Abstract
ObjectivesThe aim of this study was to evaluate whether the orientation of the heart, measured as an angle between the long axis of the heart and ascending aorta midline (heart-aorta-angle, HAA), associates with ascending aortic (AA) dilatation. Furthermore, the association between HAA and wall shear stress (WSS) was studied.MethodsHAA was retrospectively measured in 1000 consecutive coronary artery computed tomographic angiography (CCTA) images in patients with low-to-moderate pretest probability for coronary artery disease (CAD). To evaluate the effects of HAA on AA flow, 4D flow MRI was performed for 28 patients with AA dilatation (> 40 mm) and WSS was analyzed.ResultsThe mean age of patients undergoing CCTA was 52.9 ± 9.8 years; 66.5% were women. Their median HAA was 128.7° and interquartile range 123.3–134.1°. HAA was significantly smaller in patients with dilated AA (median 126.7° [121.3–130.8°]) compared with the patients with normal AA (median 129.5° [124.3–135.3°], p < 0.001). HAA was smaller in males (p < 0.001) and in patients with diabetes (p = 0.016), hypertension (p = 0.001), CAD (p = 0.003), hypercholesterolemia (p < 0.001), and bicuspid aortic valve (p = 0.025) than without these factors. In a subpopulation without any of these underlying diseases (n = 233), HAA was still significantly smaller in the patients with dilated AA (median 127.9° [124.3–134.3°]) compared with patients with normal AA (median 131.9° [127.6–136.9°], p = 0.013). In 4D flow MRI, a smaller HAA correlated with increased total WSS in the outer curvature of the proximal AA (r = − 0.510, p = 0.006).ConclusionA smaller HAA associates with AA dilatation and affects the blood flow in the proximal AA.Key Points• A smaller angle between the long axis of the heart and ascending aorta midline associated with ascending aortic dilatation.• A smaller heart-aorta-angle correlated with increased total wall shear stress in the outer curvature of the proximal ascending aorta.
Highlights
The diameter of thoracic aorta has been shown to increase with aging, male gender, and increased body surface area (BSA) [1]
A smaller angle between the long axis of the heart and ascending aorta midline associated with ascending aortic dilatation
According to the European Society of Cardiology (ESC) guidelines, 230 patients (23%) were stratified as having ascending aortic (AA) dilatation in the coronary artery computed tomographic angiography (CCTA) population when the measurement results from all three levels were combined
Summary
The diameter of thoracic aorta has been shown to increase with aging, male gender, and increased body surface area (BSA) [1]. The length of the thoracic aorta has been shown to be related to age; i.e., aortic elongation may be a part of the normal aging process. Adriaans et al have demonstrated that the thoracic aortic length increases by 59–66 mm between the ages of 20 and 80 years [5]. The associations between AA dilatation and the angle between the heart and AA (the heart-aortaangle, HAA) have not been studied previously. The heart is oriented with the right ventricle on the anterior side and the left atrium on the posterior side [6]. The axis of the heart is orientated at approximately 45° to the left of an anteroposterior line drawn from the spine to the anterior chest wall [7]. The HAA has been reported to be approximately 140 ± 7° [9]
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