Catheter interventions help to prevent stroke

Sep 6 2005

According to WHO statistics, stroke is the second most frequent cause of death worldwide. Cardiac causes account for up to 20% of strokes. Transcatheter occlusion of patent foramen ovale and left atrial appendage eliminate the most important sources for cardiac embolism.

PFO closure prevents clots from entering arterial circulation and causing stroke In more than 50% of patients who sustained a stroke without any other obvious cause, a PFO (patent foramen ovale) is diagnosed. A PFO is a tunnel-like connection between the right and the left atrium of the heart that can be found in 20-25% of the healthy population. Usually, this tunnel closes spontaneously after birth. If the PFO remains open, clots may cross the tunnel from the venous to the arterial side, block brain vessels and thereby cause strokes. This can be prevented either by life-long blood thinning therapy or by occlusion of the tunnel using a device.

"PFO closure by catheter technique is safe and effective in preventing stroke", said Prof. Horst Sievert from the CardioVascular Center Frankfurt (Germany), world leader in transcatheter PFO occlusion. Since 1994, he has performed more than 1000 PFO occlusions using different devices. Only 1.5% of patients sustained a TIA or stroke after occlusion of the PFO, whereas the recurrence rate of stroke using blood-thinning medication ranges from 2-14%.

Most PFO devices are made of a left atrial disc, a connection part within the tunnel and a right atrial disc. A coil-shaped device is also available. These devices are implanted into the heart and stay there forever. The newest development is PFO closure without implant (Cierra device). In this case, a device is advanced into the PFO tunnel and radiofrequency energy is applied, welding the surrounding tissues together. The first procedure in the world was performed on 4th April in the CardioVascular Center Frankfurt. Prof. Sievert said "PFO closure without implant may become the gold standard in most patients as it leaves no foreign material in the heart".

Transcatheter occlusion of PFO is a widely used, safe technique and can be performed in about half an hour. As there is no need for general anesthesia, patients are allowed to leave the hospital a few hours after the intervention.

Alternatives to anti-coagulant therapy for atrial fibrillation Atrial fibrillation is a type of arrhythmia that occurs when the two upper chambers of the heart quiver rapidly, inhibiting the heart from completely pumping out all of the blood. This can cause the blood to pool inside the heart and form clots, which could lead to a major stroke if they leave the heart. About 15 percent of all strokes are caused by atrial fibrillation. An anticoagulant is standard therapy for atrial fibrillation.

Heart implant devices do exist. Researchers from the CardioVascular Center in Frankfurt (Germany) are seeking to determine whether blocking one of the most important sources where blood clots are formed will prevent strokes from occurring in patients with atrial fibrillation. There is one heart implant device system, where doctors use a catheter to place a blocking device at the opening of the left atrial appendage inside the heart. The procedure has been successfully performed in more than 350 patients so far.

"In atrial fibrillation 90% of thrombi, or blood clots, form in the left atrial appendage which does not fulfill any physiological function," said Yves Bayard from the CardioVascular Center. "By blocking this appendage, we thought we might be able to artificially prevent strokes that are caused by clots."

"This initial study supports the concept that implanting a mechanical device to block the left atrial appendage can be done safely and with relative ease," says principal investigator Prof. Horst Sievert from the CardioVascular Center Frankfurt. "It may become a valuable alternative for patients with chronic, non-rheumatic atrial fibrillation in whom standard anticoagulation therapy is contraindicated or poorly tolerated."

Prof. Sievert's first feasibility study ended in December 2003 with 111 patients enrolled. Another large European registry study with 180 patients finished enrolment in April 2005. The procedure takes less than one hour and hospitalization of the patient is not necessary.