Keeping Future Hearts Beating

The heart is a crucial organ for an embryo to progress past 10 weeks old, without it the circulatory system collapses.  Problems with the way the heart beats are known as ‘Arrhythmias’ and these can be just as lethal.

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These heart rhythm problems effect approximately 2 million people annually in the UK. There’s a variety of different types, some of which people can lead a normal life if properly diagnosed but if left untreated can cause serious cardiac issues.

A normal healthy heart normally contracts from the top down at roughly 80 beats per minute. In a heart with a conduction disorder, like arrhythmias, the heart rate can be faster than normal, slower than normal, more irregular or a combination of these.

One way to treat Arrhythmias is with a pacemaker. This is a medical device which is implanted into the chest to control the rhythm of the heart using low energy electrical impulse to encourage a normal heartbeat.

Pacemakers are usually composed of a generator and battery attached to leads inside the heart. The first fully implantable pacemaker was made 60 years ago. It supported the patient’s heart rhythm for 3 hours then had to be replaced by a new device.

Since then technology has come a long way and this has resulted in a smaller device with improved functionality thanks to adjustments made to generator size, battery life and lead design. Modern pacemakers can provide a stable heart beat for 10 years before having to be changed.

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The next generation of pacemakers have two issues to tackle: increasing battery life and having an automatic, involuntary response to the functions of the heart. There is already research into using solar energy to power the pacemakers but more options need to be investigated.

A possible alternative to the electronic pacemaker is the biological pacemaker. These are being produced in different ways. Gene-based approaches made a biological pacemaker in 2002 which was tested on Guinea pigs, it stimulated the release of an electrical current over the muscle cells of the lower heart.

Similarly, cell- based approaches have also been used. This requires a cluster of randomly beating cells to be transplanted into the heart to generate pacemaker activity. There has even been some investigation into using a combination of both gene and cell based approaches, for example, the delivery of cells carrying pacemaker genes into the heart.

Up to now, the delivery methods of biological pacemakers on large animals has required open chest surgery which Is highly invasive and therefor limits the potential for simply repeating it in humans. However, with over 200,000 patients a year undergoing permanent pacemaker implantation it is clear an alternative is needed and biological pacemakers could be just that.

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