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Potential Causes of Cryptogenic Stroke

Potential causes i Stock 641236100

A cryptogenic stroke is known as a stroke of “unknown cause”; however, awareness of the possible causes is important in reducing the risk of another stroke.

PFO in heart

PFO (Patent foramen ovale)

During fetal development, a baby gets blood and oxygen from the mother through the umbilical cord. A channel between the right and left sides of the heart called the foramen ovale allows the blood from the veins to bypass the lungs. This channel, or hole, normally closes after birth, but in about 25% of people, the foramen ovale doesn’t close completely.¹

When it remains open, it’s called a patent foramen ovale, or a PFO. Typically, a PFO causes no problems at all. However, in some cases, it can allow a blood clot to pass from the right side of the heart to the left side, and this increases the risk of a stroke.

The foramen ovale remains open post-birth

Open foramen ovale Before birth Open foramen ovale
Natural closure of the foramen ovale Post-birth Natural closure of the foramen ovale
Foramen ovale remains open, creating a PFO Post-birth Foramen ovale remains open, creating a PFO

Other potential causes

Atrial Fibrillation

Atrial fibrillation (AFib or AF) is an irregular heartbeat. While many people with AFib live healthy lives, the condition does put you at a certain risk of stroke. When the blood doesn’t move through the heart the way it should, blood clots can form and travel to the brain, causing a stroke.


Thrombophilia is a condition in which the blood has an increased tendency to form blood clots. This can be either passed down through the family or acquired during one’s lifetime. If a blood clot travels to the brain and blocks a blood vessel, it can cause a stroke.


Atheroma is the build-up of fatty plaque within the aorta, the main artery that supplies blood from the heart to the body. When fatty plaque develops within the aortic arch, it can loosen and circulate through the blood to the brain, blocking a blood vessel, and this can cause a stroke.

How does a PFO affect stroke risk?

Blood clots can develop in your veins and travel to the right side of the heart. Normally, they are then pumped to the lungs, which act as a filter. However, a PFO can allow those clots to bypass the lungs and cross to the left side of the heart. From there, they can be pumped to the brain and cause a stroke.

Patients who have a PFO and have had a cryptogenic stroke may be at an increased risk of having another stroke. In many patients, another stroke can be prevented by having the PFO closed.

Understand your options for PFO treatment

If you’ve had a cryptogenic stroke and have also been diagnosed with a PFO, it’s important to talk to your doctor about the benefits and risks of available treatment options to reduce your risk of another stroke.

Treatment options

How does a stroke impact your life?

A stroke is an attack on the brain. Since the brain is in charge of all our senses and everything we do, an attack on it can affect the way we function.

Learn more
  1. Kent, D.M and Thaler, D.E. Is Patent Foramen Ovale a Modifiable Risk Factor for Stroke Recurrence? Stroke, 2010. DOI:10.1161/STROKEAHA.110.595140.
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