Pathophysiology and Natural History of Aortic Regurgitation
Aortic regurgitation (AR) causes left ventricular (LV) volume overload through the regurgitant flow from the aorta into the left ventricle (LV) due to incomplete aortic valve closure in diastole. There are a wide variety of causes of AR including not only changes to the leaflets themselves but also geometric changes to the perivalvular tissues, such as aortic root enlargement. Furthermore, AR causes progressive myocardial injury by means of complex mechanisms, such as both LV volume overload and increased afterload, myocardial ischemia, and energy loss due to turbulence. In addition, when compensatory mechanisms for these myocardial injury factors become inadequate, cardiac failure ensues for which the prognosis is poor. For this reason, when significant LV enlargement and/or systolic dysfunction is observed in severe AR, then surgery is required before patients develop symptomatic cardiac failure. It is essential to comprehend the pathophysiology and natural history of AR to make an appropriate diagnosis of AR and determine the optimal therapeutic strategy.
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