[Early haemodynamic changes after radiofrequency ablation of the atrioventricular junction]

The effect of radiofrequency ablation of the atrioventricular junction may be accompanied by undesired effect of right ventricular stimulation. The objective of the study was to evaluate early haemodynamic effects of catheter ablation in patients with permanent atrial fibrillation resistant to pharmacotherapy.

The study included 19 patients aged 66.9 +/- 12.4 years on an average. Depending on the basal ejection fraction (EF), we divided the patients in to two groups (the 1 st group patients had EF less than 50 %, the 2nd group patients had EF equal to 50 % or higher). The patients were underwent radiofrequency ablation of the atrioventricularjunction and a pacemaker implantation. Haemodynamic changes were evaluated by measuring the ejection volume (EV) and the minute volume (MV) using echocardiography basally prior to and after the intervention, at different stimulation frequencies. For a more precise evaluation of the patients' condition, we defined the EVi am MVi indices as the ratio between the above values at different stimulation frequencies and the basal value.

EV in patients with a low EF increases at all stimulation frequencies with the maximum effect observed in the frequency band from 60-100/min. At stimulation frequency of 60/min, the volume increased from 26.4 ml before ablation to 39.5 ml after ablation. MV grows or remains unchanged at all frequencies except for 60/min, at which the growth in EV cannot compensate the drop in MV due to a fall in frequency. Patients in the 2nd group had a high EV value (52.3 ml) before ablation. After the intervention, their EV increased only at stimulation frequency of 60 and 80/min (64.0 and 55.1 ml, respectively). Also these patients' MV was high before ablation (6,097 ml). After the intervention, their MV decreased for all stimulation frequencies, but showed a growing tendency. Statistical evaluation showed negative correlation between EVi and MVi on the one hand, and between EF and the average of the left ventricle in systole on the other.

Our results have shown that radiofrequency transcatheter ablation of the atrioventricular node (RFCA AVN) is beneficial for certain patients in both the groups, even though the mechanisms of improving their clinical condition are different.