le ▁has ▁to ▁generate ▁to ▁open ▁the ▁a ort ic ▁val ve ▁during ▁vent ric ular ▁syst ole , ▁and ▁coron ary ▁ar tery ▁disease ▁which ▁increases ▁the ▁st iff ness ▁of ▁the ▁left ▁vent ric le , ▁thereby ▁increasing ▁the ▁filling ▁pressure ▁of ▁the ▁left ▁vent ric le ▁during ▁vent ric ular ▁di asto le . ▁ ▁The ▁left - to - right ▁sh unt ▁increases ▁the ▁filling ▁pressure ▁of ▁the ▁right ▁heart ▁( pre load ) ▁and ▁forces ▁the ▁right ▁vent ric le ▁to ▁p ump ▁out ▁more ▁blood ▁than ▁the ▁left ▁vent ric le . ▁ ▁This ▁constant ▁over loading ▁of ▁the ▁right ▁side ▁of ▁the ▁heart ▁causes ▁an ▁over load ▁of ▁the ▁entire ▁pul mon ary ▁vas cul ature . ▁ ▁Event ually , ▁pul mon ary ▁hy pert ension ▁may ▁develop . ▁ ▁The ▁pul mon ary ▁hy pert ension ▁will ▁cause ▁the ▁right ▁vent ric le ▁to ▁face ▁increased ▁after load . ▁ ▁The ▁right ▁vent ric le ▁is ▁forced ▁to ▁generate ▁higher ▁press ures ▁to ▁try ▁to ▁overcome ▁the ▁pul mon ary ▁hy pert ension . ▁ ▁This ▁may ▁lead ▁to ▁right ▁vent ric ular ▁failure ▁( d il at ation ▁and ▁decre ased ▁syst ol ic ▁function ▁of ▁the ▁right ▁vent ric le ). ▁ ▁If ▁the ▁AS D ▁is ▁left ▁un correct ed , ▁the ▁pul mon ary ▁hy pert ension ▁progress es ▁and ▁the ▁pressure ▁in ▁the ▁right ▁side ▁of ▁the ▁heart ▁becomes ▁greater ▁than ▁the ▁left ▁side ▁of ▁the ▁heart . ▁