Hot-Wiring Failing Hearts -- In-Depth Doctor's Interview

How does the Rheos device regulate the heart?

Dr. Fadi Matar: The body adjusts itself, as far as blood pressure and heart rate, using sensors, like a thermostat. The “thermostat” of the blood pressure and heart rate is located in the neck, the carotid arteries, and it’s called the carotid bulb. Those sensors sense elevations in blood pressure and send the signal to the brain stem, which will automatically regulate the blood pressure and the heart rate and the heart function to counteract whatever happened that raised that signal. This device, the Rheos, takes advantage of that thermostat and stimulates it via electrodes. It’s a battery that’s tunneled underneath the skin and wraps the carotid artery, and it has electrodes that send continuous electrical stimulations, , that the different parameters of those stimulations can be adjusted and see how to adjust the blood pressure. What happens is that system fools the receptors and tells them the blood pressure is very high. Actually, the blood pressure doesn’t have to be that high, but the system thinks that it is high, so it sends it to the brain, and the brain sends back a signal to the heart, to the vessels, to the kidneys, and they work in concert to reduce the blood pressure and reduce the heart rate and modulate the heart function.

What does the device mean for someone who is constantly suffering from the fatigue associated with heart failure, for a person who really can’t even get out of bed in the morning?

Dr. Matar: There are two kinds of heart failure. The typical heart failure is when the heart muscle fails, meaning it doesn’t squeeze. If it doesn’t squeeze, it doesn’t send enough blood to the body. This is not the type of heart failure that the Rheos system is trying to improve. The Rheos system is testing the second kind of heart failure, where the squeeze is not that bad, but the relaxation is deficient. The heart muscle is an active pump. In order to pump fluid out, it has to receive it, so if it receives a certain amount of fluid and if it’s stiff, it doesn’t accommodate enough blood, and it won’t be able to pump enough – if it doesn’t receive enough, it doesn’t pump enough. This second type of heart failure is what we are trying to see if this Rheos helps. It’s called diastolic congestive heart failure instead of systolic. Systolic is when the heart systole is weak; diastolic, the heart muscle doesn’t relax, so patients with various reasons for it, like hypertension, aging, or with different types of disease entities that make the heart stiff. With this patient population, the heart is stiff and it doesn’t relax; it doesn’t get enough blood, therefore, they feel fatigued. We’re hoping that by stimulating the baro-receptors – the signal that comes back from the brain stem to the heart is a favorable reflex that lets the heart relax better – and we hope that with continuous stimulation of the heart, we will improve on diastolic function filling of the heart and hence improve the output of the heart with reduction of the congestion. Think about it like a thick rubber ball. If you fill that rubber ball with a certain volume of blood and you put a monometer to check the pressure in it, the pressure will be high, it backs up in the lung, and you can develop congestive heart failure. If you have just a regular balloon, you fill that balloon with the same amount of volume, and you put a pressure monometer, the pressure will be lower, so that would be compliant; this is a normal heart.

How well does the Rheos system work?

Dr. Matar: We are involved in clinical trials, and it’s going to be in a select few sites in the U.S., and then we don’t know yet, because we don’t have enough patients with diastolic heart failure. It will be awhile before we know if this system is going to help this patient population, but we completed a clinical trial, in the U.S. pivotal trial of the hypertension – the follow up data is being acquired right now. We don’t have the final data on hypertension yet, but we do have data from Europe, because this device was implanted in Europe in a previous smaller trial with very favorable results on hypertension. We do see patients with hypertension who had this device implanted in a previous trial that come for follow up, and we know as soon as we turn the device on to test it. Blood pressures can drop from 190, let’s say over 100, with a touch of a button, can drop down to 130, 120, 140 over 67. You turn that device off, pressure goes back up, and so we see that – like a switch, on and off.

What could the implications be for heart failure, if the Rheos is successful?

Dr. Matar: Diastolic heart failure is very hard to treat. Systolic heart failure, we have more therapies to it, but diastolic heart failure, the muscle is pumping fine, but the muscle doesn’t relax, and we don’t have a lot of data or medications to help those patients. We end up giving the patients diuretics to get rid of the salt, get rid of the fluids, make them feel better, and we give them some medications to reduce the pumping action of the heart, hopefully to relax it better, but none of them are as effective as we like, so we do have a gap of treatment success in this patient population. If that device is successful and efficacious, I can foresee that a lot of patients end up improving and feeling better. What we are trying to do is to improve the quality of life and make them function and do things without necessarily having to take tons of pills, because medications, have their own side effects. Diuretics, the patient is in the bathroom all night long, or they lose salt, they lose potassium, they get cramps, and they are not 100 percent efficacious, so that is where we hope that we can achieve benefit to our patients and make them feel better.

What are the risks of the device?

Dr. Matar: It’s a surgical procedure, and the risks of the procedure are risks that occur with any surgeries – risk of infection, risk of injuring the nerve that runs between the carotid artery and the jugular vein. There’s a vagus nerve there, so the surgeons need to be careful while implanting that device. There is also the potential for stroke. You have to choose the right patient. You don’t want a patient with severe blockages in the carotid arteries where you’re manipulating, so that’s factored in our selection criteria. For the patients to get included in the clinical trial, they have to be low surgical risk, in terms of carotid artery disease, they should be a good candidate for surgery, because the surgery itself has the same risks entailed by any procedure – general anesthesia risk – so nothing specific for that surgery other than manipulation of the carotid artery and the nerve that runs close by the vagus nerve. You don’t want to injure that.

END OF INTERVIEW

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