Valve Replacement: Mechanical or Tissue?

Valve Replacement: Mechanical or Tissue?
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Valve Replacement: Mechanical or Tissue?

Valve Replacement: Mechanical or Tissue?

If you need a new aortic valve, age is the main factor when choosing which type to get.

Q. I'm 66 and will be having my aortic valve replaced soon. My surgeon suggested a tissue valve, but he also mentioned that I could get a mechanical valve instead. What are the key differences between these two choices?

A. In general, both types of replacement valves work very well. But there are pros and cons with each one. Historically, a person's age has been the main consideration when choosing between the two. Currently, the American College of Cardiology and the American Heart Association recommend mechanical valves for people under age 50 and biologic (tissue) valves for those over 70. For people like you who fall between those ages, neither type has an absolutely clear advantage over the other.

Mechanical valves are made from a special type of carbon or titanium and other sturdy materials. Their main advantage is their durability: a mechanical valve will usually last for the rest of the person's life. That is why they have been historically favored in younger people with an expected life span of several more decades. However, blood clots can lodge in the valve flaps or hinges and prevent the valve from working properly. That can be an imminently life-threatening situation. Additionally, those clots may break off and travel through the bloodstream. If a clot blocks an artery to the brain, that causes a stroke.

To avoid this problem, nearly all people who get mechanical heart valves must take anti-clotting medication, usually warfarin (Coumadin), for the rest of their lives. Warfarin increases the risk of bleeding, which can show up as bleeding from the nose, gums, or minor injuries — or, more rarely, as worrisome internal bleeding. However, careful monitoring of the degree of warfarin's effect on the blood can limit this danger.

Tissue valves, which are made from pig heart valves or cow heart-sac tissue, typically last about 15 years. But they usually don't require the lifelong use of anti-clotting drugs. Older people are more vulnerable to the bleeding side effects of warfarin. They're also less likely to outlive their new valves. So for them, a tissue valve is usually considered the better choice. However, for people who are already taking warfarin for another problem, such as atrial fibrillation or deep-vein thrombosis, a mechanical valve might make more sense.

Studies have been somewhat contradictory as to which valve is best for people in their 50s and 60s. In recent years, there's been a trend toward using tissue valves in people at the younger end of that range. The theory is that by the time those people need a second valve, it can be replaced using a minimally invasive procedure — a logical but unproven approach. In the next decade, we should have much more data to make an informed recommendation.

(Harvard Heart Letter)



Bull Sharks Linger in Warming Sydney Waters

A man watches large waves on Bondi Beach in Sydney on July 2, 2025, as large swells and high winds hit the east coast of Australia. (Photo by SAEED KHAN / AFP)
A man watches large waves on Bondi Beach in Sydney on July 2, 2025, as large swells and high winds hit the east coast of Australia. (Photo by SAEED KHAN / AFP)
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Bull Sharks Linger in Warming Sydney Waters

A man watches large waves on Bondi Beach in Sydney on July 2, 2025, as large swells and high winds hit the east coast of Australia. (Photo by SAEED KHAN / AFP)
A man watches large waves on Bondi Beach in Sydney on July 2, 2025, as large swells and high winds hit the east coast of Australia. (Photo by SAEED KHAN / AFP)

Bull sharks are lingering off Sydney's beaches for longer periods each year as oceans warm, researchers said Friday, predicting they may one day stay all year.

The predators are migratory, swimming north in winter when Sydney's long-term ocean temperatures dip below 19 degrees Celsius (66 degrees Fahrenheit) to bask in the balmier waters off Queensland.

A team of scientists looked at 15 years of acoustic tracking of 92 tagged migratory sharks in an area including Bondi Beach and Sydney Harbour.

Records show the sharks now spend an average of 15 days longer off Sydney's coast in summer than they did in 2009, said James Cook University researcher Nicolas Lubitz.

"If they're staying longer, it means that people and prey animals have a longer window of overlap with them."

Shark attacks are rare in ocean-loving Australia, and most serious bites are from three species: bull sharks, great whites, and tiger sharks, according to a national database.

There have been more than 1,200 shark incidents around Australia since 1791, of which over 250 resulted in death.

Researchers found an average warming of 0.57C in Bondi for the October-May period between 2006 and 2024, said the study published in the peer-reviewed journal Science of The Total Environment.

Over a longer period, remotely sensed summer sea-surface temperatures in the area rose an average 0.67C between 1982 and 2024, they said.

"If this trend persists, which it likely will, it just means that these animals are going to spend more and more time towards their seasonal distributional limit, which currently is southern and central New South Wales," Lubitz said.

"So it could be that a few decades from now, maybe bull sharks are present year-round in waters off Sydney," he added.

"While the chances of a shark bite, and shark bites in Australia in general, remain low, it just means that people have to be more aware of an increased window of bull shark presence in coastal waters off Sydney."

Climate change could also change breeding patterns, Lubitz said, with early evidence indicating juvenile sharks were appearing in rivers further south.

There was some evidence as well that summer habitats for great whites, which prefer colder waters, were decreasing in northern New South Wales and Queensland, he said.

Tagged sharks trigger an alarm when they swim within range of a network of receivers dotted around parts of the Australian coast, giving people real-time warnings on a mobile app of their presence at key locations.