Heart transplantation

When a heart can no longer pump blood effectively, it may be replaced with a healthy donor heart. This operation is called a heart transplant. The donor heart can restore effective circulation, allowing blood to reach the body’s tissues.

A heart and lungs can be transplanted together if both organs need replacing. Suitable donor organs are limited, however, and transplantation is a major operation that carries risks.

Rejection of a donor heart

The recipient’s immune system may recognise the donor tissue as foreign and attack it. This is called rejection and can damage the transplanted organ. To reduce the risk, the recipient needs immunosuppressant drugs, which suppress the immune response. These drugs also make the recipient more susceptible to infections because the immune system is less able to defend against pathogens.

Coronary stents

The coronary arteries supply the heart muscle with blood. If a coronary artery becomes narrowed, less blood can reach the heart muscle. A coronary stent is a small mesh tube inserted into the narrowed artery to hold it open. This improves blood flow to the heart muscle.

A stent can restore blood flow relatively quickly and may remain effective for a long time. However, inserting it involves a procedure with risks. One risk is that a blood clot may form around the stent and obstruct blood flow. Medication may be needed to reduce clotting.

Heart valve replacement

Heart valves keep blood moving in the correct direction through the heart. If a valve is faulty, it can disrupt blood flow. Replacing it with an artificial valve can improve the flow of blood through the heart.

Types of replacement valve

A biological valve generally does not last as long as a mechanical valve, so it may need to be replaced. However, it usually does not require lifelong anticlotting medication solely because of the valve.

A mechanical valve is more durable, but blood can clot on it. A person with a mechanical valve generally needs long-term anticoagulant medication to reduce the risk of clots forming.

Both types of valve require an operation to replace the faulty valve, and the operation itself carries risks.

Faulty heart valves

Heart valves open to let blood flow forwards through the heart and close to prevent it flowing backwards. This keeps blood moving in one direction.

A valve can become faulty in two ways:

• A valve that does not open fully leaves a narrower opening, restricting the forward flow of blood.
• A leaking valve does not close properly, so some blood flows backwards when the valve should be closed.

Either fault makes circulation less effective. The heart has to work harder to pump enough blood forwards: it must pump against the restriction or compensate for blood flowing backwards.