Why the left atrium does not enlarge in ASD even though the shunt traverses this chamber ?

ASD is  the most common acyanotic heart disease  with  left to right shunt . Highest qp/qs  are  seen  with ASDs The shunt  begins  from left  atrium  and goes on to complete a circuit. LA——-ASD———RA————RV———-PA———-PVs———LA In this circuit all chambers  enlarge except the LA . (Inspite of the fact about 200-300 % cardiac output traverses this chamber ) Why ? Take Our Poll Post -test The most popular answer in the above poll  is LA is  a transit chamber . If it is so . . .  RA is equally  a transit chamber ,  why it enlarges significantly ?
Source: Dr.S.Venkatesan MD - Category: Cardiology Authors: Tags: cardiology -congenital heart disease Infrequently asked questions in cardiology (iFAQs) ATRIAL SEPTAL DEFECT ra rv mpa enlarged LA normal in ASD Source Type: blogs