Future Heart to Be Built on Demand



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Read about Canadians technological contributions to the treatment of circulatory disorders and answer the questions that follow.

Future Heart to Be Built on Demand

What if you could just order up a heart on demand? If getting a heart transplant were as easy as replacing a car part, patients waiting for heart transplants would be relieved.

We may be closer to creating a heart in a lab than you think.

Ever since the South African surgeon Christiaan Barnard performed the first heart transplant in 1967, the world has been intensely focused on the possibilities of someday making this a routine procedure.

The shortage of organs that could be transplanted is one of the crueler realities of modern medicine. Across the United States, more than 4,000 people are currently waiting for a heart to be donated to them, but only 2,300 of them will actually receive one, according to the United Network for Organ Sharing.

Given the organ shortage, Michael Sefton, director of the Institute of Biomaterials and Biomedical Engineering at the University of Toronto says

"let's do something better than transplants." He suggested growing a heart in a laboratory from scratch.

"I was amazed that nobody laughed," Sefton says. "Or at least they didn't laugh in public."

The ultimate goal is to create what Sefton calls a "heart in the box," which is a transplantable heart that could be stored in hospitals, ready for a patient.

In fact, they have already begun to create a heart muscle, grown in a lab from mouse cells, pulsing on its own.

Growing Heart Valves by Hand

Piece by piece, teams of researchers worldwide are figuring out how to grow other body parts besides a heart, including not only muscle, but valves, arteries and nerve tissue.

Dr. John Mayer at Harvard Medical School is on the front lines, learning how to grow heart valves by hand. The key is to make a tiny polymer frame or mold on which the cells that would make a valve that can be made to grow in the right shape. Their first use could be to replace damaged valves in children.

"I think we're moving closer to actually having something that we would be able to offer patients within the next three to five years, I would hope," says Mayer. Sefton estimates the cost for creating a functioning heart for pre-clinical testing will be $5 billion.

Another researcher, Dr. Joseph Vacanti, who is based at Massachusetts General Hospital is tackling one of the most intricate parts of the problem. For the heart to get nourishment while it does its job, it needs to be laced with microscopic blood vessels. Vacanti has figured out how to grow them on frames, which are made the same way computer circuits are.

"But instead of making electrical circuitry that's required in miniaturization for computer chips, we're making vascular circuitry," says Vacanti.

Made to Order Valve

Someday, the scientists hope, there will be commercial labs where, if you need a new organ or just some replacement tissue, it can be grown to specifications.

"My colleagues cringe when I use this, but it becomes, you know, like fixing a car," says Sefton. "Replace the carburetor with a new one."

"The idea of doing this in 10 years is steadily becoming less and less ridiculous," he adds, "just ambitious and just exciting."

And if parts can be made to order, perhaps the agonizing wait for transplants will end.

Artificial heart

An artificial heart is a prosthetic device that is implanted into the body to replace the original biological heart.

It is distinct from a cardiac pump, which is an external device used to provide the functions of both the heart and the lungs.

Thus, the cardiac pump need not be connected to both blood circuits.

Also, a cardiac pump is only suitable for use not longer than a few hours, while for the artificial heart the current record is 17 months.

This synthetic replacement for an organic mammalian heart (usually human), remains one of the long-sought goals of modern medicine.

Although the heart is conceptually a simple organ (basically a muscle that functions as a pump), it embodies complex subtleties that defy straightforward emulation using synthetic materials and power supplies.

The obvious benefit of a functional artificial heart would be to lower the need for heart transplants, because the demand for donor hearts greatly exceeds supply.

Tofy Mussivand born c. 1943 in Varkaneh, Hamadan Province, Iran, is an Iranian-Canadian medical engineer who invented an Artificial Cardiac Pump, a device that pumps blood and takes over the function of breathing during a heart surgery.

The Artificial Cardiac Pump temporarily takes over the function of breathing and pumping blood for a patient. It has two parts, the pump and the aerator. Cardiac pumps are most often used in heart surgery, so that a patient's heart can be disconnected from the body for longer than the twenty minutes or so it takes for a prepared patient to die.

1.) Who performed the first heart transplant? When?

2.) Why is there a demand for hearts to be grown in a laboratory?

3.) Make a list of advantages to the idea of growing a heart in a laboratory

4.) Some people, for various reasons, may not support the idea of growing a heart in a laboratory. What might some of these reasons be? Make a list.

5.) What are the pros and cons of an artificial heart?

6.) Compare an artificial heart to one grown in a laboratory.

7.) Are artificial hearts used? Are they a permeate solution?

8.) You are a member of parliament. Parliament is taking a vote whether or not to allow hearts to be grown in a laboratory. Take a position either supporting or not supporting this and sum up your argument in paragraph form. Provide reasons for your argument!

Angina

Angina causes pain or tightness in the chest area, creating a sort of “squeezing” sensation that sometimes resembles indigestion. This condition is not a disease in itself. It’s most often a symptom of coronary heart disease, in which the arteries supplying blood to the heart narrow and stiffen. Angina can also signify coronary microvascular disease, which is heart disease affecting smaller coronary arteries.

There are various types of angina, which all signal some sort of heart disease and should be checked out by your doctor.

Congestive Heart Failure

This condition is more common in older people and occurs when the heart can no longer pump blood to the rest of the body like it should. Doctors describe it as losing “pumping capacity.” The condition usually results from damage caused by a heart attack, high blood pressure, diabetes, coronary artery disease, cancer treatments, or other health issues and may result in excess fluid backing up into the lungs and other tissues. Congestive heart failure ranges from mild to severe, with symptoms such as:

• weight gain

• edema (swelling) in the abdomen, feet, ankles, and legs

•  fatigue

• dizziness

• shortness of breath

• eventual disability

Treatment involves medications, and other medical procedures and surgery for more severe cases.

Coronary Heart Disease

This type is the most common form of heart disease. It occurs when the arteries that supply blood to the heart become narrowed and hardened due to the buildup of plaque, known as “atherosclerosis.” Coronary heart disease is the leading cause of death in the United States for men and women.

Treatment depends on severity and involves keeping high blood pressure and high blood cholesterol under control, adopting lifestyle changes such as regular exercise, and in some cases, surgery options like angioplasty and bypass surgery.

Coronary Microvascular Disease

Also called MVD, small vessel disease, or cardiac syndrome X, this disease affects the heart’s tiny arteries. It damages the lining in the artery walls and causes them to narrow, increasing your risk for heart attack and heart failure. Symptoms include chest pain (angina), shortness of breath, and fatigue. Treatments mostly involve medications.

Ischaemic Heart Disease

The word “ischaemic” means a “reduced blood supply.” Ischaemic heart disease is any heart disease that results in a reduced blood supply to the heart. Though there may be many causes, most incidences of this disease may be attributed to atherosclerosis, a narrowing of the arteries that supply the heart with blood. This disease is also referred to as coronary artery disease.

Inflammatory Heart Disease

This disease involves inflammation of the heart muscles or the surrounding tissues, which may be caused by bacterial, viral, or fungal infections, or by immune diseases. Symptoms usually include:

• angina

• shortness of breath

• swelling in the feet and ankles

• fatigue

Those most at risk include individuals who had a congenital birth defect or previous injury to the heart, intravenous drug users, and those with an artificial heart valve. Treatment depends on the extent of the damage to the heart muscle and typically involves medications or surgery.

Pulmonary Heart Disease

Also called “right-sided heart failure,” pulmonary heart disease occurs when a disease of the lungs affects the heart. Blood flow to the lungs may then slow down or become blocked, increasing blood pressure in the lungs. As a result, the right side of the heart has to work harder, which can lead to damage to the heart muscle itself.

Congestive heart failure may result. Pulmonary heart disease may be caused when a pulmonary artery becomes blocked or by respiratory diseases like emphysema. Treatments may involve medications, vasodilators, and oxygen therapy.

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