SCIENTISTS have lessened symptoms of heart failure by reinstating the body’s natural heart rhythm using brain circuits made in silicon, thanks to research part-funded by the British Heart Foundation.

It’s estimated around 920,000 people are living with heart failure in the UK and almost 1.4 million have survived a heart attack. After such an event, pacemakers are often fitted to either speed up the heart or to overcome electrical conduction problems between different chambers of the heart. There is no cure for heart failure – its progression is only slowed by current medication.

The heartbeat is never constant, it varies with every breath. It speeds up when you inhale and slows down when you exhale. This difference in heart rate is known as respiratory sinus arrhythmia.

Designing more effective pacemakers

Researchers at the Universities of Bath and Bristol have adopted this arrhythmia in a new bionic pacemaker and applied it to a heart in heart failure. They found that this new form of heart pacing dramatically increases the efficiency of the heart in rats.

Normally, pacemakers don’t listen to signals from our bodies; they simply pace the heart at a monotonous, regular rate. These researchers, however, built a pacemaker that read the body’s own breathing signals to speed up and slow down the heart every breath.

Professor Alain Nogaret, a physicist at the University of Bath, led the design of the nonlinear electronics which resynchronise respiration and cardiac rhythms, to create the ‘smart’ bionic pacemaker.

New hope for heart failure patients

Professor Nogaret said: “By managing to recreate neurons on a chip, we have developed a pacemaker that restores natural heart rate variability – instead of simply working at a steady rate. That’s the major advantage of this work and why we hope to be able to treat heart failure in patients in the years to come.”

Dr Erin O’Callaghan, lead author of the study, said: “We used state-of-the-art high-resolution echocardiography to monitor the heart’s performance during respiratory sinus arrhythmia pacing in rats with heart failure. Within two weeks, there was a 20 per cent increase in blood pumped by the heart which was not the case when we used conventional pacemakers.”

Julian Paton, Professorial Research Fellow in Physiology at the University of Bristol, and senior author on the study, said: “Our findings give hope for heart failure patients and may revolutionise the future design of cardiac pacemakers. Our next step in the research is to find out if respiratory sinus arrhythmia can reverse heart failure in human patients, as it has done in rats.”

Reducing hospital admissions

Professor Jeremy Pearson, British Heart Foundation Associate Medical Director, said: “These fascinating experiments provide proof that a new approach, delivering better control of heart rate by a pacemaker, could improve the treatment of people with heart failure.

“With heart failure admissions reaching record levels in England – rising by a third in the last five years – it’s vital we fund more research to find new and improved ways of detecting, diagnosing and treating this often cruel and debilitating disease.”