THE DISCOVERY OF THE PACEMAKER

Shreya Verma OHS

The transformation of particular organs, or groups of cells, into mechanical objects has had a major role in revolutionising medicine. In the case of the pacemaker, the replication of the specialised cells in the Sino atrial node had to be represented.

John Hopps, known by many as the father of biomedical engineering, was interrupted by an assignment in 1949 whilst working on studying the use of radiofrequency reheating for purifying beer. This very disruption to his research formed the pathway into transforming the lives of millions of cardiac patients around the world.

His assignment was held at the Banting Institute where cardiac surgeons were utilizing the slowing effect of hypothermia to decrease the speed of the heart during open heart surgery. Below a certain temperature, the heart tissue becomes completely immobile, and so the team were working on a way to induce cardiac contraction during this state of hypothermia.

Although it may seem obvious to us now, Hopps came up with what was an enlightening observation that an electrical impulse would force the heart to beat. He then went on to carry out a variety of experiments, coming up with the first pacemaker prototype in 1950. The initial observation followed by the construction produced an innovative device that then revolutionised the nature of heart surgery.

This machine was 30cm in length and powered by a 60Hz current, with vacuum tubes to generate the impulses. Moreover, to improve his design, Hopps developed electrode catheters which were able to pass through the jugular vein in the neck, so that the impulse could be delivered to the heart without the opening of the chest even being required! From the first step of this journey, where the team at Banting Institute were looking to find a way to keep the heart beating during open surgery, to being able to perform this operation through the connection of a vein was certainly a remarkable progression.

The cardiac pacemaker used today is possibly the most intriguing invention known to cardiology as the very machine that keeps 3 million people’s hearts beating per year. Without this, illnesses such as Bradycardia, a clinically slow beating of the heart, would proceed with its detrimental effects which include a lack of oxygen delivery to the brain and other vital organs. Bradycardia occurs when the sinus atrial node (SAN), often known as the heart’s natural pacemaker, stops providing signals to the heart at the same rate. Thus, the implantation of an electronic pacemaker mechanically takes over the role of the SAN and delivers impulses either at a fixed rate or on demand to the cardiac muscle to allow the heart to beat accordingly.

Similar to Hopps’ prototype, the pacemaker that’s used today has two electrode catheters that enter one or multiple of the heart’s chambers through the jugular vein. The generator bit of the pacemaker, therefore, is inserted just under the skin near the heart, making the surgery less invasive as possible.

The design of the machine stemmed in the 1950s, however the way it operates today is purely due to the progression of digital devices in the field of medicine. Now, due to the presence of a computerised generator, the pacemaker is able to automatically detect an abnormal heart rhythm and send this data through wires to the computer and then to the generator which adjusts the electrical activity. Doctors are then able to assess the data recorded by the computer and adjust the settings of the pacemaker if necessary.

Thus, this shows that the scientific discovery of the pacemaker initiated a domino effect on innovative advancements of the device. If Hopps had not originally come up with the idea of controlling the heart with a mere external electrical impulse, this machine would not have been introduced to our population and computerized accordingly. The thought of a computer controlling the very organ keeping us alive is certainly unnerving, but a revolution nevertheless!

Bibliography

https://www.mayoclinic.org/diseasesconditions/bradycardia/symptoms-causes/ syc-20355474#:~:text=If%20you%20have%20 bradycardia%2C%20your,Fatigue https://www.ahajournals.org/doi/10.1161/01. CIR.0000016183.07898.90#:~:text=There%20 are%20about%203%20million,the%20recipient’s%20 activities%20or%20lifestyle. https://bcmj.org/articles/john-hopps-and-pacemakerhistory-and-detailed-overview-devices-indications-and http://www.jeffersoncardiology.com/servicespacemakers-defibrillators.html https://www.bhf.org.uk/informationsupport/ treatments/pacemakers