There’s been 2-3 people in the news lately who have gotten self-contained artificial hearts installed. Unfortunately, the first guy has had some non-heart related illnesses.
My question is this:
I’m making a big assumption that the heart is set to a fixed beat. What if the guy wants to exercise? Is there a way to speed it up so that his body gets the right amount of blood? Is it controlled some other way?
I haven’t been able to find a decent website concerning the device.
It depends on the design of the device used; I’ve seen a twin-speed model on TV that could be switched by a kind of remote control.
Strangest thing I saw about artificial hearts was one that dispensed with the usual attempt to pump the blood in a similar way to the natural heart and just used a small turbine which was spun by a magnetic field; as a consequence of the correct function of the device, the patient had no pulse, but a faint high-pitched whine could be heard instead.
Why would the heart be set to a fixed beat? The human heart operates under the rule that the blood into the heart equals the blood out. With exercise, venous return increases so to increase the cardiac output the heart rate increases, mediated by a parasympatholytic vagus nerve response. Why couldn’t this be mimicked in a model?
The perfect artificial heart will, of course, be tied into biosensors, and deliver the output needed. I would like windshield wipers like that.
Some artificial hearts are designed from the get go as stopgaps until a transplant, so they don’t contemplate an ambulatory patient, and are basically “on” or “off” with some speed control, about the same fine response you get from a Lionel Train transformer.
That doesn’t mean they can’t compensate for any increase in activity. Cite, please?
Yojimboguy,
regarding “smart windshield wipers,” my parents’ VW Passat has variable speed wipers that automatically adjust to the amount of rainfall. I haven’t investigated what the the sensor measures.
back to the OP…cardiac pacers which have been in widespread use for many years are available with the “automatic transmission” option. I know some devices are triggered into a higher pacing rate by vigorous rhythmic perturbations as might be seen in jogging.
A corollary then…what about OTHER vigorous (ahem) rhythmic (ahem) perturbations? =0
BDG