ARRHYTHMIA UNIT

An electrophysiological study (EPS) is an invasive cardiology test that uses catheters to diagnose certain heart rhythm disorders ( tachyarrhythmias and bradyarrhythmias ) in order to provide the most appropriate treatment for affected patients. The electrophysiological study allows doctors to determine the origin of a tachyarrhythmia or bradyarrhythmia previously documented on an ECG, with the aim of planning the most suitable treatment. In other cases, it allows doctors to determine if the patient's symptoms ( palpitations, dizziness, syncope, dyspnea ) could be due to tachyarrhythmias or bradyarrhythmias. Therefore, it is indicated in patients with certain documented arrhythmias, as well as in patients with symptoms highly suggestive of these arrhythmias occurring intermittently but not documented on an ECG or Holter monitor.

The electrophysiology study (EPS) is performed in an electrophysiology lab. The patient is fasting, lying down, and conscious, although sedated for comfort. Local anesthesia is applied to the puncture site (usually the groin) to minimize pain. From this point, several catheters (thin, long, flexible wires) are inserted through local veins or arteries and guided to the heart using X-ray imaging . These catheters record the heart's electrical activity from within, and we can even stimulate the heart to try to induce the arrhythmias or electrical disturbances we are looking for. Medication may be administered during the test to help confirm the arrhythmia diagnosis. You may experience palpitations during the procedure, either caused by the catheters or the medication, but these are always in a controlled environment and are reversible. Once the diagnosis is made, in most cases, the most appropriate treatment is administered during the same procedure. The duration of the study varies depending on the arrhythmias in question, and the patient must remain in bed and at rest for several hours afterwards.

Electrophysiological studies ( EPS) are very safe procedures. Most of the time, you will only notice slight discomfort at the puncture site, or the appearance of a small bruise that will almost always be reabsorbed spontaneously. The occurrence of serious complications related to the procedure is fortunately exceptional (cases of phlebitis, arteriovenous complications , hemorrhage , cardiac perforation , embolisms , etc. , have been described in the literature ). In any case, the personnel involved in these procedures have the necessary experience and training to recognize any potential complications early and provide appropriate treatment as soon as possible.

Radiofrequency catheter ablation involves creating a heat lesion in the underlying heart tissue. It is a highly effective and safe method for damaging the heart tissue responsible for certain arrhythmias. This technique is usually performed in conjunction with electrophysiological studies (EPS) for the treatment of tachyarrhythmias. That is, when a patient is evaluated for palpitations or tachycardia documented on an ECG and an EPS is performed that establishes the diagnosis, ablation is then performed to treat and eliminate these arrhythmias. Radiofrequency ablation allows for the creation of a highly localized, controlled, and safe burn to damage or eliminate the tissue responsible for the arrhythmias. Similar catheters to those used during EPS are used for the ablation, but with the added capability of creating these burns. During the ablation, the patient may experience a sensation of heat or slight chest discomfort; therefore, analgesia or light sedation is usually administered to minimize discomfort. The occurrence of serious complications related to the procedure is fortunately exceptional (cases of phlebitis, arteriovenous complications , hemorrhage , cardiac perforation , embolisms , etc., have been described in the literature). In any case, the personnel involved in these procedures have the necessary experience and training to recognize potential complications early and provide appropriate treatment as soon as possible.

 Atrial fibrillation is the most common arrhythmia found in the population. The exact causes are not known in most cases and the mechanism that produces it is currently under investigation, but it is related, among others, to the presence of high blood pressure, alterations in the function of the heart valves, and artery disease. that supply the heart... but it is also common to detect it in younger patients without risk factors who practice sports with greater or lesser intensity. Among the strategies for its treatment is pulmonary vein ablation, which has been shown to be the most effective treatment for this arrhythmia. However, as it is an invasive procedure, it is commonly reserved for patients in whom the arrhythmia is not controlled despite the use of drugs or if these are poorly tolerated. Although on other occasions it is proposed as a first-line treatment to avoid chronic treatments in young patients.

Radiofrequency ablation seeks the electrical isolation of the pulmonary veins, which are considered the most important sources of triggers that precipitate the crises of this arrhythmia. Until a few years ago, the conventional method consisted of applying point-to-point radiofrequency impacts or burns around the entire perimeter of each of the pulmonary veins, which resulted in a laborious and prolonged procedure until effective isolation of them was achieved.

Cryoablation is an advanced technique for treating paroxysmal and persistent atrial fibrillation, in which the energy source is cold rather than heat, as in the conventional procedure. While the approach is the same, the main advantage of this technique lies in the fact that the lesion in the antrum of each vein is created by freezing it with a balloon that is inserted into the vein. Thus, in a single application, and very quickly and effectively, each vein is isolated, significantly reducing the procedure time and, consequently, its risks. Recent studies have demonstrated that cryoablation is a highly effective (lower arrhythmia recurrence rate) and safe (fewer complications) technique compared to the conventional radiofrequency ablation technique that has been traditionally used.

What is pulsed field technology or electroporation?

Pulsed-field technology , or electroporation, is a technique used in atrial fibrillation (AF) ablation that employs high-intensity electrical pulses to induce changes in the cell membranes of the heart muscle fibers. These pulses cause the formation of transient pores in the cell membranes, increasing their permeability and allowing the entry of substances that would not normally pass through. This phenomenon can be exploited to selectively destroy the cells or tissues of interest without causing significant damage to surrounding tissues. In the context of atrial fibrillation, electroporation is used to create precise lesions in the cardiac tissue responsible for the abnormal electrical impulses without damaging adjacent structures such as the esophagus, blood vessels, or nerves.

In atrial fibrillation ablation, as with other available technologies, electroporation is used to isolate the pulmonary veins, i.e., to destroy myocardial cells in the antrum and ostium of these veins where they enter the left atrium. This technique is used as an alternative to traditional ablation, which is usually performed using radiofrequency (heat) or cryoablation (cold).

What has pulsed field ablation technology demonstrated?

Pulsed field ablation technology has proven effective in creating precise and controlled tissue lesions in the heart. Clinical studies have shown that this technique can be a viable alternative to conventional ablation techniques, such as radiofrequency and cryoablation, especially in patients with atrial fibrillation and complex cardiac anatomy or in patients who have failed previous techniques, but also as a first-line ablation technique.

1. Ablation effectivenessElectroporation has shown a high success rate in creating tissue lesions in the isolation of pulmonary veins.
2. High-quality injuries: Lesions created by electroporation are of high quality and precision, which can result in more effective interruption of abnormal electrical impulses.
3. Fewer side effectsStudies have also shown that electroporation causes less damage to surrounding tissues compared to traditional techniques, reducing complications and improving the safety of the procedure.

What advantages does electroporation offer in atrial fibrillation ablation?

1. High precision and controlElectroporation allows for extremely precise ablation, as electrical pulses can be applied in a controlled manner to specific areas of the heart. This is especially useful in patients with complex anatomy or structures that are difficult to treat with conventional techniques.
2. Reduction of damage to surrounding tissues and lower risk of complicationsUnlike radiofrequency thermal ablations, which use heat to destroy tissue, or cryoablation, which uses cold, electroporation does not rely on heat generation. This reduces the risk of damaging tissues adjacent to the ablation areas, such as blood vessels, nerves, or the esophagus. This also results in less discomfort after the procedure.
3. Less invasive and faster procedure:  Unlike radiofrequency, which involves longer procedures (3-4 hours) and usually requires general anesthesia, pulsed field ablation, like cryoablation, are quick procedures (1 hour) that can be performed under deep sedation.
4. Durability of injuries: Lesions created by electroporation may be more durable compared to radiofrequency, reducing the likelihood of atrial fibrillation recurrence after the ablation procedure by reconnecting the lesions produced.

Future perspectives

Pulsed-field ablation (PFA) or electroporation technology has become a viable alternative and is being widely used worldwide. Given its recent implementation, further studies are still needed to fully understand its impact and directly compare it with traditional ablation methods in terms of long-term efficacy and safety. In summary, electroporation represents a significant advancement and alternative in the treatment of atrial fibrillation, offering a new option to improve the quality of life and prognosis of our patients with AF.

Atrial fibrillation ablation using pulsed field technology at UICAR

At the Arrhythmia Unit of UICAR we have the most advanced pulsed field ablation systems.

PulseSelect (Medtronic) is a self-centering, guidewire-mounted, 9-electrode circular catheter that performs pulmonary vein isolation using sequential pulsed-field applications from a fixed-ring configuration, prioritizing simplicity, safety, and reproducibility . It offers a faster, more versatile, and potentially safer way to perform atrial fibrillation ablation, maintaining efficacy comparable to conventional techniques and reducing the risk of injury to adjacent tissues. Clinical studies supporting its approval showed a very low rate of serious complications (0,7%) and clinical success rates approaching 80% at one year in patients with paroxysmal and persistent atrial fibrillation.

Affera Sphere-360 and Sphere-9 (Medtronic) are two more advanced and versatile pulsed field ablation technologies, designed to offer greater flexibility to the electrophysiologist depending on the type of arrhythmia and the patient's anatomy.

Sphere-360 is a next-generation single-shot PFA catheter designed to isolate pulmonary veins with a single application around the vein. Its flexible mesh design adapts to different anatomies and is integrated with the Affera mapping system. In clinical studies, it demonstrated 88% freedom from arrhythmia recurrence at one year, long-lasting pulmonary vein isolation in 98% of cases, and no adverse events in the group treated with the optimized waveform.

Sphere-9 is an all-in-one mapping and ablation catheter that allows for mapping, ablation, and results verification without changing catheters. It combines two energy sources: pulsed field (PFA) and radiofrequency (RF), enabling customized treatment based on the specific needs of the procedure. Its 9 mm mesh tip allows for the creation of wide lesions and enables not only pulmonary vein isolation but also more complex ablation lines, particularly in persistent atrial fibrillation. The SPHERE Per-AF study demonstrated an 80% efficacy rate with a 1,4% safety event rate in patients with persistent atrial fibrillation.