An artificial heart is a device that performs the function of heart within the human body. As in case of Peter it was used between the times of heart transplantation or replaced instead of the original heart. VAD (Ventricular Assistance Device) is different from.artificial heart. Which supports a failing heart. Furthermore, it is also distinct from CPB (Cardiopulmonary Bypass) which supports the heart and lungs during a heart surgery. An artificial heart keeps the blood oxygenated for longer periods of time. Which beats about 100,000 times every 24 hours. Additionally, some power source must charge it.
Each year 7 Million people die from a heart diseases, more than any other condition. In many countries there are treatments for the heart diseases, including a surgery. But, until recently, the only hope for some heart patients was an Artificial Heart. However, the number of people requiring a transplant is much greater than the number of hearts available and many patients die before having a transplantation surgery.
Peter Bilic, a heart patient, thought that he was also going to be included in the list of patients who died because they didn’t get a transplant. But he was lucky in this regard. Biomedical scientist developed a device named “Total Artificial Heart”. His heart was removed and an artificial heart was placed instead. He was able to go home within a few weeks of his operation.
The development of the first artificial heart was achieved by Vladimir Demikhov in 1937 and this was transplanted in a dog. In 1953, a Heart-Lung Machine was designed and used by John Gibbon during an open heart surgery. On December 12, 1957, Willem John Kolff, the pioneer of hemodialysis and artificial organs.
Transplanted an artificial heart into a dog. Also surprisingly, the dog survived for almost 90 minutes after the transplant. Kolff’s continued the attempts to make an artificial heart , resulting in the development of heart that was placed in a calf. As a result, it remained functional inside the calf’s body for around 268 days.
Latter, one of the graduates named Robert Jarvik, designed a better version of Kolff’s artificial heart and this was named as Jarvik 7. After getting permission from FDA, Jarvik 7 was implanted into human on December 2, 1982. In 1963, Stanly Crawford and Domingo, implanted left ventricle assistance device (LVAD) into a patient .Who was suffering from severe cardiac arrest.
This mechanical support helped him to survive for about 4 days ,after which the support was discontinued. Due to some complications and the patient died. In 1990, Brian Williams was the first patient to undergo successful implantation of LVAD. He was discharged from hospital after the approval of FDA. Thus becoming the first person to have an artificial device transplanted.
Anatomy and physiology of human heart
To completely understand the structure and working of an artificial heart, one must know the anatomy of human heart. Heart is a muscular organ, present between the lungs in the chest cavity and is responsible for pumping the blood throughout the body. In humans, the heart consists of four chambers: two atria and two ventricles.
Atria and ventricles separate by valves that open and close in a rhythmic manner and are therefore responsible for the normal functioning. To avoid the over-expansion and injury,a fluid filled sac pericardium surrounds the heart. The brain controls the heart, which sends out signals causing the cardiac muscles to expand and relax.
De-oxygenated blood enters the right atrium through vena cava. The brain then sends the signals and causes the right atrium to contract, pushing the blood through the (Tricuspid Valve) into the right ventricle. The right ventricle then contracts and push the blood into the Pulmonary Vein. Through the Pulmonary Valve, from where it goes to lungs and oxygenate itself.
The oxygenated blood then enters the left atrium.Which then contracts, pushing the oxygenated blood through the bicuspid valve (Mitral Valve) and into the right ventricle. The contraction of the right ventricle causes the blood to pass to the Aorta, from where it is distributes to the whole body. The blood not only carries oxygen but also nutrients, waste products and many proteins.
Structure of artificial heart
An artificial heart is metal device containing plastic, ceramic and animal parts in its manufacturing. The basic structure is made of titanium-vanadium-aluminum alloy, diaphragm within the structure is made of polyurethane while the valves in the heart are the actual animal valves obtained from pig or some other mammal. For minimizing the chances of rejection, the overall size and volume of the heart is to kept as low as possible. So a typical artificial heart is about 2.4 lb. (1200gm) and has a volume of about 1.4 pints (660ml).
An artificial heart is based on part of the heart that is supported. Blood enters the heart in the right or left atrium. As it passes through the ventricles it pumps into the aorta or pulmonary artery. Depending on the part of heart being supported by the artificial heart. Artificial heart needs a continual supply of energy.That is made possible through the use of compressed air or electricity. This air is provided by the pumping chamber. So as to maintain the flow of air, a control console is also present. The size of the control console varies. It may be as large as to carry it beside you on the wheels or may be small enough that it rests on your chest.
There are different prototypes of artificial heart from the last century until now that are made. The most important of them include Total Artificial Heart Pump, POLVAD, Phoenix 7, SynCardia, MagScrew, Abiomed AbioCor II and Carmat Bioprosthetic Heart, the latest being the Soft Artificial Heart.
There have been almost 1458 implants of 14 different artificial heart designs from the year 1968 to 2014. Since January 2010 , in recorded ,more than 550 SynCardia Hearts got transplanted. The patients who got SynCardia Heart transplanted , are able to live for more than one year without any complications. The reason lies in its elegant design. SynCardia hearts do not require any artificial device to aid its operation.
The only device needed is located outside the body in the form of Pneumatic drivers. SynCardia has also designed a Total Artificial Heart (TAH) that consist of two ventricles and four valves, able to pump the blood through the body.
Which is made of special bio-plastic that is not rejected by the human body. Unlike the other types of artificial hearts like the LVAD. However, that assists only the failing part of the heart. While TAH replaces both the right and left side of the heart. There are two sizes available: 70cc TAH and 50cc TAH.
Soft artificial heart
Utilizing the new technology of 3-D Printing or Bio-printing. Cohrs and his colleagues tried to make an artificial heart similar to an original. It consists of silicon, works with the aid of pressurized air, weighs about 400gm, has a volume of 680cm3 and is able to beat only 3000 times. The soft artificial heart (SAH) works and moves in the same way as a normal heart. However is yet to undergo more modifications, to be able to function fully.
“Our goal is to develop an artificial heart that is roughly the same size as the patient’s own one and which imitates the human heart as closely as possible in form and function” –Cohrs.