Modern electrodes used in arrhythmia ablation procedures can collect not one but even a dozen or more electrical impulses in the heart during one cycle. 3D mapping systems analyze not 100 or 200 but tens of thousands of points in a short time. This makes it possible to treat even the most complex arrhythmias effectively. A few years ago, arrhythmia treatment was much more complex, and in some cases, even impossible – recalls Prof. Oskar Kowalski, the head of Electrophysiology and Cardiac Simulation Laboratory at the Silesian Center of Heart Diseases in Zabrze.
More atypical arrhythmias
According to the expert observations from the Heart Rhythm Section of the Polish Cardiac Society, the number of patients suffering from increasingly complex arrhythmia is still growing. Specialists believe that this is mainly due to the increasing average age of Polish society and more numerous comorbidities in elderly patients.
-Over the last several years, we have observed that the number of people with very complex types of arrhythmias is steadily growing. It is undoubtedly related to the fact that the average population age in Poland is increasing. Our patients are getting older and more often have more damaged hearts. As a result, we observe more and more cases of atypical arrhythmias. Atypical arrhythmias do not have any clear definition on ECG, and their type can only be determined during the ablation procedure. A patient referred for AF ablation may, in fact, suffer from atypical atrial flutter, which is ablated in a completely dissimilar manner. A different surgical strategy and a different goal than the typical pulmonary vein isolation in the treatment of atrial fibrillation is required – explains Oskar Kowalski, MD, Prof. SUM, head of the Electrophysiology and Cardiac Simulation Laboratory at the Silesian Center for Heart Diseases in Zabrze.
As the expert points out, doctors were helpless in most atypical arrhythmia types only a few years ago. Technical capabilities of the first electroanatomical systems used today during the ablation of arrhythmia substrate did not allow for precise localization of sources of disturbing conduction of impulses in the heart and tracing the nature of arrhythmia. In the most complex cases, the effectiveness of treatment was limited.
In terms of arrhythmia diagnostics and therapy using 3D heart mapping systems, impressive progress has been made over the past few years.
–3D cardiac mapping systems that we use today in arrhythmia substrate ablation procedures have more advanced and ‘intelligent’ algorithms. No less impressive is the development of special electrodes for arrhythmia mapping, which, thanks to their high sensitivity, can find micro-signals in the heart that we would not have been able to see in the past. Something we once saw as scar tissue, today we can read as a damaged but still active tissue. It allows us to accurately trace an actual course of arrhythmia and how it spreads through the heart. We find precisely the place generating arrhythmia, and we ablate exactly this fragment of tissue. This means a significant increase in the effectiveness of this procedure – says Prof. Oskar Kowalski.
Dense 3D maps
As the expert stresses, only a few years ago, 3D maps of heart cavities were created from about 100-150 points, which were supposed to reflect the shape and the way of electric activation. Today, modern 3D cardiac mapping systems make it possible to collect tens of thousands of such points quickly.
– It once used to be that at 200 ablation points, the computer would start to hang up. It was simply not able to analyze such an amount of information. Today, in a few minutes, we can make a 3D map of the heart with a density of 20-30 thousand points. This results in more ablation points than one point per square millimeter in each area of our interest. In addition, the collected points are analyzed through the prism of much higher sensitivity. We are assisted by unique algorithms that automatically analyze the course of heart rhythm disturbances and show us the critical points, i.e., the most “suspected” of inducing arrhythmia – explains Prof. Oskar Kowalski.
According to Prof. Oskar Kowalski, around arrhythmia substrate ablation, the timing of procedures has also changed over the past few years.
– Nowadays, with the more outstanding capabilities of electroanatomical and multi-field electrodes, we can significantly reduce ablation procedure time. For example, in the past, an ablation electrode collected only one beat in one cycle. It is now even more than a dozen beats. The shorter the procedure is, the more comfortable and safer it is for the patient. This is an important trend – says Prof. Oskar Kowalski.
An example of a tool used at the Silesian Center for Heart Diseases in Zabrze is the HD Grid ablation catheter.
– HD Grid electrodes, which are jokingly referred to in the electrophysiology community as a pack due to their shape, are modern and practical tools that streamline the process of 3D cardiac mapping. These catheters have three advantages. First, they are multi-field, and it means that with a single application of the electrode to the heart wall, we instantly collect several points creating a 3D model of the heart cavity. Second, the electrodes themselves receiving the heart’s electrical stimulation signals placed on the catheter are relatively small. The system is much better at differentiating even a tiny signal from noise. As a result, the catheters collect proper signals of much smaller amplitude. It means that three-dimensional maps are much more accurate while being created faster. Furthermore, HD Grid catheters are very gentle. In practice, this means minimizing the risk of perioperative complications and enhancing patient safety – explains Prof. Oskar Kowalski.