Clinical Research Directory

Ablation of Human Cardiac Fibrillation Based on Models of Hierarchical Organization of Tissue Excitation

The mechanisms that maintain persistent atrial fibrillation (AF) in humans remain unknown. In the research project PI18/01268 funded in the previous call for Strategic Action in Health, the group has demonstrated that the hierarchical organization of (i) rotational domains, (ii) frequency domains and (iii) physiological responses to pharmacological provocation with adenosine, allow the identification of domains of high-frequency reentrant activity (hereinafter "DFASI domains") maintainers of AF. As a result, the investigators have developed non-invasive technological models and quantitative indices for the efficient localization of these domains, whose therapeutic approach through ablation has allowed to improve the clinical results of the patients studied, safely without increase in complications (Calvo D et al. Sci Rep. 2025 Dec 16;15(1):43892). Likewise, and in response to the objectives of the PI18/01268 project, the investigators have identified hierarchical organization patterns in human ventricular fibrillation (VF) that indicate the existence of universal fibrillatory mechanisms, opening the door to new therapeutic opportunities (Europace 2022;24\[11\]:1788-1799).

A Prospective Evaluation of Microwave Ablation (MWA) in the Treatment of Relapsed Graves' Disease

Graves' disease is the most common cause of hyperthyroidism, with conventional treatment options being anti-thyroid drugs (ATD), radioiodine (RAI) and surgery. For ATD, it has been the first-line treatment over decades. Despite its ability to induce remission, minor side effects such as skin rash, gastrointestinal disturbance and arthralgia occur in around 5% of patients, while serious adverse reactions including agranulocytosis and hepatotoxicity are potentially life threatening. Patients are usually treated with ATD for 12 to 18 months but the relapse rate was reported to be up to 50-60% which these patients would require more definitive treatment options with RAI or thyroidectomy. However, RAI is not preferable in patients with Graves' ophthalmopathy as it could further worsen eye symptoms. RAI may also cause hypothyroidism in a substantial proportion of patients, with a subsequent need for lifelong thyroxine replacement. As for thyroidectomy, it carries an overall 2-10% risk of complications including bleeding, transient or permanent recurrent laryngeal nerve injury and hypoparathyroidism. Due to the drawbacks of the various conventional treatment options, there has been increasing interest in the development of minimally invasive treatment alternatives in recent years. With the evolution of thermal ablative strategies, high-intensity focused ultrasound (HIFU) and radiofrequency ablation (RFA) have been reported as feasible treatment options for relapsed Graves' disease. There has also been increasing reports in the use of microwave ablation (MWA) in the treatment of benign thyroid nodules. MWA works via generation of electromagnetic field and is performed by inserting a microwave antenna into the thyroid gland percutaneously under ultrasound (USG) guidance. The active tip of the antenna causes oscillation of the surrounding water molecules which induces frictional heat and creates a thermal ablative effect. As compared to RFA, MWA is not affected by heat sink effect and may require a shorter treatment time. Similar to other thermal ablative approaches, MWA has the merits of avoiding surgical scar, organ preservation as well as being an ambulatory procedure.