How do heart valves function?
Heart valves function by opening and closing with every heartbeat, every day of your life. According to the book Beyond Stem Cells, the two big problems are stenosis (narrowing) and regurgitation (leaking backward), and researchers are studying ways to help the body grow its own valve.
Key points
- How heart valves function: four valves, each with thin leaflets that open and close like doors so blood moves one way.
- Heart valves location: the aortic and mitral valves are on the left side of the heart. The tricuspid and pulmonary valves are on the right.
- Aortic stenosis means narrowing. Aortic stenosis causes: calcium builds up, the leaflets stiffen and the heart has to work harder.
- Regurgitation means blood leaking backward because the valve does not close all the way.
- Some children are born with a valve that has two leaflets instead of three, or one that is underdeveloped.
- Types of heart valve replacement: mechanical valves last a long time but usually need lifelong blood thinners. Tissue valves from treated animal tissue avoid that but wear out.
- A replacement valve is a fixed size, so it cannot grow with a child.
- Researchers are studying scaffolds that let the body's own cells build a living valve that might grow with a child.
- This is early, developing research. It goes alongside your regular doctor's care, not instead of it.
Heart Valves, Explained
Read the full transcript · Download the MP3 · Voices are AI-generated from a script based on the book.
How heart valves function, and where they are
Most people know they have heart valves and not much more. The book starts with the basics: what the valves are, where they sit and what they do every single heartbeat.
Types of heart valves: four one-way doors
The heart has four valves that keep blood moving in one direction. Each valve has thin flaps of tissue called leaflets, usually two or three. They swing open to let blood through and close so it cannot come back. They do this every heartbeat for your whole life, so they take a lot of wear.
Heart valves location
According to the book, the aortic valve controls flow from the left lower chamber (the left ventricle) out to the aorta. The mitral valve sits between the left upper and lower chambers. The tricuspid and pulmonary valves manage blood flow on the right side of the heart.
Why a valve problem affects the whole body
Because these small valves control blood flow through the heart, the book says the whole body can feel it when they do not work well. That can show up as reduced circulation, tiredness and heart function that slowly gets worse.
What goes wrong: aortic stenosis, regurgitation and valves you are born with
The book describes two big problems, plus valve differences some children are born with.
Aortic stenosis and its causes
Stenosis just means narrowing. The book calls aortic stenosis the most common form of valve disease in adults. It usually comes from calcium building up in the leaflets, which stiffens them so the door cannot open all the way. The heart then has to push blood through a smaller opening and work harder.
Regurgitation: a door that does not shut
Regurgitation means blood leaking backward because the valve does not close all the way. With the mitral valve, blood leaks back into the left upper chamber with each beat. The book says that makes the heart pump less efficiently and can lead to fluid building up in the lungs.
Valves some children are born with
Some children are born with a valve that has only two leaflets instead of three, or a valve that is underdeveloped. Children with these conditions often need more than one procedure as they grow.
Types of heart valve replacement today
According to the book, today's main approach is surgery to replace the valve. There are two main types, and each has trade-offs.
Mechanical valves
Mechanical valves are made from very tough materials and last a long time. The trade-off is that people usually need blood thinners for life, which means bleeding risks and frequent blood tests. The book also notes they can make a clicking sound with each heartbeat, and some people find that stressful.
Tissue valves from treated animal tissue
These valves usually do not require lifelong blood thinners, but they wear out over time, often meaning another surgery. The book says they tend to wear out faster in younger people.
Why children face a harder road
A replacement valve is a fixed size and cannot grow with a child. Many children end up needing surgery after surgery as they get bigger. The book points out that this touches school, friendships and family life too.
Can a heart valve be replaced without open heart surgery?
The book describes minimally invasive, catheter-based techniques that place a valve through small incisions rather than open-heart surgery, already used for aortic stenosis in some high-risk patients. Researchers are developing similar catheter-based approaches to deliver regenerative valves. Whether any approach fits a person is a decision for their heart team.
What researchers are studying: helping the body grow its own heart valve
The regenerative idea is to move from replacing a valve to helping the body build one. The book is clear that researchers are still studying and developing this.
A scaffold, like a garden trellis
One approach starts with a donor valve and washes out all of its cells, leaving just the framework. Because the donor cells are gone, the book says the parts that would set off rejection are gone too. The person's own cells are drawn to the scaffold. Some line the inside so blood does not clot on it, and others go deeper and make collagen.
Scaffolds that slowly dissolve
Another kind of scaffold is made from plastic-like materials that slowly dissolve in the body. The book compares this to temporary supports on a building that come away once the building can hold itself up. Over months, even years, the scaffold is replaced by the person's own tissue.
Blood flow helps shape the valve
The push and pull of blood through the valve sends signals to the cells, so they line up and build in the right pattern. The goal is a living valve that can adapt and, for children, might grow with them.
Who it may fit, and the follow-up it takes
The book says younger people may have the most to gain, while traditional valves may still be the better fit for some older adults. This work takes careful follow-up and imaging over years. It goes alongside your regular doctor's care, not instead of it, with a heart team that understands both the upside and the limits.
Chapter 3 in one line
The goal is shifting from replacing a valve to helping your body grow one.
Episode 3 transcript.
Read along, or skim the parts you care about most.
EliseOkay so, chapter three. And this one's about heart valves?
GuideHeart valves. Yeah.
EliseWhich, honestly, I kind of know I have. That's about it.
GuideThat's most people. So you've got four of 'em. And each one has these thin little flaps called leaflets.
EliseFlaps.
GuideYeah, think of them like doors. They swing open, blood goes through, they close so it can't come back.
EliseOkay. Every heartbeat?
GuideEvery heartbeat. For your whole life. So they take a lot of wear.
EliseHuh. So what goes wrong?
GuideTwo big ones, according to the book. First is stenosis. That just means narrowing. Calcium builds up, the flaps get stiff, and the door can't open all the way.
EliseSo the heart's pushing through a smaller opening.
GuideRight, it has to work harder. And the other one is regurgitation.
EliseThat word.
GuideI know, I know. It just means blood leaking backward. The door doesn't shut all the way.
EliseOh, okay. And some people are born with this stuff, right?
GuideYeah. Some kids are born with a valve that only has two flaps instead of three, or one that's underdeveloped.
EliseSo what do people do now? Like, today?
GuideMostly surgery to replace the valve. And there are two main kinds. Mechanical valves, made from really tough materials—
EliseMm-hm.
Guide—and those last a long time. But you usually need blood thinners for life. Which means bleeding risks and a lot of blood tests.
EliseOof.
GuideAnd the book mentions they can make a clicking sound. Every heartbeat.
EliseWait, you can hear it?
GuideSome people can, yeah. And some find that pretty stressful.
EliseI would lose my mind. Okay, and the other kind?
GuideValves made from treated animal tissue. You usually don't need the lifelong blood thinners. But they wear out over time.
EliseSo you're back in surgery.
GuideOften, yeah. And they tend to wear out faster in younger people.
EliseAnd kids? Because kids grow.
GuideThat's the big one. A replacement valve is a fixed size. It can't grow with the child.
EliseOh no. So they just... outgrow it?
GuidePretty much. So a lot of kids end up needing surgery after surgery as they get bigger.
EliseThat's rough. On the whole family.
GuideYeah, the book actually talks about that. School, friendships, family life. It all gets hit.
EliseOkay, so what's the regenerative idea here?
GuideSo instead of just swapping in a replacement part, the goal is to help the body build its own valve.
EliseBuild its own. How?
GuideWith a scaffold. So they take a donor valve and wash out all the cells. Like, all of 'em. What's left is just the framework.
EliseLike the skeleton of it?
GuideKind of, yeah. Think of a garden trellis. No plant on it yet, just the shape.
EliseOkay, I like that.
GuideAnd because the donor cells are gone, the book says the stuff that would set off rejection is gone too. Then your own cells move in and start growing on it.
EliseWait. Your cells just... find it?
GuideThey're drawn to it, yeah. Some line the inside so blood doesn't clot on it. Others go deeper and make collagen, the strong stretchy stuff.
EliseAnd the scaffold just stays there?
GuideOver time it slowly gets replaced by your own tissue. Months, even years.
EliseSo what's left is... you.
GuideThat's the idea. A living valve. And for kids, it might grow with them.
EliseHuh. That's kind of amazing.
GuideAnd there's another kind of scaffold too. Made from these plastic-like materials that slowly dissolve in the body.
EliseDissolve?
GuideYeah. The book compares it to temporary supports on a building. You take 'em away once the building can hold itself up.
EliseOh, that makes sense. And the blood flow itself, does that matter?
GuideA lot, actually. The pushing and pulling of blood through the valve sends signals to the cells. They line up and build in the right pattern.
EliseSo the heart's kind of training its own valve.
GuideThat's a nice way to put it. Yeah.
EliseOkay, real talk. Is this something people can just go get?
GuideSo, researchers are still studying it and developing it. The book is pretty honest about that. It takes careful follow-up, lots of imaging over years.
EliseAnd it's not for everybody?
GuideRight. The book says younger people might have the most to gain. For some older folks, the traditional valves might still be the better fit.
EliseGot it.
GuideAnd this goes alongside your regular doctor's care, not instead of it. You'd work with a heart team who knows both the upside and the limits.
EliseOkay. So if you had to sum up chapter three?
GuideThe goal is shifting from replacing a valve to helping your body grow one.
EliseLove it. And, quick reminder, this is general info, not medical advice. Talk to your own provider.
GuideAlways.
This is general information, not medical advice. Talk to your own provider.
Frequently asked questions.
How do heart valves function?
Heart valves act like one-way doors. Each of the four valves has thin leaflets that open to let blood through and close so it cannot flow backward, with every heartbeat.
What are the four types of heart valves and where are they located?
The aortic and mitral valves are on the left side of the heart. The aortic valve controls flow from the left ventricle to the aorta, and the mitral valve sits between the left upper and lower chambers. The tricuspid and pulmonary valves are on the right side.
What causes aortic stenosis?
According to the book, aortic stenosis usually comes from calcium building up in the valve leaflets. The leaflets stiffen and cannot open all the way, so the heart has to work harder to push blood through.
What are the types of heart valve replacement?
The book describes two main types. Mechanical valves are very durable but usually need lifelong blood thinners. Valves made from treated animal tissue usually do not, but they wear out over time, often faster in younger people.
Can a heart valve be replaced without open heart surgery?
The book describes catheter-based techniques that place a valve through small incisions instead of open-heart surgery, already used for aortic stenosis in some high-risk patients. Researchers are studying similar approaches for regenerative valves. Whether any option fits a person is a decision for their heart team.
Can my body grow its own heart valve?
Researchers are studying scaffolds that the body's own cells can grow into, slowly forming a living valve that might grow with a child. The book is clear that this is still being developed. It goes alongside your regular doctor's care, not instead of it.
Where is Beyond Stem Cells located?
Beyond Stem Cells is at 5912 S Cody St, Suite 201, Littleton, CO 80123, serving the Denver metro. This podcast is general education, not medical advice.
Want to learn more about regenerative medicine in the Denver metro? See regenerative medicine at Beyond Stem Cells, frequently asked questions, our medical team, related Episode 9 on healing after a heart attack, Episode 1 on how the body heals.
Further reading: National Heart, Lung, and Blood Institute: heart valve diseases.
Want the whole book? Get the free Beyond Stem Cells book.
Regenerative care in Littleton and the Denver metro.
Beyond Stem Cells sits just off S Cody St in Littleton, an easy drive from Ken Caryl, Highlands Ranch, Centennial, Englewood and Lakewood.
Questions about your own situation?
The podcast is general education. If you want to talk about your own health, request a consultation with our team.
Beyond Stem Cells · 5912 S Cody St, Suite 201, Littleton, CO 80123 · (833) 720-7836 · info@beyondstemcells.com
Medical disclaimer: This page is general education based on the book Beyond Stem Cells by John Comandari and Neville Campbell, MD. It is not medical advice. Individual results vary and no specific outcome is promised. Talk to your own provider about your situation.