Pulmonary Embolism and Right-to-Left Shunts

Every fetus has a small hole in their heart, called a foramen ovale when they are developing in the womb. For most people this hole closes shortly after birth, but it doesn't close completely in 1 out of every 4 people. This is called a "patent" foramen ovale, or PFO. In people with a PFO it is possible for a blood clot in a vein to enter the heart, pass through the opening, and then go into an artery - this is referred to as a paradoxical embolism which passes through a "Right-to-Left Shunt," or RLS. If this occurs, the blood clot can cause a stroke. The most common RLS (more than 90%) is a PFO. Much rarer causes include other types of holes in the heart (like an atrial septal defect, or ASD), or a vascular communication in the lungs (like a pulmonary arteriovenous malformation, or AVM). We are investigating whether people with a PE are at higher risk of stroke if they happen to have a