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Table of Contents
ORIGINAL ARTICLE
Year : 2022  |  Volume : 27  |  Issue : 1  |  Page : 99-103

Determinants of descending thoracic aortic size measured by echocardiography


1 Department of Medicine, University of Nigeria, Ituku-Ozalla Campus, Enugu State, Nigeria
2 Department of Pharmacology and Therapeutics, University of Nigeria, Ituku-Ozalla Campus, Enugu State, Nigeria
3 Department of Medicine, Abia State University Teaching Hospital, Aba, Abia State, Nigeria
4 Department of Medicine, University of Nigeria Teaching Hospital, Ituku-Ozalla, Enugu State, Nigeria
5 Department of Medicine, Enugu State University Teaching Hospital, Parklane, Enugu State, Nigeria
6 Department of Surgery, University of Nigeria, Ituku-Ozalla Campus, Enugu State, Nigeria
7 Department of Medicine, Iruah Specialist Hospital, Iruah, Edo State, Nigeria
8 Department of Medicine, Alex Ekwueme Federal University Teaching Hospital, Abakaliki, Ebonyi State, Nigeria

Date of Submission13-Jun-2020
Date of Decision09-May-2021
Date of Acceptance13-May-2021
Date of Web Publication3-Dec-2021

Correspondence Address:
Emmanuel C Ejim
Department of Medicine, University of Nigeria, Ituku-Ozalla Campus, Enugu State.
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijmh.IJMH_41_20

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  Abstract 

Background: Aortic size is known to be an important predictor of cardiovascular diseases. There is a dearth of data on factors affecting thoracic aorta size in the black African population. Objective: To determine the predictors of descending thoracic aortic size measured by echocardiography. Materials and Methods: Transthoracic echocardiographic reports of 167 consecutive subjects were retrospectively reviewed. Data obtained from the register included age, gender, weight, height, body mass index, systolic blood pressure, diastolic blood pressure, and heart rate. Results: A total of 167 individuals aged between 12 and 96 years were studied. These were composed of 94 males and 73 females with mean age of 51.64 ± 16.31 and 46.90 ± 15.77, respectively. The mean descending thoracic aortic dimension was 23.35 ± 3.73 mm. The aortic measurement was found to be significantly higher in the male subjects (p < 0.05). A multi-variate correlation analysis revealed significant correlations between descending thoracic aortic dimension and (1) age, (2) weight, (3) body mass index, (4) systolic blood pressure, (5) diastolic blood pressure, (6) pulse pressure, and (6) mean arterial blood pressure (p < 0.05). These relationships were further explored using regression models. The most important predictors of aortic dimension in this study were age, weight, and sex (p < 0.05). Our result suggests a linear relationship between age and descending thoracic dimension. Conclusion: Age, body weight, and gender significantly affect the size of the descending thoracic aorta and could predict cardiovascular risk.

Keywords: Descending thoracic aorta, dimensions, echocardiography


How to cite this article:
Ejim EC, Oguanobi NI, Ubani-Ukoma CB, Udora NC, Chigbo EJ, Okwulehie VA, Okonkwo AK, Iyidobi T. Determinants of descending thoracic aortic size measured by echocardiography. Int J Med Health Dev 2022;27:99-103

How to cite this URL:
Ejim EC, Oguanobi NI, Ubani-Ukoma CB, Udora NC, Chigbo EJ, Okwulehie VA, Okonkwo AK, Iyidobi T. Determinants of descending thoracic aortic size measured by echocardiography. Int J Med Health Dev [serial online] 2022 [cited 2023 Feb 8];27:99-103. Available from: https://www.ijmhdev.com/text.asp?2022/27/1/99/331726




  Introduction Top


Historically, aortic measurements were established using M-mode echocardiography, measuring from leading edge to leading edge.[1] Aortic size is known to vary significantly by age and body size, and to be an important predictor of cardiovascular diseases. The relationship between increasing aortic size and risk of spontaneous rupture or dissection has been well documented.[2] Unlike the prevalence and incidence of abdominal aortic aneurysms, which seems to be on the decline over the past two decades, the burden of descending thoracic aneurysm has been on the increase.[3],[4] Assessment of the sizes of the different segments of the thoracic aorta is an essential part of every echocardiographic examination. There is a dearth of data on factors affecting the size of the thoracic aorta in this part of the world. We, therefore, set out to find the factors that determine the size of the descending thoracic aorta on transthoracic echocardiography.


  Materials and Methods Top


The reports of echocardiography that had been performed on 167 consecutive subjects at a private echocardiographic laboratory in Enugu over a period of four years (from January 2016 to December 2019) were retrospectively reviewed. Tranthoracic echocardiography was done with a Siemens CV 70 echocardiographic machine. The machine has the capability to perform M-mode, 2-Dimensional, and Doppler studies, as well as transoesophageal imaging. Uniform standard protocols were employed in echocardiographic measurements.[1],[5] The descending thoracic aorta was measured at the level of the left atrium on a parasternal long axis view, using M-mode leading edge to leading edge technique.[1]

All the echocardiographic measurements were performed by one cardiologist. While conducting the echocardiography on our study participants, the cardiologist endeavored to adhere to uniform guidelines in order to ensure accuracy and reliability of results.

Data obtained from the register included age, gender, weight, height, body mass index (BMI), systolic blood pressure, diastolic blood pressure, and heart rate. Blood pressure was measured using Mercury column sphygmomanometer with a cuff of an appropriate size after the patient had been seated quietly for about 5 min. The first and fifth Korotkof sounds were used as the systolic and diastolic blood pressures, respectively. The mean arterial pressure and pulse pressure were calculated from the parameters described earlier.

Data analysis

Data were presented as means ± standard deviation for continuous variables and as proportions for categorical variables. A comparison of continuous variables between groups was made with independent Student’s t-test. For discrete variables, distributions between groups were compared with Chi-square test and Fisher’s exact test as appropriate (where an expected cell is less than 5). Multivariate correlation analysis was used to assess the relationships between descending thoracic aortic dimension (DTA) and clinical parameters. Parameters with significant correlations were further evaluated using regression models.

All statistical analyses were carried out using the Statistical Packages for Social Sciences (SPSS Inc. Chicago Illinois) software version 22.0. Statistical tests with probability values less than 0.05 were considered statistically significant.


  Result Top


A total of 167 individuals aged between 12 and 96 years were studied. These were composed of 94 males and 73 females with a mean age of 51.64 ± 16.31 and 46.90 ± 15.77, respectively (p< .001). Although the male participants in this study were significantly older and had higher measured anthropometrical indices (height and weight), there was no significant differences in BMI [Table 1]. The mean DTA was 23.35 ± 3.73 mm. The aortic measurement was found to be significantly higher in the male subjects [Table 1].
Table 1: Clinical characteristics and DTA of the subjects

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A multivariate correlation analysis revealed significant positive correlations between DTA and (1) age (r = 0.564; P < 0.001), (2) weight (r = 0.287; P < 0.001), (3) BMI (r = 0.282; P < 0.001), (4) systolic blood pressure (r = 0.287; P < 0.001), (5) diastolic blood pressure (r = 0.168; P = 0.030), (6) pulse pressure (r = 0.188; P = 0.015), and (6) mean arterial blood pressure (r = 0.247; P = 0.001) [Table 2]. These relationships were further explored using multiple regression models. In order to avoid the confounding effects of colinearity of the related parameters, several regression models were evaluated with the blood pressure indices and related anthropometric parameters (weight and BMI), which were independently included in a mutually exclusive manner. The results of the regression analysis are presented in [Table 3] and [Figure 1] and [Figure 2]. Blood pressure indices were not found to be significant independent predictors of the DTA. The most important predictors of the aortic dimension in this study were age, weight, and sex, with these parameters accounting for 77%, 16%, and 7%, respectively, of the variability of the DTA [Figure 1]. Our result suggests a linear relationship between age and the descending thoracic dimension [Figure 2]. The regression equation for DTA in relation to the independent variables from this study can be expressed as follows: DTA (mm) = 10.567 (regression constant) + 0.128 (regression coefficient for Age)*Age + 0.058 (regression coefficient for weight)*Weight.
Table 2: Clinical correlates of DTA

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Table 3: Determinants of DTA: A regression analysis

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Figure 1: Relative importance of clinical predictor of DTA

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Figure 2: Regression models of the relationship between age and DTA

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  Discussion Top


This retrospective review of our echocardiography registry revealed a significant relationship between the DTA and age, gender, anthropometric variables, and blood pressure indices.

The male subjects were found to have significantly higher aortic dimensions than the females. A similar observation has been reported by previous studies.[6],[7] The gender differences in the DTA raise important research question regarding its significance, whether it is due to differential body size, anatomical/anthropometrical or lifestyle factors. It is likely that multifactorial mechanisms play roles in this sex disparity. The preponderance of risk factors such as hypertension and smoking seem notable in the male population.[6] However, the male participants in our study did not have higher blood pressures and the role of lifestyle risk factors that were not evaluated in this study is considered an important subject of future research interest.

Age-related increase in thoracic aortic size is a recognized risk factor for aortic regurgitation and aortic dissection.[8],[9] Our study noted a significant positive correlation between age and descending thoracic dimension. Previous clinical echocardiographic studies have yielded apparently conflicting results due to differences in the age range of their study population. Studies on the predominantly pediatric population did not find any age-related change in the thoracic aortic dimension,[10],[11] whereas those with a balanced age-group representation documented age-related changes.[12],[13],[14] This increase in the aortic dimension may be due to the combined effects of age-related changes in aortic vasculature and other age-dependent atherosclerotic-associated disorders such as hypertension, diabetes, and dyslipidemia. These structural and functional changes result in increased thickening of the vascular wall with reduced elasticity and abnormal stretch response.[15],[16]

Anthropometric parameters with a significant correlation to aortic dimension in this study were weight and BMI. This is in agreement with reports from previous studies.[7],[12],[13],[17] Our study observed positive correlations between the aortic dimension and blood pressure indices (systolic, diastolic, and mean arterial blood pressures). The role of high blood pressure in the pathophysiology of dilated aorta can be attributed to artherosclerosis that is associated with elevated blood pressure. Interestingly, a number of studies, including the Framingham Heart Study, have reported an association between aortic root dilation and blood pressure in hypertensive subjects.[7]

Among all the risk factors of the dilated descending thoracic aorta identified in this study, age ranked as the most important, accounting for more than 75% of the variability in the aortic dimension followed in that order by weight and gender. Our findings suggest a linear relationship between age and the aortic dimension. These proportions are significantly higher than the reports by Agmon et al[18] and the Framingham Heart Study,[6] both of which were population-based studies on the non-negro population.


  Conclusion Top


Age, body weight, and sex are the principal determinants of DTAs and could predict cardiovascular risk.

Financial support and sponsorship

Nil.

Conflicts of interest

The authors have no potential conflict of interests.



 
  References Top

1.
Sahn DJ, DeMaria A, Kisslo J, Weyman A. Recommendations regarding M-mode echocardiography: Results of a survey of echocardiographic measurements. Circulation1978;58: 1072-83.  Back to cited text no. 1
    
2.
Pape LA, Tsai TT, Isselbacher EM, Oh JK, O’gara PT, Evangelista A, et al; International Registry of Acute Aortic Dissection (IRAD) Investigators. Aortic diameter > or = 5.5 cm is not a good predictor of type A aortic dissection: Observations from the international registry of acute aortic dissection (IRAD). Circulation 2007;116:1120-7.  Back to cited text no. 2
    
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Sampson UK, Norman PE, Fowkes FG, Aboyans V, Yanna Song, Harrell FE Jr, et al. Global and regional burden of aortic dissection and aneurysms: Mortality trends in 21 world regions, 1990 to 2010. Glob Heart 2014;9: 171-80.e10.  Back to cited text no. 3
    
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Sampson UKA, Norman PE, Fowkes GR, Aboyans V, Song Y, Harrell FE, et al. Estimation of global and regional incidence and prevalence of abdominal aortic aneurysms 1990 to 2010. Global Heart 2014;8:159-70.  Back to cited text no. 4
    
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6.
Rogers IS, Massaro JM, Truong QA, Mahabadi AA, Kriegel MF, Fox CS, et al. Distribution, determinants, and normal reference values of thoracic and abdominal aortic diameters by computed tomography (from the Framingham Heart Study). Am J Cardiol 2013;111:1510-6.  Back to cited text no. 6
    
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Vasan RS, Larson MG, Levy D. Determinants of echocardiographic aortic root size. The Framingham Heart Study. Circulation 1995;91:734-40.  Back to cited text no. 7
    
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Dawber TR, Meadors GF, Moore FE. Epidemiologic approaches to heart disease: The Framingham Study. Am J Public Health.1951; 41:279-86.  Back to cited text no. 8
    
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Mohiaddin RH, Schoser K, Amanuma M, Burman ED, Longmore DB. MR imaging of age-related dimensional changes of thoracic aorta. J Comput Assist Tomogr 1990;14:748-52.  Back to cited text no. 9
    
10.
Nidorf SM, Picard MH, Triulzi MO, Thomas JD, Newell J, King ME, et al. New perspectives in the assessment of cardiac chamber dimensions during development and adulthood. J Am Coll Cardiol 1992;19:983-8.  Back to cited text no. 10
    
11.
Valdez RS, Motta JA, London E, Martin RP, Haskell WL, Farquhar JW, et al. Evaluation of the echocardiogram as an epidemiologic tool in an asymptomatic population. Circulation 1979;60:921-9.  Back to cited text no. 11
    
12.
Roman MJ, Devereux RB, Kramer-Fox R, O’Loughlin J. Two-dimensional echocardiographic aortic root dimensions in normal children and adults. Am J Cardiol 1989;64:507-12.  Back to cited text no. 12
    
13.
Henry WL, Gardin JM, Ware JH. Echocardiographic measurements in normal subjects from infancy to old age. Circulation 1980;62:1054-61.  Back to cited text no. 13
    
14.
Gerstenblith G, Frederiksen J, Yin FC, Fortuin NJ, Lakatta EG, Weisfeldt ML. Echocardiographic assessment of a normal adult aging population. Circulation 1977;56:273-8.  Back to cited text no. 14
    
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Sonesson B, Hansen F, Stale H, Länne T. Compliance and diameter in the human abdominal aorta–the influence of age and sex. Eur J Vasc Surg 1993;7:690-7.  Back to cited text no. 15
    
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Bader H. Dependence of wall stress in the human thoracic aorta on age and pressure. Circ Res 1967;20:354-61.  Back to cited text no. 16
    
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Reed CM, Richey PA, Pulliam DA, Somes GW, Alpert BS. Aortic dimensions in tall men and women. Am J Cardiol 1993;71:608-10.  Back to cited text no. 17
    
18.
Agmon Y, Khandheria BK, Meissner I, Schwartz GL, Sicks JD, Fought AJ, et al. Is aortic dilatation an atherosclerosis-related process? Clinical, laboratory, and transesophageal echocardiographic correlates of thoracic aortic dimensions in the population with implications for thoracic aortic aneurysm formation. J Am Coll Cardiol 2003;42:1076-83.  Back to cited text no. 18
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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