Aortic insufficiency (IA) is defined as an abnormal regurgitation of blood from the aorta to the left ventricle in diastole, due to a lack of tightness of the aortic valves. It represents about 10% of valvular pathologies but the annual mortality of nonoperated patients can be as high as 10% to 20%. The quantification of AI is therefore important as it can remain perfectly asymptomatic for a long time.

Doppler echocardiography is currently the key examination to confirm the presence of valvulopathy, to allow positive diagnosis of valve leakage regardless of location, to specify the etiology and mechanism of regurgitation. The quantification of IA requires, in transthoracic ultrasound, to take into account many parameters that individually have all certain limitations. The recommendations are therefore to have an integrative approach considering a combination of different parameters and an overall interpretation. This makes it possible to evaluate with greater precision the importance of the leak. Thus, there is the difficulty of quantifying moderate and severe AI for lack of a truly unique criterion. One of the evaluation criteria commonly used in transthoracic ultrasound is diastolic regurgitation in the aortic arch but this assessment is sometimes difficult. The left subclavian artery (SCG) is more accessible than the aortic arch in terms of the ultrasound window. The measurements will be easier to record since the vessel is more superficial and there are fewer air interpositions than for the aortic arch. The quantification of the AI based on this new element will be compared to the other previously validated ultrasound criteria. The investigators will use this study to describe the feasibility of collecting coronary flow in the artery (IVA), and they will compare systolic velocity, diastolic rate / systolic rate ratio compared to a control group without severe aortic insufficiency (grades 2 and 3). The flows recorded in the IVA will be compared to the importance of the aortic leakage according to its different modes of quantification (ultrasound and MRI). The aim of the study will be to show that diastolic reflux in the left subclavian artery is a marker of severe AI (grades 2 and 3) by comparing this regurgitation with that measured at the level of the aortic arch and other validated ultrasound criteria and cardiac MRI.

Inclusion Criteria:

• Patient able to give informed consent to participate in the study
• Patient with transthoracic echocardiography and MRI prescription

Exclusion Criteria:

• Contraindication to MRI
• Pathologies of the thoracic aorta (aneurism, dissection, stenosis)
• Pathologies of the left subclavian artery (stenosis, narrowing)
• Persistent arterial canal
• Arteriovenous fistula of the upper limb