An unusual shadow above the aortic valve

A 55-year-old West African man was referred for routine echocardiography. He was completely asymptomatic, a non-smoker, working out at the gym several times weekly. He was taking hydrochlorothiazide for hypertension.Clinical examination revealed a blood pressure of 156/74 mm Hg and systolic and diastolic murmurs suggestive of aortic insufficiency. Pulses were equal bilaterally and he had no marfanoid features or hyperelasticity. ECG showed mild left ventricular hypertrophy and chest X-ray revealed a normal cardiac shadow and mediastinum.Transthoracic echocardiography demonstrated an unusual appearance above the aortic valve (figure 1A), moderate aortic regurgitation and a shadow in the aortic arch. Transoesophageal echocardiography was performed to evaluate the dilated aorta, arch and aortic valve further (figure 1B, C). The native aortic valve was trileaflet with moderate regurgitation. CT was also performed (figure 1D).

What is the most likely diagnosis? Acute type A aortic dissectionWilliams syndromeLoa loa worm infectionIntimo-intimal intussusceptionGiant cell aortitis.