A smaller heart-aorta-angle associates with ascending aortic dilatation and increases wall shear stress

Abstract

Objectives The 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.Methods HAA 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. Results The mean age of patients undergoing CCTA was 52.9 ± 9.8 years; 66.5% were women. Their median HAA was 128.7°a nd 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). Conclusion A 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.

Ascending aorta curvature and flow displacement are associated with accelerated aortic growth at long-term follow-up: A MRI study in Marfan and thoracic aortic aneurysm patients

“…The association of smaller ascending aorta curvature radius with accelerated aortic growth is consistent with the mathematical model showing that aortic curvature has more impact on the force of blood that is exerted on the aortic wall than other markers associated with accelerated aortic growth such as blood pressure, aortic diameter and patient size [9] . The alteration of blood flow patterns through a sharper curve has also been observed in a study investigating the angle between the heart and the aorta [19] . In that study it was observed that having a smaller heart-aorta angle was associated with increased wall shear stress particularly at the outer curvature of the proximal aorta in patients with ascending aorta dilatation.…”

Pulmonary Artery Dilatation Is a Common Finding in a Coronary Artery CT Angiography Population

“…CCTA imaging was performed on the basis of clinical indications; thus, the patients were not exposed to additional radiation and patients' clinical treatment was unaffected by this retrospective study. The population of the present study has also been evaluated in prior publications (14)(15)(16).…”

Synthesis of multidimensional pathophysiological process leading to type A aortic dissection: a narrative review

“…Decreasing compliance of the ascending aorta increases the jet speed in the aortic lumen (Figure 2) (56,57). In patients with more prominent angulation between the cardiac outflow tract and the lumen of ascending aorta, the direction of the jet is shifted towards the great curvature of ascending aorta causing higher stress in the affected region (55). It has been reported that angulation increases by age resulting in higher aortic wall stress in the aged population (55,58).…”

“…However, due to anatomical properties of the cardiac outflow tract and ascending aorta, the jet direction does not comply with the ideality. The intensity and distribution of stress towards the aortic wall caused by intraluminal hemodynamics during systole are related to aortic shape, the angle between outflow tract from the left ventricle to ascending aorta, diameter, and shape of aortic orifice, and aortic wall compliance (51)(52)(53)(54)(55)(56)(57). These factors may alter the speed and direction of the transvalvular blood flow jet from the ideality.…”

“…In patients with more prominent angulation between the cardiac outflow tract and the lumen of ascending aorta, the direction of the jet is shifted towards the great curvature of ascending aorta causing higher stress in the affected region (55). It has been reported that angulation increases by age resulting in higher aortic wall stress in the aged population (55,58). Likewise, abnormal valvular morphology may shift the jet direction towards the aortic wall (51,53,59,60).…”