Heart valves
Heart valves prevent the back flow of blood.
There are two sets of valves in the heart.
One set of valves is between the atria and ventricles, which prevents the backflow of blood into the atria when ventricles contract.
Another set of valves is between the ventricles and arteries, which prevents the backflow of blood into the ventricles when the heart muscle relaxes.
Sometimes, these valves can become faulty, often due to increased stiffness due to use. In this case:
1.The valve may not open fully, reducing the volume of blood pumped by the heart to either the lungs or body.
2. They leak, allowing blood to flow backwards into either the atria or ventricles.
If this is not corrected the heart will not be functioning correctly and eventually it will lead to death.
Doctors treat this by replacing the faulty valves with either:
1.Biological valves from pigs or cattle
2.Mechanical valves which are artificial man made valves (titanium/polymers).
| Heart valve | Advantages | Disadvantages |
|---|---|---|
| Biological | No need for long-term blood thinners, so lower risk of clotting problems. Works more naturally and quietly. | Wears out sooner – usually lasts 10–15 years. May need replacement surgery again later, especially in younger patients. Small risk of immune system rejecting the biological valves |
| Mechanical | Very durable – can last 20–30 years or more. Suitable for younger patients because it doesn’t wear out easily. | Blood clots can form on the valve – patient must take lifelong anticoagulant (blood-thinning) drugs. Can sometimes be heard clicking inside the chest. |
Heart failure
Heart failure is a condition where the heart becomes too weak or stiff to pump enough blood to meet the body’s needs.
In the case of heart failure a donor heart, or heart and lungs can be transplanted. However, there is a long waiting list for a donor organ. The donor organ has to be tissue typed to reduce the risk of organ rejection by the immune system.
Artificial hearts (mechanical hearts) are occasionally used for:
1. Keeping patients alive whilst waiting for a heart transplant.
2. To allow the heart to rest as an aid to recovery.
| Heart transplant type | Advantages | Disadvantages |
|---|---|---|
| Biological (human heart) organ transplant. | Works like a real heart – can fully restore normal blood flow and activity. No external power source needed. Better long-term survival and quality of life than artificial hearts (if successful). | Donor hearts are scarce – long waiting lists. Immune system may reject the new heart – patient must take immunosuppressant drugs for life and donor heart has to be tissue typed to match. Risk of infection and side effects from those drugs. |
| Artificial (mechanical) heart transplant | Can be used temporarily to keep a patient alive until a donor heart is found. No immune rejection (it’s not living tissue). Artificial hearts are more readily available, so shorter waiting time. | Needs an external power source (battery or power cable). Blood clots can form → risk of stroke. Not a long-term solution – limited lifespan and frequent maintenance. |
Practice Questions
1.State the function of the heart valves
2. State two consequences if valves become faulty
3. Why should a doctor fit a mechanical valve into a younger patient, rather than a mechanical valve?
4. Describe how heart failure is treated.