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The Gregorio Marañón University General Hospital in Madrid, Spain, has reached a new milestone in its research and patient care efforts with the arrival in the US of ACORYS, an innovative noninvasive cardiac mapping system that has received approval from the FDA. This device, developed in collaboration with the Polytechnic University of Valencia, Valencia, Spain, has been transferred to the private sector through the spin-off company Corify Care.

What Is Cardiac Mapping?

Cardiac mapping is a technique that allows the electrical activity of the heart to be visualized to identify the source of an arrhythmia. There are various mapping systems, and traditionally, this procedure is performed through invasive electrophysiologic studies in which catheters are inserted into the heart to record its electrical signals from within the organ, creating three-dimensional maps of its electrical function.

Thanks to this technology, specialists can precisely locate the areas responsible for generating abnormal signals and apply treatments such as cardiac ablation. This type of procedure is used, for example, in conditions such as atrial fibrillation, the most prevalent arrhythmia.

The Cardiac Vector

The origin of electrical activity is based on the potential difference between the inside and outside of the cardiac cell membrane. The movement of ions through channels and pumps causes this potential difference to vary, producing an electrical signal. During the cardiac cycle, heart cells depolarize (contract), enter a plateau phase, and then repolarize (relax) to return to the resting potential. This electrical activity has two important characteristics: automaticity (the ability to generate its own impulse) and conduction (the propagation of the impulse). Automaticity is a slower process, whereas conduction propagates impulses more rapidly.

The sum of these signals is called the cardiac vector and is represented as an arrow because it has direction, amplitude, and orientation. These three properties vary throughout the cardiac cycle, depending on the electrical state of each of the cells that make up the heart.

The Inverse Problem of Electrocardiography

All this electrical activity is recorded by pairs of electrodes that form leads; each lead can be represented as a vector whose origin is one electrode and whose endpoint is the other. Each lead captures how strong the cardiac vector is and how aligned it is with the lead itself. In physics, this is called the scalar product of two vectors. The goal of electrophysiology is to reconstruct the heart’s internal electrical activity by studying the information received from these leads.

The number of leads that can be created with n electrodes is the number of possible pairs that can be formed. In mathematics, this is called combinations of n elements taken two at a time, that is, n over 2. For example, if we had 10 electrodes, there would be 45 possible combinations. However, the human brain cannot analyze so much information; thus, a standard ECG typically focuses on the 12 most informative leads, which are most representative of cardiac electrical activity. Because the new systems use hundreds of electrodes, the amount of data they collect is enormous.

The Square of Electrocardiography

To simplify the explanation of all these complex ideas, let’s imagine a square full of people. Each person will represent a heart cell, and to symbolize electrical activity, we’ll give each of them a flashlight. At rest, the flashlights are off. When the cardiac cycle begins, the people in a special location (the sinoatrial node) start turning on their flashlights due to automaticity, which causes the rest of the people in the square to switch theirs on in an orderly, progressive manner (the property of conduction).

The sum of all these light sources would represent the cardiac vector; the leads would be like walls on which lights and shadows appear depending on the moment in the cardiac cycle and how the combined light aligns with the wall’s orientation. The goal of electrocardiography is to use these lights and shadows to determine which flashlights have been turned on and at what moment they did so. In invasive techniques, signals are recorded from inside the heart in a direct and straightforward way; by contrast, when electrodes are placed on the body’s surface, solving the inverse problem is much more complex.

Conclusion

Thanks to biomedical research, noninvasive cardiac mapping devices have been developed with promising results. These advances reflect a growing trend in the world of medicine: integrating physiology, AI, and computational modeling to design increasingly accurate diagnostics that cause the least possible discomfort to patients.

The authors declared having no conflicts of interest.

This story was translated from Univadis Spanish, part of the Medscape Professional Network.