RESUMO
BACKGROUND: Left ventricular (LV) pacing is unsuccessful in a significant number of patients, mainly due to sub-optimal LV pacing location. Nevertheless, data about the impact of different pacing sites on LV function in ischaemic myocardium are scarce. The purpose of this study was to investigate the effect of combinations of alternative LV pacing sites on LV mechanics after experimental acute anterior myocardial infarction (AMI), in order to define the optimal configuration. METHODS: Atrioventricular epicardial pacing at alternative pacing sites was performed in 16 healthy pigs simultaneously, after experimental AMI. Standard right ventricular (RV) apical pacing was combined with: i) LV apex lateral wall; ii) LV basal posterior wall; iii) LV basal anterior wall, and; iv) LV basal anterior wall + LV basal posterior wall. Moreover the pacing configurations of, v) LV basal posterior wall + LV apex lateral wall; vi) LV basal posterior wall + LV basal anterior wall, and; vii) LV basal anterior wall + LV apex lateral wall were also investigated. Haemodynamic parameters, together with classic and novel echocardiographic indices were used, to evaluate the effect of each pacing combination. A speckle tracking technique using EchoPAC software was used. RESULTS: After AMI, the pacing combination of LV apex lateral wall and LV basal posterior wall had the most favourable effect on LV function, leading to similar haemodynamic and torsional effects with sinus rhythm (all variables p>0.05). CONCLUSIONS: In pig hearts after AMI, the combination of pacing LV apex lateral wall and LV basal posterior wall managed to maintain the LV function at a level comparable to the sinus rhythm.
