Changes of current of injury after active fixation lead in different sites of right ventricular pacing

AIM To investigate changes of current of injury (COI) after active fixation lead in apex and median septum of right ventricular pacing. METHODS Eighty-eight patients with active fixation lead implanted in the right ventricle were divided into right ventricular apex group and median septum group. We determined COI at 0 min, 5 min and 10 min after lead fixation and conventional pacing parameters, and analyzed the correlation between COI and conventional pacing parameters. RESULTS In our 88 patients, COI could not be accurately measured in 2 patients due to the large amplitude of intracardiac electrogram (ICEG). In the remaining 86 cases, COI gradually reduced with the passage of time after lead fixation. COI was determined at 5 min after lead fixation decreased compared with that was determined at 0 min (6.6±1.5) mV vs.(7.6±1.7) mV, P<0.05, COI at 10 min decreased compared with that at 5 min (5.5±1.5) mV vs.(6.6±1.5) mV, P<0.05, and COI was determined at 10min decreased significantly compared with that at 0 min (P<0.01). But no statistical difference was found in COI of right ventricular active fixation lead between apex group and median interval group (P>0.05). Pearson correlation analysis showed an inverse correlation between COI measured at 0 min and the pacing threshold (correlation coefficient: -0.497, P<0.01). COI of the 2 patients with postoperatively dislocated lead was less than 5.0 mV. CONCLUSION COI of right ventricular active fixation lead gradually reduces with the passage of time after lead fixation and no statistical difference has been found between implantation in apex and median septum. COI measured at 0 min is inversely correlated with the pacing threshold.