Saving Stroke Patient with MERCI

By Shahfizal Musa

BANGI, 22, September  2010 - Radiologists in Universiti Kebangsaan Malaysia Medical Centre (UKMMC) is trained to rescue patients attacked by stroke due to blood clot by physically pulling the clot out from the blood vessel in the brain.

This is meant for a patient who failed to come to the hospital within four and half hours after an attack.

A stroke victim can have the attack reversed and have a complete recovery provided he can be brought to the hospital within four and a half hours.  Treated with an anti clotting drug, which dissolves the blood clot in the brain, the patient can be cured.

The catch is, it must be given within four and a half hours or it would work against the patient causing his brain to bleed.

What if the patient arrived at the hospital later than four and a half hours? Is he condemned for life? UKMMC now offers new hope for the late comers with an instrument call the MERCI device.

“Between four and a half and 6 hours, there is still a window of opportunity where the radiologist will try to rescue the patient by removing the clot. This is done by inserting a catather into the blood vessel and pulling the  clot out using the MERCI device,” said  Prof Dato’ Dr. Raymond Azman Ali, the Senior Consultant Neurologist.

The MERCI device is also used on patients who cannot be given the anti clotting drug Recombinant Tissue Plasminogen Activator or  r-tPA. So once the patient arrives at the emergency ward, the UKMMC stroke Team will refer him to a radiologist who will do the scanning, to confirm the cause of the stroke.

When a patient reached the hospital after 4 hours, every second counts. They do not have the luxury of waiting to be admitted for a neurosurgeon to do his rounds and see them.  If the patient is to have his normal life back, the blood clot in his brain must be removed immediately.

So the UKMMC radiologist will have to do the job instead of waiting for a neurologist. With the help of the MERCI device the blood clot can pulled out from the brain.

The MERCI device consists of a catheter and a small cork-screw shaped device at the end which operates by wrapping around the clot and trapping it.

The catheter is a plastic tube that can be inserted into the body through a blood vessel allowing access by surgical instruments. In this case the cork screw shaped retriever will travel all the way up to the brain to retrieve the blood clot.

To get to the blood clot in the brain the catheter will be inserted in the blood vessel that was blocked at the groin. It will then be pushed up through the vein up into the brain.

It is quite an amazing feat, considering the whole process starts in the groin. The plastic tube that contains the cork screw will travel from the groin up to neck and into the brain.

The process is quite complex. The vein that is blocked have to be identified right down to the groin. The vein in the human body is like a maze thus care must be taken to ensure that the affected vein is identified and not any others.

Once the catheter is deployed and in position, the corkscrew shaped device will engage the blood clot, grab it very slowly, trap it and pull it out all the way down back to the groin. 

The MERCI device, however, is reserved only for those who cannot be treated by the drug r-tPA and the late comers.

“We can do that here but it is a complex process and we reserved it to those who come in within 4 to 6 hours,” said Dr Raymond.

So a stroke victim now has a double lifeline to speed their recovery. First is the treatment with the anti clotting drug and for late comers there is still hope for a speedy recovery with the MERCI device.