also in univariate analysis, the mean AA diameter was higher in individuals with an increased cIMT (p = 0.021), but such association disappeared in adjusted models. The AA diameter was not associated with high calcium content in the carotid siphons in either univariate or multivariate analyses. This population study shows no association between the AA diameter and cervicocephalic atherosclerosis in community-dwelling older adults, suggesting a non-atherosclerotic origin of AA aneurysms.

Prevalent cardiac, renal and cardiorenal damage in patients with advanced abdominal aortic aneurysms

Chronic kidney disease (CKD), cardiac damage (CD) and the combination of the two are associated with increased morbidity and death in patients admitted to vascular surgery units. We assessed the prevalence of cardiac and renal damage and cardiorenal syndrome (CRS) in 563 patients with abdominal aortic aneurysms (AAA) who underwent cardiac screening before either an endovascular procedure (EVAR) or open surgery (OS) for aneurysm repair. CD was defined by ≥stage B as per the ACC/AHA classification of congestive heart failure (CHF), while CKD was defined by estimated GFR <60 mL/min/1.73 m(2) (CKD-EPI). Anemia [World Health Organization (WHO) guidelines] and iron deficiency (ID) (criteria for CHF patients) were also calculated. AAA patients were stratified into the following groups: CD, CKD, CRS or none of these conditions [no risk factors (NoRF)]. The prevalence of isolated cardiac and renal structural damage, of combined cardiorenal damage and of ID was 24.1, 15.0, 20.6 and 23.4 %, respectively. The frequency of anemia (mostly unrecognized) among the groups increased from NoRF (12.8 %)/CKD (19 %)/CD (25 %) up to CRS (38.8 %). This large-scale observational study provides clues for the increased CD/CKD risk profiles of unselected AAA patients, and underlines the need for better identification of ID/anemia and for appropriate treatment of CKD and CD before these patients undergo EVAR/OS.