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 an RLS compared to PE patients who don't have an RLS. This study will simply observe and compare the differences in stroke-related outcomes between those 2 groups.

Participation in the study last roughly 90-days and includes the following activities:

• The study team will review your medical records to collect general information such as your age, sex, race/ethnicity, height, weight, medications, medical history, and other medical information

• Magnetic Resonance Imaging (MRI) of your brain will be done as soon as possible following your enrollment in the study. For more information on MRI scans, please see the "MRI scan" section below.

• A Transcranial Doppler (TCD) with bubble study will be performed to determine if an opening is present in your heart or lungs. TCD is performed using ultrasound. A contrast called agitated saline will be injected into your vein for this test.

• You will be asked to return for a follow-up visit 90 days after your pulmonary embolism. At this visit, the following will occur:

  1. A second MRI of your brain will be performed.
  2. You will complete a questionnaire to evaluate whether you may have had a stroke since being discharged from the hospital
  3. You will meet with a member of the study team who will collect information about your health status.

Inclusion Criteria:

1. Age ≥18
2. Acute pulmonary embolism (any grade/size)
3. Patient or legally authorized representative is able to provide consent to participate in the study

Exclusion Criteria:

1. Patients who, in the opinion of the study investigators, are unable to participate in required study activities
2. Patients unable to undergo MRI imaging

Study participants will be selected from the population of patients admitted to Tufts Medical Center