How does Patent Foramen Ovale cause paradoxical emboli

Maybe I'm overthinking it, how could an embolus possibly travel from right atrium to left atrium when the LA has a higher pressure than RA after birth? The PFO is also pushed close at all times by the left atrial pressure. Same thing for Atrial Septal Defect. Doesn't Eisenmenger syndrome need to happen (reversal to right to left shunt) for a clot to travel from right to left heart?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums