Future Of Pacemakers Could Be This Flexible Electrode On Your Heart

Collaboration across different scientific disciplines is one of the most valuable methods for the innovation of novel technology. A new device reported this month combines the fields of engineering, materials science, medicine, and mathematics to revolutionize the cardiac electrotherapy is delivered.

Human heart and ciculatory system: Newly designed flexible electrodes on a plastic film are able to wrap around the heart. Image by Bryan Brandenburg.Human heart and ciculatory system: Newly designed flexible electrodes on a plastic film are able to wrap around the heart. Image by Bryan Brandenburg.

There are a few different ways in which an electric current or potential can be used to treat common heart conditions. These include pacing, in which 'paced' electrical pulses are used to stimulate a regular heartbeat as with a pacemaker; defibrillation, when a large shock is used to restart a stalled heart; and cardiac ablation wherein a small region of heart tissue is effectively burned by an electric current in order to remove abnormalities. Currently, delivery of these therapies is accomplished by inserting small leads of catheters directly to the heart or under the skin, or else by large patches stuck externally on the chest. 

A traditional bulky pacemaker: Housing this piece of machinery in your chest may soon be obsolete for those suffering from arrhythmia. Image by Steven Fruitsmaak.A traditional bulky pacemaker: Housing this piece of machinery in your chest may soon be obsolete for those suffering from arrhythmia. Image by Steven Fruitsmaak.

Each of these delivery methods has a drawback arising from the trade-off between the precision with which the electrotherapy can be delivered to a particular location and the size of the area over which it can be delivered.Ablation therapy, for example, relies on a small lead which can be positioned precisely in the heart, but once there it can only pinpoint a tiny region of tissue to treat. In contrast, defibrillation, using adhesive external electrode pads, can stimulate a large region of the heart, but with a fair amount of collateral effects leading to unnecessary pain for the patient as well as wasted energy. On top of addressing these issues, the new device covered here is also the first to offer simultaneous mapping of the physiological response to the therapy providing clinicians with real time feedback.

The device in question consists of a conformal thin polymer sheet on to which has been printed eight electrodes encircling the heart. Along with the electrodes, a series of temperature sensors have also been incorporated to monitor the temperature of surrounding tissues -- of particular import for ablation therapy. One of the best features of this system is the ease with which additional functionality could be incorporated. This could include other sensors or maybe even a stand-alone power supply, eliminating the need for a surgically installed wire. Such developments are far from unheard of.

Advances in a number of scientific fields have enabled the production of this device. Materials scientists are responsible for the conformal polymer which allows the sheet of electrodes to make intimate contact with the heart muscle. The electrodes too represent a materials achievement in the area of high-quality flexible conductors. Interestingly, mathematicians also play a role as the electrodes are designed to use a fractal pattern known as the Greek cross. This allows flexibility to be maintained while also maximizing electrode surface area. These fractal electrodes have 14x the contact area as compared with other flexible electrodes. Additionally, they have far more edges than standard solid electrodes and it is known that more current is transferred at electrode edges. This increased efficiency in current transfer means lower power devices. Engineers too have played a role in advancing this medical technology thanks to the increasing availability and versatility of 3D imaging and printing. It is now a relatively simple task to reproduce in plastic an accurate model of a heart or various other organs which can then be used as a mold in order to produce custom therapeutic devices.

While this research may be a first step forward, it highlights the tremendous leaps that can be made when those from diverse backgrounds work together toward a common goal. A lesson that holds true in technological development as well as life in general.