Can human physiology be supported without a pulse?
Normally, no -- at least in regard to our common definition of death. However, if you are one of the select few that have been equipped with new artificial heart technology developed by the Texas Heart Institute, then blood flow can be pumped around your body -- without the need for a pulse.
We do not actually need a pulse to stay alive, we just require a means to ensure that bloody flow is continually circulated through the body. Doctors Bud Frazier and Billy Cohn created a new, continuous-flow artificial heart based on these principles, the continuous-flow left ventricular assist device (VLAD).
By using two turbines to replace the muscle of the heart, the system keeps blood moving continually by mimicking the heart's pumping rhythm, without recreating the pulse.
Although it in no way looks like a natural organ, the device has so far been tested on 50 calves, and its first human subject, Craig Lewis, can be considered a success -- at the least as a temporary measure. After being given a maximum of 12 hours to live due to a plethora of medical conditions, the surgery was performed to take out his original heart and replace it with the 10,000 RPM artificial alternative.
Within 48 hours, Lewis was able to sit up, speak, and even sketched. Although he passed away 5 weeks later, the causes are reportedly to have been due to his original conditions -- and the artificial device would never have been able to eradicate these issues, but it did allow him to live longer and say his goodbyes.
Since Lewis, several other patients have been fitted with the devices.
Cohn and Frazier's continuous-flow left ventricular assist device was previously placed in a calf named Meeko, who lived on to lead a normal life after having his heart taken out and replaced with the turbines. The surgery was performed by cutting the heart free, sewing collars of rubberized Dacron onto the atria, and then connecting the turbines on to the collars before activation.
Creating an artificial heart has been difficult up until now, as many metal and plastic experiments have resulted in the wearing out of material, and an inability to beat -- mimicking the human pulse -- for more than 18 months.
Currently, there are other developments within artificial heart development -- including the 'Total Artificial Heart' made by Arizona-based SynCardia Systems Inc., which replaces ventricles and a number of valves instead of taking out the entire organ. However, it does require toting around a 12 pound external engine to power the heart, and according to the second patient to receive the operation, John Martino, it is extremely loud -- and is only a measure for patients who are waiting for a transplant rather than a permanent solution.
This new VLAD technology has the potential to help patients with conditions such as terminal heart disease in the future, and as the scientists themselves say, may mean we are a step closer to a 'perfect' artificial heart.
Cohn tells Popular Science that: "I think we're on the verge, right now, of solving the artificial-heart problem for good. All we had to do was get rid of the pulse."
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Thumbnail credit: Anais GÃmez-C