Introduction:
Transient conduction disorders are frequently encountered after heart surgeries, especially valve ones. Pacemaker inplantation because of complete atrio-ventricular (AV) block varies between 2.5-5.7% for isolated aortic valve replacment (AVR). However, perioperative risk predictors of complete AV block are still not well characterized. The aim of the study was to identify the clinical, anatomical and surgical factors that may be predictive for the incidence of complete AV block.

Material and methods:
The group studied consisted of 598 patients, who underwent isolated AVR in years 2004-2008. Patients requiring additional procedures were excluded from the study. Those enrolled were divided into groups: A - with complete AV block (n=17), B - with sinus/nodal rhythm (n=581). The influence of following parameters on the need of permanent pacing because of complete AV block was analyzed: age, gender, prosthesis suturing technique, presence of bicuspid valve, rhythm at the end of the procedure, cross clamping time, resence of calcifications, prosthesis size, the need for reoperation.

Results:
Perioperative transient conduction disorders were present in 55 patients (9.2%). Complete AV block, occurred in 17 patients (2.8%). Patients with perioperative AV block with the need for permanent pacing occurred in 11 patients (20%). The only parameter significantly more frequent in group A was the necessity for perioperative pacing because of conduction disorders (in group A- 64.7%, B- 7.6%, p< 0.01). The difference in occurrence of
other parameters, did not reach statistical significance and therefore is not treated as a predictive factor for complete AV block incidence.

Conclusions:
Irreversible AV block is an uncommon condition following aortic valve replacement. This study confirms what has been claimed in recent reports: finding any anatomical and surgical predictors for complete AV block is difficult, and whether they exists remains controversial. The only factor that could have an influence on complete AV block incidence was the need for perioperative pacing.