Acute Effect of Selective Chemical Inactivation of Sympathetic or Parasympathetic Atrial Ganglionated Plexus Structures on Atrial Fibrillation Inducibility in Pigs.

We studied the role of both parts of the autonomic intracardiac nervous system in the pathogenesis of atrial fibrillation (AF). In 12 pigs weighing 39±3 kg, AF was induced by burst stimulation. Chemical inactivation of intrinsic cardiac neurons within the right atria was performed by transendocardial injections of liposomal neuromodulators into the dorsal part of the right atrial wall. Sympathetic and parasympathetic terminals were inactivated with 6-hydroxydopamine (6-OHDA, n=6) and ethylcholine aziridinium ion (AF64A, n=6), respectively. Neuromodulators were encapsulated in liposomes (LS) with diameters of 310±50 nm for OHDA and 290±50 nm for AF64A. LS-6-OHDA and LS-AF64A were injected into the ganglionated plexuses after measuring the baseline effective refractory period and assessing myocardial resistance to AF. These measurements were repeated 90 min after the injections. The optimal doses were 0.2 mg/kg for LS-6-OHDA and 0.4 mg/kg for LS-AF64A (in 4 ml of suspension). Immediately after injections of liposomal neuromodulators, almost all pigs showed an increase in HR, and a short-term BP elevation was observed in the LS-AF64A group. At the end of the experiment, similar decrease in the effective refractory period and similar increase in the resistance to AF were observed in all animals. Thus, selective chemical inactivation of cholinergic and adrenergic terminals of the intracardiac nervous system with liposomal neuromodulators increased the resistance to AF in an acute experiment. However, the short observation period does not allow making a definite conclusion about the role of the autonomic nervous system in the pathogenesis of AF, which requires verification of the obtained data in a chronic experiment.

[Cryoballoon ablation for pulmonary vein isolation to treat atrial fibrillation: first experience in Russian Federation].

Cryoballon ablation (CBA) for pulmonary vein (PV) isolation is a new method for catheter-based treatment of patients with atrial fibrillation (AF). The purpose of our work is to describe the CBA technique and to report its short-term results. Methods. CBA was performed in 12 patients (8 men; age 53.1+/-5.7 years) with highly symptomatic drug-refractory AF. Paroxysmal AF was present in 11 and persistent AF - in 1 patient. CBA procedure was carried out under general anesthesia with intubation in 6 and under light sedation in 6 patients. After transseptal access and direct PV angiography, 28 mm-cryoballoon was introduced into the left atrium, and more or equal 2 cryoapplications were delivered to each PV, once good PV occlusion was obtained. PV isolation was verified utilizing a circular mapping catheter. Arrhythmia recurrences were monitored every 3 months after ablation using 24-hour Holter, and additional ECG registrations. Holter monitoring was also performed in a case of symptoms. Results. Complete electrical PV isolation was achieved by only cryoballoon ablation in 11 patients, and additional cryocatheter touch-up ablation was required in left PVs in 1 patient. Total procedure time was 203.1+/-34.2 min, fluoroscopy time - 50.5+/-14.0 min. There were no complications. During a mean follow-up period of 136.8+/-59.8 days 9 (75%) patients were free from arrhythmia recurrence after a single procedure. Redo ablation was required in 1 patient, in whom electrical reconnection to all PVs was documented. Conclusion. CBA is a novel promising technique for treatment of patients with AF, and now is available in Russian Federation. The method standardizes and facilitates interventional AF treatment with acute isolation of 96% PVs. The short-term follow-up shows freedom from atrial tachyarrhythmias in 75% of patients.