Computational evaluation of mechano-elastic properties and of paramagnetic contrast enhancement of thoracic aortic wall in acute myocardial infarction and in non-coronarogenic myocardial damage, from the data of dynamic ECG-gated MRI (MR-elastometry)

Abstract

Background. The state of the aorta is a key factor in the prognosis of the patient’s life, since the distension of the ascending aorta in systole determines the blood supply to the myocardium in diastole. Paramagnetic contrast-enhanced MRI provides a reliable assessment of pathological neoangiogenesis, however, in fact, studies of the aorta are performed descriptively, without calculating mechanical strength and extensibility. Objective. To develop and clinically test on the patients with atherosclerotic lesions and myocarditis a method for quantitative assessment of extensibility and mechanical elasticity of the aortic wall.Design and methods. Were examined 12 patients with acute myocardial infarction with ST segment elevation, as a control group 11 patients without clinical and instrumental signs of atherosclerosis of large arteries and aorta. All underwent MRI of the chest and heart with paramagnetic contrast enhancement (PMCE) and ECG synchronization. The indices of aortic distensibility, distensibility normalized to pulse BP, Young’s modulus of the aortic wall, systolic distension of the ascending aorta (mL), index of strengthening of the aortic wall in PMCE were calculated.Results. Ascending aortic distensibility decreased in patients with myocarditis and acute infarction. Young’s modulus and distensibility of the ascending aorta significantly correlated with the value of the aortic wall enhancement index in PMCE. Myocardial damage in acute infarction and myocarditis was noted with a decrease in systolic expansion of the ascending aorta below 10 ml due to its reduced elasticity.Conclusion. There is a relationship between pathological accumulation of a paramagnet in the wall of the ascending aorta, a decrease in its elasticity, a decrease in the volume of systolic aortic dilation, and the development of hypoperfusion myocardial damage. Magnetic resonance elastometry of the aortic wall makes it possible to assess violations of aortic distensibility and predict the development of ischemic damage in the myocardium of the left ventricle.