'Bionic' pacemaker reinstates heart rate variability
Researchers from The University of Auckland have designed a pacemaker that re-establishes the heart’s naturally irregular beat, unlike other pacemakers that pace the heart metronomically. This puts it closer to the typical heart rate of a healthy individual, which is constantly on the move.
“If you analyse the frequencies within your heart rate, you find the heart rate is coupled to your breathing,” said Professor Julian Paton, Director of the Manaaki Manawa Centre for Heart Research at The University of Auckland. “It goes up on inspiration, and it goes down on expiration, and that is a natural phenomenon in all animals and humans. And we’re talking about very ancient animals that were on the planet 430 million years ago.”
Prof Paton was part of a group of scientists who decided to investigate the function of this variability. They made a mathematical model that predicted it saved energy — which made them question why a metronomic heartbeat was used in heart-failure patients who lacked energy.
“All cardiovascular disease patients lose their heart rate variability, which is an early sign that something is going wrong. Prof Paton explained, “People with high blood pressure, people with heart failure, their heart rate is not being modulated by their breathing. It may be a little bit, but it’s very, very depressed, very suppressed.
“We decided that we would put the heart rate variability back into animals with heart failure and see if it did anything good.”
Following positive signals in rats, the latest research was on a large animal model of heart failure, published in the journal Basic Research in Cardiology. According to research co-leader Dr Rohit Ramchandra, the study showed that introducing a natural variation in the heartbeat improves the heart’s ability to pump blood through the body.
“The other big news is that we get a 20% improvement in cardiac output, which is effectively the ability of the heart to pump blood through the body,” he said.
“The pacemaker is almost like a bionic device,” Prof Paton said. “It understands the signals from the body that tell the device when we’re breathing in and when we’re breathing out. And then the device has to communicate back to the body and pace the heart up during breathing in and down during breathing out.”
Plans are now in place to recruit human patients into a trial planned for later this year in New Zealand. The trial will be supported by Ceryx Medical, a startup company that owns the IP on the electronics within the bionic pacemaker.
Dr Martin Stiles, the cardiologist who will lead the trial, said, “We typically see improvements in heart function with current pacemakers, but this bionic pacemaker has far exceeded our expectations. This discovery may revolutionise how heart failure patients are paced in the future.”
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