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Figure 1 Mechanisms of functional aortic regurgitation in type A aortic dissection: Panel A is a schematic of normal aortic valve anatomy in the short-axis view (left) and long-axis view (right). The dotted lines represent the attachment of the leaflet tips to the sinotubular junction. Note that the leaflet tips coapt fully in diastole (short-axis view) and that the diameter of the sinotubular junction is similar to that at the base of the annulus. Panel B shows incomplete leaflet closure that occurs when the sinotubular junction dilates (arrows) relative to the aortic annulus resulting in leaflet tethering and a persistent diastolic orifice. This is usually best visualized in the short-axis view but may also be seen in the long-axis view if it is optimally aligned. Panel C shows aortic leaflet prolapse that occurs when the dissection extends into the aortic root and disrupts normal leaflet attachments to the aortic wall, thereby resulting in abnormal leaflet coaptation and eccentric AR. This is usually best visualized in the long-axis view where one or more leaflets are seen prolapsing into the left ventricular outflow tract in diastole. Panel D shows dissection flap prolapse that occurs when a redundant dissection flap prolapses through intrinsically normal aortic leaflets resulting in AR that is often short-lived and may be intermittent. The regurgitant flow occurs through the funnel shaped by the dissection flap.
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