RESUMO
OBJECTIVE: To evaluate changes on left ventricular function as assessed by systolic time intervals (STI), by programming "physiological" pacemakers either on VVI or DDD mode. STUDY DESIGN: Comparison of STI values--electromechanical systole (QS2); left ventricular ejection time (LVET); pre-ejection period (PEP); PEP/LVET--in patients submitted to double chamber pacing programmed in DDD or VVI mode. SETTING: Cardiac Pacing Center in a Department of Cardiology at a University Hospital. PATIENTS: We have studied 12 patients (3 men, 9 women), mean age 56.16 years (range 25-76 years) treated with double chamber pacing. INTERVENTIONS: Initial measurements of STI in DDD or one week in VVI mode, and again after one week in DDD mode. RESULTS: Significant changes were found after the first week in VVI pacing, versus baseline determination in DDD pacing, for LVET, PEP, and PEP/LVET (p less than 0.05). At the end of the second week (DDD pacing), there were also statistically significant differences for QS2 (P less than 0.05), LVET (P less than 0.01) and PEP/LVET (P less than 0.05) values when compared with the ones obtained in VVI pacing, at the end of the preceding week. No significant changes were found between the initial and the final STI determinations (both in DDD pacing). CONCLUSION: We concluded for a better performance of the left ventricle at rest when "physiological" pacing is compared with VVI pacing.