Earlier on Singularity Hub, we took a detailed look into the magic of heart replacement surgery (and even growing hearts with stem cells). It’s a great way to tack on a few extra years to patients who are suffering from heart failure, but what about the other people who are not eligible for a donor heart? Patients who are in immediate danger of death and have end-stage heart failure on both sides of the organ cannot currently be implanted with donor hearts but they can be given the AbioCor artificial heart. The AbioCor system uses hydraulic pressure to pump blood between two chambers, simulating the effect of the human heart. Could the artificial heart put an end to long waiting lists for donor organs?
The artificial heart has come a long way since its first clinical use in the 1960’s. Wireless technology and an internal microprocessor make the AbioCor better than its predecessors. The entire system is implanted during a procedure where the diseased heart is cut out and the arteries are clamped onto the thoracic unit. Wires are laid in the body down to the abdomen, where the controller and battery are implanted. Wires then connect the controller to a receiver planted in the chest called the TET, or Transcutaneous Energy Transfer. Wearing a similar device on the outside of the skin allows for an external battery to power the system without having wires breaking through the patients skin.
The internal battery allows the patient more mobility, as the external power source can disconnected for up to 45 minutes as the patient bathes or conducts other activities of that nature. Being hooked up to the power isn’t that bad either, as a fanny-pack portable battery system can provide up to four hours of continuous juice before needing to be recharged. Despite all these seemingly beneficial quality of life improvements, there are still some drawbacks.
Battery life may seem to be a problem, but that may be easily overcome as battery technology evolves. The main issue with the AbioCor system is its size. Weighing in at around two pounds and taking up the space of about two hearts, the system is too big to fit in many people’s chest cavities. Researchers have duly noted this problem and are currently working on a smaller version that will fit into more people and even some children.
An even bigger challenge to researchers is the longevity of the system. The longest time a patient has survived on the AbioCor system is about 17 months from the time of implantation (not a very appetizing prospect for potential recipients), and in that time the system operated perfectly. Doctors, however, are worried that the system can only last about 2 to 5 years before the plastic and metal components wear out and require additional surgery to replace them.
Comparing such a nearly sublime quality of life given by the AbioCor system to the artificial heart technology of even a decade ago would make any human cringe. The most famous artificial heart, the Jarvik-7, was first used in 1982 and did not boast any sort of internal battery system. Instead, two tubes were permanently implanted in the patient that allowed hydraulic fluid to pass in and out of the body to an external pump. This meant that the patient had nearly no mobility. Even worse was the constant pulsing of hydraulic fluid that was known to cause patients to be physically jolted every time the heart pumped.
So today’s artificial hearts are much better than they were before, right? Right. But all the anal-retentive scientists and doctors out there (House M.D. not included) know that the system can still be so much better. There are still a lot of complications that can occur with the system that cause limited post-implant life span such as infections and strokes. Researchers are working on these potentially deadly problems to help increase the life expectancy of patients with the AbioCor system but, even if longevity is increased, patients still have to look forward to another surgery to replace the mechanically compromised artificial heart after 2 to 5 years. Yes, life expectancy must be increased before the artificial heart replaces the donated heart in most patients faced with the option, but the mechanical integrity of the device must also be increased so that it is capable of lasting longer than the patient ever could. Only then will artificial hearts beat the donated hearts. Until then, our money is on motorcyclists and skateboarders.
