, ▁use ▁of ▁the ▁e ch oc ardi ogram ▁to ▁measure ▁the ▁card iac ▁output ▁of ▁the ▁left ▁vent ric le ▁and ▁the ▁right ▁vent ric le ▁independently ▁is ▁possible . ▁ ▁In ▁this ▁way , ▁ ▁the ▁sh unt ▁fraction ▁can ▁be ▁estimated ▁using ▁e ch oc ardi ography . ▁ ▁Trans c ran ial ▁do pp ler ▁b ubble ▁study ▁ ▁A ▁less ▁invas ive ▁method ▁for ▁detect ing ▁a ▁P FO ▁or ▁other ▁AS D s ▁than ▁trans es oph ag al ▁ul tras ound ▁is ▁trans c ran ial ▁Do pp ler ▁with ▁b ubble ▁contrast . ▁ ▁This ▁method ▁reve als ▁the ▁c ere br al ▁impact ▁of ▁the ▁AS D ▁or ▁P FO . ▁ ▁Elect ro card i ogram ▁ ▁The ▁E CG ▁find ings ▁in ▁at rial ▁sept al ▁defect ▁vary ▁with ▁the ▁type ▁of ▁defect ▁the ▁individual ▁has . ▁Ind ividual s ▁with ▁at rial ▁sept al ▁defect s ▁may ▁have ▁a ▁prolong ed ▁PR ▁interval ▁( a ▁first - deg ree ▁heart ▁block ). ▁ ▁The ▁prolong ation ▁of ▁the ▁PR ▁interval ▁is ▁probably ▁due ▁to ▁the ▁en larg ement ▁of ▁the ▁at ria ▁common ▁in ▁AS D s ▁and ▁the ▁increased ▁distance ▁due ▁to ▁the ▁defect ▁itself . ▁ ▁Both ▁of ▁these ▁can ▁cause ▁an ▁increased ▁distance ▁of ▁intern od al ▁condu ction ▁from ▁the ▁SA ▁node ▁to ▁the ▁AV ▁node . ▁ ▁In ▁addition ▁to ▁the ▁PR ▁prolong ation , ▁individuals ▁with ▁a ▁prim um ▁AS D ▁have ▁a ▁left ▁axis