Haemodynamic effects of changes in atrioventricular and interventricular delay in cardiac resynchronisation therapy show a consistent pattern: analysis of shape, magnitude and relative importance of atrioventricular and interventricular delay

摘要

Objective: To assess the haemodynamic effect of simultaneously adjusting atrioventricular (AV) and interventricular (VV) delays. Method: 35 different combinations of AV and VVdelay were tested by using digital photoplethysmography (Finometer) with repeated alternations to measure relative change in systolic blood pressure (SBP_(rel)) in 15 patients with cardiac resynchronisation devices for heart failure. Results: Changing AV delay had a larger effect than changing VV delay (range of SBP_(rel) 21 v 4.2 mm Hg, p < 0.001). Each had a curvilinear effect. The curve of response to AV delay fitted extremely closely to a parabola (average R~2 = 0.99, average residual variance 0.8 mm Hg~2). The response to VV delay was significantly less curved (quadratic coefficient 67 v 1194 mm Hg/s~2, p = 0.003) and therefore, although the residual variance was equally small (0.8 mm Hg~2), the R~2 value was 0.7. Reproducibility at two months was good, with the SD of the difference between two measurements of SBP_(rel) being 2.5 mm Hg for AV delay (2% of mean systolic blood pressure) and 1.5 mm Hg for VV delay (1% of mean systolic blood pressure). Conclusions: Changing AV and VV delays results in a curvilinear acute blood pressure response. This shape fits very closely to a parabola, which may be valuable information in developing a streamlined clinical protocol. VV delay adjustment provides an additional, albeit smaller, haemodynamic benefit to AV optimisation.