Aortic Regurgitation CW and Colour Doppler: Aortic regurgitation can occur due to damage to the aortic valve as well as due to dilatation of the aortic root so that aortic valve leaflets fail to coapt. The later condition occurs in annulo-aortic ectasia, often associated with Marfan syndrome. Aortic regurgitation due valvular damage can occur in rheumatic fever. A bicuspid aortic valve can also become regurgitant as age advances. In the yester years, tertiary syphilis was an important cause of aortic root dilatation and aortic regurgitation.
Aortic regurgitation is quantified in terms of regurgitant fraction,which is the fraction of left ventricular output that regurgitates back. It can be assessed by Doppler echocardiography as well as angiocardiography. Aortic regurgitation leads a high systolic pressure, low diastolic pressure and a wide pulse pressure. Most of the physical signs of aortic regurgitation are due to this wide pulse pressure. The pistol shot sounds over the femoral, collapsing or water hammer pulse, retinal arterial pulsations, locomotor brachii and dancing carotids are some of them.
Severe aortic regurgitation leads to dilatation of left ventricle and left ventricular failure. When the left ventricle fails, end diastolic pressure rises and leads to elevated left atrial pressure and pulmonary congestion. Symptomatic aortic regurgitation needs aortic valve replacement. Aortic valve replacement can be done using mechanical or bioprosthesis. Mechanical prosthesis requires life long anticoagulation while anticoagulation can be discontinued after an initial period in bioprosthesis. Another novel technique for aortic valve replacement, especially in children is pulmonary autograft. Homograft replacement of aortic valve can also be considered in places with homograft banks. Availability is often a problem in case of autografts.
Colour Doppler echocardiogram showing aortic regurgitation (multi coloured mosaic jet seen in left ventricle marked AR)
The left panel shows continuous wave (CW) of aortic regurgitation jet. Below the baseline forward aortic flow is seen while above the baseline the tongue shaped aortic regurgitation jet is seen. Apical five chamber view in the right panel shows colour Doppler image of aortic regurgitation with a wide multicoloured (mosaic jet) originating from the closed aortic valve into the left ventricle (labelled as AR). From extend of the AR jet into the left ventricle it is moderately severe AR.