New experimental device could reduce blood pressure

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New experimental device could reduce blood pressure
3/19/2008 12:33 PM
By: Ivanhoe Broadcast News Service

Harischandra Karunaratne, M.D., explains a new experimental device that is implanted in the chest to help lower high blood pressure.
About 72 million Americans suffer from high blood pressure.        

How does this device work?

Dr. Karunaratne: The device consists of two separate parts. The first part is the implanted battery system that generates electricity and the second part is a set of electrical leads that are wrapped around the part of the body called the carotid baroreceptors, which are attached to the battery.

What does the device do?

Dr. Karunaratne: The battery in the device generates electricity, which then transmits energy through the lead system to the carotid baroreceptors. The carotid baroreceptors function in the body much like what the thermostat functions in controlling the temperature, but instead of controlling the temperature, it controls the blood pressure of the body. When the carotid baroreceptors are stimulated by the battery, the body perceives it as a rising blood pressure. The brain then sends out impulses to the heart, to the blood vessels and to the kidney to lower the blood pressure.

So this device tells your body to make your blood pressure come down?

Dr. Karunaratne: Yes, it makes the blood pressure come down. The device actually utilizes the body’s own blood pressure controlling mechanisms to reduce the blood pressure.
         
How well does the device work?

Dr. Karunaratne: We have considerable evidence from studies that have been carried out. In patients undergoing surgery where the carotid sinus was stimulated, the blood pressure fell acutely. That was the origin of the studies which were done. Subsequently, there have been implantations of this device carried out in patients with very resistant hypertension. A recently published European study, suggested that in 10 of 13 patients there was a significant reduction in blood pressure in one year.

What do you think this device could mean for someone like George?

Dr. Karunaratne: We are hopeful. George is a patient whose blood pressure has been extremely difficult to control. I struggled with controlling his blood pressure for many years. At the time when we started this device, he was taking nine to ten blood pressure medications everyday and these drugs had significant side effects. Though we did manage to get some control of his blood pressure, it went out of control quite frequently. It was extremely expensive for him and the side effects of the drugs made it almost impossible for him to engage in any kind of activities -- even doing his housework was difficult. We implanted this device some months ago and we have seen in his case a very significant improvement in symptoms. I saw him today and he was able to walk around without getting short of breath, his swelling of his legs had gone down. He said most of the time he took his blood pressure at home, it was 100/120 systolic. He was sleeping on three to four pillows previously and is very happy that he is able to sleep on his back on one pillow.

How excited are you about the prospects of this device?

Dr. Karunaratne: The first two patients that I have seen have had a very encouraging response and I’m excited about it. But you have to understand that this is the early trial of a new device and therefore, you have to be cautious interpreting anything. Also, there is hope that we may actually have a device that can avoid all the side effects of drugs and control blood pressure. For those patients who are resistant to multiple medications and suffer from side effects from blood pressure medications, we might have an alternative to expensive and side effect laden drug therapy.

How big of a problem is high blood pressure?

Dr. Karunaratne: Probably in this country about 40 million people have high blood pressure and I think in the 60 to 74 year age group, about half of the white men and women and about two-thirds of all black men and women have high blood pressure. By treating high blood pressure, we have been able to reduce the incidence of stroke by about 40 percent and that itself is a very significant improvement. But in order to achieve that kind of blood pressure control, we have had to use multiple drugs -- four or five drugs.

How bad was George’s blood pressure at his worst?

Dr. Karunaratne: At his worst, I recorded his blood pressure at 250/130 to140. It was a stroke waiting to happen.

How has this device changed the amount of medications George is taking -- how many was he on at his worst and how many different drugs was he taking?

Dr. Karunaratne: He was taking between nine and 10 different drugs. At the moment, the protocol of the trial does not allow us to vary his blood pressure medications but observe his blood pressure while still on the same medications. What we have found in his case, is that his blood pressure has been so lowered that he has been leaving out some of the medications on his own.

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