Dr. Yonatan Buber, MD
Patent Foramen Ovale and the Risk for Cryptogenic Strkes:
Pathophysiology and Current Treatment Recommendations
The prevalence of Patent Foramen Ovales (PFOs) in the general population ranges between 25-30%, and it is roughly double that (i.e. 44-60%) among patients who are younger than 60 years of age who have suffered a cryptogenic stroke.
The PFO has an important role during fetal life of allowing oxygenated maternal blood passage to the systemic circulation, and its actual patency after birth has no clinical or hemodynamic significance, as it has not been shown to be associated with right sided chamber enlargement or the presence of arrhythmias.
The presence of a PFOs, especially those that allow the passage of a large amount of bubbles during agitated saline echocardiogram studies and those that are accompanied by an atrial septal aneurysm, has been shown to be associated with a higher risk of thromboembolic strokes. These events presumably occur due to the passage of small blood clots from the venous to the arterial system. Despite this strong association, however, routine screening for PFOs in the general population is not currently recommended, due to the very high prevalence.
For a young patient who experiences a cryptogenic stroke, a full workup is warranted, which should consist of a Holter study, laboratory evaluation for the presence of inherited or acquired thrombophilias, Carotid artery Doppler study, a trans-thoracic echocardiogram and a trans-cranial Doppler. If either the trans-cranial Doppler or the trans-thoracic echocardiogram suggest the presence of a right-to-left shunt, a trans-esophageal echocardiogram is performed to confirm this finding and further characterize the source of shunting. When a PFO is confirmed as this source, the patient should be referred to an expert Neurologist and a Cardiologist to determine whether closure of the defect is indicated.
Owing to the advanced and sophisticated technological solutions brought upon the medical community over the past several decades, PFOs are now closed in a percutaneous fashion with a dedicated, nitinol-based closure device in the catheterization laboratory and without the need for surgery. In the vast majority of the cases, general anesthesia is not required for this procedure, as the use of intra-cardiac echocardiogram is sufficient to safely guide it and thus the need for a trans-esophageal study during the procedure is omitted. In the absence of significant pro-thrombotic states, the patients are usually maintained on dual antiplatelet treatment for 3 months, following the procedure, followed by a single antiplatelet regimen for the duration recommended by the treating team. In addition, bacterial endocarditis prophylaxis is recommended for the first 6 months after the procedure. Complication rates for percutaneous PFO closure using these techniques are markedly low, with figures that are lower than 2% in most the updated series.
The main aim of percutaneous PFO closure is the prevention of recurrent strokes, and it has indeed been shown to reduce the rates of such events by around 50% as compared to antiaggregant or anticoagulant therapies. This effect is even more prominent among younger patients, and those who have larger defects (as determined by a large number of crossing bubbles in the echocardiogram studies) and a large atrial septal aneurysm. Recent reports also suggest that this procedure may also significantly reduce recurrent stroke rates for patients who have pro-thrombotic states.
Recently the American Food and Drug Association approved percutaneous PFO closure for the prevention of recurrent strokes based on the long term ( i.e. 10 years) outcomes of the RESPECT trial. The American Academy of Neurology position paper, however, still states that the effectiveness of this procedure remains to be further proven and that it should be utilized in research setting only.
Yonatan Buber, MD. Adult Congenital Heart Disease Service, Sheba Medical Center, Tel Hashomer, Israel.
Dr. Yonatan Buber, MD - Bio
An expert in the fields of congenital heart diseases, pulmonary hypertension, interventional
catheterization for congenital heart defects and general Cardiology.
Dr. Buber is a graduate of the Faculty of Medicine and Health Sciences
At the Ben-Gurion University of the Negev.
Between the years 2005-2012 Dr Buber served as an Internal medicine resident and Cardiology fellow and chief fellow at the Chaim Sheba medical center, Tel Hashomer,
Between the years 2012-2014 he served as a senior clinical fellow at the Boston Adult
Congenital Heart Disease and Pulmonary Hypertension program at Boston Children’s Hospital
and Brigham and Women’s Hospital, both affiliated to the Harvard university Medical School.
During his senior fellowship Dr. Buber was a visiting senior clinical fellow at the advanced heart disease, ventricular assist devices and cardiac transplant program at the Brigham and Women's Hospital and at the division of pediatric electrophysiology at Boston Children's Hospital.
Between the years 2014-2015, Dr Buber was trained at interventional congenital
Cardiology at Nationwide Children’s Hospital and the Ohio state Medical Center under the
supervision of Prof. John Cheatham.
Upon Dr. Buber’s return to Israel, he founded and currently serves as the director of
the Adult Congenital Heart Disease Service at the Leviev Heart Center at Tel Hashomer Medical
Dr Buber lectures at the Tel Aviv University. He authored over 30 scientific papers in top-rated
medical journals as well as textbook chapters in the fields of adult congenital heart
disease and pulmonary hypertension.
Dr Buber also serves as a committee member at the Israel Adult Congenital Heart Association,
the International Society of Adult Congenital Heart Disease, the American Congenital Heart
Association and the American college of cardiology- Adult Congenital Heart Disease chapter.