|Year : 2018 | Volume
| Issue : 12 | Page : 51-55
The usefulness of aortic arch width measurements on chest radiographs of adult patients with systemic hypertension and hypertensive heart disease
Solomon Daniel Halilu1, Joshua Oluwafemi Aiyekomogbon2
1 Department of Radiology, Ahmadu Bello University Teaching Hospital, Zaria; Department of Radiology, Abubakar Tafawa Balewa University Teaching Hospital, Bauchi, Nigeria
2 Department of Radiology, Ahmadu Bello University Teaching Hospital, Zaria; Department of Radiology, University of Abuja, Abuja, Nigeria
|Date of Web Publication||19-Nov-2018|
Joshua Oluwafemi Aiyekomogbon
Department of Radiology, University of Abuja, Abuja
Source of Support: None, Conflict of Interest: None
Background: Systemic hypertension is a worldwide epidemic and often called a silent killer. It is the most common cardiovascular disease among Africans, and an acknowledged potential risk factor for the development of complications such as stroke, hypertensive heart disease, hypertensive heart failure, and end-organ damage to the brain, eyes, and kidneys. Systemic hypertension and hypertensive heart disease are major causes of widened aortic arch width (AAW) which is evident on chest radiographs. Aim and Objectives: This study is aimed to establish the usefulness of AAW measurements on chest radiographs of patients with systemic hypertension and hypertensive heart disease among adults in Zaria. Materials and Methods: The present study was carried out in the Department of Radiology, Ahmadu Bello University Teaching Hospital, Zaria. Consecutive 305 hypertensive patients and equal number of normotensive individuals, age- and sex-matched controls were recruited. The chest radiographs of the participants were taken according to the standard technique. Results: The mean AAW for the hypertensive patients and controls were 4.34 cm ± 0.79 cm and 3.35 cm ± 0.63 cm, respectively. There was a significant correlation between AAW and blood pressure, particularly in patients <50 years of age. Other variables such as age, body mass index, hypertensive heart disease, and cardiothoracic ratio also correlated positively with AAW. Conclusion: The AAW showed a positive correlation with age and blood pressure with the relationship been more positive with blood pressure. Hypertensive heart disease also correlated positively with AAW.
Keywords: Aortic arch width, chest radiograph, hypertension
|How to cite this article:|
Halilu SD, Aiyekomogbon JO. The usefulness of aortic arch width measurements on chest radiographs of adult patients with systemic hypertension and hypertensive heart disease. N Niger J Clin Res 2018;7:51-5
|How to cite this URL:|
Halilu SD, Aiyekomogbon JO. The usefulness of aortic arch width measurements on chest radiographs of adult patients with systemic hypertension and hypertensive heart disease. N Niger J Clin Res [serial online] 2018 [cited 2020 Nov 29];7:51-5. Available from: https://www.mdcan-uath.org/text.asp?2018/7/12/51/245788
| Introduction|| |
Arterial hypertension is defined as elevated blood pressure >140/90 mmHg in adults aged 25 years and above according to the World Health Organization. It is a global epidemic and often called a silent killer with the prevalence of about 44% in Europe. It is the most common cardiovascular disease among black Africans, and an acknowledged potential risk factor for the development of complications such as stroke, hypertensive heart disease, hypertensive heart failure, and end-organ damage to the brain, eyes, and kidneys., The prevalence in Nigeria is about 8%–46.4%, and it is more common in men and women older than 55 years. Arterial hypertension is broadly classified into essential (80%–90%) and secondary (10%–20%). The etiology of the former is unknown but related to predisposing factors such as family history and hereditary factors, smoking, cholesterol excess, obesity, and diet including high salt intake. Secondary hypertension is usually due to identifiable secondary event such as chronic kidney disease, renovascular, and endocrine diseases. Irrespective of its etiology, if untreated the final common pathway is the same, that is end-organ damage of target organs such as the brain (cerebrovascular disease), eye (hypertensive retinopathy), and kidney (hypertensive nephropathy), and closely associated with diabetes with its myriad of complications.
Several studies have shown that long-standing hypertension is associated with hypertensive heart disease and hypertensive heart failure with chest radiograph showing cardiomegaly and aortic arch enlargement., Hypertension affects the arterial wall and the heart in many ways. Studies have shown that long-standing hypertension is characterized by aortic unfolding and hypertensive heart failure is also associated with enlargement of the aortic shadow on chest radiograph.,,,,, Aging also affects the heart and aortic arch geometry.,,
Chest radiographs have been used in the management of these patients. X-ray is readily available and cheap, and should, therefore, be employed as a basic tool for the evaluation of hypertensive patients more so that most of our patients cannot afford the more expensive modalities such as echocardiography, angiography, and computed tomography.
This study is aimed at establishing the usefulness of aortic arch width (AAW) measurements on chest radiographs of patients with systemic hypertension and hypertensive heart disease among adults in Zaria.
| Materials and Methods|| |
This prospective study was carried out over 6 months from July 2013 to January 2014 in Radiology Department of Ahmadu Bello University Teaching Hospital (ABUTH), Zaria. A total of 305 patients with clinical diagnosis of systemic hypertension and equal numbers of individuals with normal blood pressure as control were used for this study based on the prevalence of systemic hypertension in Nigeria. Using Fischer's statistical formula withpas 0.23 and q as 0.77, the sample size of 305 was then obtained. Inclusion criteria include hypertensive patients referred from cardiology unit of Department of Medicine at ABUTH, while the age-and-sex matched controls were nonhypertensive individuals consecutively selected from the Family Medicine Department of the same institution, referred for chest radiographs, being a requirement for medical examinations for employment, visa application, routine medical checks, and preschool admissions. Those excluded were patients with chest deformities such as scoliosis and thoracopathies, those with chronic obstructive pulmonary disease, Marfan's syndrome, aortitis associated with pulmonary tuberculosis and syphilis, pregnancy irrespective of gestational age, children, and those with poor inspiratory efforts. These were clinically ruled out by history and physical examination. The last menstrual period of female participants was taken to exclude pregnancy, and normal inspiratory effort was assessed on frontal chest radiographs by ensuring that the 6th right anterior rib bisects the right hemidiaphragm at the midpoint.
General electric conventional static X-ray machine (Germany, 2004) was used for chest radiographic image acquisition. The acquired images on 17 × 14 inch film cassette were processed with automatic film processor, Medipot 903 Colenta R. The acquired and processed images were read with X-ray viewing box using optimal illumination. The participants were weighed, and their respective heights were also measured aimed at obtaining the body mass index. The blood pressure of the participants was also measured with a standard mercury sphygmomanometer.
The procedure was explained to them and informed consent obtained before their inclusion in the study. Each participant was positioned erect either standing or sitting facing the chest X-ray stand with the hands by the hips and palms facing outward. The shoulders were rotated forward to displace the scapulae away from the chest field, and the chin was elevated and placed over the grid device. The X-ray tube was directed from behind the participant at a distance of 180 cm or 240 cm (using the air-gap technique) with centering point at T4 and T5 intervertebral disc space. Exposure factors (KVp, mAs) were appropriately selected and optimized based on participant's habitués (KVp ranging from 65 to 80 and mAs ranging from 12.5–20). The participants were instructed to take adequate inspiration while remaining stationary before the exposure in arrested deep inspiration. Participant's compliance is required for obtaining a good-quality radiograph. Adequate inspiration devoid of motional blur and dressing artifacts was strictly observed.
On a well-centered chest radiograph where the medial ends of both clavicles are equidistant to the spinous process, the AAW was assessed by drawing a vertical line passing through the spinous processes of the thoracic vertebrae. The distance from this vertical line to the left margin of the arch above the level of the carina gave the AAW in centimetre as depicted in [Figure 1]. Furthermore, the cardiothoracic ratio (CTR) which is the ratio of the widest cardiac diameter to that of the widest intrathoracic diameter was measured as shown in [Figure 1].
|Figure 1: Chest radiograph postero-anterior view showing aortic arch width measurement (A) in cm, the distance (B) between the most lateral point of the right cardiac border and the vertical line through the spinous processes, the distance (C) between the most lateral point of the left cardiac border and the vertical line through the spinous processes, and the widest intra-thoracic diameter (D). R indicates the right side of the patient|
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The approval for the study was obtained from the Ethical and Research Committee of ABUTH, Zaria. Anonymity was maintained on all the information obtained from the patients, and the patients had the choice to deny consent or opt out of the study at any stage without necessarily affecting the quality of care.
The collected data were analyzed using Statistical Package for Social Science (IBM SPSS Version 20.0 Armonk, NY, USA: IBM Corp, 2011. The Student's t-test, Chi-square test, correlation coefficient, and regression test were used to compare the AAW. Independent sample t-test was used to compare data obtained from male and female participants. All tests of significance were two-tailed, and P ≤ 0.05 was considered statistically significant.
| Results|| |
A total of 305 patients with clinically diagnosed systemic hypertension and 305 age-and-sex matched controls were used for the study. The age range for hypertensive patients and controls were from 18 to 90 years with a mean age of 50.11 ± 14.18 years. The hypertensive patients and controls consisted of 144 males (47.2%) and 161 females (52.8%) with a male to female ratio of 1:1.1 [Table 1]. The AAW among the hypertensive patients ranged from 2.0 cm to 6.5 cm with a mean of 4.34 cm ± 0.79 cm, while that of the controls ranged from 2.0 cm to 4.8 cm with a mean of 3.35 cm ± 0.63 cm [Table 2]. The correlation between AAW and sex among hypertensive patients and controls is shown in [Table 2]. Higher values were noted among males, but the differences that existed among the gender groups were not significant. There was a significant correlation between AAW and blood pressure (P < 0.001), and other covariates also correlated significantly with AAW as shown in [Table 3] and [Table 4]. This relationship is more significant in hypertensive patients below the age of 50 years (P < 0.001) [Table 4].
|Table 2: Relationship of aortic arch width with sex among the hypertensive and control groups|
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|Table 3: Correlations of aortic arch width with other variables among the entire participants|
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|Table 4: Correlations of aortic arch width with blood pressure and other variables for hypertensive patients below 50 years|
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A total of 194 of 305 hypertensive patients, constituting 63.6% had hypertensive heart disease which is defined as CTR >0.52. Systemic hypertension and hypertensive heart disease significantly affect AAW with the highest effects in the third tertile (P < 0.05), as shown in [Table 5] and [Table 6].
|Table 5: Effect of hypertension on aortic arch width among hypertensive and controls (n=610)|
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|Table 6: Effect of hypertensive heart disease on aortic arch width (n=305)|
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In both sexes, the AAW was significantly higher in hypertensive patients compared to controls [Figure 2] and [Figure 3]. Scattered graph [Figure 4] showed the relationship between AAW and mean blood pressure (mmHg), and it revealed linear increase in AAW with increasing mean blood pressure.
|Figure 4: Scattered graph showing the relationship between aortic arch width (cm) and mean blood pressure among hypertensive patients|
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| Discussion|| |
Systemic arterial hypertension (SAH) being a global epidemic and a silent killer affecting about one billion people of the worlds over seven billion people can be evaluated with basic radiographic chest examination among other things.,, The AAW showed the positive correlation with CTR in the index study. Furthermore, SAH and hypertensive heart disease had statistically significant effects on CTR and AAW (P < 0.05). The AAW in hypertensive and hypertensive heart disease patients was shown in this study to be stronger in the third tertile when compared to controls with normal blood pressure. This agrees with the findings by Danbauchi and Ikeme et al. In the index study, the AAW for hypertensive patients was 4.42 (0.813), 4.26 (0.760), and 4.34 (0.786) for males, females, and both sexes, respectively. This study records larger value of AAW in males than females of the same age group (in both hypertensive and controls) which is consistent with the observations of other researchers.,, However, Stuart et al. recorded a higher value of AAW in females than males of the same age group in the study among Jamaican population. He attributed this variation to higher blood pressure levels in women.
There was a positive relationship between age and AAW in the index study, and this concurs with the finding of Danbauchi and Brockington. There was also a positive correlation between AAW and diastolic blood pressure, systolic blood pressure, and mean blood pressure in this study. Similar observation was made by Danbauchi, Brockington, and Ikeme et al. In this study, also we observed that aortic arch enlargement correlated significantly with hypertensive heart disease and this was also corroborated by Stuart et al. and Lawal and Falase. The relationship between SAH and AAW was stronger below 50 years suggesting that enlargement of the aortic arch is more significant as a marker of hypertension in patients below 50 years. Danbauchi posited that an AAW of 3.5 cm or more in patients below 50 years of age should be taken as significant for hypertension. This observation therefore calls for an objective measurement and documentation of the AAW whenever a chest radiograph is obtained rather than the usual subjective search for aortic unfolding. Hypertension is a significant cause of AAW enlargement as documented by Danbauchi, Ikeme et al., and Stuart et al. Earlier authors also reported that hypertension causes a constant widening of the aortic arch shadow on chest X-ray and that the severity of hypertension and possible duration are the main factors. The larger value of AAW in hypertensive patients in this study with a mean of 4.34 cm compared to a mean of 3.35 cm in the controls is in agreement with the aforementioned research findings. However, it should be noted that AAW enlargement can also be due to other causes such as aging, Marfan's syndrome, connective tissue disease, and aortitis associated with pulmonary tuberculosis and syphilis.,,, Of all the possible causes of aortic arch widening, SAH, and aging are the dominant factors reported.,,,,, AAW increase of 1 mm every 3 years from 43 years of age was observed by some authors.,,,,, Age-related widening of the aortic arch is due to proximal aortic stiffness in individuals aged 50 years and above without cardiovascular disease, and is associated with increased left ventricular mass and mass-to-volume ratio independent of body size, central pressure, and cardiovascular risk factors.
| Conclusion|| |
The AAW showed positive linear relationship with increasing age and blood pressure, and the relationship being more positive with blood pressure. Furthermore, a positive correlation was established between AAW and hypertensive heart disease. Consequently, measuring and documenting AAW on chest radiograph should be done as a baseline by any physician who sees hypertensive patients as this will help in patient's management.
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Conflicts of interest
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]