POSSIBILITIES TO MODIFY AV CONDUCTION IN ATRIAL FIBRILLATION PATIENTS

Most of atrial fibrillation(AF)pts have organic artrial injury which ismaintained at modified AV conduction as an AV substrate.Nevertheless this procedure allows to control ventricular contractionsrate(VCR)in AF pts.Supposing that "slow" pathways potentials arepotentials of atrial fibers eonneated with the AV node we used highfrequency current in the meadseptal right atrial area in 24 pts aged 52-74(mean 66±4.9 yrs)having paroxysmal(n=16)and chronic(n=8)AF.AF was induced in pts who had sinus rhythm before ablation andif VSR exceeded 50-70 beats/min the procedure was repeated.Favourable results were obtained in 18(75% of pts).These pts didnot reveal decreased Wenekebach point or increased effectiverefractory period of the AV junction.VSR decreased from 163±27 to65±9(p=0.001)during AF.Then atropine was given and if VSRexceeded 120/min we considered the procedure to be ineffective.Digoxine and beta-blockers which were ineffective before ablationbecame effective to control VSR after it.From 6 to 12 months afterthe procedure,these pts underwent exercise testing(AF was inducedin the sinus rhythm pts):maximum VCR was 116±10.8/min.Becauseof the procedure inefficacy,complete AV block was reached duringablation in 2(8%)pts in whom artificial pacemaker was implanted.Thus modification of AV conduction is an effective procedure tocontrol VSR in AF pts and allows to flee 75% of pts fromantiarrhythmic drugs.

AV JUNCTION ELECTROPHYSIOLOGIC DATA IN PATIENTS HAVING PAROXYSMS OF ATRIAL FIBRILLATION

The aim of the study was to investigate peculiarities of AV junctionconduction in paroxysmal atrial fibrillation（AF）pts.We retrospectively assessed electrophysiologic investigations data in53 pts having paroxysmal AF.Assessment of the AV junctionconduction was performed during rapid and programmed stimulationin the setting of sinus thythm.Sixteen（30.1%）pts were revealed tohave signs of longitudinal dissociation of AV conduction which wascharacteristic of suddenly increased A2-H2 interval by more than 50msThe remaining pts did not reveal dual AV conduction pathways.Tenpts revealed polyfascicular antegrade AV conduction and distallydisturbed conduction which was manifested by the lengthened H2-V2interval to 70-150 ms during programmed stimulation performed fromthe sinoatrial zone.These pts had ventricular contractions rate of118±16.4/min in the setting AF both spontaneously induced andinduced by the stimulation which were reliably（p【0.05）lesscompared to other pts（168.6±29.4/min）.Thirty three（62.2%）pts whohad no multiple AV conducting pathways revealed distally slowed（to40-60 ms）conductionas well.Thus 92.5% of pts having AF paroxysms revealed concealed AVconduction disturbance and 30.2% revealed polyfascicular one.Wedid not reveal marked tachysystole in pts having multiple AVconduction pathways and distally disturbed conduction which must betaken into account while performing modification of the AVconduction in these pts.