Double whammy of drugs plus ultrasound unblocks arteries

Feb 20 2006

According to a pilot study led by the University of Cincinnati, standard clot-busting medication when used in combination with low-energy ultrasound appears to re-open clogged arteries in stroke patients better than medication alone.

The study by Dr. Joseph Broderick, a neurologist and Dr.Thomas Tomsick, MD, a neuroradiologist, is known as the Interventional Management of Stoke Study or IMS-II.

It involved 73 participants between the ages of 18 and 80 treated in 13 participating centers and suffering from severe ischemic stroke.

Each was given lower than standard doses of tissue plasminogen activator (tPA) during a 30-minute period and within three hours of the onset of stroke.

TPA is a very effective clot-busting drug that can produce a dramatic reversal of stroke symptoms and is used in certain patients having a heart attack or stroke.

It works by dissolving blood clots, which cause most heart attacks and strokes.

Quickly reopening clogged brain arteries in stroke patients is important because the longer the blood supply to the brain is blocked, the more likely long-lasting brain damage will occur.

Although it was approved by the U.S. Food and Drug Administration for treating strokes almost 10 years ago, it is still not given to most stroke victims.

The patients after being given the initial dose of tPA were then immediately taken for an angiograph where a small tube was placed into a groin artery and threaded to the site of the blocked artery in their brain.

Twenty-one participants without a visible and treatable clot received no additional therapy.

The remainder of participants (52) who had visible, treatable clots was treated with up to 22 milligrams of additional tPA delivered through the catheter directly to the blockage.

Whenever possible, they were also given a low-energy ultrasound treatment at the site of the clot to break it up.

In 18 cases where the catheter could not access the clot, a standard catheter was used to deliver tPA to the clot site.

Partial or complete reopening of the blocked brain artery occurred in 69 percent of the 34 patients receiving the ultrasound treatment.

This was an improvement when compared with the IMS-I study, in which 55 percent of patients involved achieved partial or complete reopening of the blocked artery.

The IMS-I study used only a microcatheter to deliver tPA directly to the location of the stroke-causing clot.

According to the American Heart Association, approximately 700,000 people suffer a stroke every year, and it is the leading cause of serious, long-term disability in the United States.

It becomes more common as people age, rising sharply from approximately 3 percent of those aged 55 to 64, to 6 percent of those between 65 to 74, to 12 percent of those over 75.

Yet it seems the vast majority of stroke victims are not given tPA.

According to doctors tPA can only be given within three hours of the onset of stroke, because the risk of hemorrhage is too high after that time and because many stroke victims often ignore the symptoms or the stroke occurs while they're sleeping and it is too late to get the drug when they get to the hospital.

Another factor is that a CT scan is needed to determine the type of stroke because tPA is only effective in treating ischemic strokes, which are those caused by a blood clot.

Although 85 percent of strokes are caused by such clots, the remainder are caused by bleeding, and tPA cannot be used to treat them.

There are concerns by many experts that tPA is too risky a drug as it can in some victims cause fatal hemorrhaging, and some have strong reservations about the drug's use in most clinical settings.