Artificial hearts aren’t new to medicine, they’ve been in use in patients for several decades. They are usually used as a short-to-medium-term solution with very sick patients who are waiting for a heart transplant or those who are ineligible for a transplant. And although the technology isn’t quite at a sci-fi level yet, we’re getting closer to a self-sustaining, fully artificial heart each day.
What is an artificial heart?
An artificial heart is an electronic device capable of maintaining the circulation of blood in the body. Broadly speaking, there are two main kinds of artificial hearts – the mechanical heart and the heart-lung machine.
As you could probably guess – the mechanical heart functions as a regular heart – it simply pumps blood. The heart-lung machine on the other hand also oxygenates the blood in addition to pumping it for circulation. This type of machine is typically used when a patient is undergoing heart surgery.
Under non-surgical situations, however, the kind of artificial heart prescribed to patients is the mechanical heart. Interestingly, there are also two main groups of mechanical hearts – ventricular assist devices (VADs) and total artificial heart (TAH).
Now, here’s the thing – the left and right ventricles are the hardest working parts of the heat. The right ventricle pumps the oxygen-poor blood to the lungs. The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle. The left ventricle then pumps the oxygen-rich blood through the aortic valve out to the rest of the body.
Because it is the left ventricle that is responsible for pumping blood to the body, it is the strongest of the chambers. So, in the case of heart failure, the left ventricle is often the most likely part of the heart to need extra help. If this is the case, doctors will typically insert a left ventricular assist device (LVAD) if other efforts to manage the condition have failed.
On the flip side, there are times when an LVAD alone won’t do the trick, so the patient will need a total artificial heart (TAH). Currently, TAHs are a last resort that are only used with patients who can’t benefit from LVADs or are waiting for a heart transplant.
History of artificial hearts
So, who invented the artificial heart? Well, it’s not that simple, because no one person can take all the credit. That said, the idea of mechanical circulatory support was first introduced by Julien LeGallois way back in 1812. But this remained a theory until 1937 when Vladimir P. Demikhov developed the first total artificial heart and conducted the world’s first coronary artery bypass surgery.
The earliest version of LVADs was developed in the 1960s and they were big machines the patients were hooked up to. In 1982, Dr. Robert Jarvik created the world’s first permanent artificial heart, which was successfully transplanted into patient Barney Clark, who went on to live for 112 days.
Although these early artificial hearts weren’t exactly user-friendly, many scientists and engineers across the globe made it their life’s work to create more efficient designs small enough to fit into a man’s chest and strong enough to “beat” 35 million times per year. And although we’re not quite there yet, we’re not that far away either.
Recent advances in artificial heart technology
These days, artificial hearts are typically small devices that are implanted into the patient and connected to a portable external controller through tubes that exit the skin. That said, the technology and operating mechanisms of artificial hearts can vary widely. For instance, in 2017, a group of Chinese researchers created an artificial heart based on rocket technology. The heart utilizes magnetic and fluid levitation to minimize friction. This allows it to boost its operational efficiency and help the power generator last longer.
Later in the same year, a group of Swiz engineers developed a soft total artificial heart that actually beats. The coolest part is that they utilized 3-D-printing technology, using silicone as the base material. In the end, the heart weighed only 13.8 ounces and was able to pump fluid with pretty much the same rhythm as a human heart. However, the prototype only beats for about 30 minutes, so it’s going to take a while before it goes mainstream.
In 2018, researchers at the Oregon Health and Science University announced they were developing an artificial heart which contains a single moving piece with no valves. They believe it could be the first TAH that could last the rest of a person’s life. The OHSU artificial heart replaces both ventricles with a titanium tube containing a hollow rod that moves back and forth, pushing blood to the lungs and then through the rest of the body.
More recently, Carmat announced its latest artificial heart that can control blood flow in real-time. How does that work? Well, it’s equipped with sensors that help detect the user’s blood pressure based on their activity level and in response, the device’s algorithm regulates blood flow. The entire device weighs about 2 pounds and contains batteries that can last about 4 hours.
Currently, the average life expectancy of a patient on the artificial heart is one year. But patients have been reported to live up to 4 years on these devices. Despite all these exciting advancements, there are still a few major hurdles to scale before we arrive at a permanent solution for a failing heart.
Current limitations of artificial heart technology
In a recent article, Tchantchaleishvili and Philips shared some insight on the limitations currently facing artificial heart technology. And one of them is getting an implantable energy source powerful enough to sustain the device for a lifetime… and that’s a lot of power! Because of the current limitations in battery technology, the authors argue that the only way to generate this much power is through Plutonium‐238. But perhaps due to terrorism fears, and fears of accidental exposure, artificial hearts won’t be going nuclear anytime soon. So, the possibility of a fully implantable artificial heart may not be on the horizon for a few more years at least
Biocompatibility is another very important challenge. For instance, blood clots are one of the possible complications of artificial hearts. And this can lead to stroke if not quickly managed. That said, the chances of blood clots are much lower these days, thanks to the tremendous development in anti-clotting medications and materials science.
The journey to immortality
The road to immortality may start with an invulnerable heart, but it’s going to take a lot more than that for humans to live forever… the human body is just too complex. At the very least, we’re going to need a technology that allows our cells to regenerate infinitely. And it may not be so far away. Researchers at Northwestern University have already figured out a way of turning off the genetic switch responsible for aging in worms… so, fingers crossed.
