VIEW AN ABSTRACT

Aim: To determine the atrioventricular intervals (AVI) providing maximal cardiac output (max CO) during sequential pacing 80 and 100 ppm by means of impedance cardiography (ICG).
Patients and methods: 19 patients (pts), 15 males and 4 females, of an average age 75.0±7.6 years, with PM implanted for advanced AV block - AVB (in 10 pts of ischemic, in 9 pts of non-ischemic etiology, ejection fraction of left ventricle 50-65%, diastolic dysfunction in 14 pts), CO was determined by ICG (Task Force Monitor CNSystems, Austria) in lying position during normal breathing. The PM was programmed DDD 80 and 100 ppm (to achieve stationary pacing frequency), AVI 100, 120, 140, 160, 180 ms (AVI in both frequencies settings programmed in random order). Equalizing phase 2 min, measurement phase 2 min.
Results: Range of optimal AVI (defined as providing max CO) in D00 pacing, was 100-160 ms in 80 ppm and 100-180 ms in 100 ppm. The optimal AVI in 100 ppm in comparison with 80 ppm was shorter in 4, identical in 9 and longer in 4 pts. It was not possible to determinate optimal AVI in 2 pts. See the table.
Discussion: In case of max CO determined for limit AVI (100 or 180 ms), it is necessary to add measurement in AVI 75 and 200 ms at least. It is not sufficient to determine “optimal” AVI at settings of two pacing frequencies for optimizing dynamic AVI.
Conclusion: “Optimal” AVI defined as providing maximal CO by means of ICG in patients with advanced AVB shows significant inter-individual variation. It was unexpected that AVI difference during D00 pacing 100 and 80 ppm in individual patients varied from minus 20 to plus 40 ms. ICG may help in programming base and dynamic AVI in patients with advanced AVB. (MŠMT – MSM 0021622402)