How does heart transplant surgery work? - Roni Shanoada

2,282,159 views

2022-05-24・ TED-Ed

How does heart transplant surgery work? - Roni Shanoada

2,282,159 views・2022-05-24

TED-Ed


Please double-click on the English subtitles below to play the video.

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Your heart beats more than 100,000 times a day.
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In just a minute, it pumps over five liters of blood throughout your body.
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But unlike skin and bones, the heart has a limited ability to repair itself.
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So if this organ is severely damaged,
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there’s often only one medical solution: replacing it.
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Today, nearly 3,500 heart transplants are performed each year
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in a complex and intricate procedure with no room for error.
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The process begins by testing potential recipients
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to ensure they’re healthy enough for this demanding operation.
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Doctors are especially concerned with identifying immunocompromising illnesses
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or any other conditions that could compromise a patient's chance of survival.
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The next step is to match an eligible recipient with a heart donor.
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Donors are often comatose patients with no chance of being resuscitated
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or victims of a fatal event whose hearts are still healthy.
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In both cases, these patients need to be registered as an organ donor
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or have their families give consent.
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And even when a heart is available,
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surgeons can’t just pair any donor with any recipient.
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The recipient’s immune system will view a transplanted heart
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as a foreign organism that must be attacked.
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So doctors need to match recipients with donors that share their blood type
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and have similar antigens.
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If a match can be made, the surgery can begin.
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Once the donor's heart is confirmed to be healthy,
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the organ is immersed in an ice slush
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and injected with a solution to induce cardiac arrest.
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These treatments stop the heart from pumping
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to ensure it can be removed cleanly.
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Surgeons then place the organ in a mix of cold saline
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and preservation solution.
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This is when the clock starts.
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Disconnected from its blood supply,
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the heart’s cells start taking on damage from lack of oxygen.
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The organ will only remain viable outside the body for a few hours,
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so it needs to reach its recipient as fast as possible.
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Once the heart arrives, the recipient is put under general anesthesia.
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The surgeon makes an incision down the length of the chest,
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cutting through the breastbone to separate the rib cage
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and expose the heart.
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To keep blood flowing while they remove the damaged organ,
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surgeons use a cardiopulmonary bypass machine.
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This takes over the heart's job,
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generating enough force to push blood through the patient's circulatory system.
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After the old heart is removed,
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the surgeon begins sewing the donor heart into place.
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This is an incredibly precise process, where each blood vessel and artery
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must be carefully attached to avoid leaks.
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The procedure can last several hours,
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potentially longer if there’s scar tissue from previous surgeries.
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Once it’s finished, the bypass machine is turned off
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and blood is allowed to flow into the aorta.
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Doctors carefully monitor the new heart to ensure it’s beating on its own
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before sewing the recipient back up.
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Even after the procedure is complete, there's still work to be done.
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Surgeons are unable to directly connect the heart
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to the recipient’s nervous system,
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and it can take years for the body to fully innervate the new organ.
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During this period, the transplanted organ has a higher resting heart rate
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and risk of stroke, making exercise difficult and dangerous.
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And since it’s incredibly rare to find a perfect match
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between donor and recipient,
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the immune system will also have some response to the new heart.
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Immunosuppressive drugs can help manage the risk of rejection,
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but they also leave patients open to contracting dangerous infections.
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It requires constant monitoring and testing to balance these two concerns.
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Despite these challenges, about 70% of heart transplant recipients survive
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for at least five years after the operation,
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and just over 20% live another 20 years.
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So when this procedure is successful, it's truly lifesaving.
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Unfortunately, people in developing countries are often unable
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to access this surgery,
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and many viable hearts can’t be donated due to legal and regulatory issues.
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Thousands of people remain on waiting lists,
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and many are never able to find a suitable donor.
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