Cryptogenic Stroke

Stroke is the leading cause of disability in the United States and is the third most common cause of death.It remains a major health problem which costs the medical health system significant amounts of money.

It is usually associated with risk factors, some of which are non-modifiable like advanced age, gender, black race and family history.Other risk factors are modifiable and include hypertension, diabetes, mellitus, carotid disease, dyslipidemia, alcohol abuse, smoking, and cardiac illnesses.

Despite extensive work up in patients who present with stroke, thirty percent of strokes continue to have an unclear etiology and no clear cause can be delineated.This typically occurs in the young people who have no risk factors for strokes, and despite this, present with TIA's or significant strokes.In this patient population when we find no clear reason for the stroke, we call it a cryptogenic stroke.One of the most common causes for a cryptogenic stroke is patent foramen ovale.

Patent foramen ovale (PFO) is a small hole which exists inside the interatrial septum which is a divider between the right and left atria (heart).This hole is present at birth in twenty-five percent of the population.It serves the purpose of shunting the oxygenated blood from mother to fetus during the embryonic stage.During this stage, the human lungs are not mature enough to oxygenate the blood.Therefore, all the oxygenated blood comes from mother to fetus, and it crosses through the PFO to the left side of the heart, which is the systemic chamber that subsequently pumps the blood into the organs of the fetus.The PFO closes at delivery in most people, but in twenty-five percent of people it remains open.It is usually physiologically silent. This means it does not allow any blood to shunt through it.A problem arises when the hole still lets blood flow in either direction and strokes happen when the blood flows from the right side to the left side causing what we call paradoxical embolus or cryptogenic stroke.

There are multiple studies which show the associated risks of the presence of PFO with stroke and these are increased five fold by the coexistence of an atrial septal aneurysm which is a redundant segment of the septum that could predispose to clot formation.

The test of choice to diagnose patent foramen ovale with right to left shunt is transesophageal echocardiogram (TEE) with bubble study.The bubble study means injecting agitated saline into the heart.We usually watch that with the ultrasound to see if the bubbles go across the interatrial septum.This is the most sensitive and specific test to diagnose this anomaly.Transthoracic echo alone can miss a lot of PFO's.

Once all other causes of CVA (stroke) have been ruled out and the PFO is found with right to left shunt, then it has to be considered the cause for the cerebral vascular event.Three options for treatment are:medical therapy with antiplatelet agents such as Plavix, aspirin, Ticlopidine or Aggrenox, or anticoagulation with Coumadin.Other options for treatment to prevent future events include closure of the PFO using transcatheter techniques.There are multiple devices on the market to achieve this purpose.

In summary, the PFO is the most commonly missed cause of CVA (stroke) in young people.It should be looked for due to the significant indications of recurrent strokes in the young.

Dr. Younes is in private practice at Freedman Memorial Cardiology in Alexandria. To learn more about Dr.Younes and his services, visit his Profile Page.

Wellness Center  |  Women's Health Library  |  Men's Health Library 
Children's Health Library  |  Senior Health Library