[Effect of ventricular and sequential stimulation on the left- ventricular systolic function]

Left ventricular systolic function at rest was determined by echocardiography and Doppler in 20 patients after dual chamber pacemaker implantation due to second and third degree A-V block. Measurements were performed in each patient during VVI and DDD mode pacing at three different atrio-ventricular (A-V) intervals: 100, 150 and 200 ms. The essential hemodynamic superiority of DDD stimulation over VVI mode in the form of significant increase of forward stroke volume index (SVI) and cardiac index (CI) during dual chamber stimulation at identical rate stimulation was observed. Closer individual analysis of the values of CI during DDD stimulation at three different A-V intervals (100, 150 and 200 ms) gave the possibility of programming optimal A-V intervals (the highest value of CI) for each patient. The sequential atrio-ventricular stimulation as compared to right ventricular stimulation essentially improves the left ventricular systolic function at rest in patients without symptoms of heart failure. Maximum hemodynamic advantage during DDD stimulation depends on individual selection of A-V delay in each patient.