Saturday, 14 September 2013

Fishing for blood clots

Nets are generally used by fishermen to catch fishes. But can you imagine a net to retrieve blood clots from a human body.  What is more, these are clots or thrombi that have formed due to stroke and they have stopped the supply of oxygen and blood to the brain, causing paralysis.
Such nets are now being used regularly in the United States to get to the blood clots and remove them from the brain of patients who had suffered a stroke or have had a series of strokes.
Generally, upwards of four strokes occur in a human being when blood clots block a blood vessel from carrying blood to the brain. When the clot stops the flow of blood, the brain is starved of oxygen and glucose and the cells die by millions, damaging the tissues (infarcts) leading to paralysis and in some cases even death.
Till now, the clots were removed or dissolved with the help of drugs. The drug, rt-PA, is almost fully effective if administered to victims within three hours of a stroke felling them. Unfortunately, it fails to dissolve large blood clots.
Doctors also use anticoagulants, which are popularly known as blood thinners, to treat clots. These medications- heparin, low molecular weight heparin, and warfarin-slow the time it takes for blood to clot and also prevent growth of a clot. However, all of them have side effects.
Other techniques to remove a clot include MERCI Retrieval System, which can be used at any time. This is a minimally invasive catheter-based system to retrieve and remove clots in patients experiencing acute ischemic stroke. The catheter is inserted into the brain to remove the clot. Another option is the Penumbra System, but this can be used only within eight hours of a patient suffering a stroke. Here, suction is used to remove the clots and restore blood flow.
Now, a team of doctors and researchers in the US have successfully tested a new technique to remove clots. They have used small nets to get to the place where the clot has formed. The net is sent to the brain through an artery in the leg.
When the net reaches the clot, the tip expands into a net and pulls out the clot into itself.
The device has been named as Solitaire and it has so far yielded promising results in a recent medical trial at the University of California, Los Angeles. This devise is different from the MERCI and its success too is double of MERCI.
Researchers were stunned to find that when MERCI was used, 598 per cent of the patients reported improved mental and motor functioning within a three month period. This compared well with those treated with MERCI (33 per cent).
More importantly, only 17 per cent of those treated with Solitaire died following treatment compared to 38 per cent treated with the MERCI.
Another study involving 178 patients showed those  treated with Solitaire had almost double the chance of living independently after treatment.
Why this success rate?. One reason is that it has allowed doctors to  successfully open up arteries and save the brain. What makes this device all the more valuable to a patient suffering from stroke is that it has been proved to effectively reverse a stroke even while it is happening.
This is because the brain cells can survive if blood supply can be restored quickly. This is what Solitaire can do.
Moreover, it is always advisable to use clot retrieval devices than go in for clot dissolving drugs.
By the way, the Solitaire was approved by the US Food and Drug Administration (FDA) for use as a clot retriever in March 2012. This is actually called Covidien Solitaire FR Revascularization Device.
Dissolving blood clots
By the way, a John Hopkins study in the US has come up with a new technique to dissolve blood clots in brain and also lower the risk of brain damage after stroke.
The research is supported by the National Institute of Neurological Disease and Stroke
The technique which involves minimally invasive treatment   removes potentially lethal blood clots in the brain safely without cutting through easily damaged brain tissue or removing large pieces of skull.
More importantly, this technique was particularly successful in treating victims of intracerebral hemorrhage (ICH), which is considered to be the last  untreatable form of stroke.
ICH is caused by high blood pressure and in such cases the clot builds up pressure and leaches inflammatory chemicals. This leads to irreversible brain damage, causing death or extreme disability. Very few undergo the more invasive and risky craniotomy surgery, which involves removing a portion of the skull and making incisions through healthy brain tissue to reach and remove the clot. Roughly 50 percent of people who suffer an intracerebral hemorrhage die from it.
This new technique, if found positive, allows patients with stroke and paralysis to recover independent functioning of the organs that had been affected. The USP in this technique is that the brain remains safe and only a small hole the size of a coin is made in the skull to get to the damaged tissue which is then treated with rt-PA which is allowed to drip on the damaged cells.  

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