Researchers at The Florey Institute, working closely with doctors who care for heart surgery patients, have made a major breakthrough in understanding why kidney damage often follows heart surgery.
They’ve developed the world’s first animal model to closely monitor kidney health during and after surgery, giving them a detailed look at what happens to the kidneys when the heart-lung machine is used.
The heart-lung machine is a life-saving device used during cardiac surgery to keep blood and oxygen flowing while the heart is stopped. But this study shows that while it helps the heart, it may harm the kidneys.
Using 12 sheep as a model, the researchers tracked kidney health before, during, and weeks after surgery. They found that as soon as the heart-lung machine was used, blood flow and oxygen levels to the kidneys dropped sharply.
This lack of oxygen didn’t stop after the surgery ended—it continued for weeks. In fact, oxygen levels remained low in the kidneys even four weeks after the operation.
This ongoing oxygen shortage caused a cascade of problems: inflammation, cell death, and eventually scarring in the kidney tissue. These are all signs of serious injury, and the researchers believe this helps explain why many patients develop acute kidney injury (AKI) after heart surgery, and why some later go on to develop chronic kidney disease (CKD).
In the first two days after surgery, nearly half of the animals (42%) developed AKI. And four weeks later, the damage was still visible—not just in how the kidneys were functioning, but in how the tissue itself looked under a microscope.
Professor Yugeesh Lankadeva, who led the research, said the findings shine new light on a long-standing medical mystery. “We now have clear evidence that heart surgery causes a drop in kidney oxygen levels, and that this drop continues well beyond the operating room,” he explained.
“This link between surgery and lasting kidney injury is crucial for understanding how short-term damage can turn into long-term disease.”
What makes this study stand out is how closely it reflects what happens in real human surgeries. The researchers worked side by side with cardiac anesthesiologists, surgeons, ICU doctors, and perfusionists from several major Australian hospitals.
Their combined effort created a realistic model that can now be used to develop new ways to detect and treat kidney damage caused by heart surgery.
Dr. Taku Furukawa, the study’s first author and a practicing doctor working toward his Ph.D., said he’s seen firsthand how often patients suffer from kidney problems after heart surgery. “This study gives us vital knowledge about why this happens,” he said. “I’m excited to use this research to help create new tools and treatments that could save kidneys—and lives.”
In short, this groundbreaking work not only explains how cardiac surgery can harm the kidneys, but also opens the door to better ways of protecting patients in the future. The goal now is to use this model to develop targeted therapies and tests that can stop AKI before it leads to chronic illness.
If you care about heart disease, please read studies about a big cause of heart failure, and common blood test could advance heart failure treatment.
For more information about heart health, please see recent studies about a new way to repair human heart, and results showing drinking coffee may help reduce heart failure risk.
The research findings can be found in Anesthesiology.
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