You don't need a PFO, if not done right and the bubbles get just a bit bigger this would be a great way to take them from the venous side of the lungs and send them right to the heart and brain on the arterial side.
The old WKPP "Why we don't bounce dive" explanation.
Here is the article being referenced: Why We Do Not Bounce Dive After Diving in the WKPP | Global Underwater Explorers
In fairness though, the title of the article is "Why We Do Not Bounce Dive After Diving"
It may not hold the same relevance in the scenario listed.