Artificial Heart
Your heart is like an engine in your body that keeps everything running. Basically, the heart is a muscular pump that maintains oxygen and blood circulation through your body and lungs. In a day, 2,000 gallons of blood is pumped by your heart. Like any engine, if the heart is not well taken care of it can break down and pump less efficiently, a condition called heartfailure.
As the number of patients suffering from heart diseases have increased over the years, so has the need for heart transplants. Unfortunately, not everyone who needs a heart transplant will receive a matching donor heart in time,the supply of donor hearts remains limited.Recognizing this need for an effective and immediately available alternative, research for total artificial hearts established.
Mechanical devices could be beneficial for people who are not eligible for transplant due to their age or some other health conditions like high resistance to blood flow in the lungs. First completely self-contained artificial heart is the AbioCor Implantable Replacement Heart by Abiomed. Doctors in Louisville, Kentucky treat first AbioCor patient-Robert Tools with the first totally implantable artificial heart in 2001.
How Does Artificial Heart Work ?
Blood at a rate of 60 to 100 beats per minute is pumped by an average adult human heart.
The heart contracts in two stages:
- In the first stage, the left and right atria contract simultaneously, pumping blood to the left and right ventricles.
- In the second stage, the ventricles contract together to propel blood out of the heart.
Then before the next heartbeat the heart muscles relax and allows blood to fill up the heart again.
Patients with an implanted AbioCor heart still have atria that beat simultaneously, but both the ventricles are replaced in the artificial heart, which can only force blood out one ventricle at a time. So, it alternately sends blood to the lungs and then to the body, instead of simultaneously as a natural heart does. More than 10 liters per minute can be pumped by the AbioCor, which is enough for everyday activities.
The core mechanism of the device is the hydraulic pump that shuttles hydraulic fluid from side to side
- Hydraulic pump — The basis of this device is that the force that is applied at one point is transmitted to another point using an incompressible fluid. To create pressure A gear inside this pump spins at 10,000 revolutions per minute (rpm).
- Porting valve — They act similar to the valves of the natural heart opens and closes to let the hydraulic fluid flow from one part of the artificial heart to the other through an artificial ventricle, blood gets pumped to the lungs when the fluid moves to the right and gets pumped to the rest of the body when the fluid moves to the left.
- Wireless energy-transfer system — Also referred to as the Transcutaneous Energy Transfer (TET), this device includes internal and external coils , that via magnetic force transmit electricity from an external battery without piercing the surface across the skin.The electricity is received by the internal coil and sent to the internal battery and controller device.
- Internal battery — The battery implanted inside the patient’s abdomen region is rechargable. which provides the patient 30 to 40 minutes to carry out daily activities, such as showering, while being disconnected from the main battery pack.
- External battery — This battery is worn across the patient’s waist on a Velcro-belt pack. Each rechargeable battery gives approximately about four to five hours of electricity.
- Controller — This small electronic device is implanted in the patient’s stomach wall. It keeps in check as well as controls the pumping speed of the heart.
The AbioCor heart composed of plastic and titanium can be connected to four locations:
- Left atrium
- Right atrium
- Pulmonary artery
- Aorta
The device is grapefruit sized and weighs about 2 pounds (0.9 kilograms)
It took a 7 hour surgery to implant a AbioCor artificial heart.The surgeons are not just cutting off and extracting the natural heart’s right and left ventricles, but are also placing a foreign object into the patient’s chest. The patient is to placed on a heart-lung machine and later removed. The surgery calls for a lot of stitches, to properly connect the heart to artificial ventricles. Grafts connect the AbioCor to remaining parts of the natural heart. Grafts are a kind of artifical tissue used to connect the patient’s natural tissue to the artificial device.
This device is designed to double the life expected for patients who before the operation had only about 30 days to live. It receives wireless transmissions from the device to provide performance status and also alarm notifys in case of any irregularities. In the hearts ventricles blood flows in a swirling vortex without forming any stagnant slow-moving pools which increase the risk of blood clots.It is also coated with a special polyurethane material to prevent blood cells from clinging or clotting on its surface.
Laman Gray said , that initial candidates for the heart will be the “sickest of the sick.”
FDA and Abiomed officials have laid a few parameters for the initial recipients of the artificial heart which are:
- Should Have end-stage heart failure
- Having a life-expectancy of less than 30 days
- Is not eligible for a natural heart transplant
- Has no other suitable treatment option
Another requirement is that the device must fit inside the patient’s chest. To determine this the patient must go through a chest X-Ray and a CAT Scan . Then, using a computer-aided design (CAD) program, virtually the natural heart is removed and replaced with the AbioCor heart in the patients chest. Doctors can proceed with the operation to implant the artificial heart if it fits virtually using the program.
Nevertheless doctors still insists the public to become organ donors, however AbioCor may help save many of those who dont find a compatible donor heart or have health conditions which prevent natural transplants hence having no other option.